A short-term in vitro drug sensitivity assay in pediatric malignancies.

A short-term in vitro chemosensitivity test has been applied to 131 specimens from 109 children with various malignancies. The clinical outcome was correlated with in vitro percentage inhibition (PI) of DNA synthesis by the drug tested. In 62 correlations, PIs of responsive and of resistant patients differed significantly, with a cut-off value of 37%. The test predicted clinical resistance in 53/54 cases, with a specificity of 98%, and clinical response in 8/8 cases, with a sensitivity of 100%. This test can be useful particularly in predicting chemoresistance in relapsing patients, to avoid unnecessary toxicity.