Limitations of the fast green assay for chemosensitivity testing in human lung cancer

Ex vivo programmed cell death and the prediction of response to chemotherapy

Since the earliest introduction of cytotoxic chemotherapy, investigators have pursued laboratory techniques designed to match patients to available drugs. Most of the work, published through the 1980s, reflected the prevailing view of cancer as a disease of dysregulated cell proliferation. Noteworthy, the description of apoptosis and programmed cell death, fundamental to our modern understanding of human tumor biology, did not occur until well after the heyday of in vitro chemosensitivity testing. By incorporating the modern tenets of carcinogenesis associated with perturbations in cell survival we can now re-examine laboratory assays of drug response in the context of drug-induced programmed cell death. Although there is interest in the use of genomic analyses for the prediction of chemotherapy response, the painful recognition that genotype does not equal phenotype will continue to limit broad application of these platforms. Biosystematics instructs that biological pathways rarely follow predicted routes. Efforts to force human biology to behave according to preconceived scientific dictates have proven costly and unsuccessful. Whole-cell experimental models with the capacity to evaluate all the operative mechanisms of cellular response to injury, acting in concert, provide valid tools for the study of human cancer. Educated by cellular behavior, we can expeditiously examine molecular processes of interest. This article briefly reviews the history of whole-cell experimental models of in vitro chemosensitivity testing then focuses on cell-death measures as the most robust predictors of clinical outcome in human cancer.

In vitro response of human small-cell lung-cancer cell lines to chemotherapeutic drugs; no correlation with clinical data

Three cell lines derived from small-cell lung carcinoma (SCLC) tumors of patients who had no clinical response after treatment with a multi-drug regimen were compared to 3 cell lines derived from tumors of patients who, upon treatment, showed a complete clinical response. These 2 groups of cell lines were considered to represent the in vitro counterparts of the 2 extremes of the clinical spectrum of sensitivity for chemotherapeutic drugs in small-cell lung cancer. To assess whether the in vivo (in)sensitivity of a tumor to a certain drug regimen is retained in vitro, the cell lines were tested for drug sensitivity using the microtiter-well tetrazolium assay and the results were compared with the in vivo data. No correlation was found. Since in vitro models using cell lines are based on the assumption that a cell line reflects the properties of the tumor from which it is derived, several additional parameters such as MAb staining against different SCLC-associated antigens and DNA content were analyzed in the biopsies and the cell lines. The results showed that selection of discrete tumor-cell populations in vitro occurs. Results of in vitro chemosensitivity testing for individual SCLC patients should be interpreted with caution.