FDA Advisory Committee Backs Replimune's RP1 Efficacy in Advanced Melanoma Amid Deepening Regulatory Questions
On August 6, 2026, the FDA granted accelerated approval to Replimune Group's Tudriqev (vusolimogene oderparepvec / RP1) in combination with nivolumab for advanced melanoma patients progressing on prior anti-PD-1 therapy. This regulatory milestone followed a 10-to-3 vote in favor of the drug by the Cellular, Tissue, and Gene Therapies Advisory Committee (CTGTAC) on July 30, 2026.1 However, the decision has sparked intense debate and confusion within the oncology community, with leading experts questioning the FDA’s consistency and the clinical trial design that underpinned the approval.
The controversy centers on the fact that RP1 is an intratumoral injection (a genetically modified herpes simplex virus). Historically, intratumoral injections are known to cause local regression of the injected lesion, but rarely demonstrate a true systemic ("abscopal") effect. Because the approval was based on a small, single-arm trial with no comparative or synthetic control arm, and extremely "messy" patient-level data, many experts argue that a systemic benefit remains unproven. During the advisory committee, even biostatisticians and clinicians who voted "yes" expressed severe reservations, noting that the data was highly confounding and did not definitively establish a clinically meaningful benefit.
Furthermore, the approval has highlighted a perceived lack of predictability in the FDA’s decision-making process under the current leadership of Commissioner Marty Makary and CBER.2 Under previous leadership, such applications would have faced a far more rigorous review by the Oncologic Drugs Advisory Committee (ODAC), where single-arm data of this nature would have struggled to secure support. The current environment has left many industry observers in "the fog" regarding the agency's regulatory standards.
Quotes
"So my yes was pretty close to a no. And what I really want to do is abstain because I don't know the answer... But don't take that as a, yes, this is convincing data. Okay? Yes, I can evaluate." — Janet Wittes, CTGTAC Statistician
"In the past, you could sort of figure it out. You know, oh, you have no chance here. In this case, I don't know. I mean, I'm in the fog. And if anybody pretends not to be in the fog, I want to hear from them." — Paul Goldberg, The Cancer Letter
-
An instance of Rigid regulatory objections collapse when independent advisory panels prioritize high unmet clinical need. — The independent advisory committee overrode concerns regarding highly confounding data to recommend the drug's accelerated approval. ↩︎
-
An instance of Leadership churn at regulatory agencies triggers a systemic softening of clinical standards. — New leadership at the FDA has introduced an unpredictable, less rigorous review climate that permits the approval of highly controversial single-arm trial data. ↩︎