The FDA rejected Replimune's RP1 (vusolimogene oderparepvec) on April 10, 2026, marking the second rejection of the melanoma treatment12
The initial rejection occurred in July 2025, with the FDA determining the phase 1/2 Ignyte trial was not 'adequate and well-controlled' and had patient population heterogeneity that made results difficult to interpret1
In the resubmission, the FDA found that submitted data were 'insufficient to conclude substantial evidence of effectiveness' despite being reviewed by a different team than the initial review12
Replimune added phase 3 trial data to its resubmission, but the FDA noted only 10% of the planned patient population had been treated, and cited lack of response duration data and difficulty interpreting progression-free survival data1
Replimune disputed the rejection, claiming the FDA provided 'inconsistent communication' and contradicted positions expressed at a September 2025 Type A meeting23
RP1 is an engineered herpes simplex virus designed to activate the immune system against cancer cells and is used in combination with Bristol Myers Squibb's Opdivo1
The company warned that a second rejection could make RP1 development 'no longer viable,' and CEO Sushil Patel stated the company will need to eliminate jobs and scale back U.S. manufacturing23
Replimune's stock price fell approximately 20% following the rejection announcement1
Sources:
1. https://www.fiercebiotech.com/biotech/fda-refuses-replimunes-melanoma-prospect-second-time
2. https://www.biopharmadive.com/news/replimune-fda-reject-melanoma-rp1/816659/
3. https://www.morningstar.com/news/dow-jones/202604108049/replimune-disputes-fda-rejection-of-skin-cancer-treatment-criticizes-review-process