The semi-automated fluorometric microculture cytotoxicity assay (FMCA), based on the measurement of fluorescence generated from cellular hydrolysis of
fluorescein diacetate (FDA) by viable cells, was employed for cytotoxic
drug sensitivity testing of
tumor cells from patients with hematological or solid
tumors. In total, 390 samples from 20 diagnoses were tested with up to 12 standard cytotoxic drugs. The technical success rate for different
tumor types ranged from 67 to 95%. Fluorescence was linearly related to cell number but variably steep depending on
tumor type. Samples from most solid
tumors thus showed higher signal-to-noise ratios than hematological samples. A wide spectrum of in vitro
drug activity was obtained, with acute
leukemias and non-Hodgkin's
lymphomas being sensitive to almost all tested drugs, whereas renal and
adrenocortical carcinomas were essentially totally resistant. Between these extremes were samples of breast and ovarian
carcinomas and
sarcomas. When in vitro response was compared with known clinical response patterns, a good correspondence was observed. The results indicate that the FMCA is a rapid and efficient method for in vitro measurement of
tumor-specific
drug activity both in hematological and in solid
tumors. The assay may be suitable for new
drug development and direction of phase-2 trials to suitable patients.