The FDA granted accelerated approval to Tudriqev (vusolimogene oderparepvec-wtpg) on August 6, 2026, in combination with nivolumab for adults with unresectable advanced cutaneous melanoma whose disease progressed on a PD-1-blocking regimen. Tudriqev is a genetically modified herpes simplex virus type 1, or HSV-1, designed to replicate inside tumors, break cancer cells apart, and stimulate a broader antitumor immune response.
Tudriqev turns a modified herpes virus into an intratumoral cancer therapy
Tudriqev is based on HSV-1, but it has been genetically engineered for oncolytic use. The therapy is injected directly into accessible tumors, where the virus is intended to preferentially replicate in cancer cells and cause cell lysis.
The treatment is also engineered to stimulate immune activity. Vusolimogene oderparepvec expresses granulocyte-macrophage colony-stimulating factor, or GM-CSF, and a fusogenic glycoprotein designed to increase tumor-cell killing and immune activation.
The biological idea is that local tumor destruction can release tumor antigens and inflammatory signals, helping immune cells recognize cancer beyond the injected lesion. Nivolumab is added to block PD-1 signaling and potentially restore T-cell activity in tumors that had already progressed on prior PD-1-based therapy.
The approval is specifically for melanoma that has progressed on PD-1 therapy
The indication is narrower than first-line melanoma treatment. Tudriqev plus nivolumab is approved for adults with unresectable advanced cutaneous melanoma whose disease progressed on a PD-1-blocking antibody-based regimen.
That matters because PD-1 inhibitors such as nivolumab and pembrolizumab are foundational melanoma therapies, but primary or acquired resistance remains common. Once melanoma progresses after PD-1 treatment, subsequent options can be limited by tumor biology, prior therapy, toxicity, and patient fitness.
Our personalized mRNA melanoma vaccine article covers a different strategy aimed at improving antitumor immunity, while our cancer immunotherapy article explains how immune activation can interact with checkpoint blockade.
IGNYTE enrolled 140 patients, but FDA’s efficacy population included 91
The pivotal evidence came from IGNYTE, an open-label, multiregional, single-arm study that enrolled 140 adults with stage IIIB, IIIC, or IV unresectable advanced melanoma after progression on at least eight consecutive weeks of prior anti-PD-1 therapy.
The peer-reviewed publication analyzed all 140 treated patients and reported a confirmed objective response rate of 32.9%, including a 15.0% complete response rate. Median duration of response was 33.7 months, and reductions were observed in both injected and noninjected lesions.
FDA used a more restrictive efficacy-evaluable population. Of the 140 treated patients, 91 with at least one noninjected lesion were included in the regulatory efficacy analysis. In that group, the objective response rate was 24.2% with a 95% confidence interval of 15.8% to 34.3%, and median duration of response was 14.1 months.
Why the FDA number is lower than the published trial headline
The difference between 32.9% and 24.2% is not a contradiction. It reflects different analysis populations and a more conservative regulatory approach to response assessment.
Because Tudriqev is injected directly into tumors, FDA focused heavily on whether the treatment showed activity beyond injected lesions. The agency restricted its efficacy population to patients with at least one noninjected lesion and scrutinized response-assessment methods closely.
That distinction is especially important for intratumoral therapies. A treatment can make an injected tumor shrink without proving that it generates a meaningful systemic anticancer effect. FDA’s analysis therefore tried to separate local injection effects from broader disease control.
FDA had already rejected the application twice
This approval followed an unusually difficult regulatory path. FDA issued Complete Response Letters in July 2025 and again in April 2026.
According to FDA’s Summary Basis for Regulatory Action, the main concerns were unreliable response-assessment methodology, inability to establish the contribution of Tudriqev to the combination with nivolumab because there was no concurrent control arm, and heterogeneity in the IGNYTE population that made historical comparisons difficult.
The June 2026 resubmission did not provide a new randomized efficacy dataset that resolved those concerns. Instead, FDA re-evaluated the totality of evidence, including longer-term IGNYTE follow-up, early randomized data from the confirmatory IGNYTE-3 trial, exploratory analyses, and advisory committee deliberations.
