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Perspectives
A g u i d e t o d r u g d i s c o v e ry — o p i n i o n
Protein therapeutics: a summary
and pharmacological classification
Benjamin Leader, Quentin J. Baca and David E. Golan
Abstract | Once a rarely used subset of medical treatments, protein therapeutics
have increased dramatically in number and frequency of use since the introduction
of the first recombinant protein therapeutic — human insulin — 25 years ago.
Protein therapeutics already have a significant role in almost every field of
medicine, but this role is still only in its infancy. This article overviews some of the
key characteristics of protein therapeutics, summarizes the more than 130 protein
therapeutics used currently and suggests a new classification of these proteins
according to their pharmacological action.
Proteins have the most dynamic and diverse
role of any macromolecule in the body,
catalysing biochemical reactions, forming
receptors and channels in membranes, providing intracellular and extracellular
scaffolding support, and transporting
molecules within a cell or from one organ to
another. It is currently estimated that there are
25,000–40,000 different genes in the human
genome, and with alternative splicing of
genes and post-translational modification of
proteins (for example, by cleavage, phosphory­
lation, acylation and glycosylation), the
number of functionally distinct proteins is
likely to be much higher1–3. Viewed from the
perspective of disease mechanisms, these estimates pose an immense challenge to modern
medicine, as disease may result when any one
of these proteins contains mutations or other
abnormalities, or is present in an abnormally
high or low concentration. Viewed from the
perspective of therapeutics, however, these
estimates represent a tremendous opportunity
in terms of harnessing protein therapeutics
to alleviate disease. At present, more than
130 different proteins or peptides are
approved for clinical use by the US Food
and Drug Administration (FDA), and many
more are in development.
Protein therapeutics have several
advantages over small-molecule drugs.
First, proteins often serve a highly specific
and complex set of functions that cannot be
mimicked by simple chemical compounds.
Second, because the action of proteins is
highly specific, there is often less potential for
protein therapeutics to interfere with normal
biological processes and cause adverse effects.
Third, because the body naturally produces
many of the proteins that are used as therapeutics, these agents are often well tolerated
and are less likely to elicit immune responses.
Fourth, for diseases in which a gene is
mutated or deleted, protein therapeutics
can provide effective replacement treatment
without the need for gene therapy, which
is not currently available for most genetic
disorders. Fifth, the clinical development and
FDA approval time of protein therapeutics
may be faster than that of small-molecule
drugs. A study published in 2003 showed
that the average clinical development and
approval time was more than 1 year faster for
33 protein therapeutics approved between
1980 and 2002 than for 294 small-molecule
drugs approved during the same time period4.
Last, because proteins are unique in form
and function, companies are able to obtain
far-reaching patent protection for protein
therapeutics. The last two advantages make
proteins attractive from a financial perspective compared with small-molecule drugs.
A relatively small number of protein
therapeutics are purified from their native
nature reviews | drug discovery
source, such as pancreatic enzymes from
hog and pig pancreas5,6, and α‑1-proteinase
inhibitor from pooled human plasma7,8,
but most are now produced by recombinant
DNA technology and purified from a wide
range of organisms. Production systems
for recombinant proteins include bacteria,
yeast, insect cells, mammalian cells, and
transgenic animals and plants9–13. The
system of choice can be dictated by the cost
of production or the modifications of the
protein (for example, glycosylation, phosphorylation or proteolytic cleavage) that are
required for biological activity. For example,
bacteria do not perform glycosylation
reactions, and each of the other biological
systems listed above produces a different
type or pattern of glycosylation. Protein
glycosylation patterns can have a dramatic
effect on the activity, half-life and immunogenicity of the recombinant protein in the
body. For example, the half-life of native
erythropoietin, a growth factor important in
erythrocyte production (see below), can be
lengthened by increasing the glycosylation
of the protein. Darbepoetin-a is an erythro­
poietin analogue that is engineered to
contain two additional amino acids that are
substrates for N‑linked glycosylation reactions. When expressed in Chinese hamster
ovary cells, the analogue is synthesized with
five rather than three N‑linked carbohydrate
chains; this modification causes the half-life
of darbepoetin to be threefold longer than
that of erythropoietin14.
Perhaps the best example of trends in the
production and use of protein therapeutics
is provided by the history of insulin in the
treatment of diabetes mellitus type I (DM‑I)
and type II (DM-II). Untreated, DM‑I is
a disease that leads to severe wasting and
death due to lack of the protein hormone
insulin, which signals cells to perform
numerous functions related to glucose
homeostasis and intermediary metabolism15. In 1922, insulin was first purified
from bovine and porcine pancreas and used
as a life-saving daily injection for patients
with DM‑I16. At least three problems
hindered the widespread use of this protein
therapy: first, the availability of animal pancreases for purification of insulin; second,
the cost of insulin purification from animal
volume 7 | january 2008 | 21
© 2008 Nature Publishing Group
Perspectives
Box 1 | Functional classification of protein therapeutics
Protein therapeutics in the tables in this article are organized by function and therapeutic
application. The numbers of therapeutics per group reflect the relative difficulty associated with
drug development across the various classes of protein therapeutics. Every effort has been made to
include in these tables all US Food and Drug Administration (FDA)-approved Group I and Group II
protein-based therapies. Groups III and IV present selected examples that highlight the use of
proteins in vaccines and diagnostic agents.
Group I: protein therapeutics with enzymatic or regulatory activity
• Ia: Replacing a protein that is deficient or abnormal (TABLES 1,2).
• Ib: Augmenting an existing pathway (TABLES 3,4).
• Ic: Providing a novel function or activity (TABLE 5).
Endocrine and metabolic disorders with defined molecular aetiologies dominate Group Ia. As more
diseases are linked to deficiencies of specific proteins, this class will continue to grow. Group Ib is
dominated by therapies that augment haematological and endocrine pathways and immune
responses. The many interferon and growth factor therapies in Group Ib effectively treat disease
even when their precise pharmacological mechanism of action is unknown. Group Ic demonstrates
the rational use of naturally occurring proteins to modify the pathophysiology of human diseases.
The future growth of this class depends on understanding protein function in human physiology as
well as protein function in other organisms.
Group II: protein therapeutics with special targeting activity
•IIa: Interfering with a molecule or organism (TABLES 6,7).
•IIb: Delivering other compounds or proteins (TABLE 8).
Group IIa therapeutics use their special targeting activity to interfere with molecules or organisms
by binding specifically to them and blocking their function, targeting them for destruction,
or stimulating a signalling pathway. This group has grown as monoclonal antibody technology has
matured and will probably expand further as signalling pathways and aetiologies of disease are more
clearly identified. Group IIb therapeutics deliver other compounds or proteins to a specific site.
This class has great potential to grow, as demonstrated by the breadth of the specifically targeted
Group IIa therapies.
Group III: protein vaccines
•IIIa: Protecting against a deleterious foreign agent.
•IIIb: Treating an autoimmune disease.
•IIIc: Treating cancer.
Although this is currently a small class of therapies, there is great potential for the production of
recombinant vaccines that provide broad protection against infectious agents. Similarly,
individualized vaccines against cancers are likely to be in great demand. Selected examples of the
57 FDA-approved vaccines in TABLE 9 highlight the use of recombinant protein technology in
vaccine production. Many of the FDA-approved vaccines protect against multiple infectious
agents and include synthetic, recombinant and purified protein components. A complete list of
FDA-approved vaccines may be found at: http://www.fda.gov/cber/vaccine/licvacc.htm.
Group IV: protein diagnostics
Group IV protein diagnostics, for which selected examples are shown in TABLE 10, are a class that
powerfully affect clinical decision-making. These diagnostics use technology and therapeutics
developed in other classes to answer clinical questions. This table presents primarily in vivo protein
diagnostics, but in vitro protein diagnostics are also critical to medical decision-making and are too
numerous to address comprehensively here.
pancreas; and third, the immunological
reaction of some patients to animal insulin.
These problems were addressed by isolating
the human insulin gene and engineering
Escherichia coli to express human insulin
by using recombinant DNA technology.
By growing vast quantities of these bacteria,
large-scale production of human insulin was
achieved. The resulting insulin was abundant, inexpensive, of low immunogenicity
and free from other animal pancreatic
substances. Recombinant insulin, approved
by the US FDA in 1982, was the first
commercially available recombinant protein
therapeutic, and has been the major therapy
for DM‑I (and a major therapy for DM‑II)
ever since16–20.
Recombinantly produced proteins can
have several further benefits compared with
non-recombinant proteins. First, transcription and translation of an exact human gene
can lead to a higher specific activity of the
protein and a decreased chance of immuno­
logical rejection. Second, recombinant proteins are often produced more efficiently and
inexpensively, and in potentially limitless
22 | january 2008 | volume 7
quantity. One striking example is found in
the protein-based therapy for Gaucher’s
disease, a chronic congenital disorder of
lipid metabolism caused by a deficiency
of the enzyme β-glucocerebrosidase (also
known as glucosylceramidase) that is characterized by an enlarged liver and spleen,
increased skin pigmentation and painful
bone lesions21,22. At first, β-glucocerebrosidase purified from human placenta was
used to treat this disease, but this requires
purification of protein from 50,000 placentas
per patient per year, which obviously places
a practical limit on the amount of purified
protein available. A recombinant form of
β-glucocerebrosidase was subsequently
developed and introduced, which is not
only available in sufficient quantities to treat
many more patients with the disease, but
also eliminates the risk of transmissible
(for example, viral or prion) diseases associated with purifying the protein from human
placentas23–25. This also illustrates a third
benefit of recombinant proteins over nonrecombinant proteins — the reduction of
exposure to animal or human diseases.
A fourth advantage is that recombinant
technology allows the modification of a
protein or the selection of a particular gene
variant to improve function or specificity.
Again, recombinant β-glucocerebrosidase
provides an interesting example. When this
protein is made recombinantly, a change
of amino-acid arginine‑495 to histidine
allows the addition of mannose residues
to the protein. The mannose is recognized
by endocytic carbohydrate receptors on
macrophages and many other cell types,
allowing the enzyme to enter these cells
more efficiently and to cleave the intracellular lipid that has accumulated in pathological
amounts, which results in an improved
therapeutic outcome23. Last, recombinant
technology allows the production of proteins
that provide a novel function or activity,
as discussed below.
The 25 years since the approval of
recombinant insulin by the FDA have seen a
remarkable expansion in the number of thera­
peutic applications of proteins. More than
130 proteins (over 95 of which are produced
recombinantly) are currently approved for
clinical use by the FDA, and many more
are in development. An appreciation of the
many therapeutic uses of proteins may be
facilitated by categorizing such therapies
according to their mechanism of action,
and, in this article, we summarize currently
approved protein therapeutics by suggesting
a classification system that is based on their
pharmacological action (BOX 1). Examples
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© 2008 Nature Publishing Group
Perspectives
Table 1 | Protein therapeutics replacing a protein that is deficient or abnormal (Group Ia)*
Therapeutic
Trade name
Function
Examples of clinical use
Endocrine disorders (hormone deficiencies)
‡
Insulin16–20
Humulin, Novolin
Regulates blood glucose, shifts potassium into cells
Diabetes mellitus, diabetic
ketoacidosis, hyperkalaemia
‡
Insulin human
inhalation146–149
Exubera
Insulin formulated for inhalation with faster onset
of action
Diabetes mellitus
Insulin aspart150;
insulin glulisine151;
Insulin lispro150
Novolog (aspart),
Apidra (glulisine),
Humalog (lispro)
Insulin analogues with faster onset of action and
shorter duration of action
Diabetes mellitus
Isophane insulin150 NPH
Insulin protamine crystalline formulation with slower
onset of action and longer duration of action
Diabetes mellitus
‡
‡
‡
Insulin detemir152;
Insulin glargine150
Levemir (detemir),
Lantus (glargine)
Insulin analogues with slower onset of action and
longer duration of action
Diabetes mellitus
‡
Insulin zinc
extended150
Lente, Ultralente
Insulin zinc hexameric complex with slower onset
of action and longer duration of action
Diabetes mellitus
Pramlintide
acetate153
Symlin
Mechanism unknown; recombinant synthetic peptide
analogue of human amylin (a naturally occurring
neuroendocrine hormone regulating post-prandial
glucose control)
Diabetes mellitus, in combination
with insulin
Growth
hormone (GH),
somatotropin133–137
Genotropin, Humatrope,
Norditropin, NorIVitropin,
Nutropin, Omnitrope,
Protropin, Siazen,
Serostim, Valtropin
Anabolic and anticatabolic effector
Growth failure due to GH deficiency
or chronic renal insufficiency,
Prader-Willi syndrome, Turner
syndrome, AIDS wasting or cachexia
with antiviral therapy
‡
Mecasermin154
Increlex
Recombinant insulin-like growth factor 1 (IGF1) induces
mitogenesis, chondrocyte growth and organ growth,
which combine to restore appropriate statural growth
Growth failure in children with GH
gene deletion or severe primary IGF1
deficiency
Mecasermin
rinfabate155
IPlex
Similar to mecasermin; IGF1 bound to IGF binding
protein 3 (IGFBP3) is thought to keep the hormone
inactive until it reaches its target tissues, thereby
decreasing hypoglycaemia-like side effects
Growth failure in children with GH
gene deletion or severe primary IGF1
deficiency
‡
‡
Haemostasis and thrombosis
Factor VIII27,28,118
Bioclate, Helixate,
Kogenate, Recombinate,
ReFacto
Coagulation factor
Haemophilia A
Factor IX29,30,141,142
Benefix
Coagulation factor
Haemophilia B
§
Antithrombin III
(AT-III)143,144
Thrombate III
Purified human AT-III from pooled plasma inactivates
thrombin by forming a covalent bond between the
catalytic serine residue of thrombin and an arginine
reactive site on AT-III; AT-III replacement therapy
prevents inappropriate blood-clot formation
Hereditary AT-III deficiency in
connection with surgical or
obstetrical procedures or for
thromboembolism
Protein C
concentrate145
Ceprotin
After activation by the thrombin–thrombomodulin
complex, protein C inhibits coagulation factors Va
and VIIIa
Treatment and prevention of venous
thrombosis and purpura fulminans
in patients with severe hereditary
protein C deficiency
§
*Continued in TABLE 2. Protein therapeutics derive their specificity and function from their structure. Molecules ranging from large and complex enzymes to short peptide
sequences have specific biological activity due to their amino-acid-based secondary and tertiary structure. For example, somatostatin is active as either a 14 or 28 amino-acid
peptide, and its even shorter synthetic analogues share a characteristic hairpin-loop structure that defines their specificity and biological activity. Some very short peptide
therapeutics are better thought of as small-molecule drugs, as they lack secondary and tertiary structures that define their biological activity. For this reason, therapeutics such as
glatiramer acetate (a four amino-acid peptide consisting of acetate with l‑Glu, l‑Ala, l‑Tyr and l‑Lys) are not addressed in this article. Protein therapeutics are recombinant unless
otherwise stated. ‡Also classed in Group Ib. §Non-recombinant.
of protein therapeutics in each category and
clinical conditions in which they are used
are discussed in the text, and a listing of
FDA-approved protein therapies and their
functions and clinical uses is presented
in TABLES 1–8. Examples of protein-based
vaccines and diagnostics that highlight the
growing importance of proteins in medicine
are provided in TABLES 9,10.
Group I: enzymes and regulatory proteins
Protein therapeutics in this group function
by a classic paradigm in which a specific
endogenous protein is deficient, and the
deficit is then remedied by treatment with
exogenous protein. Protein therapeutics
that we have classified in Group Ia are used
to replace a particular activity in cases of
protein deficiency or abnormal protein
nature reviews | drug discovery
production. These proteins are used in a
range of conditions, from providing lactase
in patients lacking this gastrointestinal
enzyme26 to replacing vital blood-clotting
factors such as factor VIII27,28 and factor
IX29,30 in haemophiliacs. A classic example,
as mentioned above, is the use of insulin
for the treatment of diabetes. Another
important example is in the treatment of
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© 2008 Nature Publishing Group
Perspectives
cystic fibrosis, a common lethal genetic
disorder. In this disease, defects in the
chloride channel encoded by the CFTR gene
lead to abnormally thick secretions, which
can (among other effects) block pancreatic
enzymes from travelling down the pancreatic
duct into the duodenum31. This prevents
food from being properly digested and
results in malnutrition. Patients with cystic
fibrosis are often treated with a combination
of pancreatic enzymes isolated from pigs —
including lipases, amylases and proteases
— that allow the digestion of lipids,
sugars and proteins. Patients who have had
their pancreas removed or who suffer from
chronic pancreatitis can also benefit from
this therapy5,6. Other striking examples
include various diseases caused by metabolic
enzyme deficiencies, such as Gaucher’s
disease as mentioned above, mucopolysaccharidosis, Fabry disease and others.
Additional protein therapies that replace a
particular activity are listed in TABLES 1,2.
It may sometimes be desirable to enhance
the magnitude or timing of a particular normal protein activity, and protein therapeutics
that we have classified in Group Ib are
administered to achieve this. Such protein
therapeutics have been successful in treating
haematopoietic defects; the most prominent
example is recombinant erythropoietin,
a protein hormone secreted by the kidney
that stimulates erythrocyte production in
the bone marrow31. In patients with chemotherapy-induced anaemia or myelodysplastic
syndrome, recombinant erythropoietin is
used to increase erythrocyte production
and thereby ameliorate the anaemia. In
patients with renal failure, whose levels of
endogenous erythropoietin are below normal, recombinant protein is administered to
correct this deficiency32–36. Another example
is provided by the treatment of neutropaenic
patients with granulocyte- or granulocytemonocyte colony stimulating factor (G-CSF
or GM‑CSF, respectively)36,37, which stimulate an increase in the number of neutrophils
produced by the bone marrow to allow these
patients to better combat microbial infections. Similarly, thrombocytopaenic patients
can be treated with interleukin 11 (IL11)38,
which increases platelet production and
thereby prevents bleeding complications.
