> ## Content Index
> Fetch the complete content index at: https://www.fdaweb.com/llms.txt
> Use this file to discover other available public pages before exploring further.

# Reviewers Concerned About Data Supporting Replimune Melanoma BLA
- URL: https://www.fdaweb.com/reviewers-concerned-about-data-supporting-replimune-melanoma-bla/
- Published: 2026-07-28T12:00:00.000Z
- Updated: 2026-09-14T13:43:53.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5161526

FDA reviewers have raised substantial concerns about the clinical evidence supporting Replimune Group's BLA resubmission for accelerated approval of its investigational oncolytic immunotherapy, vusolimogene oderparepvec (RP1), in combination with nivolumab for patients with advanced melanoma whose disease progressed after prior PD-1 inhibitor treatment.

In [briefing documents](https://www.fda.gov/media/193878/download?ref=fdaweb.com) released ahead of an advisory committee meeting, FDA staff said the company's pivotal evidence from the single-arm Phase 1/2 IGNYTE trial does not adequately demonstrate that RP1 contributes to the combination's antitumor activity or that the reported efficacy results are reliable enough to support accelerated approval.

The agency identified three principal review concerns. First, FDA said Replimune's application of RECIST v1.1 tumor response criteria "confounds interpretation" of the trial's efficacy findings and limits the agency's ability to independently verify the reported objective response rate and duration of response.

Second, FDA concluded that the responses observed in the single-arm IGNYTE study were not sufficiently compelling to establish that RP1 adds benefit beyond nivolumab alone. Without a randomized control arm, the company relied on comparisons with historical studies of immune checkpoint inhibitor rechallenge. FDA said those comparisons are unreliable because patient populations differed substantially across studies, making it impossible to establish a meaningful historical benchmark or determine whether RP1 contributed to the observed responses.

The third concern involves overall survival. Replimune submitted three-year survival data from IGNYTE as supportive evidence, but FDA said overall survival results from a single-arm study without a concurrent control group cannot be interpreted as evidence of treatment effect because they cannot distinguish potential drug benefit from the natural course of the disease or other confounding factors.

The advisory committee will be asked to discuss whether the IGNYTE study was designed and conducted in a manner that allows reliable assessment of response rate and durability of response, whether the observed responses demonstrate meaningful systemic antitumor activity attributable to RP1, and ultimately whether the efficacy results are evaluable and clinically meaningful.

The resubmission follows FDA's April complete response letter rejecting the application. The agency declined to approve RP1 despite clinical trial results showing tumor shrinkage or disappearance in roughly one-third of patients. The decision, together with several other high-profile regulatory setbacks issued this spring, drew criticism from industry groups and investors, who argued the agency had become less predictable under former FDA commissioner **Marty Makary** and the Trump administration. ([see earlier story](https://www.fdaweb.com/critics-pile-on-makarys-ouster-with-melanoma-drug-denial/)).

The agency reportedly had previously warned Replimune that its single-arm trial design could jeopardize approval. Still, the decision drew heightened scrutiny because it occurred amid internal upheaval at FDA during Makary’s tenure. Makary publicly defended the rejection and accused Replimune of engaging in “corporate spin” after criticism emerged following the decision.

RP1 is a genetically engineered virus designed to destroy tumor cells and stimulate immune activity alongside the immunotherapy drug Opdivo.