Scientists Protest FDA’s Rejection of Replimune’s Tumor Destroying Therapy

On July 23, 2025, the FDA rejected Replimune’s application for accelerated approval of RP1, an oncolytic immunotherapy targeting advanced melanoma, citing inadequacies in trial design and effectiveness evidence1245.

The FDA’s main criticisms were that the IGNYTE trial was not ‘adequate and well-controlled,’ citing issues with the heterogeneity of the patient population, particularly varied prior therapies and disease severity among participants124.

In response, 22 leading melanoma and cancer experts who designed and ran the IGNYTE trial published an open letter protesting the FDA’s decision, arguing that the trial design accurately reflected real-world clinical scenarios and current treatment pathways2.

These experts called for the FDA to ‘re-review’ Replimune’s application, asserting that the diverse patient group is a necessity given modern melanoma treatment guidelines2.

The rejection led to a dramatic 76-77% drop in Replimune’s stock price and significant setbacks for the company’s commercial plans15.

Internal conflicts within the FDA and interventions by its top cancer drug regulator played a notable role in the controversial last-minute rejection, according to agency insiders3.

Sources:

1. https://www.fiercebiotech.com/biotech/replimunes-request-melanoma-approval-rejected-fda-cratering-stock

2. https://www.biospace.com/fda/scientists-behind-trial-of-replimmunes-tumor-destroyer-protest-fdas-rejection

3. https://www.statnews.com/2025/08/04/replimune-skin-cancer-drug-rejection-pazdur-prasad/

4. https://www.raps.org/News-and-Articles/News-Articles/2025/7/Recon-FDA-rejects-Replimune-s-oncolytic-virus-drug

5. https://www.ainvest.com/news/replimune-group-plunges-77-36-fda-rejects-rp1-2507/