Replimune (REPL) Faces Investor Lawsuit After FDA Blocks Cancer Drug Approval - Hagens Berman

REPL Investors with Losses Encouraged to Contact the Firm

SAN FRANCISCO, Sept. 9, 2025 /PRNewswire/ -- Replimune Group Inc. (NASDAQ: REPL) is under fire from investors following a dramatic regulatory setback that sent its stock into freefall. A newly filed securities class action accuses the biotech firm and its leadership of concealing critical risks tied to its flagship cancer therapy, RP1, and overstating the strength of clinical trial data used to support its FDA application.

The lawsuit, filed on behalf of investors who acquired Replimune stock between November 22, 2024, and July 21, 2025, alleges that the company's public statements misrepresented the likelihood of regulatory success and failed to disclose material deficiencies in its trial design.

Hagens Berman urges Replimune investors who suffered substantial losses to submit your losses now.

Class Period: Nov. 22, 2024 – July 21, 2025
Lead Plaintiff Deadline: Sept. 22, 2025
Visit: www.hbsslaw.com/investor-fraud/repl
Contact the Firm Now: [email protected]
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FDA Rejection Sparks Market Meltdown

On July 22, 2025, Replimune revealed that the FDA had issued a Complete Response Letter (CRL) for its Biologics License Application for RP1, a novel immunotherapy aimed at treating advanced melanoma. The CRL effectively halted the drug's approval process, citing concerns about the adequacy of the supporting clinical data.

The announcement triggered a steep sell-off, with Replimune shares plunging 77% in a single trading session—erasing billions in market capitalization and leaving investors reeling.

Alleged Misrepresentations and Trial Design Flaws

According to the complaint, Replimune repeatedly emphasized RP1's "durable response" data from its IGNYTE trial and leaned heavily on the FDA's prior Breakthrough Therapy and Accelerated Approval designations to reassure investors. However, plaintiffs argue that these statements were misleading, as the company allegedly failed to disclose that:

• The IGNYTE trial's design lacked sufficient rigor to meet FDA standards.
• The agency was likely to reject the application due to methodological shortcomings.

The CRL itself, cited in the lawsuit, stated that the trial did not constitute "a sufficiently well-designed or controlled investigation to provide substantial evidence of effectiveness."

FDA Flags Key Scientific Concerns

The FDA based the rejection on two primary concerns:

• Patient Diversity: Regulators found the trial's patient population too heterogeneous, making it difficult to draw reliable conclusions about RP1's efficacy.
• Combination Therapy Ambiguity: The agency questioned the confirmatory trial's ability to isolate the effects of RP1 from other drugs used in combination, raising doubts about the validity of the results.

While the FDA did not cite safety concerns, the CRL has effectively stalled RP1's path to market, casting doubt on Replimune's near-term prospects.

Hagens Berman Launches Investor Investigation

The law firm Hagens Berman Sobol Shapiro LLP is investigating whether Replimune misled investors about the regulatory risks and trial limitations. Reed Kathrein, a partner at the firm, commented: "When a company's valuation hinges on a single trial, transparency around that trial's design and data is absolutely critical. We're examining whether Replimune's disclosures fell short of that standard."

If you invested in Replimune and have substantial losses, or have knowledge that may assist the firm's investigation, submit your losses now »

If you'd like more information and answers to frequently asked questions about the Replimune case and our investigation, read more »

Whistleblowers: Persons with non-public information regarding Replimune should consider their options to help in the investigation or take advantage of the SEC Whistleblower program. Under the new program, whistleblowers who provide original information may receive rewards totaling up to 30 percent of any successful recovery made by the SEC. For more information, call Reed Kathrein at 844-916-0895 or email [email protected].

About Hagens Berman
Hagens Berman is a global plaintiffs' rights complex litigation firm focusing on corporate accountability. The firm is home to a robust practice and represents investors as well as whistleblowers, workers, consumers and others in cases achieving real results for those harmed by corporate negligence and other wrongdoings. Hagens Berman's team has secured more than $2.9 billion in this area of law. More about the firm and its successes can be found at hbsslaw.com. Follow the firm for updates and news at @ClassActionLaw.

SOURCE Hagens Berman Sobol Shapiro LLP