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The development of reliable methods for the in vitro testing of sensitivity of cancer cells to various drugs has been a longstanding objective in cancer treatment. The development of individualized chemotherapy could minimize undesired toxic side effects and increase the chance of recovery. The known methods for in vitro chemosensitivity tests are mainly based on monitoring the metabolic changes induced in cancer cells by the drugs. These experiments, as well as attempts to cultivate isolated cancer cells, did not give reliable results. In this study, I used a marker for proliferation to detect the effect of drugs on the potential of cancer cells to divide. An ideal marker should be present in all cells, be expressed early in the cell cycle, and have a short half-life. Ornithine decarboxylase (ODC), which catalyzes the conversion of ornithine to putrescine, fulfilled these prerequisites. Because ODC has an extremely short half-life, it disappears when cellular proliferation is arrested. The decay of ODC was assayed both by determining its activity and by immunohistochemical analyses. This approach was successfully used to determine the sensitivity of lymphocytes from hematological cancer patients to various drugs. It is conceivable that this method could serve as an important tool to improve cancer chemotherapy. [ABSTRACT FROM AUTHOR]

Chemosensitivity is affected by molecular biological factors, including factors related to the induction of apoptosis and the activity of proliferation. We analyzed immunohistochemically the expression of p53, Bcl-2, and Ki-67 in various types of cancers and assessed the correlation between this expression and chemosensitivity. Moreover, we investigated whether the expression of these factors could be a useful predictor for the clinical response to chemotherapy. Study subjects comprised 63 preoperative patients with untreated malignant tumors (9 with esophageal cancer, 12 with stomach cancer, 12 with colon cancer, 16 with liver cancer, and 14 with breast cancer). Immunohistochemical staining (the labeled streptavidin biotin technique: LSAB method) was used to assess expression of p53 protein, Bcl-2 protein, and Ki-67. A chemosensitivity test was carried out with the histoculture drug response assay method using four drugs: mitomycin C, 5-fluorouracil, doxorubicin hydrochloride (ADM), and cisplatin (CDDP). Immunohistochemical studies for p53 were found to be useful for predicting chemosensitivity. [ABSTRACT FROM AUTHOR]

A method of assessing chemosensitivity of tissue utilizing tissue fluorescence and image analysis was implemented to provide a rapid and quantitative means of assessing the effect of drugs on tissue metabolic activity and proliferative capacity. The fluorescent microscopic image captured by a silicon-intensified target (low-light-detecting) camera and linked to an imageprocessing unit was measured for fluorescent brightness and tumor image area. An established rodent model served to characterize the system's ability to measure serially the tumor's metabolic activity and growth. Further studies on fresh human tumors were conducted with a novel topoisomerase II inhibitor, NC-190. Tumor image area and fluorescent brightness were measured 24 h pretreatment, 48 h posttreatment, and 48 h post-drug removal. Fifty-five percent (28/51) of fresh human tumors showed sensitivity to 48-h exposure to 10, 30, or 100 MNC-190. The potential benefit of this technique is the ability to predict the response of tumors to chemotherapeutic agents as a laboratory tool for preclinical drug evaluation and clinically prior to the commencement of therapy. [ABSTRACT FROM AUTHOR]

The mainstay of clinical antineoplastic chemotherapy is multiagent combinations, most of which were developed empirically. Because of the desire to speed research and decrease costs, there is increasing interest in moving new drugs into clinical trials in potentially active combinations based on preclinical testing data. Different mathematical models have been proposed for evaluating drug interactions, which can be classified as synergistic (combinations demonstrating greater than the additive activity expected from each agent alone), additive, or antagonistic (drugs showing less activity in combination than expected from the sum of each agent alone). Here, we briefly review some of the principles for testing cytotoxic drug interactions. We focus this review on application of the Combination Index method (as developed by Chou and colleagues) in the evaluation of drug interactions in cell culture assays. [ABSTRACT FROM AUTHOR]

We provide a detailed description of the ChemoFx® Assay, a phenotype-based cell culture assay for predicting anticancer drug responses in individual cancer patients. The ChemoFx Assay is based on the outgrowth and short-term primary culture of epithelial cells derived from pieces of solid tumor adenocarcinomas that are obtained at the time of tumor resection. Malignant epithelial cells are grown attached in wells of microtiter plates and treated with six escalating doses of chemotherapeutic drug. Using an operator-controlled automated image analysis system, cell kill is measured microscopically by counting the number of live cells remaining after dead cells have detached and are subsequently rinsed away. A dose-response graph is automatically generated by comparing the number of cells in drug-treated wells with those in control wells. [ABSTRACT FROM AUTHOR]

