Download Tumor Chemosensitivity Assays - Chemosensitivity Testing Studies

DRUG RESPONSE ASSAY: AN INCREASING TREND IN DESIGNATION
OF TAILORED-CHEMOTHERAPY FOR MORE RATIONAL MANAGEMENT OF
CANCER PATIENTS
Assoc. Prof. Dr. Engin ULUKAYA
Uludag University, Medical School, Biochemistry Department, 16059, Görükle, BURSA,
TÜRKİYE (TURKEY in English)
Summary
Drug response assay, in other words tumor chemosensitivity assay, has long been known but
technical difficulties regarding the performance of the assay in the past caused a significant
drawbacks. However, recent technological achievements (e.g. luminometric measurements)
seem to overcome these difficulties. Therefore, individualization of drug treatment via drug
response assay may again take its place in oncology clinics. Promising results regarding the
ATP-tumor chemosensitivity assay are reported especially in the treatment of recurrent
ovarian carcinoma. Athough its widespread use in clinics needs more randomized studies, the
trend in using the assay could be expected to develop fast in parallel with the increasing
number of chemotherapeutic agents that are coming in to market.
Introduction
Although many chemotherapeutic drugs have been introduced for last 40 years, it seems that
there is still no satisfactory improvement in the succesful treatment of cancer patients. This is
mainly because cancer is a heterogenous disease, which means responses to same anti-cancer
drugs can be various from patient to patient even though they all develop the same organoriginated cancer with histologically same phenotype. Because of this fact, it is not likely to
expect the same outcome in all the patients who are treated with the same drug(s).
The systemic treatment of malignancies has been based on physicians’ empirical judgement,
relying on data obtained from clinical trials. However, even histopathologically identical
tumors behave so differently that the response rate of tumors to the chemotherapeutics was,
and still is, sometimes greatly varied. These variations may result in failure of the treatment of
cancer patients, or even toxicity which leads to the death of the patients. As it is known,
chemoresistance is a key feature of success in cancer treatment. In fact, this is one of the
nightmare scenarios which may be faced up during treatment of cancer. Therefore, to know
the resistance or sensitivity in advance is of immense importance in the success.
The effectiveness of current therapeutic approaches is limited mainly by tumor heterogeneity,
as it is known. That is why one of the aims of basic cancer researchers is to predict the
response of patients with cancer to chemotherapeutic agents by employing laboratory methods
variously called 'tumor chemosensitivity assays', 'drug response assays', or 'drug sensitivity
assays'.
The tumor chemosensitivity assay (TCA), which is called ONKOGRAM in Turkish, can be
used as a tool to let oncologists know about which anti-cancer drugs are more likely to work
well enough (or not) on their patients. It is believed that the response rate, the progression free
survival as well as the overall survival rate of cancer patients could be improved by
performing such a test. More benefits are also expected, as stated below. There are a number
of tests being used for this aim as briefly explained in the next sections. To perform the test,
the cancer tissue removed from patients during routine surgical operation should send to the
laboratory in a medium. After that, as many as up to 20, even 30, different drugs are incubated
with the cancer cells isolated from the cancer tissue in order to determine their cell-killing
potency.
Prediction of response or overall survival is of immense importance in oncology practice.
Therefore, there is no doubt that oncologists would like to make these predictions as early as
possible. It would not be an overreaction to say that every oncologist has eagerly this wish.
Detecting the chemosensitivity and/or chemoresistance of tumor tissue freshly removed from
the patient during routine surgical operation to anti-cancer agents in vitro has appeared to be
an attractive way of getting this wish come true. TCAs have already been in use in the field of
oncological research and these tests should be able to fill the gap in predictive oncology.
There is an increasing trend to develop new methods with this aim [1]. A working tumor
chemosensitivity assay would be of immense benefit to the pharmaceutical industry, and to
oncologists and their patients [2]. These assays could also be used to design new treatment
modalities, as has been reported for recurrent ovarian cancer in a very recent paper [3]. The
first experiments regarding this issue date back to the early 1950s [4, 5], but little attention
was paid until the well-known paper published in the New England Journal of Medicine in
1978 [6]. The attention was taken a bit further in the 1983 report published in the same
journal by Von Hoff [7].