An advisory committee voted 10-3 that the efficacy signal was clinically meaningful
On July 30, 2026, FDA convened its Cellular, Tissue, and Gene Therapies Advisory Committee. The committee voted 10 to 3 that the IGNYTE efficacy results were evaluable and clinically meaningful.
FDA’s summary notes that committee members acknowledged substantial methodological limitations while also emphasizing the unmet need after PD-1 failure, the biologically plausible mechanism, durable responses in some patients, and tumor shrinkage in both injected and noninjected lesions.
This is why the approval is best understood as a balance between uncertainty and unmet need rather than as a clean, conventional phase 3 approval.
This is not the first oncolytic virus approved for melanoma
Tudriqev is not the first FDA-approved oncolytic virus. Talimogene laherparepvec, or T-VEC, received traditional FDA approval in 2015 for local treatment of unresectable cutaneous, subcutaneous, and nodal melanoma lesions after initial surgery.
T-VEC also uses a modified HSV-1 backbone, but its approved role is different. FDA’s 2015 label specifically noted that T-VEC had not been shown to improve overall survival or affect visceral metastases.
Tudriqev is important because it is paired with systemic PD-1 blockade after prior PD-1 failure, with the goal of turning local viral therapy into a broader immune response.
Safety includes both immune effects and live-virus precautions
In the 140-patient IGNYTE publication, 90.0% of patients experienced at least one treatment-related adverse event. Most were grade 1 or 2. Grade 3 or 4 treatment-related adverse events occurred in 12.9%, and no treatment-related deaths were reported.
The most common treatment-related events included fatigue, chills, fever, and nausea. FDA labeling also includes warnings for accidental exposure, herpetic infection or reactivation, complications related to tumor injection, and immune-mediated events.
Because Tudriqev is a replication-competent engineered virus, handling and wound-care precautions matter in a way they do not for standard small-molecule or antibody therapies.
Accelerated approval means the story is not finished
FDA granted Tudriqev accelerated approval based on objective response rate and duration of response, not on proven improvement in overall survival.
Replimune is required to verify clinical benefit in a confirmatory randomized trial. IGNYTE-3 compares Tudriqev plus nivolumab with physician’s choice of therapy in advanced melanoma that has progressed after PD-1 and CTLA-4 therapy. The trial is designed to provide the controlled evidence that was missing from IGNYTE.
Continued approval can depend on whether that confirmatory study verifies a meaningful clinical benefit.
What the evidence cannot yet answer
IGNYTE was single-arm, so it cannot directly establish how much of the observed activity came from Tudriqev, nivolumab retreatment, patient selection, or other factors. FDA itself highlighted this limitation repeatedly.
The difference between the peer-reviewed 140-patient analysis and FDA’s 91-patient regulatory population also shows how sensitive response estimates can be to analysis rules. Cross-study comparisons with lifileucel, nivolumab plus ipilimumab, or BRAF/MEK therapy are not substitutes for a randomized comparison.
The study was sponsored by Replimune, and several investigators had financial relationships with the company or other melanoma drug developers. The combination also relied on nivolumab supplied through collaboration with Bristol Myers Squibb.
The approval is notable because FDA accepted uncertainty in exchange for earlier access
Tudriqev is scientifically interesting because it tries to convert local viral destruction into systemic immune activity after checkpoint therapy has failed. It is regulatorily interesting because FDA approved it despite unresolved methodological concerns that had already led to two rejection letters.
The 24.2% response rate and 14.1-month median response duration were enough for accelerated approval in a high-unmet-need setting, but the confirmatory trial now has to show that those responses translate into a clinical benefit that justifies keeping the therapy on the market.
References
- U.S. Food and Drug Administration. FDA Approves New Engineered Viral Immunotherapy for Patients with Treatment-Resistant Advanced Melanoma. August 6, 2026. FDA press release.
- Wong MKK, et al. RP1 Combined With Nivolumab in Advanced Anti-PD-1-Failed Melanoma (IGNYTE). J Clin Oncol. 2025;43:3589-3599. DOI: 10.1200/JCO-25-01346.