In vitro fertilization (IVF) is another
area in which Group Ib proteins are applied.
Increased levels of follicle-stimulating hormone (FSH) are normally produced by the
anterior pituitary gland just before ovulation.
These high levels of FSH can be enhanced by
treatment with recombinant FSH, leading to
maturation of an increased number of follicles
and to an increased number of oocytes
available for IVF39,40. Similarly, recombinant
human chorionic gonadotropin (HCG)41 is
used in assisted reproductive technology to
promote follicle rupture, a process that must
occur before the oocytes can be transported
into the fallopian tubes for fertilization.
Group Ib proteins can also have life-saving
effects on thrombosis and haemostasis.
Alteplase (recombinant tissue plasminogen
activator (tPA; also known as PLAT)), is used
to treat life-threatening blood clots in conditions such as coronary artery occlusion, acute
ischaemic stroke and pulmonary embolism42–46. Endogenous tPA is secreted by the
endothelial cells that line blood vessels. The
secreted tPA normally cleaves plasminogen
to plasmin, which then degrades fibrin and
thereby lyses fibrin-based clots15. Although
endogenous tPA may be present at normal
or even increased levels near the site of a
blood clot, administration of relatively large
amounts of exogenous tPA may be required
to disrupt these clots. Reteplase, a genetically
modified form of recombinant tPA, is used
to treat acute myocardial infarction47,48, and
enecteplase, another genetically engineered
derivative of tPA, has greater specificity
than tPA for binding to plasminogen and
therefore causes a more efficacious lysis of
fibrin in blood clots49,50. Supraphysiological
levels of coagulation factor VIIa may catalyse
thrombosis and thereby stop life-threatening
bleeding in patients with haemophilia A or
B51,52. Also, recent studies have suggested
that recombinant activated protein C53,54 can
improve immunoregulation and prevent
excessive clotting reactions in patients with
severe, life-threatening sepsis and organ
dysfunction. Many other Group Ib protein
therapeutics are also used for immunoregulation — chronic hepatitis B and C, Kaposi’s
sarcoma, melanoma, and some types of
leukaemia and lymphoma have been treated
with various forms of interferon, as noted
in TABLE 3. Other disease states treated
with Group Ib proteins are summarized in
TABLES 3,4.
Occasionally, the activity of a particular
protein is desirable even though the body
does not normally express that activity.
Protein therapeutics that we have classified in
Group Ic contain examples of this paradigm,
including foreign proteins with novel functions and endogenous proteins that act at
a novel time or place in the body. Papain,
for example, is a protease purified from the
Carica papaya fruit. This protein is used thera­
peutically to degrade proteinaceous debris
in wounds55. Collagenase, obtained from
fermentation by Clostridium histolyticum,
24 | january 2008 | volume 7
can be used to digest collagen in the necrotic
base of wounds56,57. The protease-mediated
debridement or removal of necrotic tissue
is useful in the treatment of burns, pressure
ulcers, post-operative wounds, carbuncles
and other types of wounds. Recombinant
human deoxyribonuclease I (DNASE1) also
has an interesting novel use. Normally found
inside human cells, this recombinant enzyme
can be used to degrade the DNA left over
from dying neutrophils in the respiratory
tract of patients with cystic fibrosis58. Such
DNA could otherwise form mucus plugs
that obstruct the respiratory tract and lead
to pulmonary fibrosis, bronchiectasis and
recurrent pneumonias. Thus, recombinant
protein technology has allowed the therapeutic application of a normally intracellular
enzyme in a novel extracellular environment.
There are many other successful examples
of this approach to protein therapy. For
instance, certain forms of acute lymphoblastic
leukaemia are unable to synthesize asparagine
and therefore require the availability of this
amino acid to survive. l‑Asparaginase, purified from E. coli, can be used to lower serum
levels of asparagine in such patients and
thereby inhibit cancer cell growth59,60. Studies
of the medical leech, Hirudo medicinalis,
revealed that its salivary gland produces hirudin, a potent thrombin inhibitor. The gene for
this protein was then identified, cloned and
used recombinantly to provide a new protein
therapy, lepirudin, which prevents clot formation in patients with heparin-induced thrombocytopaenia61,62. Other organisms can also
be used to produce proteins that are capable
of breaking up clots that have already formed;
for example, streptokinase is a plasminogen
activating protein produced by group C
β-haemolytic streptococci63–66. Many more
therapeutic proteins that provide a novel
function or activity are presented in TABLE 5.
Group II: targeted proteins
The exquisite binding specificity of monoclonal antibodies and immunoadhesins67
can be exploited in numerous ways using
recombinant DNA technology. Many protein
therapeutics that we have classified in Group
IIa use the antigen recognition sites of
immunoglobulin (Ig) molecules or the receptor-binding domains of native protein ligands
to guide the immune system to destroy
specifically targeted molecules or cells. Other
monoclonal antibodies and immunoadhesins
neutralize molecules by simple physical
occupation of a functionally important
region of the molecule. Immunoadhesins
combine the receptor-binding domains of
protein ligands with the Fc region of an Ig.
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© 2008 Nature Publishing Group
Perspectives
Table 2 | Protein therapeutics replacing a protein that is deficient or abnormal (Group Ia)*
Therapeutic
Trade name
Function
Examples of clinical use
Metabolic enzyme deficiencies
β-Glucocerebrosidase21,22,24
Cerezyme
Hydrolyzes glucocerebroside to glucose and ceramide
Gaucher’s disease
‡
β-Glucocerebrosidase23,25,156
Ceredase (purified from
pooled human placenta)
Hydrolyzes glucocerebroside to glucose and ceramide
Gaucher’s disease
Alglucosidase-α157
Myozyme
Degrades glycogen by catalyzing the hydrolysis of
α-1,4 and α-1,6 glycosidic linkages of lysosomal glycogen
Pompe disease (glycogen storage
disease type II)
Laronidase158–160
(α-l-iduronidase)
Aldurazyme
Digests endogenous glycosaminoglycans (GAGs)
within lysosomes, and thereby prevents an
accumulation of GAGs that can cause cellular, tissue,
and organ dysfunction
Hurler and Hurler-Scheie forms of
mucopolysaccharidosis I
Idursulphase161
(Iduronate-2sulphatase)
Elaprase
Cleaves the terminal 2-O-sulphate moieties from
the GAGs dermatan sulphate and heparan sulphate,
thereby allowing their digestion and preventing
GAG accumulation
Mucopolysaccharidosis II (Hunter
syndrome)
Galsulphase162
Naglazyme
Cleaves the terminal sulphate from the GAG dermatan
sulphate, thereby allowing its digestion and preventing
GAG accumulation
Mucopolysaccharidosis VI
Agalsidase-β163,164
(human
α-galactosidase A)
Fabrazyme
Enzyme that hydrolyzes globotriaosylceramide (GL3)
and other glycosphingolipids, reducing deposition of
these lipids in capillary endothelium of the kidney and
certain other cell types
Fabry disease; prevents accumulation
of lipids that could lead to renal and
cardiovascular complications
Pulmonary and gastrointestinal-tract disorders
α-1-Proteinase
inhibitor8,165
Aralast, Prolastin
Inhibits elastase-mediated destruction of pulmonary
tissue; purified from pooled human plasma
Congenital α-1-antitrypsin deficiency
Lactase26
Lactaid
Digests lactose; purified from fungus Aspergillus oryzae
Gas, bloating, cramps and diarrhoea
due to inability to digest lactose
Digests food (protein, fat and carbohydrate); purified
from hogs and pigs
Cystic fibrosis, chronic pancreatitis,
pancreatic insufficiency, post-Billroth
II gastric bypass surgery, pancreatic
duct obstruction, steatorrhoea, poor
digestion, gas, bloating
‡
‡
Pancreatic enzymes Arco-Lase, Cotazym,
(lipase, amylase,
Creon, Donnazyme,
protease)5,6
Pancrease, Viokase,
Zymase
‡
Immunodeficiencies
‡
Adenosine
deaminase166
(pegademase
bovine, PEG-ADA)
Adagen
Metabolizes adenosine, prevents accumulation of
adenosine; purified from cows
Severe combined immunodeficiency
disease due to adenosine deaminase
deficiency
Pooled
immunoglobulins167
Octagam
Intravenous immunoglobulin preparation
Primary immunodeficiencies
Albumarc, Albumin,
Albuminar, AlbuRx,
Albutein, Flexbumin,
Buminate, Plasbumin
Increases circulating plasma osmolarity, thereby
restoring and maintaining circulating blood volume
Decreased production of albumin
(hypoproteinaemia), increased loss
of albumin (nephrotic syndrome),
hypovolaemia, hyperbilirubinaemia
‡
Other
Human albumin168
‡
*Continued from TABLE 1. Protein therapeutics are recombinant unless otherwise stated. ‡Non-recombinant.
The Fc region can target a soluble molecule
for destruction because cells of the immune
system can recognize the Fc region, endo­
cytose the attached molecule and break down
the molecule chemically and enzymatically.
When bound to specifically recognized
molecules on the surface of a cell, the Fc
region can target the cell for destruction by
the immune system. Cell killing can be
mediated by macrophages, by other immune
cells or by complement fixation.
Several Group IIa protein therapeutics
have been approved for the treatment of
inflammatory diseases, such as the immuno­
adhesin etanercept, which is a fusion
between two human proteins: tumour necrosis factor (TNF) receptor and the Fc region of
the human antibody protein IgG1. The TNF
receptor portion of the molecule binds excess
TNF in the plasma, while the Fc portion of
the molecule targets the TNF for destruction.
By combining these two functions, the drug
nature reviews | drug discovery
neutralizes the deleterious effects of TNF
(a cytokine that stimulates increased activity
of the immune system) and thereby provides
an effective therapy for inflammatory
arthritis and psoriasis68–70. Another Group
IIa protein that targets TNF is infliximab.
This recombinantly produced monoclonal
antibody binds to TNFα, and is used to
neutralize the action of TNFα in inflammatory conditions such as rheumatoid arthritis
and inflammatory bowel disease71–73.
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Perspectives
Table 3 | Protein therapeutics augmenting an existing pathway (Group Ib)*
Therapeutic
Trade name
Function
Examples of clinical use
Erythropoietin,
Epoetin-α32–36,169,170
Epogen,
Procrit
Stimulates erythropoiesis
Anaemia of chronic disease, myleodysplasia,
anaemia due to renal failure or chemotherapy,
preoperative preparation
Darbepoetin-α14
Aranesp
Modified erythropoietin with longer half-life;
stimulates red blood cell production in the
bone marrow
Treatment of anaemia in patients with chronic
renal insufficiency and chronic renal failure
(+/- dialysis)
Filgrastim36, 37
(granulocyte colony stimulating
factor; G-CSF)
Neupogen
Stimulates neutrophil proliferation,
differentiation and migration
Neutropaenia in AIDS or post-chemotherapy
or bone-marrow transplantation, severe
chronic neutropaenia
Pegfilgrastim171 (Peg-G-CSF)
Neulasta
Stimulates neutrophil proliferation,
differentiation and migration
Neutropaenia in AIDS or post-chemotherapy
or bone marrow transplantation, severe
chronic neutropaenia
Sargramostim36, 37 (granulocytemacrophage colony stimulating
factor; GM-CSF)
Leukine
Stimulates proliferation and differentiation
of neutrophils, eosinophils and monocytes
Leukopaenia, myeloid reconstitution
post-bone-marrow transplantation,
HIV/AIDS
Oprelvekin38
(interleukin11; IL11)
Neumega
Stimulates megakaryocytopoiesis and
thrombopoiesis
Prevention of severe thrombocytopaenia,
especially after myelosuppressive
chemotherapy
Human follicle-stimulating
hormone (FSH)39,40
Gonal-F,
Follistim
Augments ovulation
Assisted reproduction
Human chorionic gonadotropin
(HCG)41
Ovidrel
Stimulates ovarian follicle rupture and ovulation
Assisted reproduction
Lutropin-α172
Luveris
Recombinant human luteinizing hormone;
increases estradiol secretion, thereby
supporting follicle-stimulating
hormone-induced follicular development
Infertility with luteinizing hormone
deficiency
Type I alpha-interferon,
interferon alfacon 1, consensus
interferon173–178
Infergen
Mechanism unknown; immunoregulator
Chronic hepatitis C infection
Interferon-α2a (IFNα2a)179–183
Roferon-A
Mechanism unknown; immunoregulator
Hairy cell leukaemia, chronic myelogenous
leukaemia, Kaposi’s sarcoma, chronic
hepatitis C infection
PegInterferon-α2a184–186
Pegasys
Recombinant interferon-α2a conjugated to
polyethylene glycol (PEG) to increase half-life
Adults with chronic hepatitis C who have
compensated liver disease and who have not
been previously treated with IFNα; used alone
or in combination with ribavirin
Interferon-α2b (IFNα2b)187–189
Intron A
Mechanism unknown; immunoregulator
Hepatitis B, melanoma, Kaposi’s sarcoma,
follicular lymphoma, hairy-cell leukaemia,
condylomata acuminata, hepatitis C
PegInterferon-α2b190
Peg-Intron
Recombinant interferon-α2b conjugated to
polyethylene glycol (PEG) to increase half-life
Adults with chronic hepatitis C who have
compensated liver disease and who have not
been treated previously with IFNα
‡
Interferon-αn3 (IFNαn3)191,192
Alferon N
Mechanism unknown; nonrecombinant human
IFNα-n3 purified from pooled human leukocytes
Condylomata acuminata (genital warts
caused by human papillomavirus)
Interferon-β1a (rIFN-β)178,193–196
Avonex,
Rebif
Mechanism unknown; antiviral and
immunoregulator
Multiple sclerosis
Interferon-β1b (rIFN-β)197–199
Betaseron
Mechanism unknown; antiviral and
immunoregulator
Multiple sclerosis
Interferon-γ1b (IFNγ)200–204
Actimmune
Increases inflammatory and antimicrobial
response
Chronic granulomatous disease, severe
osteopetrosis
Aldesleukin205–208
(interleukin 2 (IL2), epidermal
thymocyte activating factor;
ETAF)
Proleukin
Stimulates T and B cells, natural killer cells,
and lymphokine-activated killer cells
Metastatic renal cell cancer, melanoma
Haematopoiesis
Fertility
Immunoregulation
*Continued in TABLE 4. Protein therapeutics are recombinant unless otherwise stated. ‡Non-recombinant.
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Table 4 | Protein therapeutics augmenting an existing pathway (Group Ib)*
Therapeutic
Trade name
Function
Examples of clinical use
Alteplase42–46
(tissue plasminogen
activator; tPA)
Activase
Promotes fibrinolysis by binding fibrin and converting
plasminogen to plasmin
Pulmonary embolism, myocardial
infarction, acute ischaemic stroke, occlusion of central venous access
devices Reteplase
(deletion mutein of tPA)47,48
Retavase
Contains the non-glycosylated kringle 2 and protease
domains of human tPA; functions similarly to tPA
Management of acute myocardial
infarction, improvement of ventricular
function
Tenecteplase49,50
TNKase
tPA with greater specificity for plasminogen
conversion; has amino-acid substitutions of Thr103 to
Asp, Asp117 to Gln, and Ala for amino-acids 296–299
Acute myocardial infarction
§
Urokinase209,210
Abbokinase
Nonrecombinant plasminogen activator derived from
human neonatal kidney cells
Pulmonary embolism
Factor VIIa51,52
NovoSeven
Pro-thrombotic (activated factor VII; initiates the
coagulation cascade)
Haemorrhage in patients with
haemophilia A or B and inhibitors to
factor VIII or factor IX
Drotrecogin-α53,54
(activated protein C)
Xigris
Antithrombotic (inhibits coagulation factors Va and
VIIIa), anti-inflammatory
Severe sepsis with a high risk of death
Salmon calcitonin211,212
Fortical,
||
Miacalcin
Mechanism unknown; inhibits osteoclast function
Postmenopausal osteoporosis
Teriparatide213–216
(human parathyroid
hormone residues 1–34)
Forteo
Markedly enhances bone formation; administered as
a once-daily injection
Severe osteoporosis
Byetta
Incretin mimetic with actions similar to glucagonlike peptide 1 (GLP1); increases glucose-dependent
insulin secretion, suppresses glucagon secretion,
slows gastric emptying, decreases appetite (first
identified in saliva of the Gila monster Heloderma
suspectum)
Type 2 diabetes resistant to treatment
with metformin and a sulphonylurea
||
Octreotide218,219
Sandostatin
Potent somatostatin analogue; inhibits growth
hormone, glucagon and insulin
Acromegaly, symptomatic relief of
VIP-secreting adenoma and metastatic
carcinoid tumours
Dibotermin-α220,221
(recombinant human bone
morphogenic protein 2;
rhBMP2)
Infuse
Mechanism unknown
Spinal fusion surgery, bone injury
repair
Recombinant human bone
morphogenic protein 7
(rhBMP7)222
Osteogenic
protein 1
Mechanism unknown
Tibial fracture nonunion, lumbar
spinal fusion
||
Histrelin acetate223,224
(gonadotropin releasing
hormone; GnRH)
Supprelin LA,
Vantas
Synthetic analogue of human GnRH; acts as a potent
Precocious puberty
inhibitor of gonadotropin secretion when administered
continuously by causing a reversible downregulation of
GnRH receptors in the pituitary and desensitizing the
pituitary gonadotropes
Palifermin225
(keratinocyte growth factor;
KGF)
Kepivance
Recombinant analogue of KGF; stimulates
keratinocyte growth in skin, mouth, stomach and
colon
Severe oral mucositis in patients
undergoing chemotherapy
Becaplermin226–228
(platelet-derived growth
factor; PDGF)
Regranex
Promotes wound healing by enhancing granulation
tissue formation and fibroblast proliferation and
differentiation
Debridement adjunct for diabetic
ulcers
§
Trypsin229
Granulex
Proteolysis
Decubitus ulcer, varicose ulcer,
debridement of eschar, dehiscent
wound, sunburn
Nesiritide230, 231
Natrecor
Recombinant B-type natriuretic peptide
Acute decompensated congestive
heart failure
Haemostasis and thrombosis
‡
Endocrine disorders
Exenatide217
‡||
Growth regulation
Other
*Continued from TABLE 3. Protein therapeutics are recombinant unless otherwise stated. ‡Also classed in Group Ic. §Non-recombinant. ||Synthetic.
