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TUMOR IMMUNOLOGY
Attila Bacsi PhD
THE BIOLOGY OF TUMORS BRIEFLY
• MORE THAN 100 TUMOR TYPES
• Most tumors develop later in life, mechanisms to control tumor
development must exist.
• 14 million new cancer cases/year worldwide /50% mortality.
• Contonuous cell division in a lifetime.
• Each of us carries 60 or more germline mutations not present in
parents.
THE HALLMARKS OF CANCER (OLD STYLE)
Hanahan and Weinberg Cell, 2011 pp646-
SO FAR INDEPENDENT
OF THE IMMUNE
SYSTEM
THE HALLMARKS OF CANCER (ONE STEP FORWARD)
Hanahan and Weinberg Cell, 2011 pp646-
BENIGN OR MALIGNANT TUMORS
SOME IMPORTANT QUESTIONS ARISE:
DO IMMUNOCYTES RECOGNIZE TUMORS?
DOES THE IMMUNE SYSTEM CONTROL THE DEVELOPMENT OF TUMORS?
(IMMUNOSURVEILLANCE)
CAN THE IMMUNE SYSTEM BE MODIFIED TO ERADICATE TUMORS?
MHC-DEPENDENT
REJECTION OF TUMORS
INFECTIVE FACIAL TUMOR IN THE INBREAD POPULATION OF
THE TASMANIAN DEVIL
About 2/3 of Hungary
Population half million
MULTIPLE MUTATIONS
LEAD TO DEVELOPMENT OF
TUMORS
ACTIVATION OF ONCOGENES
Mitogens
Growth factor receptors
Secondary messengers
Transcriptional activators
Malignant
Cell cycle genes
Tissue
cells
cells
INACTIVATION OF TUMOR
SUPPRESSOR GENES
Growth inhibitors
Cell cycle inhibitors
Programmed cell death genes
DNA repair enzymes
doi:10.1038/35101031
VARIOUS ONCOGENES ARE ASSOCIATED WITH
DEFINED TUMORS
ONCOGENE
ASSOCIATED TUMORS
c-erb-B2
Breast and ovarian carcinomas
ras
Many carcinomas and leukemias
c-sis
Gliomas
c-abl
Chronic myelogenous leukemia, acute lymphocytic leukemia
c-myc
Lymphomas
BRCA-1
APC
NF-1
Breast and ovarian carcinomas
Colonic adenocarcinomas
Neurofibromas and neurofibrosarcomas
Rb
Retinoblastomas, osteosarcomas, small cell lung carcinomas
p53
Many carcinomas
bcl-2
Chronic lymphocytic leukemia, lymphomas
CHROMOSOMAL TRANSLOCATION IN
BURKITT’S LYMPHOMA
8
c-myc
14
8q-
CH
VH
14q+
CH
VH
c-myc
Uncontrolled proliferation due to the activation of cmyc oncogene.
EBV induced tumor
TUMOR-ASSOCIATED VIRUSES
TUMOR-SPECIFIC ANTIGENS AND
TUMOR ASSOCIATED ANTIGENS
TUMOR-SPECIFIC ANTIGENS
CT ANTIGENS
Cancer/testis
antigens
are
expressed almost entirely by
cancerous cells, showing little or
no expression in healthy tissue,
with the exception of normal
testis, embryonic ovaries and
placenta.
THE TUMOR-SPECIFIC IMMUNE RESPONSE
DENDRITIC CELLS ARE ABLE TO ACTIVATE
TUMOR-SPECIFIC T-CELLS
(CROSS-PRESENTATION)
DOI: 10.1126/science.1203486
WHY ARE THEN TUMORS NOT
ELIMINATED?
Tumors are not highly immunogenic
Limited cytotoxic T-cell activity:
MHCI – mutation, β2m,TAP
Apoptosis: soluble Fas
TGF-β: inhibition of immune response
TOLEROGENIC
MICROENVIRONMENT
MECHANISMS OF TUMOR ESCAPE
MODULATION OF DC-FUNCTION BY THE TUMOR
TSLP-INDUCED DCS RECRUIT TH2 AND TREG CELLS
MANIPULATION OF THE IMMUNE
RESPONSE BY A TUMOR
MANY TUMORS LOOSE EXPRESSION OF HLA CLASS I PROTEINS
Loss of HLA class I expression in prostate cancer
Class I molecules are stained brown. The stain and HLA
class I molecules are not seen on the tumor mass but are
restricted to lymphocytes infiltrating the tumor and
tissue stromal cells.
