Replimune Faces Mounting Legal Challenges Following Drug Rejection

Biopharmaceutical company Replimune finds itself confronting significant legal challenges as multiple shareholder class action lawsuits emerge in the wake of a regulatory setback for its lead cancer therapy. The litigation centers on allegations that company leadership provided materially misleading statements regarding the prospects of its pivotal IGNYTE clinical trial.

Regulatory Setback Sparks Investor Actions

The catalyst for this legal pressure emerged on July 22, 2025, when the U.S. Food and Drug Administration declined to approve RP1, Replimune’s investigational therapy, in combination with nivolumab for advanced melanoma. The regulatory agency determined that the submitted data from the IGNYTE trial failed to provide substantial evidence of effectiveness, describing the study as “inadequate and not sufficiently controlled.”

This regulatory decision triggered an immediate and severe market reaction. Replimune’s stock price collapsed by 77 percent in a single trading session, erasing billions of dollars in market capitalization. This dramatic valuation decline now forms the foundation for the subsequent investor litigation.

Law Firms File Sequential Complaints

Legal actions began accumulating rapidly in early September. Hagens Berman initiated the first securities class action on September 3, 2025, alleging that Replimune concealed critical risks associated with RP1 while exaggerating clinical trial data.

This was followed by similar filings from other prominent law firms. Bragar Eagel & Squire, P.C. announced comparable litigation on September 7, while The Gross Law Firm disclosed its own class action on September 8. The latter firm specifically alleges that company management “recklessly overvalued” the IGNYTE study’s prospects, ultimately leading to the FDA’s negative assessment.

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

All complaints reference the identical class period, spanning from November 22, 2024, through July 21, 2025.

Company at Critical Juncture

Facing an existential threat to its development program, Replimune management has taken steps to address the regulatory concerns. On September 2, the company announced it had scheduled a Type-A meeting with FDA officials to clarify the issues raised in the complete response letter.

Chief Executive Officer Sushil Patel has been unequivocal about the stakes involved, stating that without an accelerated approval pathway, the entire RP1 program—including its Phase 3 development—would be “not viable.”

• July 22, 2025: FDA rejection triggers 77% stock collapse
• September 2, 2025: Replimune schedules FDA meeting to address concerns
• September 3, 2025: Hagens Berman files securities class action
• September 7, 2025: Bragar Eagel & Squire, P.C. submits similar complaint
• September 8, 2025: The Gross Law Firm announces class action

The coming weeks will prove decisive for Replimune’s future, with both the outcome of FDA discussions and the progression of legal proceedings determining the company’s trajectory. For investors, the situation represents a particularly high-risk proposition.