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.