HUMAN EPITHELIAL TUMORS CAN INHIBIT THE RESPONSE
OF LYMPHOCYTES EXPRESSING NKG2D
TUMOR IMMUNOTHERAPY
(Monoclonal antibodies)
POLYCLONAL ANTIBODIES
clones of many B cells
polyclonal
antibodies
binding to multiple epitopes
MONOCLONAL ANTIBODIES
clones of a single B cell
monoclonal
antibodies
binding to a
single epitope
POLYCLONAL ANTIBODIES
Ag
Immunserum
Polyclonal
antibody
- Products of a set of B-lymphocyte clones
- Heterogeneous in antigen specificity, affinity, and isotype
Set of B-cells
Ag
Activated B-cells
Antibodyproducing
plasma-cells
Antigen-specific
antibodies
MONOCLONAL ANTIBODIES (MAb)
 Products of clones of one
B-lymphocyte
 Homogeneous in specificity,
affinity, and isotype
 Can be found in humans in a
pathologic condition called
multiple myeloma, which is a
malignant proliferation of a
plasma cell (see supplementary)
STEPS OF MAb GENERATION
(1) Immunization of a mouse
(2) Isolation of B cells from the spleen
(3) Cultivation of myeloma cells
(4) Fusion of myeloma and B cells
(5) Separation of cell lines
(6) Screening of suitable cell lines
(7) in vitro (a) or in vivo (b) multiplication
(8) Harvesting
*For more details see supplementary
SELECTION OF HYBRIDOMA CELLS
Immunization
Spleen
B cells,
*HGPRT+
Myeloma cell
HGPRT-
aminopterine
PEG fusion
HAT selection
Testing supernatants for specific antibody production
HAT= hypoxanthine, aminopterine, thymidine
*Hypoxantine-guanine phosphoribosyltransferase
FEATURES OF POLYCLONAL AND MONOCLONAL
ANTIBODIES
Polyclonal antibodies
Monoclonal antibodies
Number of recognized
antigen determinants
several
(frequent cross-reactions)
mostly one
Specificity
polyspecific
monospecific
Affinity
Varying
(diverse antibodies)
high
Concentration of nonspecific immunoglobulins
high
low
Cost of preparation
low
high
Standardisability
Impossible (or uneasy)
easy
Amount
limited
unlimited
Applicability
method-dependent
excellent
DIFFERENT TYPES AND IMMUNOGENICITIES
OF ANTIBODIES USED IN THERAPY
Mouse
Chimeric
Human
Humanized
*Humanized antibodies are from non-human species whose protein sequences have been modified
to increase their similarity to antibody variants produced naturally in humans (except CDR loops)!
TUMOR IMMUNOTHERAPY
MAIN
STRATEGIES
FOR CANCER IMMUNOTHERAPY
Sattwa S. Neelapu Mol. Oncol (2015 in press)
MONOCLONAL ANTIBODIES
USED IN THE
TREATMENT OF
PATIENTS
WITH CANCER
ADCC---NK, macrophage,
complement
Immunotoxins
MANY THERAPEUTIC ANTI-CANCER MONOCLONAL ANTIBODIES
WORK BY DELIVERING THE TUMOR CELLS TO
NK CELL-MEDIATED ADCC
Antibodies bind to a cell-surface antigen of
the tumor cells, for example CD20. The Fc
regions of the antibodies engage FcγRIII on
an NK cell, which then becomes activated to
kill the tumor cell.
ANTIBODIES ARE USED TO
TARGET TOXINS
TO TUMOR CELLS
CHECKPOINT THERAPIES
• Blocking negative receptors used by Tregs
• Targeting stimulatory co-receptors with agonistic antibodies
BLOCKING THE INHIBITORY EFFECTS OF CTLA4
WITH A HUMAN MONOCLONAL ANTIBODY
(IPILIMUMAB ETC)
2 year survival is over 24% but quite some complications (GI).
Melanoma. Clinical trials: prostate cancer, lung carcinoma
Blocking the PD1/PDL1 interaction with a human
monoclonal antibody also works.
BLOCKING PD-1/PD-L1 INTERACTION WITH A
HUMAN MONOCLONAL ANTIBODIES
SIGNIFICANTLY IMPROVES THERAPY
Works well for melanoma, but it is in trial for many less immunogenic
tumors.
Padmanee Sharma1,2 and James P. Allison SCIENCE 2015 Vol. 348 pp56
COMBINATIONAL THERAPIES MAY HELP WHEN TUMORS
ARE NOT IMMUNOGENIC
AZ AKTÍV
TUMOR-SPECIFIKUS IMMUNTERÁPIA
LEHETŐSÉGEI
IMMUNOTHERAPY
BY VACCINATON
A tumor antigének beviteli módja
Tumor proteinderived peptide
Anti-idiotipe Ab
Tumor protein
Vírus-tumor
genome
Modified tumor cell
Plasmid DNA
Irradiated tumor
cell
Modified DC
Tumor cell lysate
Loaded DC
Heat shock
protein
Mocellin S et al.
Lancet Oncology
VACCINATION AGAINST HUMAN PAPILLOMA VIRUSES
CAN PREVENT CERVICAL CANCER
•HPV is an oncogenic virus causing genital warts.
•250000 women die of cervical cancer each year.
•Almost all cervical and ovarian cancers are HPV
positive.
•Preventing chronic HPV infection should prevent
cancer.
VACCINATION OF MELANOMA PATIENTS MAY CAUSE
THEIR TUMOR TO REGRESS
Rec. virus
Synthetic peptide vaccine
It is not yet clear when the vaccine would work.
Spectrum from remission to no response.
ADOPTIVE TRANSFER OF DENDRITIC CELLS LOADED
IN VITRO WITH TUMOR ANTIGENS
ADOPTIVE T-CELL TRANSFER
T-CELL RESPONSES TO TUMORS CAN BE IMPROVED WITH
CHIMERIC ANTIGEN RECEPTORS (CARS)
• Low affinity of TCR (compared to virus specific T
cells).
• MHC restriction prevents use in the entire
population.
• Problem solved by Fv.
• Variable fragment of the heavy and light chains
of a tumor-specific antibody made a single chain.
• Fusion of FV to an intracellular domain containing
CD28, CD137 and zeta-chain sequences.
• Generates strong signal in the absence of
costimulation.
B-CELL TUMORS CAN BE TARGETED BY CARS
SPECIFIC TO CD19
TREATMENT OF B-CELL TUMORS
USING ANTI-CD19 CAR T CELLS
THANK YOU FOR YOUR ATTENTION!