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Some Group IIa proteins are used to treat
infectious diseases. Patients at high-risk for
severe respiratory syncytial virus (RSV)
infection, one of the leading causes of hospital
admissions for paediatric respiratory
illness, are given a recombinant monoclonal
antibody, palivizumab, which binds to
the RSV F protein and thereby directs the
immune-mediated clearance of the virus
from the body74,75. Enfuvirtide is an example
of a Group II protein therapeutic that is not a
monoclonal antibody or an immunoadhesin.
By binding to gp120/gp41 — the HIV
envelope protein responsible for fusion of the
virus with host cells — this 36-amino-acid
peptide prevents the conformational change
in gp41 that is required for viral fusion, and
thereby inhibits viral entry into the cell76–78.
Table 5 | Protein therapeutics providing a novel function or activity (Group Ic)
Therapeutic
Trade name
Function
Examples of clinical use
Enzymatic degradation of macromolecules
*Botulinum toxin
type A232,233
Botox
Cleaves SNAP25 at neuromuscular junctions to
disrupt SNARE complex and prevent acetylcholine
release, causing flaccid paralysis
Many types of dystonia, particularly cervical;
cosmetic uses
*Botulinum toxin
type B233,234
Myoblock
Cleaves synaptobrevin at neuromuscular junctions to
disrupt SNARE complex and prevent acetylcholine
release, causing flaccid paralysis
Many types of dystonia, particularly cervical;
cosmetic uses
*Collagenase56,57
Collagenase,
Santyl
Collagenase obtained from fermentation by
Clostridium histolyticum; digests collagen in necrotic
base of wounds
Debridement of chronic dermal ulcers and
severely burned areas
Human deoxyribonuclease I,
dornase-α58
Pulmozyme
Degrades DNA in purulent pulmonary secretions
Cystic fibrosis; decreases respiratory tract
infections in selected patients with FVC
greater than 40% of predicted
*Hyaluronidase
(bovine, ovine)235
Amphadase
Catalyses the hydrolysis of hyaluronic acid to
(bovine), Hydase increase tissue permeability and allow faster drug
(bovine), Vitrase absorption
(ovine)
Used as an adjuvant to increase the absorption
and dispersion of injected drugs, particularly
anaesthetics in ophthalmic surgery and certain
imaging agents
Hyaluronidase
(recombinant
human)236
Hylenex
Catalyses the hydrolysis of hyaluronic acid to
increase tissue permeability and allow faster
drug absorption
Used as an adjuvant to increase the absorption
and dispersion of injected drugs, particularly
anaesthetics in ophthalmic surgery and certain
imaging agents
*Papain55
Accuzyme,
Panafil
Protease from the Carica papaya fruit
Debridement of necrotic tissue or liquefication
of slough in acute and chronic lesions, such as
pressure ulcers, varicose and diabetic ulcers,
burns, postoperative wounds, pilonidal cyst
wounds, carbuncles, and other wounds
Enzymatic degradation of small-molecule metabolites
*l-Asparaginase60
ELSPAR
Provides exogenous asparaginase activity,
removing available asparagine from serum;
purified from Escherichia coli
Acute lymphocytic leukaemia, which requires
exogenous asparagine for proliferation
*Peg-asparaginase59
Oncaspar
Provides exogenous asparaginase activity, removing
available asparagine from serum; purified from E. coli
Acute lymphocytic leukaemia, which requires
exogenous asparagine for proliferation
Rasburicase237
Elitek
Catalyzes enzymatic oxidation of uric acid into an
inactive, soluble metabolite (allantoin); originally
isolated from Aspergillus flavus
Paediatric patients with leukaemia, lymphoma,
and solid tumours who are undergoing
anticancer therapy that may cause tumour lysis
syndrome
Haemostasis and thrombosis
Lepirudin61,62
Refludan
Recombinant hirudin, a thrombin inhibitor from the
Heparin-induced thrombocytopaenia
salivary gland of the medicinal leech Hirudo medicinalis
‡
Bivalirudin238,239
Angiomax
Synthetic hirudin analogue; specifically binds both
the catalytic site and the anion-binding exosite of
circulating and clot-bound thrombin
Reduce blood-clotting risk in coronary
angioplasty and heparin-induced
thrombocytopaenia
*Streptokinase63–65,240
Streptase
Converts plasminogen to plasmin; produced by
group C b-haemolytic streptococci
Acute evolving transmural myocardial
infarction, pulmonary embolism, deep vein
thrombosis, arterial thrombosis or
embolism, occlusion of arteriovenous
cannula
*Anistreplase241,242
(anisoylated
plasminogen
streptokinase activator
complex; APSAC)
Eminase
Converts plasminogen to plasmin; p-anisoyl group
protects the catalytic centre of the plasminogenstreptokinase complex and prevents premature
deactivation, thereby providing longer duration of
action than streptokinase
Thrombolysis in patients with unstable angina
Protein therapeutics are recombinant unless otherwise stated. *Non-recombinant. ‡Synthetic. FVC, forced vital capacity; SNAP25, synaptosomal-associated protein, 25 kDa;
SNARE, soluble N-ethylmaleimide-sensitive factor attachment protein receptor.
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Perspectives
Another area in which Group IIa antibodies have been successful is oncology.
For example, rituximab is a human/mouse
chimeric monoclonal antibody that binds to
CD20, a transmembrane protein expressed on
>90% of B‑cell non-Hodgkin’s lymphomas,
and targets the cells for destruction by the
body’s immune system79–81. Although rituximab is most often used in combination with
anthracycline-based chemotherapy, it is one
of the few monoclonal antibody anticancer
therapies that is approved as a monotherapy.
Cetuximab is a monoclonal antibody that is
used to treat colorectal cancer and head and
neck cancer; this monoclonal antibody binds
epidermal growth factor receptor (EGFR) and
impairs cancer cell growth and proliferation82.
Other recently developed Group IIa protein
therapeutics are listed in TABLES 6,7, and
many more protein therapeutics utilizing the
exquisite specificity of monoclonal antibodies
are in development, especially for cancer and
inflammatory diseases.
Many important processes are modulated
by cell-surface receptors that are activated
upon binding of their cognate ligands15.
By binding to such receptors, targeted protein therapeutics may activate cell signalling
pathways and profoundly affect cell function. Outcomes may range from cell death
(through the induction of apoptosis), to
downregulation of cell division to increased
cell proliferation. Although it has been diffi­
cult to prove that a particular target-binding
protein mediates an in vivo effect through the
modulation of a particular signalling pathway, in vitro evidence suggests that this type
of modulation is involved in the mechanism
of action of certain therapeutic proteins.
For example, the treatment of certain breast
cancers, in which the malignant cells express
the HER2/Neu (also known as ERBB2) cell
surface receptor, is enhanced by the addition
of trastuzumab (an anti-HER2/Neu monoclonal antibody) to the therapeutic regimen83.
Although trastuzumab contains an Fc region
that facilitates antibody-dependent cellular
cytotoxicity mediated by natural killer cells, it
seems unlikely that this is trastuzumab’s only
mechanism of action. Other monoclonal
antibodies, with similar Fc regions and abilities to target breast cancer cells, have failed to
show efficacy in vivo. Trastuzumab, however,
has been shown in vitro to induce intracellu­
lar signalling events that control the growth
of breast cancer cells. It is therefore likely
that a combination of mechanisms accounts
for the therapeutic activity of trastuzumab,
including inhibition of the phosphatidyl­
inositol 3-kinase (PI3K) pathway, inhibition
of angiogenesis and inhibition of HER2
receptor cleavage84,85. The complex action of
trastuzumab highlights the fact that, while
modulation of cell physiology through
simple receptor binding may play a role in
the activity of some targeted therapies, the
relative contribution of receptor binding to
the overall efficacy of the therapeutic may be
difficult to dissect.
One of the great challenges in drug therapy is the selective delivery of small-molecule
drugs and proteins to the intended therapeutic target. The body normally uses proteins to
achieve specialized transport and delivery of
molecules. An active area of current research
is focused on understanding the principles of
protein-based, targeted delivery of molecules,
so that these principles can be applied to
modern pharmacotherapy. This strategy is
exploited by protein therapeutics that we
have classified in Group IIb (TABLE 8), such
as gemtuzumab ozogamicin, which links the
binding region of a monoclonal antibody
directed against CD33 with calicheamicin,
a small-molecule chemotherapeutic agent.
By using this therapy, the toxic compound is
selectively delivered to CD33-positive acute
myeloid leukaemia cells, resulting in the
selective killing of these cells86,87. Similarly,
refractory CD20-positive non-Hodgkin’s
lymphoma cells can be destroyed selectively
by ibritumomab tiuxetan, a monoclonal
antibody that is directed against CD20
and linked to a radioactive yttrium isotope
(Y‑90)88. Another example is provided by
denileukin diftitox, which uses a monoclonal
antibody that is directed against the CD25
component of the IL2 receptor to deliver
cytocidal diphtheria toxin to T-cell lymphoma cells that express this receptor89,90.
In addition to these current examples,
interesting developments are in progress that
illustrate where the field might be heading.
For example, herpes simplex virus produces
a protein, VP22, which enters human cells.
VP22 has been used in vitro to deliver proteins or other compounds to the nucleus. In
one application, VP22 was used to target the
tumour suppressor protein p53 to cultured
osteosarcoma cells that lacked the p53 gene
(and hence the protein)91. Reintroduction of
p53 led to apoptosis of the cells. It is thought
that a novel and effective therapy for certain
forms of cancer could use protein-based
targeting of the p53 gene. Another area of
research involves the delivery of proteins
and other macromolecules to the CNS,
which is challenging owing to the highly
selective blood–brain barrier (BBB). Animal
experiments have demonstrated, however,
that fusion proteins combining a therapeutic
protein with a protein that naturally has
nature reviews | drug discovery
specific access through the BBB can allow
successful delivery of the therapeutic protein
to the CNS. For example, a fragment of the
tetanus toxin protein that naturally crosses
the BBB has been shown in animal experiments to deliver the enzyme superoxide
dismutase (SOD) to the CNS92. This type of
therapeutic could potentially be used to treat
neurological disorders such as amyotrophic
lateral sclerosis, in which CNS levels of SOD
are reported to be low. Exciting prospects
also exist for the treatment of other disorders
of the CNS in which levels of a particular
protein are abnormal.
Group III: protein vaccines
As recombinant DNA technology was being
developed, great strides were also being
made in understanding the molecular mechanisms that allow the immune system to
protect the body against infectious diseases
and cancer. Armed with this new understanding, proteins that we have classified in
Group III have been successfully applied as
prophylactic or therapeutic vaccines. TABLE 9
provides selected examples.
For humans to develop effective immunity
against foreign organisms or cancer cells,
immune cells such as helper T cells must be
activated. Immune-cell activation is mediated
by antigen-presenting cells, which display
on their surface specific oligopeptides that
are derived from proteins found in foreign
organisms or cancer cells. Vaccination against
certain organisms such as polio or measles
has most often been achieved by injecting
heat-killed or attenuated forms of these pathogens. Unfortunately, these methods have
involved a certain amount of unavoidable risk
of infection or adverse reaction. By specifically injecting the appropriate immunogenic
(but non-pathogenic) protein components
of a microorganism, vaccines can hopefully
be created that provide immunity in an individual without exposing the individual to the
risks of infection or toxic reaction.
Proteins that we have classified in Group
IIIa are used to generate protection against
infectious diseases or toxins. One successful
example is the hepatitis B vaccine93,94. This
vaccine was created by producing recombinant hepatitis B surface antigen (HBsAg)
protein, a non-infectious protein of the
hepatitis B virus. When immunocompetent
humans are challenged and rechallenged
with this protein, significant immunity
results in the large majority of individuals.
Similarly, the non-infectious lipoprotein on
the outer surface of Borrelia burgdorferi has
been engineered into a vaccine for Lyme
disease (OspA)95,96. A recently approved
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Perspectives
vaccine against human papillomavirus
(HPV) combines the major capsid proteins
from four HPV strains that commonly
cause genital warts (strains 6 and 11) and
cervical cancer (strains 16 and 18)97.
In addition to generating protection
against foreign invaders, recombinant
proteins can induce protection against an
overactive immune system that attacks
its own body or ‘self ’. One theory is that
administration of large amounts of this selfprotein causes the body’s immune system to
develop tolerance to that protein by eliminating or deactivating cells that react against
the self-protein. Proteins that we have
Table 6 | Protein therapeutics that interfere with a molecule or organism (Group IIa)*
Therapeutic
Trade name Function
Examples of clinical use
Bevacizumab243–246
Avastin
Humanized mAb that binds all isoforms of VEGFA Colorectal cancer, non-small-cell lung cancer
Cetuximab140
Erbitux
Humanized mAb that binds EGFR Colorectal cancer, head and neck cancer
Panitumumab
Vectibix
Human mAb that binds EGFR
Metastatic colorectal cancer
Alemtuzumab248
Campath
Humanized mAb directed against CD52 antigen on
T and B cells
B-cell chronic lymphocytic leukaemia in patients
who have been treated with alkylating agents and
who have failed fludabarine therapy
Rituximab79–81, 249–251 Rituxan
Chimeric (human/mouse) mAb that binds CD20,
a transmembrane protein found on over 90% of B-cell
non-Hodgkin’s lymphomas (NHL); synergistic effect with
some small-molecule chemotherapeutic agents has
been demonstrated in lymphoma cell lines
Relapsed or refractory low-grade or follicular
CD20+ B-cell NHL, primary low-grade or follicular
CD20+ B-cell NHL in combination with CVP
chemotherapy; diffuse large B-cell CD20+ NHL in
combination with CHOP or other anthracylinebased chemotherapy; rheumatoid arthritis in
combination with methotrexate
Trastuzumab84
Herceptin
Humanized mAb that binds HER2/Neu cell surface
receptor and controls cancer cell growth
Breast cancer
Abatacept252
Orencia
Fusion protein between extracellular domain of
human CTLA4 and the modified Fc portion of human
immunoglobulin G1; selective co-stimulation modulator;
inhibits T-cell activation by binding to CD80 and CD86,
thereby blocking interaction with CD28 and inhibiting
autoimmune T-cell activation
Rheumatoid arthritis (especially when refractory
to TNFa inhibition)
Anakinra253–255
Antril,
Kineret
Recombinant interleukin 1 (IL1) receptor antagonist
Moderate to severe active rheumatoid arthritis
in adults who have failed one or more diseasemodifying antirheumatic drug
Adalimumab256,257
Humira
Human mAb that binds specifically to TNFα and blocks its
interaction with p55 and p75 cell surface TNF receptors,
resulting in decreased levels of inflammation markers
including CRP, ESR, and IL6
Rheumatoid arthritis, Crohn’s disease, ankylosing
spondylitis, psoriatic arthritis
Etanercept68–70
Enbrel
Dimeric fusion protein between recombinant soluble TNF
receptor and Fc portion of human immunoglobulin G1
Rheumatoid arthritis, polyarticular-course
juvenile rheumatoid arthritis, psoriatic arthritis,
ankylosing spondylitis, plaque psoriasis
Infliximab71–73
Remicade
Chimeric mAb that binds and neutralizes TNFα, preventing Rheumatoid arthritis, Crohn’s disease, ankylosing
spondylitis, psoriatic arthritis, plaque psoriasis
induction of pro-inflammatory cytokines, changes in
endothelial permeability, activation of eosinophils and
neutrophils, induction of acute phase reactants, and
enzyme elaboration by synoviocytes and/or chondrocytes
Alefacept258,259
Amevive
Dimeric fusion protein that binds CD2 on the surface
Adults with moderate to severe chronic plaque
of lymphocytes and inhibits interaction with LFA3; this
psoriasis who are candidates for systemic therapy
association is important for the activation of T lymphocytes or phototherapy
in psoriasis
Efalizumab260,261
Raptiva
Humanized mAb directed against CD11a
Adults with chronic moderate to severe plaque
psoriasis who are candidates for systemic therapy
or phototherapy
Natalizumab262
Tysabri
Mechanism unknown; humanized mAb that binds to the
α4-subunit of α4β1 and α4β7 integrins, blocking their
interactions with VCAM1 and MadCAM1, respectively
Relapsing multiple sclerosis
Eculizumab263,264
Soliris
Humanized mAb that binds complement protein C5
and inhibits its cleavage to C5a and C5b, preventing the
formation of the terminal complement complex C5b–9
Paroxysmal nocturnal haemoglobinuria
Cancer
247
Immunoregulation
*Continued in TABLE 7. Protein therapeutics are all recombinant. CHOP, cyclophosphamide, hydroxydaunorubicin, oncovin (vincristine), prednisone/prednisolone;
CTLA4, cytotoxicT-lymphocyte-associated antigen 4; CVP, cyclophosphamide, vincristine, prednisone; EGFR, epidermal growth factor receptor; LFA3, leukocyte functionassociated antigen 3; mAb, monoclonal antibody; MadCAM1, mucosal addressin cell adhesion molecule 1; TNF, tumour necrosis factor; VCAM1, vascular cell adhesion
molecule-1; VEGFA, vascular endothelial growth factor A.
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classified in Group IIIb are used to treat
patients with disorders that arise from
this type of autoimmune phenomenon.