Tumor Chemosensitivity Assays
Since the 1950s, a number of methods for assaying tumor chemosensitivity and/or
chemoresistance have been developed. Some well known TCAs are listed in Table 1:
Table 1: Major Tumor Chemosensitivity Assays
Methodology
References
The human tumor stem cell assay (human [8]
tumor clonogenic assay)
The extreme drug resistance assay
[9, 10],
The tissue Explant Assay (Histodrug [11],
response assay, HDRA)
The differential staining cytotoxicity assay [12, 13],
(DISC Assay)
The fluorescent cytoprint assay (FCA)
[14],
The MTT viability assay
[15, 16, 17, 18]
The ATP-Tumor Chemosensitivity Assay [19, 20]
(ATP-TCA)
The major applications of TCAs include a. assessment of sensitivity and resistance, b.
optimization of therapy for efficacy, toxicity and costs, c. designation of therapy for
pretreated/relapsed tumors, d. chemotherapy of metastases of unknown primary tumors, e.
chemotherapy of rare tumors. In addition to these, there are more benefits, such as a.
evaluation of mechanisms for resistance modulation, b. evaluation of drug interactions on
cellular level, c. evaluation of new substances, combinations, and principles, d. evaluation of
therapeutic index.
In chemosensitivity assays, there are mainly two approaches: using ready-to-use cell lines or
preparing up primary cultures. The cell lines have traditionally been used by pharmaceutical
companies. Cell lines have some advantages over primary cultures (e.g. shorter assay time,
technically less complication, less labor, quicker to perform) [21] but they are often found to
be poorly representative of the behaviour of “real” tumor cells [20]. Therefore, using primary
culture, instead of commercially available cell lines, are of immense importance in drug
evaluation assays. The common feature of these methods (either for cell lines or primary
cultures) is basically the employment of cell culture techniques. Both types differ in their
processing, and the technique used to measure sensitivity/resistance. All those techniques
involve 4 basic steps: 1) isolation of cells; 2) incubation of cells with anticancer agents for
certain period of time (2-6 days); 3) assessment of cell viability; and 4) interpretation of the
result.
Among the methods listed in Table 1 above, The human tumor stem cell assay (human tumor
clonogenic assay) is one of the first methods used as a TCA. Hamburger and Salmon used it
to test the effects of drugs on tumor tissues in 1970s [22, 23]. Subsequently, Von Hoff
improved it to the degree of a proper TCA [24]. However, clonogenic assay (or its
derivatives) measure the ability of drugs to inhibit tumor cell proliferation capacity which is
believed to result in the abolishment of these methods currently. The extreme drug resistance
assay, developed by Kern and Weisenthal, is a method in which tritiated thymidine is used to
measure the DNA synthesis rate. It is mainly used for the measurement of resistance of
proliferating cells to the drugs given. Therefore, it is also called “extreme drug resistance
assay” or “cell culture drug resistance testing, CCDRT”. In this assay, it is assumed that
thymidine incorporation into DNA reflects cell division and does not occur in non-tumor cells
that contaminate the biopsies. This could, to some extent, seem to be advantageous of this
assay but due to its inability in dealing with non-proliferating cells that could present in tumor
tissue, this assay was also considered not to provide a reliable quantification of drug
sensitivity in tumor samples [25]. The differential staining cytotoxicity assay (DISC Assay) is
a method for measuring apoptosis. One of the major modes of action of chemotherapeutic
drugs is known to be via the activation of apoptosis, which is a fundamental mechanism of
cell death that can be engaged by a range of cellular insults. It is thought that understanding
how the cell death program is initiated by following these drugs or any other kind of insults,
and hence why it fails to work for certain drugs, offers a novel approach to overcoming the
clinical problem of drug resistance [26]. DISC Assay is performed by staining of cells
followed by the microscopic evaluation. In this assay, a dye, such as fastgreen, is used, which
enters only non-living cells. The ratio of dead cells to total cells allows to evaluate cell death.
Kaspers stated that although it was laborious and requires skilled technician, it requires few
cells, the assay can be used for proliferating and non-proliferating cell populations, and can
discriminate between malignant and contaminating non-malignant cells [27]. The tissue
Explant Assay (Histodrug response assay, HDRA) relies on the three-dimensional architecture
of the tumor. It is also known as histoculture drug response assay (HDRA) in which a piece of
tumor is grown in collagen bed. Thus, this method demands as much tissue as possible. The
cell survival is measured by MTT reduction that is the principle of the MTT assay. It was
reported that chemosensitivity determined by the HDRA seems to be a strong predictor of
survival in patients with advanced HNSCC and should be considered further [28]. The
fluorescent cytoprint assay (FCA) uses a fluorescent dye that is converted in living cells.This
assay does not require cell dissociation. Tumor fragments are maintained in a collagen matrix.
