Design and interpretation of clinical trials that evaluate agents that may offer protection from the toxic effects of cancer chemotherapy.

Abstract

PURPOSE To review the features of randomized clinical trials (RCTs) used in the development of agents that may protect against chemotherapy-induced toxicities, including trials of the cardioprotective agent dexrazoxane, hematologic growth factors, and amifostine; to suggest recommendations based on information gained from such trials and improvements in the design of ongoing and future trials. METHODS Critical review of reports of RCTs obtained from a Medline search, references from these articles, and review of trials listed in the physician data query (PDQ) clinical trials data base. RESULTS Several of the phase III trials did not use a format of comparing widely accepted strategies of chemotherapy with and without a protective agent. Instead, patients in the control arms of some of the trials have been exposed to more prolonged use or increased dosage of toxic chemotherapy that placed them at greater risk of the toxicity the protective agent was designed to prevent (eg, cardiotoxicity in trials of dexrazoxane, myelosuppression or thrombocytopenia in trials of growth factors). CONCLUSION RCTs have shown clear evidence of biologic activity for the protective agents, but this does not imply therapeutic benefit as compared with alternative strategies such as avoidance of prolonged use of cardiotoxic agents or use of standard doses of chemotherapy. Ongoing and future trials of protective agents should be modified to avoid undue risk to patients.