Replimune · RP1 · 2021 – 2026
Why do RP1's reported response rates range from 24.2% to 34%?
Three response rates for three populations, the FDA's concern about non-injected lesions, a 10–3 committee vote, and accelerated approval.
EphemerisX Research · Published · 5 source documents · 1 min read
Short answer
The documents give three response rates for three different populations: 34% in the company's April 8-K, a confirmed 32.9% in its 10-K, and 24.2% in the 91-patient efficacy population of the approval. Along the way, the FDA's second letter (April 10) questioned responses in patients without non-injected lesions, the advisory committee voted 10 to 3 (July 30), and the approval followed in August.
What the evidence shows
The company's April 2026 8-K says patients with confirmed progression on an anti-PD-1 based regimen who received RP1 plus nivolumab had a 34% response rate
8-K · Apr 13, 2026; its 10-K says The confirmed ORR was 32.9%
10-K · Jun 29, 2026.
The approval 8-K reports 91 patients with at least one non-injected lesion included in the efficacy-evaluable population
8-K · Aug 7, 2026, with an objective response rate (ORR) of 24.2%
8-K · Aug 7, 2026. The three figures describe different populations.
On April 10, the FDA's second letter said over half (53%) of patients with objective response did not have noninjected target lesions
FDA · Apr 10, 2026 · p. 4, and that with those patients excluded the response rate decreases markedly
FDA · Apr 10, 2026 · p. 4; the company's 8-K said its analyses showed no material difference in response rates between injected and non-injected lesions
8-K · Apr 13, 2026.
The advisory committee then voted 10 to 3
8-K · Jul 31, 2026 that the results are evaluable and clinically meaningful, and the approval 8-K reports accelerated approval based on objective response rate and duration of response
8-K · Aug 7, 2026.
For context, the second letter quotes the FDA in 2021: your proposed target of 30% to 40% objective response rate (ORR) may not translate into unequivocally improved clinical benefit in this indication
FDA · Apr 10, 2026 · p. 3.
Follow the thread
- How did RP1 go from a second FDA letter to accelerated approval in four months?Committee vote: 10 to 3
- When did injected lesions become an FDA concern?24.2% in the 91 patients with a non-injected lesion
This investigation connects to
- What happens after a second FDA Complete Response Letter?Cross-investigation · Divergent outcome · with Aldeyra Therapeutics, CorMedix, Outlook Therapeutics, Verrica Pharmaceuticals
- How did two programs move forward after repeat FDA letters without running a new trial?Cross-investigation · Comparable evidence · with Outlook Therapeutics
- What is a Class 1 or Class 2 resubmission, and how did each play out in these records?Cross-investigation · Regulatory pathway · with Aldeyra Therapeutics, CorMedix, Outlook Therapeutics
- When is one trial enough? How the FDA weighed the evidence in three programsCross-investigation · Comparable evidence · with Aldeyra Therapeutics, Outlook Therapeutics
The documents, by date
The passages quoted
FDA Complete Response Letter, April 10, 2026 · page 3
your proposed target of 30% to 40% objective response rate (ORR) may not translate into unequivocally improved clinical benefit in this indication.”Open at the source →
FDA Complete Response Letter, April 10, 2026 · page 4
Thus, over half (53%) of patients with objective response did not have noninjected target lesions to assess systemic anti-tumor activity.Open at the source →
FDA Complete Response Letter, April 10, 2026 · page 4
When these patients are excluded from the analysis of the primary endpoint of ORR, the resulting response rate decreases markedly from your reported response rate in RPL-001-16.Open at the source →
Replimune Form 8-K, filed April 13, 2026
In the IGNYTE trial, patients with confirmed progression on an anti-PD-1 based regimen who received RP1 plus nivolumab had a 34% response rate with a median duration of 24.8 months with a favorable safety profile.Open at the source →
Replimune Form 8-K, filed April 13, 2026
In addition, the company provided detailed analyses showing no material difference in response rates between injected and non-injected lesions.Open at the source →
Replimune Form 10-K, filed June 29, 2026
The confirmed ORR was 32.9% (15.0% complete response) and the responses occurred with similar frequency, depth, duration, and kinetics for injected and non-injected lesions, including visceral lesions.Open at the source →
Replimune Form 8-K, filed July 31, 2026
The committee then voted 10 to 3, on the question: "Are the efficacy results from IGNYTE evaluable and clinically meaningful?"Open at the source →
Replimune Form 8-K, filed August 7, 2026
The IGNYTE trial enrolled 140 patients with 91 patients with at least one non-injected lesion included in the efficacy-evaluable population. In this population, TUDRIQEV plus nivolumab achieved an objective response rate (ORR) of 24.2%, with a median duration of response of 14.1 months.Open at the source →
Replimune Form 8-K, filed August 7, 2026
This indication is approved under accelerated approval based on objective response rate and duration of response.Open at the source →