A fluorescent dye accumulates in living cells and then visualized and photographed as
“cytoprints”. The MTT assay was originally developed by Mosmann [18] and is one of the
most commonly used methods to measure the tumor chemosensitivity in order to predict the
drug response. The MTT assay determines the ability of viable cells to convert a soluble
tetrazolium salt, the MTT compound, (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium
bromide) to an insoluble formazan precipitate. The formation of formazan is positively
correlated with the number of viable cells in the culture. The MTT assay is a rapid
colorimetric and quantitative method and it is usually regarded as reproducible and suitable
for initial-stage in vitro drug screening [29]. Nevertheless, the MTT assay may suffer some
interferences from some of the chemicals (e.g. N-acetyl-L-cysteine) used frequently for
various reasons in cell culture environments. In a recent study [30], the MTT assay was
therefore checked in terms of its possible chemical interactions with 22 different anti-cancer
drugs presently used for cancer treatment, including the frequently-used ones, such as
cisplatin or etoposide. Ulukaya et al in the same study concluded that before employing the
MTT assay, drugs (or any kind of substances) to be included in the assay should be checked
first in terms of possible chemical interactions with MTT otherwise it might be impossible to
evaluate the MTT viability assay results correctly.
ATP-Tumor Chemosensitivity Assay (ATP-TCA)
It seems that there is an increasing trend in the utilization of the tumor chemosensitivity
assays. In a recent report, a 3-dimensional ex vivo culture technique was stated to be a useful
method for drug development and the prediction of in vivo drug efficiency [31]. ATP-TCA is
one of the most recent methods for testing tumor response to drugs in addition to chip-based
methodologies in which some other parameters of cell survival (e.g. pH) are monitored and
measured at the same time. There is an internationally recognized society for the
chemosensitivity testing studies and it is called ISCO (The International Society for
Chemosensitivity Testing in Oncology). The ATP-TCA is created by particularly Prof. Dr. Ian
Cree (Portsmouth, England) and his co-workers who are founders of the ISCO. In ATP-TCA,
tumor cells are cultivated in vitro for 6-7 days with titrated concentrations of
chemotherapeutic drugs to evaluate tumor sensitivity and resistance. Microwell culture plates
and serum-free culture medium which support the selective growth of tumor cells are used to
perform the assay. Its serum free property is a unique feature. This is an important issue
because medium used for cell culture often provide considerable growth stimulation, either by
the addition of serum or artificial supplements. Therefore, it was reported that testing of
tumor-derived cells in serum free medium providing less growth support could have a number
of advantages in targeting drugs to the most appropriate tumors [20].
Drug inhibition of tumor cell growth is quantified using a luminometer to measure the light
emitted when adenosine triphosphate (ATP) from the cultured tumor cells is converted in the
D-luciferin-luciferase bioluminescent reaction:
Luciferase (E.C. 1.13.12.7)
ATP + D-Luciferin
AMP + 2Pi + Photon
The ATP-TCA seems to show a significant promise in evaluating the anti-cancer potential of
chemotherapeutic drugs against cancer cells isolated from many different kinds of solid
tumors. More importantly, it has also reached a phase III clinical trial (in recurrent ovarian
cancer), of which results might make a great impact on cancer treatment in near future. ATPTCA has also been evaluated on many other tumor types.
ATP-TCA utilises serum-free medium called CAM (complete assay medium) which promotes
the viability of tumor cells while it inhibits the growth of normal/stromal cells. Selective
tumor cell growth is also encouraged by the use of polypropylene microplates which do not
permit cell adherence. Its ability to select the survival of cancer cells was shown in 124
specimens under the serum-free conditions by Andreotti et al [32]. They tested 39 breast
tumors, 78 ovarian tumor or ascites specimens, and 7 other solid tumors. They reported that
the mean proportion of malignant cells was 54% (10-95%  22%) before culture, while it
increased to 83% (30-100%  14%) after culture, resulting in the mean increase in the
percentage of malignant cells before and after culture being 29%.
ATP-TCA results should be regarded as evaluable if three criteria are met [33]: 1. clear
evidence of malignant cell involvement of the sample by cytology or histology, 2. MO (no
drug control) values greater than 20 000 RLU indicating the presence of enough number of
alive cells in culture system, and 3. evidence of a dose relationship. In the analysis of results,
percent tumor growth inhibition (TGI) is calculated for each test drug concentrations (TDC).
