Replimune Stages Comeback: FDA Priority Review Fuels 86% Surge

It was a week that rewrote the script for a biotech that had been written off by many. Replimune’s shares rocketed nearly 86% in a single session, closing at $8.82 and pushing the company’s market value toward $720 million. The rally erased a substantial chunk of the losses accumulated after two earlier regulatory setbacks, and the trigger was unmistakable: the FDA agreed to treat the resubmission of RP1’s biologics license application as an urgent matter.

That designation – priority review – is reserved for therapies addressing high unmet medical needs. In this case, RP1, in combination with Nivolumab, targets patients with advanced melanoma who have progressed on anti-PD-1 therapies. Around 8,500 people die from the disease in the US each year. The resubmission is expected within days, marking the company’s third attempt after complete response letters in July 2025 and April 2026. Those earlier rejections had centred on the single-arm trial design and the lack of an adequate control group – concerns that the priority tag does not eliminate but which it certainly reframes.

The data underpinning the new filing come from the IGNYTE study, which enrolled 140 patients with advanced melanoma. The overall response rate stood at 33.6%, and 15% of participants saw a complete disappearance of visible cancer. Median duration of response ranged from 24.8 to 33.7 months, depending on the cut, and one-year overall survival reached 73.5%, with two-year survival at 63.3%. Severe treatment-related adverse events occurred in 12.9% of patients, with no treatment-related deaths. These figures explain the ferocity of the market reaction: in a hard-to-treat population, durability of response is everything, and the data show that remissions can be long-lasting.

Should investors sell immediately? Or is it worth buying Replimune?

Replimune is not resting on melanoma alone. At the ASCO annual meeting this year, the company will present three-year overall survival data from IGNYTE, alongside final Phase 1 results for its second-generation candidate, RP2. RP2 is engineered to express an anti-CTLA-4 antibody directly within the tumour – a more technically demanding approach than RP1. The Phase 1 dataset covers patients with solid tumours such as hepatocellular carcinoma and bile duct cancer, giving Replimune a potential path to diversify beyond a single indication.

Analysts quickly adjusted their view. JPMorgan upgraded the stock from Underweight to Neutral, setting a price target of $8.00, while Wedbush kept its Neutral rating but raised its target sharply from $2.00 to $6.00. Both firms acknowledged that the FDA’s decision improved the perception of the regulatory pathway, but stopped short of declaring the risk eliminated. The moves also rippled through the competitive landscape: Iovance Biotherapeutics dropped 6.5% and Bristol Myers Squibb slipped 0.6% as investors began to price in a possible return of RP1 as a serious contender.

Yet Replimune remains a pre-revenue company with a significant cash burn. Free cash outflow ran at roughly $66 million per quarter, though the company had $269.1 million in cash and equivalents at the end of last year, supplemented by a $35 million credit line. A restructuring earlier this year, including job cuts, was aimed at stretching the runway. The liquidity position means the company can operate into the near term without immediate pressure, but the burn rate underscores why a successful approval – not just a priority review – is essential.

Attention now shifts to two key milestones in June. First, the formal acceptance of the BLA by the FDA and the setting of a new PDUFA date – the official deadline for a decision. Second, an earnings call in early June, where management is expected to provide clarity on the restructuring plan, the commercial launch timeline for RP1, and the status of the confirmatory Phase 3 trial, IGNYTE-3. Investors will be listening closely for any signals that the data presented at ASCO reinforce the durability argument that the FDA has, for now, chosen to weigh more favourably.

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Replimune Stock: New Analysis - 30 May

Fresh Replimune information released. What's the impact for investors? Our latest independent report examines recent figures and market trends.

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