In vitro antiproliferative effect of cancer chemotherapeutic agents and their combination with interferon in renal cell carcinoma

We studied an antiproliferative effect of cancer chemotherapeutic agents, interferon (IFN) and, in particular, their combination effect on renal cell carcinoma. Either of colony formation assay (CFA) or [3H]-thymidine incorporation assay ([3H]-TdR assay) was employed as an in vitro chemosensitivity testing system. When compared, these two systems produced similar results with a good correlation (r = 0.97, p less than 0.01), in the antiproliferative effect of 30 drugs for 4 primary renal cell carcinomas and 5 xenotransplantable renal cell carcinomas. In vitro chemosensitivity test (CFA or [3H]-TdR assay) screened successfully only 5 "sensitive" drugs (7.9%) out of a total 63 cancer chemotherapeutic agents for 24 human renal cell carcinoma. This confirmed the findings reported by others. In the study of the antiproliferative effect of a cancer chemotherapeutic agent, human lymphoblastoid interferon (HLBI) and their combination on human renal cel carcinoma cell line (SMK-R2). Each of VBL, MTX or HLBI tended to suppress [3H]-TdR uptake in a dose-dependent manner. The combination of VBL (0.05 microgram/ml) and HLBI (10(2) or 10(3) IU/ml) produced a subadditive effect, and that of MTX (0.1 microgram/ml) and HLBI 10(2) IU/ml produced a synergistic effect on the human renal cell carcinoma cell line, the effect which is evaluated by Valeriote and Lin's criteria of combination. In particular, the synergistic effect by MTX and HLBI under the clinically achievable drug concentration seems important, when its clinical application is considered.     

In vitro chemosensitivity testing of renal cell cancer. Short-term culture technique

In an attempt to solve the problem of chemosensitivity testing of renal cell carcinoma in vitro, a modified short-term culture technique was developed. The kinetic study of hypernephroma cells and normal renal cells showed that the uptake of H3-uridine and H3-thymidine is at its maximum after eighty hours. The effect of doxorubicin, cisplatinum, vinblastine, and mitomycin C in different concentrations was tested. Tumors generally showed more resistance than sensitivity. Some tumors showed sensitivity to one or more drugs, but no one drug was persistently effective in all tumors. Our short-term culture technique solved the discrepancy between cell kinetics and test duration found in the Volm test and the problem of nongrowth in the clonogenic assay.     

In vitro drug sensitivity testing in human gliomas

In vitro drug sensitivity assays have been developed with the goal of predicting the clinical response to chemotherapy. The colony-forming assay, radiolabeled precursor inhibition assay, and microcytotoxicity assay are most commonly used. In retrospective studies, the assays correctly predict clinical response to a chemotherapeutic agent in 50% to 70% of patients and predict clinical resistance in nearly 100% of patients. All of the assays suffer from technical and theoretical problems. In vitro assays depend on cell culture and therefore do not entirely simulate in vivo conditions. Heterogeneity in chemosensitivity is commonly found and can complicate the interpretation of results. Further investigation is needed to determine if these assays will be able to select prospective chemotherapy for patients. The malignant origin of the cells in culture must be verified if meaningful conclusions are to be made.     

Comparison of in vitro cloning assays for drug sensitivity testing of human brain tumours

Three in vitro clonogenic assays were used to determine the sensitivity of an established human glioblastoma cell line (U251-MG) to five chemotherapeutic agents. The colony-forming efficiency of untreated culture was 0.695 +/- 0.170 in a monolayer assay with irradiated feeder cells, 0.018 +/- 0.006 in a low-O2 agar assay, and 0.049 +/- 0.021 in a two-layer agar system with nutrient-enriched medium (p less than 0.001). Comparison of the slope of the regression line for the dose-response curve and the interpolated ID90 for each drug showed that U251-MG was equally sensitive to aziridinylbenzoquinone and dianhydrogalactitol in all three assays. The sensitivity of this cell line to 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU), cis-dichlorodiammineplatinum (II) (CDDP) and 9-hydroxy-2-N-methylellipticine (HME), however, varied depending on the assay used. In no instance did U251-MG show greater sensitivity (lower ID90 or steeper slope) in the low-O2 agar assay than in the other assays. BCNU and CDDP were least active in the monolayer assay, whereas HME showed both the lowest ID90 and steepest slope using this technique. We conclude that different in vitro tumour clonogenic assays show different colony-forming efficiencies for the same cell line and may show different responses to certain drugs. Identification of accurate predictive models of drug sensitivity will require correlative in vivo and in vitro studies.     

