Replimune's $800 Million Question Hangs on FDA's Final Call

The FDA decides on Replimune's RP1 cancer therapy after a prior rejection. Approval unlocks an $800M market; rejection forces the firm to abandon its flagship program.

The clock has run out for Replimune. The U.S. Food and Drug Administration is due to deliver its verdict on the company's lead cancer therapy, RP1, marking the climax of a regulatory saga that has kept investors on edge for over a year. The decision, tied to a Prescription Drug User Fee Act deadline, will determine whether the biotech firm secures a market worth up to $800 million annually or is forced to abandon its flagship program.

This is no routine review. It represents a second attempt after the FDA issued a Complete Response Letter in July 2025, rejecting the initial application. The agency's criticism was substantial, citing the IGNYTE trial's design, a heterogeneous patient population, and unresolved questions about the confirmatory study. Reports indicated that the FDA's top cancer drug regulator intervened in the final review stage, a move seen as pivotal to the rejection.

In its resubmission, Replimune bolstered its case with additional data, directly addressing the regulator's concerns over PD-1 resistance criteria and the use of literature to support component contributions. The core argument rests on a Phase 1/2 IGNYTE study involving 140 patients whose disease progressed after prior PD-1 therapy. The data showed an objective response rate of 32.9%, with a subgroup of acral melanoma patients responding at a rate of 44%. The therapy also demonstrated a complete remission rate of 15.0% and a median duration of response of 33.7 months.

Market sentiment has turned deeply cautious, reflecting the binary nature of the outcome. The stock plummeted 15% in a single session this week, sinking to around $5.79—approximately 30% below its 100-day moving average. On social trading platform Stocktwits, discussion activity surged 171% over seven days as overall sentiment shifted from bullish to neutral. The stark reality, as one user noted, is that the share price could either triple or lose most of its value based on today's news.

Analyst opinions on the likelihood of approval are split, framing the decision as a bellwether for how the FDA will handle accelerated approvals moving forward. While most see a 50/50 scenario, Wedbush analysts peg the chances at 60 to 70%, suggesting recent personnel changes at the top of the FDA may have weakened internal opposition. Cantor Fitzgerald analyst Li Watsek views the PDUFA date as a critical gauge of the regulatory landscape.

A rejection would not immediately threaten Replimune's survival. The company holds $269.1 million in cash, which management states is sufficient to fund operations into the first quarter of 2027. Furthermore, a $120 million credit facility from Hercules would become available upon approval. The clinical pipeline would continue, with the Phase 3 IGNYTE-3 trial—enrolling roughly 400 patients with overall survival as the primary endpoint—already active. The REVEAL study for RP2 in uveal melanoma also proceeds. The FDA has previously indicated in meeting minutes that IGNYTE-3 could potentially support a future approval.

The unmet medical need is clear. Patients with advanced melanoma following the failure of a PD-1 therapy have few effective alternatives. Clinicians and patient advocacy groups have voiced strong support for access to RP1, according to the company's CEO. Whether Replimune has fully satisfied the FDA's substantial concerns from last summer will be revealed by the close of business, setting the company's course for the foreseeable future.