The calculation is performed as formulated below:
TGI=1.0-[(TDC-MI)/(MO-MI)]x100, where MO=mean counts for no inhibition control
cultures, MI=mean counts for maximum inhibition control cultures, and TDC=mean counts
for replicate test drug cultures [34].
ATP-TCA seems particularly to be useful in ovarian cancer. In the study of Konecny et al
[35], they reported a significant correlation between drug sensitivity/resistance and clinical
response (p=0.007). In the same study, the assay demonstrated a sensitivity, spesificity,
positive predictive value (PPV), and negative predictive value (NPV) of 95, 44, 66, and 89%,
respectively. The NPV in this study is especially notable because it gives an appreciable idea
of the patients who will show recurrence within 12 months of post-chemotherapy period. Out
of 9 patients, 8 were found in vitro resistant on the basis of sensitivity index, according to the
assay. In other study, regarding the cisplatin resistance, it was found that the assay had 90%
accuracy for cisplatin resistance of ovarian carcinoma [32]. ATP-TCA has also been
evaluated in a pilot study of recurrent ovarian cancer in which therapy was selected on the
basis of ATP-TCA results by Kurbacher et al [19]. In the study, 25 patients were treated
according to the ATP-TCA results while 30 patients were treated emprically. It was shown
that therapy guided by ATP-TCA produced a greater benefit with regard to both overall
response rate (ORR) and progression-free survival (PFS) in platinum-refractory patients.
Kurbacher at all also stated that ATP-TCA could be regarded as the most sophisticated assay
to investigate both solid tumor samples and effusions derived from patients with various
organ tumors [36]. In another study, prospective studies are needed to be routinely used of
ATP-TCA in selecting drug therapy, although it was regarded having a predictive ability for
drug response [37].
In addition to this benefit in selecting the best regimen for particular patients, ATP-TCA was
also reported that it could succesfully be used for new agent development [20]. Thereby, in
the same report, Cree at al suggested that ATP-TCA should limit the number of subsequent
phase II/III trials required, saving money and time, while permitting new agents affective for
subsets of cancer patients to be introduced faster. There are some conclusions of early clinical
trials (oral communication with C. Sartori, Germany) regarding the ATP-TCA in recurrent
ovarian cancer that are given below: 1. The ATP-TCA provides promising retrospective ex
vivo/in vivo correlations; 2. Both the positive predictive value and the predictive accuracy of
the ATP-TCA compares favorably with other predictive assays; 3. A multi-parametric
evaluation score including different informations drawn from the dose-response curves
appears to be superior to uni-parametric approaches (IC50, IC90, sensitivity index etc.); 4.
The ATP-TCA provides a rational approach for preclinical evaluation of novel active
combination regimens for ovarian cancer (preclinical phase II studies); 5. Preclinical phase II
trials are likely to identify indications for subsequent clinical phase II studies and thus appear
to be a time- and cost-saving approach in the development of new chemotherapy protocols; 6.
ATP-TCA-directed chemotherapy for recurrent ovarian cancer produces both impressive
response rates and promising long-term results (PFS and OAS), as compared to empirical
salvage chemotherapy; 7. Responses seen with ATP-TCA-based chemotherapy are often of
high quality (CR); very few patients (false positive results) progressed on ATP-TCA-directed
chemotherapy; 8. ATP-TCA-directed chemotherapy appears to be of particular value for
platinum-refractory patients; the chance to experience long-lasting PFS and OAS is increased
to a level normally seen only for platinum-sensitive individuals; 9. Standard platinum-based
protocols seem to be not always the best choice for patients with platinum-sensitive disease,
whereas patients with refractory tumors may often benefit the most from protocols others than
single agent paclitaxel; 10. The ATP-TCA is able to identify patients to benefit from novel
regimens which are normally not chosen empirically but accounted for more than 50% of
responses seen; 11. Randomized studies are warranted to confirm the promising results of the
trials.
Conclusion
In brief, it seems that there are two great benefits to expect from TCAs: Firstly, exclusion of
chemotherapeutic agents which are not likely to be effective, thereby avoidance of their
potential toxicity. Secondly, selection of chemotherapeutic agents with the greatest likelihood
of clinical effectiveness for improved response rates and prolonged survival. In addition to
these two great benefit, there are more advantages of using TCA which are briefly mentioned
below. 1. Relative efficacy of two similar drug or drug combinations is elucidated; 2. When
standard therapy fails, newer or non-standard therapies can be considered; 3. A therapeutic
index can be obtained when normal cells are also tested; 4. Financial savings are possible as
expensive new drugs can be avoided in test-resistant patients; 5. Sensitivity to radiotherapy
can also be measured. TCAs should therefore deserve some attention in order to better
management of cancer patients and need to be evaluated in prospective randomised studies.