Combined effect of tumor necrosis factor alpha and anticancer chemotherapeutic agents against human renal carcinoma cell lines.

Antitumor effect of recombinant human tumor necrosis factor alpha (TNF) alone or in combination with various anticancer chemotherapeutic agents was tested using an in vitro antiproliferative assay on four human renal carcinoma cell lines (VMRC-RCW, VMRC-RCZ, Caki-1 and A-498). When the dose-dependent effect of TNF was studied, none of the four cell lines showed a 50% or more inhibition even at a concentration of 10,000 U/ml of TNF, so that the susceptibility to TNF was low. An enhancing effect of TNF on the cytotoxic effect of almost all the chemotherapeutic agents tested was observed against VMRC-RCZ and A-498. Against VMRC-RCW and Caki-1, the combination of TNF with the chemotherapeutic agents did not result in an enhancing effect. Mitomycin C showed an enhancing effect of TNF against all four cell lines. These results suggested that the combined treatment of TNF with chemotherapeutic agents may have favorable results in clinical trials.     

Soft agarose colony formation assay for human renal cell carcinoma: comparison of optical colony counting versus tritiated thymidine incorporation

Use of the Hamburger-Salmon soft agar assay method for in vitro chemotherapy sensitivity testing of samples of renal cell carcinoma has been somewhat limited by a relatively low proliferation/evaluability rate for this tumor type (approximately 50%). The tritiated thymidine ([ 3H]-TdR) incorporation assay method of Tanigawa et al. (Cancer Res., 42: 2159, 1982) was compared to a standard optical colony counting assay technique. Fifty-seven different primary and five metastatic fresh samples of human renal cell carcinoma were studied. Evaluability rate by the [3H]-TdR assay was 90% (greater than or equal to 300 cpm control). In comparison, evaluability rate by optical colony counting was 43% for this group of tumors. [3H]-TdR incorporation increased with increasing tumor grade and increasing stage. Spindle cell tumors showed significantly higher cpm than other cell types. Twenty-three primary tumors were evaluable by both [3H]-TdR and colony counting methods. The correlation coefficient ("r") for regression lines for drug sensitivity data points (optical counting vs. [3H]-TdR) of these individual experiments ranged from 0.50 to 0.99 with a mean r +/- S.D. of 0.76 +/- 0.15. For all 260 paired drug response observations of 23 tumors exposed to different drugs, the correlation was very good with r = 0.71. Since the [3H]-TdR assay has an evaluability rate of approximately 90% for renal cell carcinoma, gives drug sensitivity information which correlates well with the colony counting endpoint and yields chemotherapy sensitivity information four days after sample accession, the [3H]-TdR assay may be a more useful method for study of human renal cell carcinoma in vitro chemotherapy sensitivity testing than standard colony counting techniques.     

Caspofungin is less nephrotoxic than amphotericin B in vitro and predominantly damages distal renal tubular cells.

BACKGROUND: Caspofungin (CAS) has recently been approved for treatment of invasive aspergillosis. In clinical trials, CAS-induced nephrotoxicity was markedly less pronounced compared to amphotericin B (AmB). Nevertheless, in a recent trial, nephrotoxicity in CAS-treated patients was considerably more pronounced than in preceding studies. Therefore, the aim of this study was to assess toxic effects of CAS on human renal proximal and distal tubular epithelial cells (PTC and DTC) in vitro, and to compare them to those of AmB. METHODS: Cells were isolated from human kidney tissue, and exposed to clinically relevant concentrations of CAS and AmB for 24 h. Total DNA content and cell viability were determined by DAPI staining and a modified MTT assay. For testing of cytotoxicity, LDH activity was measured in cell culture supernatants. To assess apoptotic effects, AnnexinV-binding assay and DAPI staining for detection of fragmented DNA were performed. RESULTS: DTC were more vulnerable towards the antifungal agents than PTC. In contrast to AmB, cell-damaging effects of CAS were less severe. DAPI staining revealed slight and dose-dependent antiproliferative effects of CAS at concentrations reflecting relevant plasma levels. At these concentrations, cell viability, determined by MTT assay, was not decreased in PTC and DTC. LDH release was marginally increased in a dose-dependent manner; apoptosis was not detected. Nevertheless, at CAS concentrations reflecting potential tissue concentrations, cell damaging effects were considerably more pronounced. CONCLUSION: Our results suggest that CAS is less nephrotoxic than AmB in vitro. The antiproliferative and cytotoxic effects of CAS predominantly affect DTC, which seem to be more susceptible to CAS-induced damage.     

