Response rate of anticancer drugs approved by the Food and Drug Administration based on a single-arm trial

Abstract

Background: In recent years, an increasing number of anticancer drugs have been approved based on the results of a single-arm trial (SAT). The magnitude of the objective response rate (ORR) in SATs is important for regulatory decisions, but there has been no clear guidance specifying the degree of ORR for approval. Methods: All anticancer drugs approved by the US Food and Drug Administration (FDA) between January 2016 and December 2019 were identified through the FDA website. From these, we selected drugs approved for solid tumors based on SATs. For each indication, one regimen was selected from the standard-of-care as the best comparison therapy (BCT), which was defined as the latest regimen for the same tumor and treatment line. We compared the ORR of the investigated product with that of the BCT. Results: Of the 31 solid tumor indications identified, we selected BCT for 28. In 23 of the 28 indications (82.1%), the ORR of the investigated product exceeded that of the BCT, and in 16 of these (69.6%), the lower limit of the 95% confidence interval (CI) of the ORR of the investigated product exceeded the point estimate of the BCT ORR. For seven products, the lower limit of the 95% CI was below the point estimate of the BCT ORR, with differences ranging from 1.0% to 3.4%. Conclusion: The lower limit of a 95% CI of the ORR of a new drug in an SAT exceeding the point estimate of the BCT ORR could be an important factor in obtaining regulatory approval.