Clinical correlations with drug sensitivities in the clonogenic assay: a retrospective study

We tested the ability of the in vitro clonogenic assay (CLAS) to predict clinical response for patients with solid tumors. Patients had objectively measurable disease and received at least one course of chemotherapy. The correlation between clinical responses and in vitro sensitivity was evaluated retrospectively. Tumor types included melanoma (19), sarcoma (five), hepatoma (one), and carcinoma of the stomach (two), colon (three), lung (one), and breast (one). Five patients received two separate courses of chemotherapy with different drugs or drug regimens. In nine of 11 (82%) instances, tumors were sensitive to a particular drug, and the patient had at least 50% regression of tumor following treatment with the tested drug. Two patients whose tumors were sensitive in vitro had no evidence of clinical response. In 25 of 26 assays, the CLAS accurately predicted tumor resistance, and only one patient had evidence of clinical response (96%). Associations of in vitro results with clinical responses were highly significant. The CLAS can accurately predict the chemosensitivity of a variety of solid tumors.