Immunological acceptance of a fetus during
pregnancy represents a special situation
with respect to vaccine use. Occasionally, a
pregnant woman can reject a fetus after she
has been immunized against certain antigens carried by a fetus from a previous pregnancy. Administration of an anti-Rhesus D
antigen Ig prevents the sensitization of an
Rh-negative mother at the time of delivery of
an Rh-positive neonate. Because the woman
fails to develop antibodies directed against
the fetal Rh antigens, immune reactions
Table 7 | Protein therapeutics that interfere with a molecule or organism (Group IIa)*
Therapeutic
Trade name
Function
Examples of clinical use
Transplantation
‡
Antithymocyte
globulin
(rabbit)265–267
Thymoglobulin Selective depletion of T cells; exact mechanism
unknown
Acute kidney transplant rejection, aplastic anaemia
Basiliximab268
Simulect
Chimeric (human/mouse) IgG1 that blocks
cellular immune response in graft rejection by
binding the alpha chain of CD25 (IL2 receptor)
and thereby inhibiting the IL2-mediated
activation of lymphocytes
Prophylaxis against allograft rejection in renal transplant
patients receiving an immunosuppressive regimen
including cyclosporine and corticosteroids
Daclizumab269
Zenapax
Humanized IgG1 mAb that blocks cellular
immune response in graft rejection by binding
the alpha chain of CD25 (IL2 receptor) and
thereby inhibiting the IL2-mediated activation
of lymphocytes
Prophylaxis against acute allograft rejection in patients
receiving renal transplants
MuromonabCD3270–272
Orthoclone,
OKT3
Murine mAb that binds CD3 and blocks T-cell
function
Acute renal allograft rejection or steroid-resistant cardiac
or hepatic allograft rejection
Omalizumab273–275 Xolair
Humanized mAb that inhibits IgE binding to
the high-affinity IgE receptor on mast cells and
basophils, decreasing activation of these cells
and release of inflammatory mediators
Adults and adolescents (at least 12 years old) with
moderate to severe persistent asthma who have a positive
skin test or in vitro reactivity to a perennial aeroallergen
and whose symptoms are inadequately controlled with
inhaled corticosteroids
Palivizumab74,75
Humanized IgG1 mAb that binds the A
antigenic site of the F protein of respiratory
syncytial virus
Prevention of respiratory syncytial virus infection in
high-risk paediatric patients
36 amino-acid peptide that inhibits HIV entry
into host cells by binding to the HIV envelope
protein gp120/gp41
Adults and children (at least 6 years old) with advanced
HIV infection
Fab fragment of chimeric (human/mouse)
mAb 7E3 that inhibits platelet aggregation by
binding to the glycoprotein IIb/IIIa integrin
receptor
Adjunct to aspirin and heparin for prevention of cardiac
ischaemia in patients undergoing percutaneous coronary
intervention or patients about to undergo percutaneous
coronary intervention with unstable angina not
responding to medical therapy
Somavert
Recombinant human growth hormone
conjugated to PEG; blocks the growth hormone
receptor
Acromegaly
‡
Crotalidae
polyvalent
immune Fab
(ovine)281,282
Crofab
Mixture of Fab fragments of IgG that bind
and neutralize venom toxins of ten
clinically important North American Crotalidae
snakes
Crotalidae envenomation (Western diamondback,
Eastern diamondback and Mojave rattlesnakes,
and water moccasins)
‡
Digoxin immune
serum Fab
(ovine)283,284
Digifab
Monovalent Fab immunoglobulin fragment
obtained from sheep immunized with a digoxin
derivative
Digoxin toxicity
Ranibizumab285
Lucentis
Humanized mAb fragment that binds isoforms
Neovascular age-related macular degeneration
of vascular endothelial growth factor A (VEGFA)
Pulmonary disorders
Synagis
Infectious diseases§
Enfuvirtide76–78
Fuzeon
Haemostasis and thrombosis
Abciximab276–278
ReoPro
Endocrine disorders
Pegvisomant279,280
Other||
*Continued from TABLE 6. Protein therapeutics are recombinant unless otherwise stated. ‡Non-recombinant. §Purified immune globulins can also be used to mitigate the acute
affects of exposure to an infectious agent. Human immune globulins targeting botulism, cytomegalovirus, hepatitis B, rabies, tetanus, and vaccinia have been approved by the
FDA. ||Two additional antivenins have been approved by the FDA: Antivenin immune globulin (equine) — Latrodectus mactans (black widow spider); Antivenin immune globulin
(equine) — Micrurus fulvius (North American coral snake). Fab, fragment antigen-binding; IgE/G/G1, immunoglobulin E/G/G1; IL2, interleukin 2; mAb, monoclonal antibody;
PEG, polyethylene glycol.
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Table 8 | Protein therapeutics that deliver other compounds or proteins (Group IIb)
Therapeutic
Trade name Function
Examples of clinical use
Denileukin
diftitox89,90
Ontak
Directs the cytocidal
action of diphtheria toxin
to cells expressing the IL2
receptor
Persistent or recurrent
cutaneous T-cell lymphoma
whose malignant cells express
the CD25 component of the
IL2 receptor
*Ibritumomab
tiuxetan88
Zevalin
A mAb portion that
recognizes CD20+ B cells
and induces apoptosis
while the chelation site
allows either imaging (In111) or cellular damage by
beta emission (Y-90)
Relapsed or refractory
low-grade, follicular, or
transformed B-cell nonHodgkin’s lymphoma (NHL),
including rituximab-refractory
follicular NHL
Gemtuzumab
ozogamicin86,87
Mylotarg
Humanized anti-CD33
IgG4k mAb conjugated
to calicheamicin,
a small-molecule
chemotherapeutic agent
Relapsed CD33+ acute myeloid
leukaemia in patients who are
more than 60 years old and are
not candidates for cytotoxic
chemotherapy
Tositumomab is a mAb
that binds CD20 surface
antigen and stimulates
apoptosis. Tositumomab
coupled to radioactive
iodine-131 binds CD20
surface antigen and
delivers cytotoxic
radiation
CD20+ follicular NHL, with
and without transformation,
in patients whose disease
is refractory to rituximab
and has relapsed following
chemotherapy; tositumomab
and then131I-tositumomab
are used sequentially in the
treatment regimen
*Tositumomab
Bexxar,
and 131IBexxar I-131
tositumomab286,287
Protein therapeutics are all recombinant. *Also classed in Group IIa. IL2, interleukin 2; mAb, monoclonal antibody.
and pregnancy loss do not occur in subsequent pregnancies, even when the new fetus
carries the Rh antigens98.
Proteins that we have classified in Group
IIIc could be used as therapeutic anticancer
vaccines. Although there are currently no
FDA-approved recombinant anticancer
vaccines, there are promising clinical trials
that use patient-specific cancer vaccines. For
example, a vaccine for B‑cell non-Hodgkin’s
lymphoma uses transgenic tobacco plants
(Nicotiana benthamiana)99. Each patient
with this type of lymphoma has a malignant
proliferation of an antibody-producing B‑cell
that displays a unique antibody on its surface.
By subcloning the idiotype region of this
tumour-specific antibody and expressing the
region recombinantly in tobacco plants, a
tumour-specific antigen is produced that can
be used to vaccinate a patient. This process
requires only 6–8 weeks from biopsy of the
lymphoma to a ready-to-use, patient-specific
vaccine. As the genomes of infectious organisms and the nature of autoimmune diseases
and cancer are more fully elucidated, more
recombinant proteins will undoubtedly be
developed for use as vaccines.
Group IV: protein diagnostics
Proteins that we have classified in Group
IV are not used to treat disease, but purified
and recombinant proteins used for medical
diagnostics (both in vivo and in vitro) are
mentioned here because they are invaluable
in the decision-making process that precedes
the treatment and management of many diseases. TABLE 10 provides selected examples.
A classic example of an in vivo diagnostic
is the purified protein derivative (PPD)
test, which determines whether an individual has been exposed to antigens from
Mycobacterium tuberculosis. In this example,
a non-infectious protein component of the
organism is injected under the skin of an
immunocompetent individual100–102. An
active immune reaction is interpreted as
evidence that the patient has been previously
infected by M. tuberculosis or exposed to the
antigens of this organism.
Several stimulatory protein hormones
are used to diagnose endocrine disorders.
Growth hormone releasing hormone
(GHRH) stimulates somatotroph cells of the
anterior pituitary gland to secrete growth
hormone. Used as a diagnostic, GHRH can
help to determine whether pituitary growth
hormone secretion is defective in patients
with clinical signs of growth hormone
deficiency103,104. Similarly, the recombinant
human protein secretin is used to stimulate
pancreatic secretions and gastrin release, and
thereby aid in the diagnosis of pancreatic exocrine dysfunction or gastrinoma. In patients
with a history of thyroid cancer, recombinant
32 | january 2008 | volume 7
thyroid stimulating hormone (TSH) is an
important component of the surveillance
methods used to detect residual thyroid
cancer cells. Before the advent of recombinant
TSH, patients with a history of thyroid cancer
were required to stop taking replacement
thyroid hormone in order to develop a
hypothyroid state to which the anterior pituitary would respond by releasing endogenous
TSH. TSH-stimulated cancer cells could then
be detected by radioactive iodine uptake.
Unfortunately, this method required patients
to experience the adverse consequences of
hypothyroidism. Use of recombinant instead
of endogenous TSH not only allowed patients
to remain on replacement thyroid hormone
but also resulted in the improved detection of
residual thyroid cancer cells105,106.
Imaging agents are a broad group of
protein diagnostics that can be used to help
identify the presence or localization of a
pathological condition. For example, apcitide
is a technetium-labelled synthetic peptide
that binds glycoprotein IIb/IIIa receptors on
activated platelets and is used to image acute
venous thrombosis107. Caromab pendetide is
an indium‑111-labelled anti-PSA (prostatespecific antigen) antibody that can be used to
detect prostate cancer108. Protein-based
imaging agents are often used to detect
otherwise hidden disease so it can be treated
early when treatment is most likely to
succeed. Imaging agents are currently used
to detect cancer, image myocardial injury or
identify sites of occult infection; these agents
are presented in more detail in Table 10.
There are numerous in vitro protein
diagnostics and two are presented here as
examples of a much larger class. Natural
and recombinant HIV antigens are essential
components of common screening (enzyme
immunoassay) and confirmatory (western
blot) tests for HIV infection. In these tests,
the antigens serve as ‘bait’ for specific antibodies to HIV gag, pol and env gene products that have been elicited in the course of
infection109–111. Oral versions of HIV tests
have also become available. Hepatitis C
infection is diagnosed by using recombinant
hepatitis C antigens to detect antibodies
directed against this virus in the serum of
potentially infected patients112,113.
Challenges for protein therapeutics
There are now many examples in which
proteins have been used successfully therapeutically. Nonetheless, potential protein
therapies that have failed far outnumber the
successes so far, in part owing to a number of
challenges that are faced in the development
and use of protein therapeutics.
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First, protein solubility, route of administration, distribution and stability are all
factors that can hinder the successful application of a protein therapy114,115. Proteins
are large molecules with both hydrophilic
and hydrophobic properties that can make
entry into cells and other compartments
of the body difficult, and the half-life of
a therapeutic protein can be drastically
affected by proteases, protein-modifying
chemicals or other clearance mechanisms.
One example of how such challenges are
being addressed is through the production of PEGylated versions of therapeutic
proteins. For example, PEG-interferon is a
modified form of interferon in which the
polymer polyethylene glycol (PEG) is added
to prolong the absorption, decrease the renal
clearance, retard the enzymatic degradation,
increase the elimination half-life and reduce
the immunogenicity of interferon15.
A second important challenge is that
the body may mount an immune response
against the therapeutic protein116. In some
cases, this immune response can neutralize
the protein and can even cause a harmful
reaction in the patient. For example, immune
responses can be generated against Group
Ia therapeutic proteins used to replace a
factor that has been missing since birth, as
illustrated by the development of antifactor
VIII antibodies (inhibitors) in patients with
severe haemophilia A who are treated with
recombinant human factor VIII117,118. More
commonly, however, immune responses are
generated against proteins of non-human
origin. Until quite recently, the widespread
clinical application of monoclonal antibodies
had been limited by the rapid induction
of immune responses against this class of
therapeutic proteins. The need for antibody
therapeutics that evade immune surveillance
and response has been a driving force in the
maturation of antibody production technology. Recombinant technology and other
advances have allowed the development
of various antibody products that are less
likely to provoke an immune response than
unmodified murine antibodies. In humanized antibodies, portions of the antibody that
are not critical for antigen-binding specificity
are replaced with human Ig sequences that
confer stability and biological activity on the
protein but do not provoke an anti-antibody
response; and fully human antibodies can be
produced using transgenic animals or phage
display technologies67,119.
The field of cancer therapeutics illustrates the pace of advances in monoclonal
antibody development. In the 1980s, most
of the monoclonal cancer therapeutics
Table 9 | Protein vaccines (Group III)*
Therapeutic
Trade name
Function
Examples of clinical use
Protecting against a deleterious foreign agent (IIIa)
Hepatitis B surface
antigen (HBsAg)93,94
Engerix,
Non-infectious protein
Recombivax HB on surface of hepatitis
B virus
Hepatitis B vaccination
HPV vaccine97
Gardasil
Quadrivalent HPV
recombinant vaccine
(strains 6, 11, 16, 18);
contains major capsid
proteins from four
HPV strains
Prevention of HPV infection
OspA95,96
LYMErix
Non-infectious
lipoprotein on outer
surface of Borrelia
burgdorferi
Lyme disease vaccination
Rhophylac
Neutralizes Rh
antigens that could
otherwise elicit antiRh antibodies in an
Rh-negative individual
Routine antepartum and
postpartum prevention
of Rh(D) immunization in
Rh(D)-negative women;
Rh prophylaxis in case of
obstetric complications or
invasive procedures during
pregnancy; suppression
of Rh immunization in
Rh(D)-negative individuals
transfused with
Rh(D)-positive red blood cells
–
–
Currently in clinical trials
Treating an autoimmune disease (IIIb)
Anti-Rhesus (Rh)
immunoglobulin G98
Treating cancer (IIIc)
–
*Selected vaccines highlight the use of recombinant protein technology in vaccine production. Vaccines for the
following agents or diseases are currently approved by the FDA: anthrax, acellular pertussis, BCG (for childhood
TB protection), diphtheria, hepatitis A and B, human papillomavirus (HPV) types 6,11,16,18, influenza types A, B,
and H5N1, Japanese encephalitis, Lyme disease, measles, meningococcus, mumps, plague, pneumococcus, polio,
rabies, rotavirus, rubella, smallpox, tetanus, typhoid, varicella-zoster, and yellow fever (see http://www.fda.gov/
cber/vaccine/licvacc.htm).
were murine, although there were a few
examples of chimeric antibodies and isolated instances of humanized and human
antibodies in clinical development. During
the 1990s, humanized and fully human
antibodies became the most common types
of antibodies introduced into clinical trials.
Since 2000, there has been a further increase
in the proportion of antibodies that are fully
human, with the proportion of murine and
chimeric antibodies being introduced into
clinical trials decreasing accordingly120.
More heavily engineered protein therapies
that are based on human antibodies have also
been developed over the past 10–15 years.
One example is the ‘minibody’ AMG 531,
which is currently in clinical trials for the
treatment of immune thrombocytopaenic
purpura. This construct consists of an Fc
region of a human antibody with two copies
of a peptide sequence linked to each of its
IgG1 heavy chains. The peptide sequence
was selected to stimulate the thrombopoietin
receptor, yet the sequence has no similarity to
its endogenous analogue thrombopoietin121.
nature reviews | drug discovery
The Fc portion extends the half-life of
AMG 531 in the circulation, and the lack
of sequence homology to thrombopoietin
will ideally prevent the development of cross­
reactive anti-thrombopoietin antibodies — a
serious adverse effect seen with a PEGylated
version of thrombopoietin122,123.
A third issue is that for a protein to be
physiologically active, post-translational
modifications such as glycosylation,
phosphorylation and proteolytic cleavage
are often required124. These requirements
may dictate the use of specific cell types
that are capable of expressing and modifying the protein appropriately. In addition,
recombinant proteins must be synthesized in
a genetically engineered cell type for largescale production. The host system must
produce not only biologically active protein
but also a sufficient quantity of this protein
to meet clinical demand124. Also, the system
must allow purification and storage of the
protein in a therapeutically active form
for extended periods of time. The protein’s
stability, folding, and tendency to aggregate
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Perspectives
may be different in large-scale production
and storage systems than in those used to
produce the protein for animal testing and
clinical trials125,126. Some have proposed
engineering host systems that co-express a
chaperone or foldase with the therapeutic
protein of interest, but these approaches
have had limited success.
Potential solutions could include the
development of systems in which entire
cascades of genes involved in protein folding
are induced together with the therapeutic
protein; the impetus for this work is the
observation that plasma cells, which are
natural protein production facilities, use such
gene cascades to produce large quantities of
monoclonal antibody127. Although bacteria
and yeast are generally considered easy to
culture, certain mammalian cell types can be
more difficult and more costly to culture128.
Other methods of production — such as
genetically engineered animals and plants
— could provide a production advantage.
