Friday's trading session delivered a dramatic reshuffling of value between two companies vying for position in the melanoma treatment arena. Replimune Group (NASDAQ:REPL) saw its shares skyrocket by 107% to close at $11.20, while Iovance Biotherapeutics (NASDAQ:IOVA) dropped 13.2% to $4.07. The combined swing in market capitalization totaled approximately $763 million, with Replimune gaining roughly $486 million and Iovance losing about $277 million, based on the most recent share counts reported by both firms.
The catalyst was a U.S. Food and Drug Administration (FDA) advisory committee's vote on Thursday, which sided 10-3 in favor of Replimune's RP1 therapy, citing the efficacy data from the IGNYTE trial as clinically meaningful. Although the panel's recommendation is non-binding, it carries significant weight in the agency's final decision, which was expected by Sunday. As of the dateline, neither the FDA nor the companies had announced a final ruling.
The divergence matters because Iovance's Amtagvi is considered the most direct commercial comparator to RP1. Amtagvi is currently the only other approved treatment for this patient population, but its accessibility is constrained by the need for surgical procedures and hospital infrastructure. Panel physicians underscored the ongoing demand for new options, with one expert, Hussein Tawbi, describing RP1 as "a lot safer, a lot easier" than Amtagvi, though he acknowledged this was not based on a randomized head-to-head study.
Replimune's one-day surge masks a more volatile week. The stock closed Friday just 15.5% above its July 24 close of $9.70, as the gains largely offset a steep decline that followed the FDA's initial remarks on Tuesday. Trading volume on Friday was exceptionally heavy, with 33.63 million shares changing hands—roughly 40% of the company's reported share total and 5.4 times its average daily volume.
The underlying data dispute remains unresolved. Replimune's own analysis of the IGNYTE trial reported an objective response rate of 33.6% with a median duration of response of 24.8 months. However, the FDA's primary reanalysis of the same 140 evaluable patients found a response rate of just 15.7% and a median duration of 14.1 months. A sensitivity analysis by the agency, excluding some patients, showed a 24.7% response rate with the same shorter duration.
FDA reviewers also noted that the single-arm trial design made it impossible to isolate RP1's specific contribution, since the regimen included Bristol Myers Squibb's (NYSE:BMY) Opdivo. They raised concerns that the observed tumor destruction in injected lesions might be a localized effect rather than evidence of systemic activity.
Even if approval is granted, Replimune faces significant financial hurdles. The company reported $268.9 million in cash and short-term investments as of March 31, following a net loss of $313.9 million for fiscal 2026. Management projects that current resources will fund operations into early 2027, but that runway does not account for potential revenue or additional expenses tied to a launch.
Looking ahead, investors will focus on the FDA's final decision and any approved label, including postmarketing requirements and launch details. Replimune has already begun recruiting for the IGNYTE-3 randomized confirmatory trial, which uses overall survival as its primary endpoint. Risks remain, including the possibility of a delayed or denied approval, a restricted label, or the need for costly additional studies. The company's short funding runway also raises the specter of dilution.