Recombinant human tumor necrosis factor alone and with chemotherapeutic agents. Effect on nude mouse-supported human bladder cancer heterografts

Although studies done in tissue culture (in vitro) have shown synergism between recombinant human tumor necrosis factor (rhTNF) and chemotherapeutic agents, whether such synergism exists in a complex in vivo environment with acceptable toxic side effects has not been determined, to our knowledge. The effect of rhTNF alone and in combination with cisplatin, etoposide, doxorubicin, or dactinomycin on the growth of heterotransplants of human bladder transitional cell carcinoma was studied using a modified subrenal capsule assay in athymic nude mice. Only etoposide potentiated rhTNF cytotoxicity; no increase in host toxicity was noted. Variably enhanced toxic side effects were seen with other combinations. It is concluded that rhTNF combined with etoposide may have potential clinically exploitable therapeutic "synergism" in the treatment of advanced bladder cancer.     

大肠癌细胞和外周血淋巴细胞对化疗药物的体外敏感性

目的:探讨大肠癌细胞及外周血淋巴细胞对化疗药物体外敏感性的及二者的相关性。方法:用MTT法检测40份大肠癌标本及外周血淋巴细胞对氟尿嘧啶(5-FU)、奥沙利铂(L-OHP)、伊立替康(CPT)单药、两药及三药(全量或半量)应用的敏感性。结果:单药最有效的药物依次为伊立替康、奥沙利铂和氟尿嘧啶,敏感率分别为35.0%、27.5%和20.0%;三药联合应用的抑制效果显著优于两药联合(P<0.05),三药全量及半量联合应用效果差异无显著性(P>0.05);癌细胞及外周血淋巴细胞对3种化疗药物的敏感性有很好的相关性(r=0.969)。结论:MTT可用于为大肠癌患者选择合适的化疗药物,由氟尿嘧啶、奥沙利铂及伊立替康的联合应用具有高效协同抑制大肠癌细胞的作用。     

In vitro chemosensitivity testing and its clinical application in human gliomas

Several in vitro chemosensitivity assays have been developed for predicting clinical response to chemotherapeutic and biologic agents, alone and in combinations. The most widely accepted assay is the colony forming assay (CFA) which assesses the clonogenic capability of stem cells. Other methods include growth inhibition assays by evaluating cell number; thymidine incorporation; or amino acid uptake. More recently an automatic colorimetric technique utilizing crystal violet dye or a tetrazolium (MTT) vital dye has been developed for more rapid assessment of cytotoxic or growth inhibitory activity in vitro. Several reports have compared the results of in vitro tests with patients' clinical response. Two major problems affect the predictive value of in vitro chemosensitivity tests. The foremost is cellular heterogeneity which exists within a single tumor as well as between tumors. Artificial selective pressure inherent to tissue culture system is the other problem. In general, in vitro tests predict clinical resistance more consistently than clinical sensitivity. However, chemosensitivity assays remain useful in screening new agents and preclinical modeling of clinical trials.     

Human renal cell carcinoma xenograft: morphology, growth and chemosensitivities

A primary human renal clear cell carcinoma has been developed as a xenograft (JDF-1). Passage 7 of the JDF-1 tumor retained the microscopic morphology of the primary tumor, electron micrographs have confirmed its epithelial characteristics and karyotyping of a subsequent passage has proved it is not a murine hybrid. Immunoperoxidase studies using a panel of murine monoclonal antibodies demonstrate an antigenic phenotype specific for human renal cancer. In vitro chemosensitivities of the JDF-1 tumor were determined by the double-layer soft-agar clonogenic assay method. JDF-1 showed no significant sensitivities to several standard chemotherapeutic agents, but alpha-2-interferon and difluoromethylornithine in combination synergistically inhibited its growth by 74 per cent.     

