Benefit and harms of new anti-cancer drugs

Phase III randomized controlled trials (RCTs) assess clinically important differences in endpoints that reflect benefit to and harm of patients. Defining benefit of cancer drugs can be difficult. Overall survival and quality of life are the most relevant primary endpoints, but difficulty in measuring these mean that other endpoints are often used, although their surrogacy or clinical relevance has not always been established. In general, advances in drug development have led to numerous new drugs to enter the market. Pivotal RCT of several new drugs have shown that benefit appeared greater for targeted anticancer agents than for chemotherapeutic agents. This effect seems particularly evident with targeted agents evaluated in biomarker-driven studies. Unfortunately, new therapies have also shown an increase in toxicity. Such toxicity is not always evident in the initial reports of RCTs. This may be a result of a statistical inability to detect differences between arms of RCTs, or occasionally due to biased reporting. There are several examples where reports of new toxicities could only be found in drug labels. In some cases, the small improvement in survival has come at a cost of substantial excess toxicity, leading some to consider such therapy as having equipoise.