Transgenic cows, goats and sheep have been
Table 10 | Protein diagnostics (Group IV)
Diagnostic
Trade name
Function
Examples of clinical use
DPPD
Noninfectious protein from Mycobacterium
tuberculosis
Diagnosis of tuberculosis exposure
*Glucagon288,289
GlucaGen
Pancreatic hormone that increases blood
glucose by stimulating the liver to convert
glycogen to glucose
Diagnostic aid to slow gastrointestinal
motility in radiographic studies; reversal
of hypoglycaemia
‡
Growth hormone releasing
hormone (GHRH)103,104
Geref
Recombinant fragment of GHRH that
stimulates growth hormone release by
somatotroph cells of the pituitary gland
Diagnosis of defective growth-hormone
secretion
§
Secretin290,291
ChiRhoStim (human
peptide), SecreFlo
(porcine peptide)
Stimulation of pancreatic secretions and
gastrin
Aid in the diagnosis of pancreatic exocrine
dysfunction or gastrinoma; facilitates
identification of the ampulla of Vater
and accessory papilla during endoscopic
retrograde cholangiopancreatography
Thyroid stimulating hormone
(TSH), thyrotropin105,106
Thyrogen
Stimulates thyroid epithelial cells or welldifferentiated thyroid cancer tissue to
take up iodine and produce and secrete
thyroglobulin, triiodothyronine and thyroxine
Adjunctive diagnostic for serum
thyroglobulin testing in the follow-up of
patients with well-differentiated thyroid
cancer
Capromab pendetide108
ProstaScint
Imaging agent; indium-111-labelled anti-PSA
antibody; recognizes intracellular PSA
Prostate cancer detection
§
Indium-111-octreotide292
OctreoScan
Imaging agent; indium-111-labelled
octreotide
Neuroendocrine tumour and lymphoma
detection
Satumomab pendetide293
OncoScint
Imaging agent; indium-111-labelled mAb
specific for tumour-associated glycoprotein
(TAG-72)
Colon and ovarian cancer detection
Arcitumomab294,295
CEA-scan
Imaging agent; technetium-labelled antiCEA antibody
Colon and breast cancer detection
Nofetumomab296
Verluma
Imaging agent; technetium-labelled antibody Small-cell lung cancer detection and
specific for small-cell lung cancer
staging
§
Apcitide107
Acutect
Imaging agent; technetium-labelled
synthetic peptide; binds GPIIb/IIIa receptors
on activated platelets
Imciromab pentetate297
Myoscint
Imaging agent; indium-111-labelled antibody Detects presence and location of
specific for human cardiac myosin
myocardial injury in patients with
suspected myocardial infarction
Technetium fanolesomab298
NeutroSpec
Imaging agent; technetium-labelled antiCD15 antibody; binds neutrophils that
infiltrate sites of infection
Diagnostic agent (used in patients
with equivocal signs and symptoms
of appendicitis)
Detects human antibodies to HIV (enzyme
immunoassay, western blot)
Diagnosis of HIV infection
In vivo infectious disease diagnostics
Recombinant purified protein
derivative (DPPD)100–102
Hormones
Imaging agents, cancer
Imaging agents, other
Imaging of acute venous thrombosis
Examples of in vitro diagnostics
HIV antigens109–111
Enzyme immunoassay,
OraQuick, Uni-Gold
Hepatitis C antigens112,113
Recombinant immuno- Detects human antibodies to hepatitis C virus Diagnosis of hepatitis C exposure
blot assay (RIBA)
Protein diagnostics are recombinant unless otherwise stated. *Also classed in Group Ib. ‡Also classed in Group Ia. §Synthetic. CEA, carcinoembryonic antigen; mAb, monoclonal
antibody; PSA, prostate-specific antigen.
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Perspectives
engineered to secrete protein in their milk,
and transgenic chickens that lay eggs filled
with recombinant protein are anticipated
in the future129. Transgenic plants can inexpensively produce vast quantities of protein
without waste or bioreactors130, and potatoes
can be engineered to express recombinant
proteins and thereby make edible vaccines9.
Finally, by using fluid-shaking bioreactors,
microlitre-sized culture systems might be
able to predict the success of large-scale
culture systems and thereby provide substantial cost savings by focusing investment on
systems that are more likely to succeed131.
A fourth important challenge is the costs
involved in developing protein therapies.
For example, switching to recombinant
methodology from laborious purification
of placentally derived protein has allowed
the production of sufficient β-glucocerebrosidase to treat Gaucher’s disease in many
patients. Even so, the cost of the
recombinant protein can be greater than
US$ 100,000 per patient per year132.
The example of Gaucher’s disease also
illustrates aspects of a fifth issue associated
with protein therapeutics: ethics (although
these ethical issues are not exclusive to
protein therapeutics). For example, the
possibility of efficacious but expensive protein
therapeutics for small but severely ill patient
populations, such as patients with Gaucher’s
disease, can present a dilemma with respect to
allocation of financial resources of health-care
systems132. In addition, the definition of illness or disease could be challenged by protein
therapeutics that can ‘improve upon’ conditions previously viewed as variants of normal.
For example, the definition of short stature
may begin to change with the possibility of
using growth hormone to increase the height
of a child133–137.
Conclusion and future directions
Medicine is approaching a new era in which
approaches to manage disease are being made
at the level of the genetic and protein information that underlies all biology, and protein
therapeutics are playing an increasingly
important role. Already, recombinant human
proteins make up the majority of FDAapproved biotechnology medicines, which
include monoclonal antibodies, natural interferons, vaccines, hormones, modified natural
enzymes and various cell therapies. The
future potential for such therapies is huge,
given the thousands of proteins produced by
the human body and the many thousands of
proteins produced by other organisms.
Furthermore, recombinant proteins not
only provide alternative (or the only)
treatments for particular diseases, but can
also be used in combination with smallmolecule drugs to provide additive or synergistic benefit. Treatment of EGFR-positive
colon cancer is illustrative of this point:
combination therapy with the small-molecule
drug irinotecan, which prevents DNA
repair by inhibiting DNA topoisomerase,
and the recombinant monoclonal antibody
cetuximab, which binds to and inhibits the
extracellular domain of the EGFR, results in
increased survival in patients with colorectal
cancer. The therapeutic synergy between
irinotecan and cetuximab may be due to the
fact that both drugs inhibit the same EGFR
signalling pathway, with one drug (cetuximab) inhibiting the initiation of the pathway
and the other drug (irinotecan) inhibiting a
target downstream in the pathway82,138–140.
The early success of recombinant
insulin production in the 1970s created an
atmosphere of enthusiasm and hope, which
was unfortunately followed by an era of
disappointment when the vaccine attempts,
non-humanized monoclonal antibodies and
cancer trials in the 1980s were largely unsuccessful. Despite these setbacks, significant
progress has been made recently. As well as
the major successes with protein therapeutics described in this article, new production
methods are changing the scale, cost and
even route of administration of recombinant
protein therapeutics. With the large number
of protein therapeutics both in current clinical use and in clinical trials for a range of
disorders, one can confidently predict that
protein therapeutics will have an expanding
role in medicine for years to come.
Benjamin Leader is at the Department of Emergency
Medicine, Brown Medical School, 593 Eddy Street,
Providence, Rhode Island 02093, USA.
Quentin J. Baca and David E. Golan are at the
Department of Biological Chemistry and Molecular
Pharmacology, 250 Longwood Avenue, Harvard
Medical School, Boston, Massachusetts 02115, USA,
and Hematology Division, Brigham and Women’s
Hospital, 75 Francis Street, Boston, Massachusetts
02115.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
Correspondence to D.E.G.
e-mail: [email protected]
doi:10.1038/nrd2399 Published online 21 December 2007
1.
2.
3.
4.
5.
Pennisi, E. Bioinformatics. Gene counters struggle to
get the right answer. Science 301, 1040–1041 (2003).
Lander, E. S. et al. Initial sequencing and analysis of
the human genome. Nature 409, 860–921 (2001).
Venter, J. C. et al. The sequence of the human genome.
Science 291, 1304–1351 (2001).
Reichert, J. M. Trends in development and approval
times for new therapeutics in the United States. Nature
Rev. Drug Discov. 2, 695–702 (2003).
Slaff, J., Jacobson, D., Tillman, C. R., Curington, C. &
Toskes, P. Protease-specific suppression of pancreatic
exocrine secretion. Gastroenterology 87, 44–52
(1984).
nature reviews | drug discovery
27.
28.
29.
30.
Brown, A., Hughes, M., Tenner, S. & Banks, P. A.
Does pancreatic enzyme supplementation reduce
pain in patients with chronic pancreatitis: a metaanalysis. Am. J. Gastroenterol. 92, 2032–2035
(1997).
American Thoracic Society. Guidelines for the
approach to the patient with severe hereditary
α‑1‑antitrypsin deficiency. Am. Rev. Respir. Dis. 140,
1494–1497 (1989).
Dirksen, A. et al. A randomized clinical trial of
α(1)-antitrypsin augmentation therapy. Am. J. Respir.
Crit. Care Med. 160, 1468–1472 (1999).
Mason, H. S., Warzecha, H., Mor, T. & Arntzen, C. J.
Edible plant vaccines: applications for prophylactic and
therapeutic molecular medicine. Trends Mol. Med. 8,
324–329 (2002).
Wurm, F. & Bernard, A. Large-scale transient expression
in mammalian cells for recombinant protein production.
Curr. Opin. Biotechnol. 10, 156–159 (1999).
Zoller, M. J. New molecular biology methods for protein
engineering. Curr. Opin. Biotechnol. 2, 526–531
(1991).
Brannigan, J. A. & Wilkinson, A. J. Protein engineering
20 years on. Nature Rev. Mol. Cell Biol. 3, 964–970
(2002).
Watson, J. D., Gilman, M., Witkowksi, J. & Zoller, M.
in Recombinant DNA 453–470 (Scientific American
Books, New York, 1992).
Egrie, J. C. & Browne, J. K. Development and
characterization of novel erythropoiesis stimulating
protein (NESP). Br. J. Cancer 84 (Suppl. 1), 3–10
(2001).
Golan, D. E. et al. Principles of Pharmacology:
The Pathophysiologic Basis of Drug Therapy 2nd edn
(Lippincott Williams & Wilkins, Philadelphia, 2007).
Banting, F. G., Best, C. H., Collip, J. B., Campbell, W. R.
& Fletcher, A. A. Pancreatic extracts in the treatment
of diabetes mellitus: preliminary report. 1922. CMAJ
145, 1281–1286 (1991).
Goeddel, D. V. et al. Expression in Escherichia coli of
chemically synthesized genes for human insulin. Proc.
Natl Acad. Sci. USA 76, 106–110 (1979).
Clark, A. J. et al. Biosynthetic human insulin in the
treatment of diabetes. A double-blind crossover trial
in established diabetic patients. Lancet 2, 354–357
(1982).
Keen, H. et al. Human insulin produced by recombinant
DNA technology: safety and hypoglycaemic potency in
healthy men. Lancet 2, 398–401 (1980).
Richter, B. & Neises, G. ‘Human’ insulin versus animal
insulin in people with diabetes mellitus. Cochrane
Database Syst. Rev. 1, CD003816 (2003).
Morales, L. E. Gaucher’s disease: a review.
Ann. Pharmacother. 30, 381–388 (1996).
Niederau, C. & Haussinger, D. Gaucher’s disease:
a review for the internist and hepatologist.
Hepatogastroenterology 47, 984–997 (2000).
Whittington, R. & Goa, K. L. Alglucerase. A review of its
therapeutic use in Gaucher’s disease. Drugs 44, 72–93
(1992).
Grabowski, G. A. et al. Enzyme therapy in type 1
Gaucher disease: comparative efficacy of mannoseterminated glucocerebrosidase from natural and
recombinant sources. Ann. Intern. Med. 122, 33–39
(1995).
Barton, N. W. et al. Replacement therapy for inherited
enzyme deficiency — macrophage‑targeted gluco­
cerebrosidase for Gaucher’s disease. N. Engl. J. Med.
324, 1464–1470 (1991).
Rosado, J. L., Solomons, N. W., Lisker, R. &
Bourges, H. Enzyme replacement therapy for primary
adult lactase deficiency. Effective reduction of lactose
malabsorption and milk intolerance by direct addition
of β-galactosidase to milk at mealtime.
Gastroenterology 87, 1072–1082 (1984).
Abildgaard, C. F. et al. Treatment of hemophilia with
glycine-precipitated factor 8. N. Engl. J. Med. 275,
471–475 (1966).
Bray, G. L. et al. A multicenter study of recombinant
factor VIII (recombinate): safety, efficacy, and inhibitor
risk in previously untreated patients with hemophilia A.
The Recombinate Study Group. Blood 83, 2428–2435
(1994).
Roth, D. A. et al. Human recombinant factor IX: safety
and efficacy studies in hemophilia B patients previously
treated with plasma-derived factor IX concentrates.
Blood 98, 3600–3606 (2001).
Haase, M. Human recombinant factor IX: safety and
efficacy studies in hemophilia B patients previously
treated with plasma-derived factor IX concentrates.
Blood 100, 4242 (2002).
volume 7 | january 2008 | 35
© 2008 Nature Publishing Group
Perspectives
31. Kasper, D. K. et al. Harrison’s Principles of Internal
Medicine 16th edn (McGraw-Hill Professional, New
York, 2004).
32. Benz, R. L., Pressman, M. R., Hovick, E. T. & Peterson,
D. D. A preliminary study of the effects of correction
of anemia with recombinant human erythropoietin
therapy on sleep, sleep disorders, and daytime
sleepiness in hemodialysis patients (The SLEEPO
study). Am. J. Kidney Dis. 34, 1089–1095 (1999).
33. Corwin, H. L. et al. Efficacy of recombinant human
erythropoietin in critically ill patients: a randomized
controlled trial. JAMA 288, 2827–2835 (2002).
34. Evans, R. W., Rader, B. & Manninen, D. L. The quality of
life of hemodialysis recipients treated with recombinant
human erythropoietin. Cooperative Multicenter EPO
Clinical Trial Group. JAMA 263, 825–830 (1990).
35. Levin, N. W., Lazarus, J. M. & Nissenson, A. R.
National Cooperative rHu erythropoietin study in
patients with chronic renal failure — an interim report.
The National Cooperative rHu Erythropoietin Study
Group. Am. J. Kidney Dis. 22, 3–12 (1993).
36. Miles, S. The use of hematopoietic growth factors
in treating HIV infection. Curr. Opin. Hematol. 2,
227–233 (1995).
37. Lieschke, G. J. & Burgess, A. W. Granulocyte colonystimulating factor and granulocyte-macrophage
colony-stimulating factor (2). N. Engl. J. Med. 327,
99–106 (1992).
38. Tepler, I. et al. A randomized placebo-controlled trial of
recombinant human interleukin‑11 in cancer patients
with severe thrombocytopenia due to chemotherapy.
Blood 87, 3607–3614 (1996).
39. Out, H. J., Driessen, S. G., Mannaerts, B. M. &
Coelingh Bennink, H. J. Recombinant folliclestimulating hormone (follitropin beta, Puregon) yields
higher pregnancy rates in in vitro fertilization than
urinary gonadotropins. Fertil. Steril. 68, 138–142
(1997).
40. Van Wely, M., Westergaard, L. G., Bossuyt, P. M. &
Van der Veen, F. Human menopausal gonadotropin
versus recombinant follicle stimulation hormone for
ovarian stimulation in assisted reproductive cycles.
Cochrane Database Syst. Rev. 1, CD003973 (2003).
41. Ludwig, M., Doody, K. J. & Doody, K. M. Use of
recombinant human chorionic gonadotropin in ovulation
induction. Fertil. Steril. 79, 1051–1059 (2003).
42. A comparison of continuous infusion of alteplase with
double-bolus administration for acute myocardial
infarction. The Continuous Infusion versus DoubleBolus Administration of Alteplase (COBALT)
Investigators. N. Engl. J. Med. 337, 1124–1130
(1997).
43. Clark, W. M. et al. Recombinant tissue-type
plasminogen activator (Alteplase) for ischemic stroke 3
to 5 hours after symptom onset. The ATLANTIS Study:
a randomized controlled trial. alteplase thrombolysis
for acute noninterventional therapy in ischemic stroke.
JAMA 282, 2019–2026 (1999).
44. Goldhaber, S. Z. et al. Alteplase versus heparin in
acute pulmonary embolism: randomised trial assessing
right-ventricular function and pulmonary perfusion.
Lancet 341, 507–511 (1993).
45. Albers, G. W. et al. Intravenous tissue-type
plasminogen activator for treatment of acute stroke:
the Standard Treatment with Alteplase to Reverse
Stroke (STARS) study. JAMA 283, 1145–1150 (2000).
46. Katzan, I. L. et al. Use of tissue-type plasminogen
activator for acute ischemic stroke: the Cleveland area
experience. JAMA 283, 1151–1158 (2000).
47. No authors listed. Randomised, double-blind
comparison of reteplase double-bolus administration
with streptokinase in acute myocardial infarction
(INJECT): trial to investigate equivalence. International
Joint Efficacy Comparison of Thrombolytics. Lancet
346, 329–336 (1995).
48. No authors listed. A comparison of reteplase with
alteplase for acute myocardial infarction. The Global
Use of Strategies to Open Occluded Coronary Arteries
(GUSTO III) Investigators. N. Engl. J. Med. 337,
1118–1123 (1997).
49. No authors listed. Single-bolus tenecteplase compared
with front-loaded alteplase in acute myocardial
infarction: the ASSENT‑2 double-blind randomised
trial. Assessment of the Safety and Efficacy of a New
Thrombolytic Investigators. Lancet 354, 716–722
(1999).
50. No authors listed. Efficacy and safety of tenecteplase
in combination with enoxaparin, abciximab,
or unfractionated heparin: the ASSENT‑3 randomised
trial in acute myocardial infarction. Lancet 358,
605–613 (2001).
51. Shapiro, A. D., Gilchrist, G. S., Hoots, W. K., Cooper,
H. A. & Gastineau, D. A. Prospective, randomised trial
of two doses of rFVIIa (NovoSeven) in haemophilia
patients with inhibitors undergoing surgery.
Thromb. Haemost. 80, 773–778 (1998).
52. Hedner, U. Dosing with recombinant factor VIIa based
on current evidence. Semin. Hematol. 41, 35–39
(2004).
53. Bernard, G. R. et al. Efficacy and safety of recombinant
human activated protein C for severe sepsis. N. Engl. J.
Med. 344, 699–709 (2001).
54. Dhainaut, J. F., Yan, S. B. & Claessens, Y. E.
Protein C/activated protein C pathway: overview of
clinical trial results in severe sepsis. Crit. Care Med.
32, S194–S201 (2004).