Studies on in vitro anti-tumor activity of tumor necrosis factor alpha against human renal carcinoma cell line (KU-2)]

We attempted to clarify the anti-tumor activity and its mechanism of human recombinant tumor necrosis factor alpha (rTNF alpha). The established cell line KU-2, derived from human renal cell carcinoma, was treated with rTNF alpha alone or in combination with the following anti-cancer agents in vitro: actinomycin D (ACD), vinblastine sulfate (VLB), nimustine hydrochloride (ACNU), and methotrexate (MTX). In vitro studies, including cytotoxic assay, colony forming assay and flow cytometric DNA analysis were performed. By cytotoxic assay, 21.4 +/- 4.0% and 34.8 +/- 4.7% of the cells were killed by 72 hour incubation with 100 ng/ml of rTNF alpha alone, and 1 ng/ml of ACD alone, respectively. An augmented cytotoxicity of 75.3 +/- 0.3% was observed by simultaneously adding 1 ng/ml of rTNF alpha and 1 ng/ml ACD. However, when KU-2 was treated with both 100 ng/ml of rTNF alpha and 3 micrograms/ml of ACNU or 2.5 ng/ml of MTX, no significant increase in cytotoxicity was noted. In the colony forming assay study, the colony forming efficiency (CE) of the control cultures was 31.8 +/- 8.1%. A 92.3 +/- 1.8% reduction in CE was demonstrated when 100 ng/ml of rTNF alpha was added to the cultures. No augmented effects were seen between rTNF alpha and chemotherapeutic agents in this study. In flow cytometric DNA analysis, no cell cycle specific effects of rTNF alpha were demonstrated, regardless of whether or not chemotherapeutic agents were added. These results indicate that the cytotoxic and cytostatic activities of rTNF alpha may be mediated by separate mechanisms of action and that rTNF alpha affects more markedly KU-2 cells having clonogenic potentials.(ABSTRACT TRUNCATED AT 250 WORDS)     

New potent verapamil derivatives that reverse multidrug resistance in human renal carcinoma cells and in transgenic mice expressing the human MDR1 gene.

Multidrug resistance in human renal cell carcinoma is mainly caused by expression of the MDR1 gene and is characterized by a broad spectrum cross resistance to many natural product chemotherapeutic agents. This resistance can be overcome by applying chemosensitizers which inhibit the function of the MDR1 gene product P-glycoprotein. The development of new reversing agents with fewer side effects and a higher potency in modifying resistance is a high priority of research on drug resistance. We have evaluated four new verapamil derivatives on 21 primary human renal cell carcinomas in vitro, and also tested them in an MDR-transgenic mice model. These mice express the human MDR1 gene in their bone marrow cells and measurement of their white blood counts provides a simple, rapid and reliable system to screen for the potency of MDR-reversing agents in vivo. We demonstrate here that all four drugs are effective in reversing multidrug resistance in primary cultures of human renal cell carcinomas when used in combination with vinblastine chemotherapy, and to a lesser extent with doxorubicin or daunomycin chemotherapy. Our in vivo data indicate that two of these reversing agents display low toxicity at high concentrations and are more effective at low, clinically achievable concentrations, than the other two drugs and R-verapamil. These results make the two new drugs attractive candidates to be taken into clinical trials.     

A method for evaluation of brain tumor growth using implantable diffusion chambers

Major drawbacks associated with in vitro assays for sensitivity of brain tumors to specific chemotherapeutic drugs include uncertainty of end-point validity, the need for large tissue samples, and cost. Furthermore, these assays do not address the question of conversion of the drug to active moeities by metabolic pathways in the host or alteration of drug activity by binding to plasma protein. We propose to develop a technique for growth and quantitation of tumor cells in small-pore diffusion chambers that contain the tumor cells and protect them from the immune system of the immunologically unrelated host. These chambers, fabricated from acrylic rings and membranes of 0.22 microns pore size, are sterilized, filled with a precisely quantitated inoculum of tumor cells, and implanted in the peritoneal cavity of rats. Replication of the cells is determined by enzymatic digestion of the supporting matrix of the cells within the chamber and counting the single cell suspension with a hemocytometer or automated cell counter. Precise comparison can thus be made between different drugs regarding their effect on cell growth in the host. This assay can be performed with the basic equipment and personnel available in most cell culture laboratories and requires a small number of tumor cells. Mass production of the diffusion chambers may make the assay less costly and faster than assays that do not involve exposure of tumor to drug in a living host. In addition, the assay should permit screening of new chemotherapeutic agents against human tumors under physiologic conditions.     

