Overview
- U.S. regulators issued a complete response letter on Friday declining approval of RP1 with nivolumab for adults with advanced melanoma.
- The FDA said results from the single‑arm RPL‑001‑16 study and limited early data from the RP1‑104 phase 3 trial did not show substantial evidence of effectiveness.
- Reviewers cited mixed patient groups, inconsistencies in how tumors were measured, and confounding from procedures like lesion reinjection, and they reported no new safety concerns.
- Replimune’s shares fell about 19% to roughly $4.76 after the letter, and trading was halted twice because of sharp swings.
- The company disputed the finding, noted a new FDA review team handled the resubmission, plans to seek a Type A meeting, and warned of job cuts and reduced U.S. manufacturing without a clear path forward; RP1 is a modified herpes virus designed to kill tumors and spark an immune response, and rivals such as Iovance’s approved Amtagvi now hold an advantage.