Story perspectives

FDA Rejects Replimune RP1 Over Trial Design, Risks 2,500 Lives

5/15/2026

Summary

Story summary

The U.S. Food and Drug Administration withheld approval of Replimune’s drug RP1, citing lack of a control arm.
The agency issued the decision after a July warning that the trial design risked denial.
In the phase 1/2 trial, one-third of 140 participants showed tumor shrinkage or disappearance, a 33.6% response rate.
Dermatologist Trisha Wise-Draper, Eric Whitman and oncologists warned the rejection could cost up to 2,500 lives and chill drug development.

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Story summary

The U.S. Food and Drug Administration withheld approval of Replimune’s drug RP1, citing lack of a control arm.
The agency issued the decision after a July warning that the trial design risked denial.
In the phase 1/2 trial, one-third of 140 participants showed tumor shrinkage or disappearance, a 33.6% response rate.
Dermatologist Trisha Wise-Draper, Eric Whitman and oncologists warned the rejection could cost up to 2,500 lives and chill drug development.