Purpose: Registration of new anticancer drugs is usually based on results of randomized controlled trials (RCTs) showing improved efficacy when compared with standard therapy. There is relatively less emphasis on toxicity. In our study, we analyze serious toxicities of newly approved anticancer drugs reported in pivotal RCTs used for drug registration.
Patients and methods: We identified RCTs evaluating agents for the treatment of solid tumors approved by the US Food and Drug Administration between 2000 and 2010. Odds ratios (OR) and 95% CI were computed for three end points of safety and tolerability: treatment-related death, treatment-discontinuation related to toxicity, and grade 3 or 4 adverse events (AEs). These were then pooled in a meta-analysis. Correlations between these end points and the hazard ratios for overall survival (OS) and progression-free survival (PFS) were also assessed.
Results: Thirty-eight RCTs were analyzed. Compared with control groups, the odds of toxic death was greater for new agents (OR, 1.40; 95% CI, 1.15 to 1.70; P < .001) as were the odds of treatment-discontinuation (OR, 1.33; 95% CI, 1.22 to 1.45, P < .001). Grade 3 or 4 AEs (OR, 1.52; 95% CI, 1.35 to 1. 71; P < .001) were also more common with new agents, especially nonhematologic AEs such as diarrhea, skin reactions, and neuropathy. There were no significant correlations between safety end points and OS or PFS.
Conclusion: New anticancer agents that lead to improvements in time-to-event end points also increase morbidity and treatment-related mortality. The balance between efficacy and toxicity may be less favorable in clinical practice because of selection of fewer patients with good performance status and limited comorbidities. Patients' baseline health characteristics should be considered when choosing therapy.