55. Burke, J. F. & Golden, T. A clinical evaluation of
enzymatic debridement with papain‑urea‑chlorophyllin
ointment. Am. J. Surg. 95, 828–842 (1958).
56. Boxer, A. M., Gottesman, N., Bernstein, H. & Mandl, I.
Debridement of dermal ulcers and decubiti with
collagenase. Geriatrics 24, 75–86 (1969).
57. Rao, D. B., Sane, P. G. & Georgiev, E. L. Collagenase
in the treatment of dermal and decubitus ulcers.
J. Am. Geriatr. Soc. 23, 22–30 (1975).
58. Fuchs, H. J. et al. Effect of aerosolized recombinant
human DNase on exacerbations of respiratory
symptoms and on pulmonary function in patients with
cystic fibrosis. The Pulmozyme Study Group. N. Engl.
J. Med. 331, 637–642 (1994).
59. Holle, L. M. Pegaspargase: an alternative?
Ann. Pharmacother. 31, 616–624 (1997).
60. Clavell, L. A. et al. Four-agent induction and intensive
asparaginase therapy for treatment of childhood acute
lymphoblastic leukemia. N. Engl. J. Med. 315,
657–663 (1986).
61. Greinacher, A. et al. Recombinant hirudin (lepirudin)
provides safe and effective anticoagulation in patients
with heparin-induced thrombocytopenia: a prospective
study. Circulation 99, 73–80 (1999).
62. Eriksson, B. I. et al. A comparison of recombinant
hirudin with a low‑molecular‑weight heparin to prevent
thromboembolic complications after total hip
replacement. N. Engl. J. Med. 337, 1329–1335
(1997).
63. Rogers, L. Q. & Lutcher, C. L. Streptokinase therapy for
deep vein thrombosis: a comprehensive review of the
English literature. Am. J. Med. 88, 389–395 (1990).
64. Kennedy, J. W., Ritchie, J. L., Davis, K. B. & Fritz, J. K.
Western Washington randomized trial of intracoronary
streptokinase in acute myocardial infarction. N. Engl.
J. Med. 309, 1477–1482 (1983).
65. Anderson, J. L. et al. A randomized trial of
intracoronary streptokinase in the treatment of
acute myocardial infarction. N. Engl. J. Med. 308,
1312–1318 (1983).
66. No authors listed. An international randomized trial
comparing four thrombolytic strategies for acute
myocardial infarction. The GUSTO investigators.
N. Engl. J. Med. 329, 673–682 (1993).
67. Clark, M. Antibody humanization: a case of the
‘Emperor’s new clothes’? Immunol. Today 21,
397–402 (2000).
68. Mease, P. J. et al. Etanercept in the treatment of
psoriatic arthritis and psoriasis: a randomised trial.
Lancet 356, 385–390 (2000).
69. Weinblatt, M. E. et al. A trial of etanercept, a
recombinant tumor necrosis factor receptor:Fc fusion
protein, in patients with rheumatoid arthritis receiving
methotrexate. N. Engl. J. Med. 340, 253–259 (1999).
70. Gorman, J. D., Sack, K. E. & Davis, J. C. Jr. Treatment
of ankylosing spondylitis by inhibition of tumor
necrosis factor α. N. Engl. J. Med. 346, 1349–1356
(2002).
71. Lipsky, P. E. et al. Infliximab and methotrexate in the
treatment of rheumatoid arthritis. Anti-Tumor
Necrosis Factor Trial in Rheumatoid Arthritis with
Concomitant Therapy Study Group. N. Engl. J. Med.
343, 1594–1602 (2000).
72. Maini, R. et al. Infliximab (chimeric anti-tumour
necrosis factor α monoclonal antibody) versus placebo
in rheumatoid arthritis patients receiving concomitant
methotrexate: a randomised phase III trial. ATTRACT
Study Group. Lancet 354, 1932–1939 (1999).
73. Present, D. H. et al. Infliximab for the treatment of
fistulas in patients with Crohn’s disease. N. Engl.
J. Med. 340, 1398–1405 (1999).
74. No authors listed. Palivizumab, a humanized
respiratory syncytial virus monoclonal antibody,
reduces hospitalization from respiratory syncytial virus
infection in high-risk infants. The IMpact-RSV Study
Group. Pediatrics 102, 531–537 (1998).
36 | january 2008 | volume 7
75. Meissner, H. C. & Long, S. S. Revised indications for
the use of palivizumab and respiratory syncytial virus
immune globulin intravenous for the prevention of
respiratory syncytial virus infections. Pediatrics 112,
1447–1452 (2003).
76. Matthews, T. et al. Enfuvirtide: the first therapy to
inhibit the entry of HIV‑1 into host CD4 lymphocytes.
Nature Rev. Drug Discov. 3, 215–225 (2004).
77. Lazzarin, A. et al. Efficacy of enfuvirtide in patients
infected with drug-resistant HIV‑1 in Europe and
Australia. N. Engl. J. Med. 348, 2186–2195 (2003).
78. Lalezari, J. P. et al. Enfuvirtide, an HIV‑1 fusion
inhibitor, for drug-resistant HIV infection in North and
South America. N. Engl. J. Med. 348, 2175–2185
(2003).
79. McLaughlin, P. et al. Rituximab chimeric anti-CD20
monoclonal antibody therapy for relapsed indolent
lymphoma: half of patients respond to a four-dose
treatment program. J. Clin. Oncol. 16, 2825–2833
(1998).
80. Maloney, D. G. et al. IDEC‑C2B8 (Rituximab) antiCD20 monoclonal antibody therapy in patients with
relapsed low-grade non-Hodgkin’s lymphoma. Blood
90, 2188–2195 (1997).
81. Coiffier, B. et al. CHOP chemotherapy plus rituximab
compared with CHOP alone in elderly patients with
diffuse large‑B‑cell lymphoma. N. Engl. J. Med. 346,
235–242 (2002).
82. Cunningham, D. et al. Cetuximab monotherapy and
cetuximab plus irinotecan in irinotecan-refractory
metastatic colorectal cancer. N. Engl. J. Med. 351,
337–345 (2004).
83. Slamon, D. J. et al. Use of chemotherapy plus a
monoclonal antibody against HER2 for metastatic
breast cancer that overexpresses HER2. N. Engl. J.
Med. 344, 783–792 (2001).
84. Vogel, C. L. et al. Efficacy and safety of trastuzumab as
a single agent in first-line treatment of HER2overexpressing metastatic breast cancer. J. Clin. Oncol.
20, 719–726 (2002).
85. Valabrega, G. M., Montemurro, F. & Aglietta, M.
Trastuzumab: mechanism of action, resistance and
future perspectives in HER2-overexpressing breast
cancer. Ann. Oncol. 18, 977–984 (2007).
86. Sievers, E. L. et al. Efficacy and safety of gemtuzumab
ozogamicin in patients with CD33-positive acute
myeloid leukemia in first relapse. J. Clin. Oncol. 19,
3244–3254 (2001).
87. Giles, F., Estey, E. & O’Brien, S. Gemtuzumab
ozogamicin in the treatment of acute myeloid leukemia.
Cancer 98, 2095–2104 (2003).
88. Witzig, T. E. et al. Randomized controlled trial
of yttrium‑90‑labeled ibritumomab tiuxetan
radioimmunotherapy versus rituximab
immunotherapy for patients with relapsed or
refractory low-grade, follicular, or transformed B‑cell
non-Hodgkin’s lymphoma. J. Clin. Oncol. 20,
2453–2463 (2002).
89. Ho, V. T. et al. Safety and efficacy of denileukin diftitox
in patients with steroid-refractory acute
graft‑versus‑host disease after allogeneic
hematopoietic stem cell transplantation. Blood 104,
1224–1226 (2004).
90. Olsen, E. et al. Pivotal phase III trial of two dose levels
of denileukin diftitox for the treatment of cutaneous
T‑cell lymphoma. J. Clin. Oncol. 19, 376–388 (2001).
91. Phelan, A., Elliott, G. & O’Hare, P. Intercellular delivery
of functional p53 by the herpesvirus protein VP22.
Nature Biotechnol. 16, 440–443 (1998).
92. Francis, J. W., Hosler, B. A., Brown, R. H. Jr &
Fishman, P. S. CuZn superoxide dismutase (SOD‑1):
tetanus toxin fragment C hybrid protein for targeted
delivery of SOD‑1 to neuronal cells. J. Biol. Chem. 270,
15434–15442 (1995).
93. Szmuness, W. et al. Hepatitis B vaccine: demonstration
of efficacy in a controlled clinical trial in a high-risk
population in the United States. N. Engl. J. Med. 303,
833–841 (1980).
94. Crosnier, J. et al. Randomised placebo-controlled trial
of hepatitis B surface antigen vaccine in French
haemodialysis units: I, Medical staff. Lancet 1,
455–459 (1981).
95. Sigal, L. H. et al. A vaccine consisting of recombinant
Borrelia burgdorferi outer-surface protein A to prevent
Lyme disease. Recombinant Outer-Surface Protein A
Lyme Disease Vaccine Study Consortium. N. Engl.
J. Med. 339, 216–222 (1998).
96. Steere, A. C. et al. Vaccination against Lyme disease
with recombinant Borrelia burgdorferi outer-surface
lipoprotein A with adjuvant. Lyme Disease Vaccine
Study Group. N. Engl. J. Med. 339, 209–215 (1998).
www.nature.com/reviews/drugdisc
© 2008 Nature Publishing Group
Perspectives
97. Shi, L. et al. Gardasil: prophylactic human
papillomavirus vaccine development — from bench
top to bed-side. Clin. Pharm. Ther. 81, 259–264
(2007).
98. MacKenzie, I. Z. et al. Efficacy and safety of a new,
chromatographically purified rhesus (D)
immunoglobulin. Eur. J. Obstet. Gynecol. Reprod. Biol.
117, 154–161 (2004).
99. McCormick, A. A. et al. Rapid production of specific
vaccines for lymphoma by expression of the tumorderived single-chain Fv epitopes in tobacco plants.
Proc. Natl Acad. Sci. USA 96, 703–708 (1999).
100.Campos-Neto, A. et al. Evaluation of DPPD, a single
recombinant Mycobacterium tuberculosis protein as
an alternative antigen for the Mantoux test.
Tuberculosis (Edinb.) 81, 353–358 (2001).
101.Coler, R. N. et al. Cloning of a Mycobacterium
tuberculosis gene encoding a purifed protein derivative
protein that elicits strong tuberculosis-specific delayedtype hypersensitivity. J. Infect. Dis. 182, 224–233
(2000).
102.Duchin, J. S., Jereb, J. A., Nolan, C. M., Smith, P. &
Onorato, I. M. Comparison of sensitivities to two
commercially available tuberculin skin test reagents in
persons with recent tuberculosis. Clin. Infect. Dis. 25,
661–663 (1997).
103.Ranke, M. B. et al. Testing with growth hormonereleasing factor (GRF(1–29)NH2) and
somatomedin C measurements for the evaluation of
growth hormone deficiency. Eur. J. Pediatr. 145,
485–492 (1986).
104.Ghigo, E. et al. New approach to the diagnosis of
growth hormone deficiency in adults. Eur. J. Endocrinol.
134, 352–356 (1996).
105.Ladenson, P. W. et al. Comparison of administration of
recombinant human thyrotropin with withdrawal of
thyroid hormone for radioactive iodine scanning in
patients with thyroid carcinoma. N. Engl. J. Med. 337,
888–896 (1997).
106.Meier, C. A. et al. Diagnostic use of recombinant
human thyrotropin in patients with thyroid carcinoma
(phase I/II study). J. Clin. Endocrinol. Metab. 78,
188–196 (1994).
107.Taillefer, R., Edell, S., Innes, G. & Lister-James, J.
Acute thromboscintigraphy with Tc‑99m‑apcitide:
results of the phase 3 multicenter clinical trial
comparing Tc‑99m‑apcitide scintigraphy with contrast
venography for imaging acute DVT. J. Nucl. Med. 41,
1214–1223 (2000).
108.Sodee, D. B. et al. Multicenter ProstaScint imaging
findings in 2154 patients with prostate cancer.
Urology 56, 988–993 (2000).
109.Urnovitz, H. B., Sturge, J. C. & Gottfried, T. D.
Increased sensitivity of HIV‑1 antibody detection.
Nature Med. 3, 1258 (1997).
110.Van de Perre, P. et al. Postnatal transmission of human
immunodeficiency virus type 1 from mother to infant.
A prospective cohort study in Kigali, Rwanda. N. Engl.
J. Med. 325, 593–598 (1991).
111.Busch, M. P. et al. Evaluation of screened blood
donations for human immunodeficiency virus type 1
infection by culture and DNA amplification of pooled
cells. N. Engl. J. Med. 325, 1–5 (1991).
112.Van der Poel, C. L. et al. Confirmation of hepatitis C
virus infection by new four-antigen recombinant
immunoblot assay. Lancet 337, 317–319 (1991).
113.Soffredini, R. et al. Increased detection of antibody to
hepatitis C virus in renal transplant patients by thirdgeneration assays. Am. J. Kidney Dis. 28, 437–440
(1996).
114.Putney, S. D. & Burke, P. A. Improving protein
therapeutics with sustained-release formulations.
Nature Biotech. 16, 153–157 (1998).
115.Mahmood, I. & Green, M. D. Pharmacokinetic and
pharmacodynamic considerations in the development
of therapeutic proteins. Clin. Pharmacokinet. 44,
331–347 (2005).
116.Schellekens, H. Bioequivalence and the
immunogenicity of biopharmaceuticals. Nature Rev.
Drug Discov. 1, 457–462 (2002).
117.Peerlinck, K., Arnout, J., Gilles, J. G., Saintremy, J. M.
& Vermylen, J. A higher than expected incidence of
factor-VIII inhibitors in multitransfused hemophilia‑A
patients treated with an intermediate purity
pasteurized factor-VIII concentrate. Thromb. Haemost.
69, 115–118 (1993).
118.Gilles, J. G., Arnout, J., Vermylen, J. & Saint-Remy,
J. M. Anti-factor VIII antibodies of hemophiliac patients
are frequently directed towards nonfunctional
determinants and do not exhibit isotypic restriction.
Blood 82, 2452–2461 (1993).
119.Mascelli, M. A. et al. Molecular, biologic, and
pharmacokinetic properties of monoclonal antibodies:
impact of these parameters on early clinical
development. J. Clin. Pharm. 47, 553–565 (2007).
120.Reichert, J. M. & Valge-Archer, V. E. Development
trends for monoclonal antibody cancer therapeutics.
Nature Rev. Drug Discov. 6, 349–356 (2007).
121.Bussel, J. B. et al. AMG 531, a thrombopoiesisstimulating protein, for chronic ITP. N. Engl. J. Med.
355, 1672–1681 (2006).
122.Li, J. Z. et al. Thrombocytopenia caused by the
development of antibodies to thrombopoietin. Blood
98, 3241–3248 (2001).
123.Basser, R. L. et al. Development of pancytopenia with
neutralizing antibodies to thrombopoietin after
multicycle chemotherapy supported by megakaryocyte
growth and development factor. Blood 99, 2599–2602
(2002).
124.Walsh, C. T. Posttranslational Modification of Proteins:
Expanding Nature’s Inventory (Roberts & Company,
Colorado, 2005).
125.Frokjaer, S. & Otzen, D. E. Protein drug stability: a
formulation challenge. Nature Rev. Drug Discov. 4,
298–306 (2005).
126.Fowler, S. B. et al. Rational design of aggregationresistant bioactive peptides: reengineering human
calcitonin. Proc. Natl Acad. Sci. USA 102,
10105–10110 (2005).
127.Dinnis, D. M. & James, D. C. Engineering mammalian
cell factories for improved recombinant monoclonal
antibody production: lessons from nature?
Biotechnol. Bioeng. 91, 180–189 (2005).
128.Datar, R. V., Cartwright, T. & Rosen, C. G. Process
economics of animal cell and bacterial fermentations:
a case study analysis of tissue plasminogen activator.
Biotechnology (NY) 11, 349–357 (1993).
129.Lillico, S. G., McGrew, M. J., Sherman, A. &
Sang, H. M. Transgenic chickens as bioreactors for
protein-based drugs. Drug Discov. Today 10, 191–196
(2005).
130.Pogue, G. P., Lindbo, J. A., Garger, S. J. &
Fitzmaurice, W. P. Making an ally from an enemy:
plant virology and the new agriculture. Annu. Rev.
Phytopathol. 40, 45–74 (2002).
131.Micheletti, M. et al. Fluid mixing in shaken bioreactors:
implications for scale-up predictions for microlitre-scale
microbial and mammalian cell cultures. Chem. Eng. Sci.
61 (2006).
132.Gross, M. L. Ethics, policy, and rare genetic disorders:
the case of Gaucher disease in Israel. Theor. Med.
Bioeth. 23, 151–170 (2002).
133.Finkelstein, B. S. et al. Effect of growth hormone
therapy on height in children with idiopathic short
stature: a meta-analysis. Arch. Pediatr. Adolesc. Med.
156, 230–240 (2002).
134.Hokken-Koelega, A. C. et al. Growth hormone
treatment in growth-retarded adolescents after renal
transplant. Lancet 343, 1313–1317 (1994).
135.Howrie, D. L. Growth hormone for the treatment of
growth failure in children. Clin. Pharm. 6, 283–291
(1987).
136.Salomon, F., Cuneo, R. C., Hesp, R. & Sonksen, P. H.
The effects of treatment with recombinant human
growth hormone on body composition and metabolism
in adults with growth hormone deficiency. N. Engl. J.
Med. 321, 1797–1803 (1989).
137.Thorner, M. O. et al. The diagnosis of growth hormone
deficiency (GHD) in adults. J. Clin. Endocrinol. Metab.
80, 3097–3098 (1995).
138.Graham, J., Muhsin, M. & Kirkpatrick, P. Cetuximab.
Nature Rev. Drug Discov. 3, 549–550 (2004).