Reliable assessment of cell death is now pivotal to many research programs aiming at generating new antitumor compounds or at screening cDNA libraries to identify genes with pro - or antiapoptotic functions. Such approaches need to rely on reproducible, easy handling, and rapid microplate-based cytotoxicity assays that are amenable to high-throughput screening technologies. We describe here a method for the direct measurement of cell death, based on the detection of a decrease in fluorescence observed following death induction in cells stably expressing enhanced green fluorescent protein (EGFP). Our data clearly show that such a decrease in EGFP fluorescence after cell death induction happens in various cell types, including those routinely used in anticancer drug screening (i.e., murine and human, lymphoid, fibroblastic, or epithelial cell lines). Moreover, the decrease in EGFP fluorescence is observed in cells induced to die by a variety of apoptosis-inducing agents, such as glucocorticoids (dexamethasone), DNAdamaging agents (etoposide, cisplatin), microtubule disorganizers (paclitaxel), protein kinase C inhibitors (staurosporine), or a caspase-independent apoptotic stimulus (CD45 crosslinking). A decrease in fluorescence can be assessed either by flow cytometry or with a fluorescence microplate reader. The kinetics and specificity of this EGFP-based assay were comparable with those of other conventional techniques used to detect cell death. This novel EGFP-based microplate assay combines sensitivity and rapidity and is amenable to high-throughput setups, making it an assay of choice for evaluation of cell cytotoxicity. [ABSTRACT FROM AUTHOR]

DIMSCAN is a semiautomatic fluorescence-based digital image microscopy system that quantifies relative total (using a DNA stain) or viable (using fluorescein diacetate [FDA]) cell numbers in tissue culture multiwell plates ranging from 6 to 384 wells per plate. DIMSCAN is a rapid and efficient tool for conducting in vitro cytotoxicity assays across a 4 log dynamic range. The specificity of detecting viable cells with FDA is achieved by using digital image processing and chemical quenching of fluorescence in nonviable cells with eosin Y. Average scan time for the most commonly used format, a 96-well plate, is 6 min. Cytotoxicity for neuroblastoma cell lines measured by DIMSCAN was found to be comparable to manual Trypan blue dye exclusion counts or colony formation in soft agar, but with a significantly wider dynamic range, which enables drug combination studies used to detect synergistic or antagonistic interactions. The linearity of DIMSCAN was validated (r2 = 0.99967 ± 0.0003) for cells stained with FDA deposited using a fluorescence-activated cell sorter, documenting a dynamic range>4 logs, and the ability to detect a single viable cell in a well 93‰ of the time. DIMSCAN has been used to demonstrate preclinical activity of cytotostatic and cytotoxic drugs and drug combinations that have subsequently shown activity in clinical trials. [ABSTRACT FROM AUTHOR]

We provide a detailed explanation of the procedure of the histoculture drug response assay (HDRA) with 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) end point among several modified HDRA procedures. Fresh surgical specimens are cut into approx 1- to 2-mm3 pieces and put on a gelatin sponge infiltrated with culture medium containing a test drug. After incubation for 7 d, cell viability is assessed by the MTT assay. HDRA uses cancer tissue fragments with cells growing in three dimensions, with maintenance of intercellular contact and interactions with stromal cells. Therefore, it seems that HDRA can assess the sensitivity of tumor cells to anticancer drugs in conditions similar to those in vivo and, consequently, shows high prediction rate. [ABSTRACT FROM AUTHOR]