Effect of hyperthermia on the cytotoxicity of 4 chemotherapeutic agents currently used for the treatment of transitional cell carcinoma of the bladder: an in vitro study

PURPOSE: Hyperthermia combined with chemotherapy is not a novel cancer treatment. However, the working mechanism of this combination therapy is not fully understood. In the current in vitro study we investigated the differences in cytotoxicity of 4 chemotherapeutic agents at 37C or 43C. MATERIALS AND METHODS: The human transitional cell carcinoma cell lines used were RT4, RT112, 253J and T24. Cells were seeded in 96-well microtiter plates. After 24 hours cells were treated for 60 minutes with increasing concentrations of mitomycin C, epirubicin, gemcitabine and EO9 at a temperature of 37C or 43C. After treatment cells were rinsed 3 times and left for 24 hours in the incubator at 37C. The influence of chemotherapy and temperature on cell survival was determined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide) assay. RESULTS: Decreased cell proliferation with increasing concentrations of chemotherapeutic agents was demonstrated. EO9 proved to be the most potent agent at each temperature. Hyperthermia alone did not demonstrate decreased cell proliferation. However, a synergistic effect on decreased cell proliferation was demonstrated in all cell lines and chemotherapeutic agents used, although each had a maximum at a different chemotherapy concentration and to a different extent. Synergism was most obvious in cell lines treated with low dose epirubicin. CONCLUSIONS: Synergism with hyperthermia and chemotherapy was clearly demonstrated for epirubicin, EO9, mitomycin C and to a lesser extent gemcitabine. Hyperthermia alone did not cause decreased cell proliferation. Synergism was most prominent with low drug doses and the most potent drug used in this in vitro study was EO9.     

Soft agar colony formation assay for in vitro chemotherapy sensitivity testing of human renal cell carcinoma: Mayo Clinic experience

Two hundred six different samples of human renal carcinoma were tested for in vitro chemotherapy sensitivity using a soft agar colony formation assay similar to that originally described by Salmon and colleagues. Eighty of 159 (50 per cent) evaluable tumor tests showed colony formation in vitro and gave clinical drug sensitivity information. Two-thirds of tumors were resistant to all drugs tested, despite a median number of drugs tested per tumor of 14.5. Five tumors (6 per cent) were remarkably sensitive to numerous anticancer drugs in vitro. The most active drugs found in vitro were teniposide, actinomycin D, bleomycin, hydroxyurea, mitoguanazone dihydrochloride, mitomycin C and L-alanosine. Fourteen other drugs tested showed low in vitro cytotoxicity.     

Stem cell studies of human malignant brain tumors. Part 2: Proliferation kinetics of brain-tumor cells in vitro in early-passage cultures

The proliferation kinetics were studied in early-passage cultures of cells from 13 human malignant brain tumors and two specimens of normal brain under conditions similar to those used in clonogenic cell-survival studies. Autoradiography was performed in all but four cases to estimate the fraction of cells actively replicating deoxyribonucleic acid (DNA), the approximate cell cycle time, and the effect of low-dose tritiated thymidine on cell proliferation. The mean tumor cell doubling time (TD) was 53 hours for five glioblastomas, 46 hours for two ependymomas, and 83 hours for two medulloblastomas. A gliosarcoma grew fastest (TD = 22 hours) in culture and a pilocytic astrocytoma grew slowest (TD = 144 hours). The approximate cell cycle time ranged from 1 to 2.5 days for all tumors tested. This suggests that chemotherapeutic agents that predominantly kill proliferating cells should be administered in vitro for at least 2 to 2.5 days to achieve maximum cell kill. The approximate growth fraction ranged from 0.65 to 0.96 for all tumors except for the two medulloblastomas and the pilocytic astrocytoma, which had growth fractions of 0.34 and 0.35, respectively. Most laboratories investigating the chemosensitivity of primary or early-passage human tumor cells require that 40% to 70% of cells be killed to consider a drug active in vitro. The results of this study suggest that the cell-cycle-specific agents cannot achieve a high enough cell kill to be considered active for some tumors that grow slowly in culture. An estimate of the in vitro growth rate is necessary to reliably interpret cell-survival results with such agents. Tritiated thymidine appeared to slow cell proliferation in some of the cultures, presumably as a result of radiation-induced DNA damage caused by tritium that had been incorporated into DNA. The degree to which cell growth ws slowed in individual tumors correlated with the patient's clinical response to radiation therapy and postoperative survival time.     

