A historical note: Rediscovering an unpublished response to Korn and Freidlin (2011)

Despite extensive research, the use of response-adaptive randomization (RAR) in clinical trials has remained controversial. Korn and Freidlin's 2011 article reignited this debate back then, prompting numerous responses, including one by Zhu, Rosenberger, and Hu that remained unpublished until now. This article features the original response by Zhu, Rosenberger, and Hu, providing a valuable opportunity to revisit the original arguments, examine subsequent developments in RAR methodology, and offer a more complete historical perspective on this enduring debate. The piece also includes a concluding section by one of the special issue's co-editor that explores the nuances and complexities of RAR implementation in the context of contemporary clinical trial design.