During the last two decades, novel nonclonogenic methods for pretherapeutic chemosensitivity testing have been developed that are likely to overcome major technical limitations of older assays such as low evaluability rates, low degree of standardization and reproducibility, lack of technical robustness, and poor methodological efficacy. Among these, the microplate adenosine triphosphate (ATP)-based tumor chemosensitivity assay (ATP-TCA) has gained particular merits for ex vivo chemosensitivity testing of native nonhematological tumors including cancers of the breast, ovary, gastrointestinal tract, cervix and corpus uteri, and lung; malignant melanomas; gliomas; sarcomas; and mesotheliomas. For this indication, the ATP-TCA can now be considered the best documented and validated technology. This assay, which is now commercially available, provides a highly reproducible, easy-to-handle kit technique; low technical failure rates; and a high methodological efficacy requiring only 1 × 106 tumor cells to test four to six different drugs or combinations. In ovarian and breast carcinomas, the predictive accuracy is <90%, with a positive predictive value of 85-90‰ and a negative predictive value near 100‰, respectively. In primary ovarian cancers, the ATP-TCA has been found to accurately predict both clinical response and survival. In two prospective clinical trials in patients with heavily pretreated ovarian cancer, chemotherapy individually selected by the ATP-TCA has been found to triple the response rates and nearly double the survival compared to empirically chosen regimens. Consequently, this assay, which is now under phase III evaluation, has successfully been used in new agent development to screen for novel chemotherapy regimens for the treatment of patients with breast and ovarian carcinoma and melanoma, respectively. This chapter highlights the recent preclinical and clinical experience with this promising technology and gives a detailed description of all the technical aspects of the ATP-TCA. [ABSTRACT FROM AUTHOR]

Highly aggressive, rapidly growing tumors are often hypoxic, owing to an inadequate supply relative to consumption of oxygen (O2) in the expanding tumor mass, or growth in tissues with physiologically low O2 concentrations (such as bone marrow). Selection of tumor cells that can grow or survive under hypoxic conditions appears from both experimental and clinical studies to impact tumor progression, response to therapy, and to increase resistance to radiation and to certain cytotoxic drugs. Therefore, the predictive value of preclinical testing of anticancer agents in cell culture might be improved by conducting testing in conditions of physiological hypoxia. We review the impact of hypoxia on anticancer drug cytotoxicity and the methods used in our laboratory to asses the cytotoxic activity of single antineoplastic drugs under conditions of physiological hypoxia. [ABSTRACT FROM AUTHOR]

The assessment of the degree or rate of cellular proliferation and cell viability is critical to the assessment of the effects of drugs, antibodies, or cytokines on both normal and malignant cell populations. This can be accomplished by either direct or indirect counting methods. Direct counting by manual or automated methods, using a hemacytometer or particle counter, respectively, allows for serial cell counting at multiple time points, but these are low-throughput approaches. High-throughput and robust alternatives to direct counting utilize either radiotracers (e.g., 3H-thymidine) or dye compounds, which can be adapted to multiwell culture plate formats. This chapter focuses on the use of tetrazolium-type indicator dyes, of which the compound 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) has been the most widely utilized. Newer tetrazolium dyes that yield water-soluble products and offer added flexibility, increases in sensitivity, and fewer steps, which are offset by increased costs, are also covered. [ABSTRACT FROM AUTHOR]

For effective cancer chemotherapy, chemosensitivity testing of anticancer drugs should be performed using fresh surgical specimens obtained from the cancer. We have developed a new in vitro chemosensitivity test named the collagen gel droplet embedded culture drug sensitivity test (CD-DST). The CD-DST method consists of a collagen gel droplet embedded culture step, exposure and washout of anticancer drug, a serum-free culture step, and evaluation of anticancer effect by image analysis. This method has many advantages including a high success rate for primary culture, the need for only a small number of cells for the test, easy quantification of the anticancer effects without contamination with fibroblasts by using an image analysis system, a good correlation between in vitro and in vivo results, and simplicity and speed. The CD-DST method can be performed in the laboratory using a system kit Primaster®. [ABSTRACT FROM AUTHOR]

The sulforhodamine B (SRB) assay was developed by Skehan and colleagues to measure drug-induced cytotoxicity and cell proliferation for large-scale drug-screening applications. Its principle is based on the ability of the protein dye sulforhodamine B to bind electrostatically and pH dependent on protein basic amino acid residues of trichloroacetic acid-fixed cells. Under mild acidic conditions it binds to and under mild basic conditions it can be extracted from cells and solubilized for measurement. Results of the SRB assay were linear with cell number and cellular protein measured at cellular densities ranging from 1 to 200‰ of confluence. Its sensitivity is comparable with that of several fluorescence assays and superior to that of Lowry or Bradford. The signal-to-noise ratio is favorable and the resolution is 1000-2000 cells/well. It performed similarly compared to other cytotoxicity assays such as MTT or clonogenic assay. The SRB assay possesses a colorimetric end point and is nondestructive and indefinitely stable. These practical advances make the SRB assay an appropriate and sensitive assay to measure drug-induced cytotoxicity even at large-scale application. [ABSTRACT FROM AUTHOR]