139.Goldberg, R. M. & Kirkpatrick, P. Cetuximab. Nature
Rev. Drug Discov. 4 (Suppl. 1) S10–S11 (2005).
140.Saltz, L. B. et al. Phase II trial of cetuximab in patients
with refractory colorectal cancer that expresses the
epidermal growth factor receptor. J. Clin. Oncol. 22,
1201–1208 (2004).
141.Warrier, I. et al. Factor IX inhibitors and anaphylaxis in
hemophilia B. J. Pediatr. Hematol. Oncol. 19, 23–27
(1997).
142.Thorland, E. C. et al. Anaphylactic response to factor IX
replacement therapy in haemophilia B patients:
complete gene deletions confer the highest risk.
Haemophilia 5, 101–105 (1999).
143.Rosenberg, R. D., Goldman, P., Bing, D. & Glass, J.
Actions and interactions of antithrombin and heparin.
N. Engl. J. Med. 292, 146–151 (1975).
144.Mannucci, P. M., Boyer, C., Wolf, M., Tripodi, A. &
Larrieu, M. J. Treatment of congenital antithrombin-III
deficiency with concentrates. Br. J. Haematol. 50,
531–535 (1982).
nature reviews | drug discovery
145.Moritz, B. et al. The efficacy and safety of protein C
concentrate (Human) vapor-heated in the treatment of
severe congenital protein C deficiency with or without
pupura fulminans. Blood 96, 53A–53A (2000).
146.Quattrin, T., Belanger, A., Bohannon, N. J. V. &
Schwartz, S. L. Efficacy and safety of inhaled insulin
(Exubera) compared with subcutaneous insulin therapy
in patients with type 1 diabetes — results of a
6‑month, randomized, comparative trial. Diabetes
Care 27, 2622–2627 (2004).
147.Hollander, P. A. et al. Efficacy and safety of inhaled
insulin (Exubera) compared with subcutaneous insulin
therapy in patients with type 2 diabetes — results of a
6‑month, randomized, comparative trial. Diabetes
Care 27, 2356–2362 (2004).
148.Skyler, J. S. et al. Efficacy of inhaled human insulin in
type 1 diabetes mellitus: a randomised
proof‑of‑concept study. Lancet 357, 331–335 (2001).
149.Edwards, D. A. et al. Large porous particles for
pulmonary drug delivery. Science 276, 1868–1871
(1997).
150.Hirsch, I. B. Drug therapy: Insulin analogues. N. Engl. J.
Med. 352, 174–183 (2005).
151.Dreyer, M. et al. Efficacy and safety of insulin glulisine
in patients with type 1 diabetes. Horm. Metab. Res.
37, 702–707 (2005).
152.Soran, H. & Younis, N. Insulin detemir: a new basal
insulin analogue. Diabetes Obes. Metab. 8, 26–30
(2006).
153.Thompson, R. G., Peterson, J., Gottlieb, A. & Mullane,
J. Effects of pramlintide, an analog of human amylin,
on plasma glucose profiles in patients with IDDM —
results of a multicenter trial. Diabetes 46, 632–636
(1997).
154.Backeljauw, P. F. & Underwood, L. E. Therapy for
6.5–7.5 years with recombinant insulin-like growth
factor I in children with growth hormone insensitivity
syndrome: a clinical research center study. J. Clin.
Endocrinol. Metab. 86, 1504–1510 (2001).
155.Kemp, S. F., Fowlkes, J. L. & Thrailkill, K. M. Efficacy
and safety of mecasermin rinfabate. Expert Opin.
Biol. Ther. 6, 533–538 (2006).
156.Ho, M. W. & O’Brien, J. S. Gaucher’s disease:
deficiency of ‘acid’ -glucosidase and reconstitution of
enzyme activity in vitro. Proc. Natl Acad. Sci. USA 68,
2810–2813 (1971).
157.Klinge, L. et al. Safety and efficacy of recombinant acid
α-glucosidase (rhGAA) in patients with classical
infantile Pompe disease: results of a phase II clinical
trial. Neuromuscul. Disord. 15, 24–31 (2005).
158.Scott, H. S. et al. Human α‑l‑iduronidase: cDNA
isolation and expression. Proc. Natl Acad. Sci. USA 88,
9695–9699 (1991).
159.Bach, G., Friedman, R., Weissmann, B. & Neufeld, E. F.
The defect in the Hurler and Scheie syndromes:
deficiency of α‑l‑iduronidase. Proc. Natl Acad. Sci. USA
69, 2048–2051 (1972).
160.Kakkis, E. D. et al. Enzyme-replacement therapy in
mucopolysaccharidosis I. N. Engl. J. Med. 344,
182–188 (2001).
161.Muenzer, J. et al. A phase II/III clinical study of enzyme
replacement therapy with idursulfase in
mucopolysaccharidosis II (Hunter syndrome). Genet.
Med. 8, 465–473 (2006).
162.Hopwood, J. J., Bate, G. & Kirkpatrick, P. Galsulfase.
Nature Rev. Drug Discov. 5, 101–102 (2006).
163.Eng., C. M. et al. Safety and efficacy of recombinant
human α-galactosidase A — replacement therapy in
Fabry’s disease. N. Engl. J. Med. 345, 9–16 (2001).
164.Schiffmann, R. et al. Enzyme replacement therapy in
Fabry disease: a randomized controlled trial. JAMA
285, 2743–2749 (2001).
165.Society, A. T. Guidelines for the approach to the patient
with severe hereditary a‑1‑antitrypsin deficiency.
Am. Rev. Respir. Dis. 140, 1494–1497 (1989).
166.Hershfield, M. S. et al. Treatment of adenosine
deaminase deficiency with polyethylene glycol-modified
adenosine deaminase. N. Engl. J. Med. 316, 589–596
(1987).
167.Ochs, H. D. & Pinciaro, P. J. Octagam 5%, an
intravenous IgG product, is efficacious and well
tolerated in subjects with primary immunodeficiency
diseases. J. Clin. Immunol. 24, 309–314 (2004).
168.Finfer, S. et al. A comparison of albumin and saline for
fluid resuscitation in the intensive care unit. N. Engl.
J. Med. 350, 2247–2256 (2004).
169.No authors listed. Association between recombinant
human erythropoietin and quality of life and exercise
capacity of patients receiving haemodialysis. Canadian
Erythropoietin Study Group. BMJ 300, 573–578
(1990).
volume 7 | january 2008 | 37
© 2008 Nature Publishing Group
Perspectives
170.Laupacis, A. Changes in quality of life and functional
capacity in hemodialysis patients treated with
recombinant human erythropoietin. The Canadian
Erythropoietin Study Group. Semin. Nephrol. 10,
11–19 (1990).
171.Heil, G. et al. A randomized, double-blind,
placebo-controlled, phase III study of filgrastim in
remission induction and consolidation therapy for
adults with de novo acute myeloid leukemia. Blood
90, 4710–4718 (1997).
172.Tarlatzis, B. et al. The use of recombinant human LH
(lutropin alfa) in the late stimulation phase of assisted
reproduction cycles: a double-blind, randomized,
prospective study. Hum. Reprod. 21, 90–94 (2006).
173.Cirelli, R. & Tyring, S. K. Interferons in human
papillomavirus infections. Antiviral Res. 24, 191–204
(1994).
174.Lindsay, K. L. Therapy of hepatitis C: overview.
Hepatology 26, 71S–77S (1997).
175.Tong, M. J. et al. Treatment of chronic hepatitis C with
consensus interferon: a multicenter, randomized,
controlled trial. Consensus Interferon Study Group.
Hepatology 26, 747–754 (1997).
176.Suzuki, H. & Tango, T. A multicenter, randomized,
controlled clinical trial of interferon alfacon‑1 in
comparison with lymphoblastoid interferon-α in
patients with high-titer chronic hepatitis C virus
infection. Hepatol. Res. 22, 1–12 (2002).
177.van Zonneveld, M. et al. Long-term follow-up of
α-interferon treatment of patients with chronic
hepatitis B. Hepatology 39, 804–810 (2004).
178.Giannini, E. et al. Long-term follow up of chronic
hepatitis C patients after α-interferon treatment:
a functional study. J. Gastroenterol. Hepatol. 16,
399–405 (2001).
179.Smalley, R. V. et al. Interferon α combined with
cytotoxic chemotherapy for patients with non-Hodgkin’s
lymphoma. N. Engl. J. Med. 327, 1336–1341 (1992).
180.Quesada, J. R. et al. Treatment of hairy cell leukemia
with recombinant α-interferon. Blood 68, 493–497
(1986).
181.Allan, N. C., Richards, S. M. & Shepherd, P. C. UK
Medical Research Council randomised, multicentre
trial of interferon-α n1 for chronic myeloid leukaemia:
improved survival irrespective of cytogenetic response.
The UK Medical Research Council’s Working Parties for
Therapeutic Trials in Adult Leukaemia. Lancet 345,
1392–1397 (1995).
182.No authors listed. Interferon α-2a as compared with
conventional chemotherapy for the treatment of
chronic myeloid leukemia. The Italian Cooperative
Study Group on Chronic Myeloid Leukemia. N. Engl. J.
Med. 330, 820–825 (1994).
183.Misiani, R. et al. Interferon α-2a therapy in
cryoglobulinemia associated with hepatitis C virus.
N. Engl. J. Med. 330, 751–756 (1994).
184.Fried, M. W. et al. Peginterferon α-2a plus ribavirin for
chronic hepatitis C virus infection. N. Engl. J. Med.
347, 975–982 (2002).
185.Zeuzem, S. et al. Peginterferon α-2a in patients with
chronic hepatitis C. N. Engl. J. Med. 343, 1666–1672
(2000).
186.Heathcote, E. J. et al. Peginterferon α-2a in patients
with chronic hepatitis C and cirrhosis. N. Engl. J. Med.
343, 1673–1680 (2000).
187.Mandelli, F. et al. Maintenance treatment with
recombinant interferon α-2b in patients with multiple
myeloma responding to conventional induction
chemotherapy. N. Engl. J. Med. 322, 1430–1434
(1990).
188.Perrillo, R. P. et al. A randomized, controlled trial of
interferon α-2b alone and after prednisone withdrawal
for the treatment of chronic hepatitis B. The Hepatitis
Interventional Therapy Group. N. Engl. J. Med. 323,
295–301 (1990).
189.Solal-Celigny, P. et al. Recombinant interferon α-2b
combined with a regimen containing doxorubicin in
patients with advanced follicular lymphoma. Groupe
d’Etude des Lymphomes de l’Adulte. N. Engl. J. Med.
329, 1608–1614 (1993).
190.Manns, M. P. et al. Peginterferon α-2b plus ribavirin
compared with interferon α-2b plus ribavirin for initial
treatment of chronic hepatitis C: a randomised trial.
Lancet 358, 958–965 (2001).
191.Simon, D. M. et al. Treatment of chronic hepatitis C
with interferon α‑n3: a multicenter, randomized,
open-label trial. Hepatology 25, 445–448 (1997).
192.Friedmankien, A. Management of condylomata
acuminata with Alferon‑N injection, interferon α‑n3
(human-leukocyte derived). Am. J. Obstet. Gynecol.
172, 1359–1368 (1995).
193.Panitch, H. et al. Randomized, comparative study of
interferon β-1a treatment regimens in MS: the
EVIDENCE trial. Neurology 59, 1496–1506 (2002).
194.Jacobs, L. D. et al. Intramuscular interferon β-1a
therapy initiated during a first demyelinating event in
multiple sclerosis. CHAMPS Study Group. N. Engl. J.
Med. 343, 898–904 (2000).
195.Byrne, E. Randomized, comparative study of interferon
β-1a treatment regimens in MS: the EVIDENCE trial.
Neurology 60, 1872–1873 (2003).
196.No authors listed. Randomised double-blind placebocontrolled study of interferon β-1a in relapsing/
remitting multiple sclerosis. PRISMS (Prevention of
Relapses and Disability by Interferon β-1a
Subcutaneously in Multiple Sclerosis) Study Group.
Lancet 352, 1498–1504 (1998).
197.Paty, D. W. & Li, D. K. Interferon β-1b is effective in
relapsing-remitting multiple sclerosis. II. MRI analysis
results of a multicenter, randomized, double-blind,
placebo-controlled trial. UBC MS/MRI Study Group
and the IFNB Multiple Sclerosis Study Group.
Neurology 43, 662–667 (1993).
198.No authors listed. Interferon β-1b in the treatment of
multiple sclerosis: final outcome of the randomized
controlled trial. The IFNB Multiple Sclerosis Study
Group and The University of British Columbia MS/MRI
Analysis Group. Neurology 45, 1277–1285 (1995).
199.Durelli, L. et al. Every‑other‑day interferon β-1b
versus once-weekly interferon β-1a for multiple
sclerosis: results of a 2‑year prospective randomised
multicentre study (INCOMIN). Lancet 359, 1453–
1460 (2002).
200.Raghu, G. et al. A placebo-controlled trial of interferon
γ-1b in patients with idiopathic pulmonary fibrosis.
N. Engl. J. Med. 350, 125–133 (2004).
201.Key, L. L. Jr et al. Long-term treatment of osteopetrosis
with recombinant human interferon γ. N. Engl. J. Med.
332, 1594–1599 (1995).
202.Ezekowitz, R. A., Dinauer, M. C., Jaffe, H. S.,
Orkin, S. H. & Newburger, P. E. Partial correction of
the phagocyte defect in patients with X‑linked chronic
granulomatous disease by subcutaneous interferon
γ. N. Engl. J. Med. 319, 146–151 (1988).
203.Baron, S. et al. The interferons. Mechanisms of action
and clinical applications. JAMA 266, 1375–1383
(1991).
204.Key, L. L. Jr, Ries, W. L., Rodriguiz, R. M. & Hatcher,
H. C. Recombinant human interferon γ therapy for
osteopetrosis. J. Pediatr. 121, 119–124 (1992).
205.Negrier, S. et al. Recombinant human interleukin‑2,
recombinant human interferon α-2a, or both in
metastatic renal-cell carcinoma. Groupe Francais
d’Immunotherapie. N. Engl. J. Med. 338, 1272–1278
(1998).
206.Atkins, M. B. et al. High-dose recombinant interleukin
2 therapy for patients with metastatic melanoma:
analysis of 270 patients treated between 1985 and
1993. J. Clin. Oncol. 17, 2105–2116 (1999).
207.Rosenberg, S. A. et al. Treatment of patients with
metastatic melanoma with autologous tumorinfiltrating lymphocytes and interleukin 2. J. Natl
Cancer Inst. 86, 1159–1166 (1994).
208.Atkins, M. B., Kunkel, L., Sznol, M. & Rosenberg, S. A.
High-dose recombinant interleukin‑2 therapy in
patients with metastatic melanoma: long-term survival
update. Cancer J. Sci. Am. 6 (Suppl. 1), 11–14 (2000).
209.Goldhaber, S. Z. et al. Randomized controlled trial of
recombinant tissue plasminogen-activator versus
urokinase in the treatment of acute pulmonaryembolism. Lancet 2, 293–298 (1988).
210.Tow, D. E., Wagner, H. N. & Holmes, R. A. Urokinase
in pulmonary embolism. N. Engl. J. Med. 277,
1161–1167 (1967).
211.Chesnut, C. H. et al. A randomized trial of nasal spray
salmon calcitonin in postmenopausal women with
established osteoporosis: the prevent recurrence of
osteoporotic fractures study. Am. J. Med. 109,
267–276 (2000).
212.Colman, E., Hedin, R., Swann, J. & Orloff, D. A brief
history of calcitonin. Lancet 359, 885–886 (2002).
213.Body, J. J. et al. A randomized double-blind trial to
compare the efficacy of teriparatide [recombinant
human parathyroid hormone (1–34)] with alendronate
in postmenopausal women with osteoporosis. J. Clin.
Endocrinol. Metab. 87, 4528–4535 (2002).
214.Neer, R. M. et al. Effect of parathyroid hormone
(1–34) on fractures and bone mineral density in
postmenopausal women with osteoporosis. N. Engl.
J. Med. 344, 1434–1441 (2001).
215.Reeve, J. Recombinant human parathyroid hormone.
BMJ 324, 435–436 (2002).
38 | january 2008 | volume 7
216.Tashjian, A. H. Jr. & Gagel, R. F. Teriparatide [human
PTH(1–34)]: 2.5 years of experience on the use and
safety of the drug for the treatment of osteoporosis.
J. Bone Miner. Res. 21, 354–365 (2006).
217.Heine, R. J. et al. Exenatide versus insulin glargine in
patients with suboptimally controlled type 2 diabetes:
a randomized trial. Ann. Intern. Med. 143, 559–569
(2005).
218.Tomassetti, P. et al. Treatment of type II gastric
carcinoid tumors with somatostatin analogues.
N. Engl. J. Med. 343, 551–554 (2000).
219.Lamberts, S. W. J., van der Lely, A-. J., de Herder,
W. W. & Hofland, L. J. Drug therapy — Octreotide.
N. Engl. J. Med. 334, 246–254 (1996).
220.Govender, S., Csimma, C., Genant, H. K. & ValentinOpran, A. Recombinant human bone morphogenetic
protein‑2 for treatment of open tibial fractures.
A prospective, controlled, randomized study of four
hundred and fifty patients. J. Bone Joint Surg. Am. 84,
2123–2134 (2002).
221.Boden, S. D., Zdeblick, T. A., Sandhu, H. S. & Heim,
S. E. The use of rhBMP‑2 in interbody fusion cages.
Definitive evidence of osteoinduction in humans: a
preliminary report. Spine 25, 376–381 (2000).
222.Friedlaender, G. E. et al. Osteogenic protein‑1 (bone
morphogenetic protein‑7) in the treatment of tibial
nonunions. A prospective, randomized clinical trial
comparing rhOP‑1 with fresh bone autograft. J. Bone
Joint Surg. Am. 83, S151–S158 (2001).
