Tudriqev's Path to Approval Spanned Three Submissions and Two Rejections

Introduction

Replimune’s Tudriqev, formerly known as RP1, has secured U.S. Food and Drug Administration (FDA) approval after an unusually difficult regulatory journey involving three submissions and two previous rejections. The approval represents a major milestone for Replimune and gives the biotechnology company its first marketed product.

Tudriqev is an oncolytic immunotherapy designed to treat advanced melanoma in patients whose disease has progressed despite earlier treatment with anti-PD-1 immunotherapy. The therapy is administered directly into tumors and is designed to destroy cancer cells while stimulating an immune response against cancer elsewhere in the body.

From First Submission to Two Rejections

Replimune initially submitted its application for RP1 in November 2024. The FDA rejected the application in July 2025, raising concerns about the evidence supporting the treatment’s effectiveness.

The company submitted the application again, but the FDA issued a second rejection in April 2026. Regulators continued to question the strength of the clinical evidence, particularly because the key IGNYTE study was a single-arm trial without a control group. The FDA also raised concerns about determining how much of the observed treatment effect came from RP1 itself versus the immunotherapy used in combination with it.

These setbacks made Tudriqev's development one of the more closely watched recent regulatory stories in oncology.

The Third Submission Changes the Outcome

Replimune made a third attempt to secure approval, and the FDA ultimately accepted the application for review.

Before the final decision, an FDA advisory committee reviewed the available evidence. The panel voted 10–3 that the clinical data were evaluable and demonstrated a clinically meaningful benefit, providing an important boost to the company's application.

The FDA subsequently granted accelerated approval to Tudriqev in combination with Bristol Myers Squibb's Opdivo (nivolumab) for eligible patients with advanced melanoma whose tumors had progressed following prior anti-PD-1 therapy.

What Makes Tudriqev Different?

Tudriqev uses a genetically modified herpes simplex virus that is injected directly into tumors. The treatment is designed to attack tumor cells at the injection site while also triggering an immune response that can target cancer cells elsewhere in the body.

Clinical data submitted by Replimune showed that 24.2% of patients experienced tumor reduction or elimination, with responses lasting a median of 14.1 months.

The therapy offers another potential option for patients with advanced melanoma who have already received immunotherapy but whose disease has continued to progress.

Why the FDA Review Was Controversial

The regulatory journey attracted attention because of the FDA's repeated concerns about the clinical trial design. A single-arm study makes it more difficult to determine how much of a treatment response can be attributed specifically to the investigational therapy because there is no randomized control group for comparison.

FDA reviewers therefore questioned whether the available evidence was sufficient to establish Tudriqev's independent clinical benefit. The advisory committee, however, concluded that the available data provided a meaningful enough signal to support approval, particularly given the treatment needs of patients with difficult-to-treat melanoma.

Accelerated Approval Comes With Further Requirements

Although the FDA has approved Tudriqev, Replimune still needs to generate additional evidence confirming the treatment's clinical benefit.

A confirmatory Phase III trial is already underway, with results expected around 2030. The study is important because accelerated approval requires additional evidence to verify the clinical benefit supporting continued approval.

This means the regulatory journey is not completely over. The outcome of the confirmatory study will remain important for Tudriqev's long-term position in the melanoma treatment market.

Commercial Significance for Replimune

The approval is particularly important because Tudriqev is Replimune's first approved and marketed product. The company now moves from a development-stage biotechnology business toward commercial operations.

The treatment will compete in a challenging melanoma market that already includes established immunotherapies and newer treatment approaches. However, Tudriqev's tumor-injected administration and its combination with Opdivo could provide Replimune with a distinctive position among treatment options for patients who have progressed after immunotherapy.

Impact on the Melanoma Treatment Landscape

The approval expands treatment options for patients with advanced melanoma who have limited alternatives after previous immunotherapy.

Tudriqev is also another example of the growing role of oncolytic immunotherapy, which aims to combine direct destruction of tumor cells with activation of the body's immune system.

Its approval demonstrates how regulators may consider promising evidence from innovative therapies even when conventional trial designs present challenges, particularly when treating serious diseases with significant unmet medical needs.

Conclusion

Tudriqev's journey from its initial submission in 2024 to FDA approval in 2026 illustrates how complex and uncertain the drug-development and regulatory process can be. After three submissions and two rejections, Replimune ultimately secured accelerated approval for its melanoma therapy.

The approval marks a major achievement for the company, but the next phase will be equally important. Replimune must now demonstrate the treatment's clinical benefit through confirmatory research while establishing Tudriqev in a competitive oncology market.

For patients with advanced melanoma who have exhausted previous immunotherapy options, the approval provides another potential treatment avenue and highlights the continuing evolution of cancer immunotherapy.