TCA, at least, currently seems to gain a quite respectful position in the treatment decision of
recurrent ovarian carcinoma (oral communication with S. Lele, USA).
References
1] Metzger R, Deglmann CJ, Hoerrlein S, Zapf S, Hilfrich J: Towards in-vitro prediction of an
in-vivo cytostatic response of human tumor cells with a fast chemosensitivity assay.
Toxicology 2001;166:97-108.
2] Cree I, Kurbacher C: Individializing chemotherapy for solid tumors-is there any
alternative? Anticancer Drugs 1997;8:541-548.
3] Di Nicolantonio F, Neale MH, Knight LA, Lamont A, Skailes GE, Osborne RJ, Allerton R,
Kurbacher CM, Cree IA: Use of an ATP-based chemosensitivity assay to design new
combinations of high-concentration doxorubicin with other drugs for recurrent ovarian cancer.
Anticancer Drugs 2002;13: 625-630.
4] Wright JL, Cobb JP, Gumport, F. M. Golomb, D. Safadi: Investigation of the relation
between clinical and tissue culture response to chemotherapeutic agents of human cancer. N
Engl J Med 1957;252:1207-1211.
5] Black MM, Spear FD: Further observations on the effects of cancer chemotherapeutic
agents on the in vitro dehydrogenase activity of cancer tissue. J Natl Cancer Inst
1954;14:1147.
6] Salmon SE, Hamburger AW, Soehnlen B, Durie BG, Alberts DS, Moon TE: Quantitation
of differential sensitivity of human-tumor stem cells to anticancer drugs. N Engl J Med
1978;298:1321-1327.
7] Von Hoff DD. Send this patient’s tumor for culture and sensitivity. N Engl J Med 1983;
308:154
8] Von Hoff DD, Sandbach JF, Clark GM, Turner JN, Forseth BF, Piccart MJ, Colombo N,
Muggia FM: Selection of cancer chemotherapy for a patient by an in vitro assay versus a
clinician. J Natl Cancer Inst 1990;82:110-6.
9] Sondak VK, Bertelsen CA, Tanigawa N, Hildebrand-Zanki SU, Morton DL, Korn EL,
Kern DH: Clinical correlations with chemosensitivities measured in a rapid thymidine
incorporation assay. Cancer Res 1984;44:1725-1728.
10] Kern DH, Weisenthal LM: Highly specific prediction of antineoplastic drug resistance
with an in vitro assay using suprapharmacologic drug exposures. J Natl Cancer Inst
1990;82:582-588.
11] Hoffman RM: Three-dimensional histoculture: origins and applications in cancer
research. Cancer Cells 1991;3:86-92.
12] Weisenthal LM, Kern DH: Prediction of drug resistance in cancer chemotherapy: the
Kern and DiSC assays. Oncology 1991;5:93-103.
13] Bosanquet AG, Copplestone JA, Johnson SA, Smith AG, Povey SJ, Orchard JA, Oscier
DG: Response to cladribine in previously treated patients with chronic lymphocytic leukaemia
identified by ex vivo assessment of drug sensitivity by DiSC assay. Br J Haematol 1999;106:
474-476.
14] Rotman B: Fluorescent cytoprinting: A simple nondestructive process for assessing
chemosensitivity in microorgan cultures. Proc Am Assoc Cancer Res 1989;30:654-655.
15] Wilson JK, Sargent JM, Elgie AW, Hill JG, Taylor CG: A feasibility study of the MTT
assay for chemosensitivity testing in ovarian malignancy. Br J Cancer 1990;62:189-194
16] Yamaue H, Tanimura H, Nakamori M, Noguchi K, Iwahashi M, Tani M, Hotta T,
Murakami K, Ishimoto K: Clinical evaluation of chemosensitivity testing fot patients with
colorectal cancer using MTT Assay. Dis Colon Rectum 1996;39:416-422
17] Taylor CG, Sargent JM, Elgie AW, Williamson CJ, Lewandowicz GM, Chappatte O, Hill
JG: Chemosensitivity testing predicts survival in ovarian cancer. Eur J Gynaecol Oncol
2001;22:278-282
18] Mosmann T: Rapid colorimetric assay for cellular growth and survival: application to
proliferation and cytotoxicity assays. J Immunol Methods 1983;65:55-63
19] Kurbacher CM, Cree IA, Bruckner HW, Brenne U, Kurbacher JA, Muller K, Ackermann
T, Gilster TJ, Wilhelm LM, Engel H, Mallmann PK, Andreotti PE. Use of an ex vivo ATP
luminescence assay to direct chemotherapy for recurrent ovarian cancer. Anticancer Drugs
1998;9:51-57.