In vitro effects of combination chemotherapy on osteoblasts: implications for osteopenia in childhood malignancy

Clinical studies suggest that combination chemotherapy adversely affects bone metabolism and in vitro studies have demonstrated that a reduction in osteoblast numbers results in diminished bone formation. The aim of this study was to investigate the in vitro effects of combinations of chemotherapeutic agents on primary human osteoblast-like (hOB) cell numbers and apoptosis, and to assess the ability of hOBs and osteoprogenitor (HCC1) cells to recover from prior treatment with chemotherapy. As glucocorticoids are frequently administered during treatment with cytotoxic agents, we evaluated whether glucocorticoids influence the chemosensitivity of hOB and human osteosarcoma (MG63) cells. Culture with clinically relevant concentrations of the individual chemotherapeutic agents reduced hOB cell numbers compared with control (p < 0.01) and also increased the numbers of apoptotic cells (p < 0.05). Potentiation of cytotoxicity was observed when agents were given in combination, thus further reducing cell numbers, and this effect was greatest when vincristine was given in combination with asparaginase. Following culture with a chemotherapeutic agent, there was greater recovery of hOB compared with HCC1 cell numbers (p < 0.01). Pretreatment with glucocorticoids ameliorated the adverse effects of chemotherapeutic agents on hOB and MG63 cell numbers and apoptosis (p < 0.05). We conclude that the use of combination chemotherapy contributes to osteopenia in childhood malignancy by a reduction in osteoblast numbers. However, this effect may be attenuated by the concomitant use of glucocorticoids.     

Prediction of individual tumor chemosensitivity in subrenal capsule assay

Fifty-three tumor specimens, including thirty-one stomach and seven esophageal cancers, were examined to determine the individual tumor sensitivity to chemotherapeutic agents. Using the subrenal capsule assay (SRC assay), tumor specimens were implanted under the renal capsule of male, 8 week old ddY mice, after cutting the tissues into 1.5 mm cubed fragments. Following the implantations, chemotherapeutic agents were injected daily for 3 days and the relative variations of tumor weights were calculated. An 84.9 per cent of the total evaluability rate was obtained and implanted tumor specimens responded to chemotherapeutic agents in 26.7 per cent. The correlation rate between tumor sensitivity in SRC assay and clinical responses was obtained in 72.9 per cent. The predictive accuracy rate of the clinical responses was 50.0 per cent, while 100 per cent of the prediction rate of clinical resistance was obtained. With regard to upper gastro-intestinal cancers, 83.9 per cent of the evaluability rate and 18.2 per cent of response rate in SRC assay were obtained. These results indicate that this assay is equivalent to other procedures for predicting individual tumor sensitivity.     

Prediction of individual tumor chemosensitivity in subrenal capsule assay

Fifty-three tumor specimens, including thirty-one stomach and seven esophageal cancers, were examined to determine the individual tumor sensitivity to chemotherapeutic agents. Using the subrenal capsule assay (SRC assay), tumor specimens were implanted under the renal capsule of male, 8 week old ddY mice, after cutting the tissues into 1.5 mm cubed fragments. Following the implantations, chemotherapeutic agents were injected daily for 3 days and the relative variations of tumor weights were calculated. An 84.9 per cent of the total evaluability rate was obtained and implanted tumor specimens responsed to chemotherapeutic agents in 26.7 per cent. The correlation rate between tumor sensitivity in SRC assay and clinical responses was obtained in 72.9 per cent. The predictive accuracy rate of the clinical responses was 50.0 per cent, while 100 per cent of the prediction rate of clinical resistance was obtained. With regard to upper gastro-intestinal cancers, 83.9 per cent of the evaluability rate and 18.2 per cent of response rate in SRC assay were obtained. These results indicate that this assay is equivalent to other procedures for predicting individual tumor sensitivity.