The differential staining cytotoxicity (DiSC) assay is one of the total cell-kill assays that can be used for drug resistance testing. Numerous publications have demonstrated the clinical value of chemosensitivity testing with that assay (and similar ones). The DiSC assay is successful in the majority of malignant samples of which the cells can be brought in suspension (not necessarily as single-cell suspension). Although the assay is laborious and requires skilled technicians, it requires few cells, can be used for proliferating and nonproliferating cell populations, and can discriminate between malignant and contaminating nonmalignant cells. The latter is a major advantage of the DiSC assay. This chapter describes the practical aspects of this assay, several topics that need to be taken into account, and potential pitfalls. As such, it is not an extensive review of studies in which the DiSC assay was used. [ABSTRACT FROM AUTHOR]

The clonogenic cell survival assay determines the ability of a cell to proliferate indefinitely, thereby retaining its reproductive ability to form a large colony or a clone. This cell is then said to be clonogenic. A cell survival curve is therefore defined as a relationship between the dose of the agent used to produce an insult and the fraction of cells retaining their ability to reproduce. Although clonogenic cell survival assays were initially described for studying the effects of radiation on cells and have played an essential role in radiobiology, they are now widely used to examine the effects of agents with potential applications in the clinic. These include, in addition to ionizing radiation, chemotherapy agents such as etoposide and cisplatin, antiangiogenic agents such as endostatin and angiostatin, and cytokines and their receptors, either alone or in combination therapy. Survival curves have been generated for many established cell lines growing in culture. One can use cell lines from various origins including humans and rodents; these cells can be neoplastic or normal. Because survival curves have wide application in evaluating the reproductive integrity of different cells, we provide here the steps involved in setting up a typical experiment using an established cell line in culture. [ABSTRACT FROM AUTHOR]

High-sensitivity cytotoxicity assays refer to assays that can detect high levels of cell kill, to many powers of 10, and that can detect, ideally, a single remaining viable cell. Two such assays are described here, which have been used with Raji B-lymphoma cells, and are applicable to other nonadherent target cells. The first is a cell-counting assay, performed over a 3-wk period, which provides a simple, reliable, and sensitive assay of cytotoxicity. By determining the time required for 16-fold multiplication, the apparent fraction surviving can be calculated. This assay does not correct for treatment-induced delays in cell division and is dependent on maintaining the cells in exponential growth. The second assay measures colony-forming units using a limiting dilution method. Feeder cells are required to obtain a high cloning efficiency. Each dilution is plated in 48 wells of a 96-well plate, and positive wells are scored rapidly, by eye, after two wk. [ABSTRACT FROM AUTHOR]

This overview chapter presents the importance of chemosensitivity testing for screening new therapeutic agents, identifying patterns of chemosensitivity for different types of tumors, establishing patterns of cross-resistance and sensitivity in treatment naive and relapsing tumors; identifying genomic and proteomic profiles associated with sensitivity; correlating in vitro response, preclinical in vivo effect, and clinical outcome associated with a particular therapeutic agent, and tailoring chemotherapy regimens to individual patients. Various assays are available to achieve these end points, including several in vitro clonogenic and proliferation assays, cell metabolic activity assays, molecular assays to monitor expression of markers for responsiveness, development of drug resistance and induction of apoptosis, in vivo tumor growth and survival assays in metastatic and orthotopic models, and in vivo imaging assays. The advantages and disadvantages of the specific assays are discussed. A summary of research areas related to chemosensitivity testing is also included. [ABSTRACT FROM AUTHOR]

Laser flow cytometry has been used for monitoring cellular retention of fluorescent drugs such as fluorescent anticancer antibiotics (e.g., doxorubicin) and fluorochromes used for the detection of cellular drug efflux and resistance (e.g., rhodamine 123, Hoechst 33342). Multi parametric flow cytometry can be used for identification of tumor cell subpopulations based on their drug retention profiles with or without the presence of an efflux blocker. This rapid proce dure can be used for identification of tumor cells with the drug-resistance phenotype based on drug efflux as well as for efflux blockers that may block efflux of a chemotherapeutic agent and thus increase cellular retention and sensitivity. It has been reported recently that some of the bone marrow stem cells (SP cells) efflux the Hoechst 33342 fluorochrome and thus can be rapidly identified by comparing red vs blue fluorescence in the presence or absence of an efflux blocker such as verapamil. The present chapter discusses some of the flow cytometric methods used for the study of cellular drug retention and the artifacts that may arise in such analysis. [ABSTRACT FROM AUTHOR]