Do post-approval phase III trials for accelerated approved cancer drugs violate equipoise?

Abstract

6026 Background: Since 1992, the Food and Drug Administration (FDA) has allowed accelerated approval of novel cancer drugs based on improvements in surrogate outcomes, provided that subsequent phase III trials, in compliance with subpart H, show evidence of clinical benefits. However, drugs that receive accelerated approval must already show promise, making it difficult to recruit for randomized studies in which patients might get other drugs which are likely to be inferior. We evaluated whether drugs granted accelerated approval were just as likely to be superior as inferior to standard therapy during phase III clinical trials, a necessary condition known as equipoise, which is used as the ethical basis for recruitment. Methods: Descriptions of marketing approval decisions and subpart H commitments for all drugs that received accelerated approval for oncology indications between 1992 and 2005 were obtained from the FDA website, transcripts of the Oncologic Drug Advisory Committee of the FDA, and PubMed searches. Results: Accelerated approval has been granted for 25 drugs and 29 indications. These approvals have been based on phase II clinical trials (23 indications) or phase III trials (6 indications). 14 approvals were for novel cancer therapeutic drugs. Post-approval phase III clinical trials, outlined in subpart H commitments, have been reported for 9 indications associated with common cancers of the colon, lung, or breast, and 1 indication associated with multiple myeloma, a less common cancer, for which 9 studies identified improved clinical outcomes with the accelerated approved drug. Of 15 drugs that received accelerated approval prior to 2003 for cancers that affect small numbers of patients, 13 are years behind planned recruitment milestones for post-approval phase III trials. Conclusion: While the equipoise theory would predict that 50% of the completed phase III trials would support the novel therapy, empirical data have identified that 90% of the studies required by subpart H commitments support the novel therapy. Therefore, it is likely to hinder recruitment to ongoing phase III trials evaluating other accelerated approved cancer drugs. No significant financial relationships to disclose.