223.Feuillan, P. P., Jones, J. V., Barnes, K., Oerter-Klein, K.
& Cutler, G. B. Reproductive axis after discontinuation
of gonadotropin-releasing hormone analog treatment
of girls with precocious puberty: long term follow-up
comparing girls with hypothalamic hamartoma to
those with idiopathic precocious puberty. J. Clin.
Endocrinol. Metab. 84, 44–49 (1999).
224.Jay, N. et al. Ovulation and menstrual function of
adolescent girls with central precocious puberty after
therapy with gonadotropin‑releasing‑hormone
agonists. J. Clin. Endocrinol. Metab. 75, 890–894
(1992).
225.Spielberger, R. et al. Palifermin for oral mucositis after
intensive therapy for hematologic cancers. N. Engl. J.
Med. 351, 2590–2598 (2004).
226.Smiell, J. M. et al. Efficacy and safety of becaplermin
(recombinant human platelet-derived growth factorBB) in patients with nonhealing, lower extremity
diabetic ulcers: a combined analysis of four randomized
studies. Wound Repair Regen. 7, 335–346 (1999).
227.Embil, J. M. et al. Recombinant human plateletderived growth factor-BB (becaplermin) for healing
chronic lower extremity diabetic ulcers: an open-label
clinical evaluation of efficacy. Wound Repair Regen. 8,
162–168 (2000).
228.Wieman, T. J. Clinical efficacy of becaplermin
(rhPDGF-BB) gel. Becaplermin Gel Studies Group.
Am. J. Surg. 176, 74S‑79S (1998).
229.Hellgren, L. Cleansing properties of stabilized trypsin
and streptokinase-streptodornase in necrotic leg
ulcers. Eur. J. Clin. Pharmacol. 24, 623–628 (1983).
230.Intravenous nesiritide vs nitroglycerin for treatment of
decompensated congestive heart failure: a randomized
controlled trial. JAMA 287, 1531–1540 (2002).
231.Colucci, W. S. et al. Intravenous nesiritide, a natriuretic
peptide, in the treatment of decompensated congestive
heart failure. Nesiritide Study Group. N. Engl. J. Med.
343, 246–253 (2000).
232.Blasi, J. et al. Botulinum neurotoxin‑a selectively
cleaves the synaptic protein snap‑25. Nature 365,
160–163 (1993).
233.Jankovic, J. & Brin, M. F. Therapeutic uses of
botulinum toxin. N. Engl. J. Med. 324, 1186–1194
(1991).
234.Schiavo, G. et al. Tetanus and botulinum‑b neurotoxins
block neurotransmitter release by proteolytic cleavage
of synaptobrevin. Nature 359, 832–835 (1992).
235.Patel, B. C. K. et al. A comparison of topical and
retrobulbar anesthesia for cataract surgery.
Ophthalmology 103, 1196–1203 (1996).
236.Aslam, S. et al. Effect of hyaluronidase on ocular
motility and eyelid function in sub-Tenon’s anaesthesia:
randomised controlled trial. Eye 20, 579–582 (2006).
237.Goldman, S. C. et al. A randomized comparison
between rasburicase and allopurinol in children with
lymphoma or leukemia at high risk for tumor lysis.
Blood 97, 2998–3003 (2001).
238.Lincoff, A. M. et al. Bivalirudin and provisional
glycoprotein IIb/IIIa blockade compared with heparin
and planned glycoprotein IIb/IIIa blockade during
percutaneous coronary intervention — REPLACE‑2
Randomized Trial. JAMA 289, 853–863 (2003).
www.nature.com/reviews/drugdisc
© 2008 Nature Publishing Group
Perspectives
239.Bittl, J. A. et al. Treatment with bivalirudin (hirulog) as
compared with heparin during coronary angioplasty for
unstable or postinfarction angina. N. Engl. J. Med.
333, 764–769 (1995).
240.The GUSTO Investigators. An international randomized
trial comparing four thrombolytic strategies for acute
myocardial infarction. N. Engl. J. Med. 329, 673–682
(1993).
241.Hunt, D. et al. Isis‑3 — a randomized comparison of
streptokinase vs tissue plasminogen-activator vs
anistreplase and of aspirin plus heparin vs aspirin
alone among 41,299 cases of suspected acute
myocardial-infarction. Lancet 339, 753–770 (1992).
242.Anderson, J. L. et al. Multicenter reperfusion trial of
intravenous anisoylated plasminogen streptokinase
activator complex (APSAC) in acute myocardialinfarction — controlled comparison with intracoronary
streptokinase. J. Am. Coll. Cardiol. 11, 1153–1163
(1988).
243.Hurwitz, H. et al. Bevacizumab plus irinotecan,
fluorouracil, and leucovorin for metastatic colorectal
cancer. N. Engl. J. Med. 350, 2335–2342 (2004).
244.Ferrara, N., Hillan, K. J., Gerber, H. P. & Novotny, W.
Discovery and development of bevacizumab, an antiVEGF antibody for treating cancer. Nature Rev. Drug
Discov. 3, 391–400 (2004).
245.Yang, J. C. et al. A randomized trial of bevacizumab,
an anti-vascular endothelial growth factor antibody,
for metastatic renal cancer. N. Engl. J. Med. 349,
427–434 (2003).
246.Kabbinavar, F. et al. Phase II, randomized trial
comparing bevacizumab plus fluorouracil (FU)/
leucovorin (LV) with FU/LV alone in patients with
metastatic colorectal cancer. J. Clin. Oncol. 21, 60–65
(2003).
247.Wainberg, Z. & Hecht, J. R. A phase III randomized,
open-label, controlled trial of chemotherapy and
bevacizumab with or without panitumumab in the firstline treatment of patients with metastatic colorectal
cancer. Clin. Colorectal Cancer 5, 363–367 (2006).
248.Keating, M. J. et al. Therapeutic role of alemtuzumab
(Campath-1H) in patients who have failed fludarabine:
results of a large international study. Blood 99,
3554–3561 (2002).
249.Keating, M. J. et al. Early results of a
chemoimmunotherapy regimen of fludarabine,
cyclophosphamide, and rituximab as initial therapy
for chronic lymphocytic leukemia. J. Clin. Oncol. 23,
4079–4088 (2005).
250.Di Gaetano, N. et al. Synergism between fludarabine
and rituximab revealed in a follicular lymphoma cell
line resistant to the, cytotoxic activity of either drug
alone. Br. J. Haematology 114, 800–809 (2001).
251.Jazirehi, A. R., Huerta-Yepez, S., Cheng, G. H. &
Bonavida, B. Rituximab (chimeric anti-CD20
monoclonal antibody) inhibits the constitutive nuclear
factor-k B signaling pathway in non-Hodgkin’s
lymphoma B‑cell lines: role in sensitization to
chemotherapeutic drug-induced apoptosis. Cancer Res.
65, 264–276 (2005).
252.Genovese, M. C. et al. Abatacept for rheumatoid
arthritis refractory to tumor necrosis factor α
inhibition. N. Engl. J. Med. 353, 1114–1123 (2005).
253.Cohen, S. B. et al. A multicenter double-blind
randomized placebo-controlled trial of Kineret
(anakinra), a recombinant interleukin 1 receptor
antagonist, in patients with rheumatoid arthritis
treated with background methotrexate therapy.
Ann. Rheum. Dis. 63, 1062–1068 (2004).
254.Fleischmann, R. M. et al. Anakinra, a recombinant
human interleukin‑1 receptor antagonist
(r‑metHuIL‑1ra), in patients with rheumatoid arthritis:
a large, international, multicenter, placebo-controlled
trial. Arthritis Rheum. 48, 927–934 (2003).
255.Tesser, J. et al. Concomitant medication use in a large,
international, multicenter, placebo controlled trial of
anakinra, a recombinant interleukin 1 receptor
antagonist, in patients with rheumatoid arthritis.
J. Rheumatol. 31, 649–654 (2004).
256.Olsen, N. J. & Stein, C. M. Drug therapy — new drugs
for rheumatoid arthritis. N. Engl. J. Med. 350,
2167–2179 (2004).
257.Weinblatt, M. E. et al. Adalimumab, a fully human
anti-tumor necrosis factor a monoclonal antibody, for
the treatment of rheumatoid arthritis in patients taking
concomitant methotrexate — The ARMADA trial.
Arthritis Rheum. 48, 35–45 (2003).
258.Ellis, C. N. & Krueger, G. G. Treatment of chronic
plaque psoriasis by selective targeting of memory
effector T lymphocytes. N. Engl. J. Med. 345,
248–255 (2001).
259.Krueger, G. G. et al. A randomized, double-blind,
placebo-controlled phase III study evaluating efficacy
and tolerability of 2 courses of alefacept in patients
with chronic plaque psoriasis. J. Am. Acad. Dermatol.
47, 821–833 (2002).
260.Lebwohl, M. et al. A novel targeted T‑cell modulator,
efalizumab, for plaque psoriasis. N. Engl. J. Med. 349,
2004–2013 (2003).
261.Gordon, K. B. et al. Efalizumab for patients with
moderate to severe plaque psoriasis: a randomized
controlled trial. JAMA 290, 3073–3080 (2003).
262.Miller, D. H. et al. A controlled trial of natalizumab for
relapsing multiple sclerosis. N. Engl. J. Med. 348,
15–23 (2003).
263.Hillmen, P. et al. Effect of eculizumab on hemolysis and
transfusion requirements in patients with paroxysmal
nocturnal hemoglobinuria. N. Engl. J. Med. 350,
552–559 (2004).
264.Hillmen, P. et al. The complement inhibitor
eculizumab in paroxysmal nocturnal hemoglobinuria.
N. Engl. J. Med. 355, 1233–1243 (2006).
265.Denton, M. D., Magee, C. C. & Sayegh, M. H.
Immunosuppressive strategies in transplantation.
Lancet 353, 1083–1091 (1999).
266.Frickhofen, N. et al. Treatment of aplastic-anemia with
antilymphocyte globulin and methylprednisolone
with or without cyclosporine. N. Engl. J. Med. 324,
1297–1304 (1991).
267.Soulillou, J. P. et al. Randomized controlled trial of a
monoclonal-antibody against the interleukin‑2 receptor
(33b3.1) as compared with rabbit antithymocyte
globulin for prophylaxis against rejection of renalallografts. N. Engl. J. Med. 322, 1175–1182 (1990).
268.Nashan, B. et al. Randomised trial of basiliximab
versus placebo for control of acute cellular rejection in
renal allograft recipients. CHIB 201 International Study
Group. Lancet 350, 1193–1198 (1997).
269.Vincenti, F. et al. Interleukin‑2‑receptor blockade with
daclizumab to prevent acute rejection in renal
transplantation. Daclizumab Triple Therapy Study
Group. N. Engl. J. Med. 338, 161–165 (1998).
270.No authors listed. A comparison of tacrolimus (FK 506)
and cyclosporine for immunosuppression in liver
transplantation. The U.S. Multicenter FK506 Liver
Study Group. N. Engl. J. Med. 331, 1110–1115 (1994).
271.Cosimi, A. B. et al. Treatment of acute renal allograft
rejection with OKT3 monoclonal antibody.
Transplantation 32, 535–539 (1981).
272.Cosimi, A. B. et al. A randomized clinical trial
comparing OKT3 and steroids for treatment of hepatic
allograft rejection. Transplantation 43, 91–95 (1987).
273.Busse, W. et al. Omalizumab, anti-IgE recombinant
humanized monoclonal antibody, for the treatment of
severe allergic asthma. J. Allergy Clin. Immunol. 108,
184–190 (2001).
274.Casale, T. B. et al. Effect of omalizumab on symptoms
of seasonal allergic rhinitis: a randomized controlled
trial. JAMA 286, 2956–2967 (2001).
275.Milgrom, H. et al. Treatment of childhood asthma with
anti-immunoglobulin E antibody (omalizumab).
Pediatrics 108, e36 (2001).
276.No authors listed. Randomised placebo-controlled trial
of abciximab before and during coronary intervention
in refractory unstable angina: the CAPTURE Study.
Lancet 349, 1429–1435 (1997).
277.Antman, E. M. et al. Abciximab facilitates the rate and
extent of thrombolysis: results of the thrombolysis in
myocardial infarction (TIMI) 14 trial. The TIMI 14
Investigators. Circulation 99, 2720–2732 (1999).
278.Ibbotson, T., McGavin, J. K. & Goa, K. L. Abciximab:
an updated review of its therapeutic use in patients
with ischaemic heart disease undergoing percutaneous
coronary revascularisation. Drugs 63, 1121–1163
(2003).
279.Trainer, P. J. et al. Treatment of acromegaly with the
growth hormone-receptor antagonist pegvisomant.
N. Engl. J. Med. 342, 1171–1177 (2000).
280.van der Lely, A. J. et al. Long-term treatment of
acromegaly with pegvisomant, a growth hormone
receptor antagonist. Lancet 358, 1754–1759 (2001).
281.Ruha, A. M. et al. Initial postmarketing experience
with Crotalidae polyvalent immune Fab for treatment
of rattlesnake envenomation. Ann. Emerg. Med. 39,
609–615 (2002).
282.Dart, R. C. & McNally, J. Efficacy, safety, and use of
snake antivenoms in the United States. Ann. Emerg.
Med. 37, 181–188 (2001).
283.Smith, T. W., Haber, E., Yeatman, L. & Butler, V. P. Jr.
Reversal of advanced digoxin intoxication with Fab
fragments of digoxin-specific antibodies. N. Engl. J.
Med. 294, 797–800 (1976).
nature reviews | drug discovery
284.Antman, E. M., Wenger, T. L., Butler, V. P. Jr, Haber, E.
& Smith, T. W. Treatment of 150 cases of lifethreatening digitalis intoxication with digoxin-specific
Fab antibody fragments. Final report of a multicenter
study. Circulation 81, 1744–1752 (1990).
285.Brown, D. M. et al. Ranibizumab versus verteporfin
for neovascular age-related macular degeneration.
N. Engl. J. Med. 355, 1432–1444 (2006).
286.Kaminski, M. S. et al. Radioimmunotherapy with iodine
(131)I tositumomab for relapsed or refractory B‑cell
non-Hodgkin lymphoma: updated results and longterm follow-up of the University of Michigan
experience. Blood 96, 1259–1266 (2000).
287.Press, O. W. et al. A phase 2 trial of CHOP
chemotherapy followed by tositumomab/iodine I 131
tositumomab for previously untreated follicular nonHodgkin lymphoma: Southwest Oncology Group
Protocol S9911. Blood 102, 1606–1612 (2003).
288.Aman, J. & Wranne, L. Hypoglycaemia in childhood
diabetes. II. Effect of subcutaneous or intramuscular
injection of different doses of glucagon. Acta Paediatr.
Scand. 77, 548–553 (1988).
289.Carson, M. J. & Koch, R. Clinical studies with glucagon
in children. J. Pediatr. 47, 161–170 (1955).
290.Jowell, P. S. et al. A double-blind, randomized, dose
response study testing the pharmacological efficacy of
synthetic porcine secretin. Aliment. Pharmacol. Ther.
14, 1679–1684 (2000).
291.Somogyi, L., Ross, S. O., Cintron, M. & Toskes, P. P.
Comparison of biologic porcine secretin, synthetic
porcine secretin, and synthetic human secretin in
pancreatic function testing. Pancreas 27, 230–234
(2003).
292.Oberg, K. Neuroendocrine gastrointestinal tumours.
Ann. Oncol. 7, 453–463 (1996).
293.Maguire, R. T., Pascucci, V. L., Maroli, A. N. & Gulfo,
J. V. Immunoscintigraphy in patients with colorectal,
ovarian, and prostate-cancer — results with site-specific
immunoconjugates. Cancer 72, 3453–3462 (1993).
294.Hughes, K. et al. Use of carcinoembryonic antigen
radioimmunodetection and computed tomography for
predicting the resectability of recurrent colorectal
cancer. Ann. Surg. 226, 621–631 (1997).
295.Goldenberg, D. M. et al. Carcinoembryonic antigen
immunoscintigraphy complements mammography
in the diagnosis of breast carcinoma. Cancer 89,
104–115 (2000).
296.Balaban, E. P. et al. Detection and staging of small-cell
lung-carcinoma with a technetium-labeled monoclonalantibody: a comparison with standard staging
methods. Clin. Nucl. Med. 17, 439–445 (1992).
297.Johnson, L. L. et al. Antimyosin imaging in acute
transmural myocardial infarctions — results of a
multicenter clinical trial. J. Am. Coll. Cardiol. 13,
27–35 (1989).
298.Kipper, S. L. et al. Neutrophil-specific Tc‑99m‑labeled
anti-CD15 monoclonal antibody imaging for diagnosis
of equivocal appendicitis. J. Nucl. Med. 41, 449–455
(2000).
299.Chapman, W. C., et al. A phase 3, randomized, doubleblind comparative study of the efficacy and safety of
topical recombinant human thrombin and bovine
thrombin in surgical hemostasis. J. Am. Coll. Surg.
205, 256–265 (2007).
300.Food and Drug Administration (FDA). Product Approval
Information: Thrombin, Topical (Human), Updated
October 23, 2007. FDA web site [online], <http://
www.fda.gov/cber/products/evithrom.htm> (2007).
Acknowledgements
We thank A. H. Tashjian Jr for many helpful discussions and
expert review of the manuscript. D.E.G. is supported by NIH
grants R37HL032854 and U54HL070819. Q.J.B. is supp­
orted by NIH grant T32GM07753. Portions of this article
have been published in abbreviated form (Golan, D. E. et al.
Principles of Pharmacology: The Pathophysiologic Basis of
Drug Therapy (Lippincott Williams & Wilkins, 2004); Golan,
D.E. et al. Principles of Pharmacology: The Pathophysiologic
Basis of Drug Therapy, 2nd edn (Lippincott Williams &
Wilkins, 2007)), and are adapted with permission.
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