20] Cree IA, Kurbacher CM: ATP-based tumor chemosensitivity testing: assisting new agent
development. Anticancer Drugs 1999;10:431-435
21] Lu DY, Chen XL, Ding J. Individualized cancer chemotherapy integrating drug sensitivity
tests, pathological profile analysis and computational coordination – An effective strategy to
improve clinical treatment. Medical Hypotheses 2006;66: 45-51
22] Hamburger AW, Salmon SE. Primary bioassay of human tumor stem cells. Science
1977;197:461-463
23] Hamburger AW, Salmon SE. Primary bioassay of human myeloma stem cells. J Clin
Invest 1977;60:846-854
24] Von Hoff DD, Sandbach JF, Clark GM, et al. Selection of cancer chemotherapy for a
patient by an in vitro assay versus a clinician. J Natl Cancer Inst 1990;82:110-116
25] Robert J. Chemosensitivity testing: Prediction of response to anticancer drugs in vitro
assays. Electronic Journal of Oncology 1999;2:198-210
26] Makin G, Hickman JA. Cell Tissue Res 2000;301:143-52
27] Kaspers GJ. Use of the differantial staining cytotoxicity assay to predict chemosensitivity.
Methods Mol Med 2005;110: 49-57
28] Singh B, Li RG, Xu L, Poluri A, Patel S, Shaha AR, Pfister D, Sherman E, Goberdhan A,
Hoffman RM, Shah J. Prediction of survival in patients with head and neck cancer using the
histoculture drug response assay. Head and Neck 2002;24: 437-442
29] Alley MC, Scudiero DA, Monks A, Hursey ML, Czerwinski MJ, Fine DL, Abbott BJ,
Mayo JG, Shoemaker RH, Boyd MR: Feasibility of drug screening with panels of human
tumor cell lines using a microculture tetrazolium assay. Cancer Res 1988;48:589-601
30] Ulukaya E, Colakogullari M and Wood EJ. Interference by anti-cancer chemotherapeutic agents in the MTT - tumor chemosensitivity assay. Chemotherapy 2004;50:43-50
31] Pirnia F, Frese S, Gloor B, Hotz MA, Luethi A, Gugger M, Betticher DC, Borner MM. Ex
vivo assessement of chemotherapy-induced apoptosis and associated molecular changes in
patient tumor samples. Anticancer Research 2006;26:1765-1772
32] Andreotti PE, Cree IA, Kurbacher CM, Hartmann DM, Linder D, Harel G, Gleiberman I,
Caruso PA, Ricks SH, Untch M, Sartori C, Bruckner H: Chemosensitivity testing of human
tumors using a microplate adenosine triphosphate luminescence assay: clinical correlation for
cisplatin resistance of ovarian carcinoma. Cancer Res 1995;55:5276-5282
33] Cree IA, Kurbacher CM, Untch M, Sutherland LA, Hunter EM, Subedi AMC, James EA,
Dewar JA, Preece PE, Andreotti PE and Bruckner HW. Correlation of the clinical response to
chemotherapy in breast cancer with ex vivo chemosensitivity. Anticancer drugs 1996;7:63035
34] Andreotti PE, Linder D, Hartmasnn DM, Cree IA, Pazzaglia M, Bruckner HW. TCA-100
tumor chemosensitivity assay: differences in sensitivity between cultured tumour cell lines
and clinical studies. J Biolumin Chemilumin 1994;9:373-78
35] Konecny G, Crohns C, Pegram M, Felber M, Lude S, Kurbacher C, Cree IA, Hepp H, and
Untch M. Correlation of drug response with the ATP tumorchemosensitivity assay in primary
FIGO stage III ovarian cancer. Gynecologic Oncology 2000;77:258-263
36] Kurbacher CM, Grecu OM, Stier U, Gilster TJ, Janat MM, Untch M, Konecny G,
Bruckner HW, Cree IA. ATP chemosensitivity testing in ovarian and breast cancer: early
clinical trials. Recent Results Cancer Res 2003;161:221-30
37] O’Meara AT, Sevin B-U. Predictive value of the ATP chemosensitivity assay in epithelial
ovarian cancer. Gynecological Oncology 2001;83:334-342