Portnoy Law Firm Files Class Action Lawsuit Against REGENXBIO

Lawsuit alleges biotech company misled investors about safety and efficacy of gene therapy trial

Mar. 16, 2026 at 3:44pm

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The Portnoy Law Firm has filed a class action lawsuit against REGENXBIO, Inc. on behalf of investors who bought securities between February 9, 2022 and January 27, 2026. The lawsuit alleges that REGENXBIO made false and misleading statements about the safety and efficacy of its RGX-111 gene therapy trial, which was placed on clinical hold by the FDA after a participant developed an intraventricular CNS tumor.

Why it matters

This lawsuit highlights the risks and challenges facing biotech companies developing experimental gene therapies. Investors rely on accurate information from these companies, and allegations of misleading statements can significantly impact stock prices and erode public trust.

The details

The class action lawsuit alleges that REGENXBIO, a clinical-stage biotechnology company, disseminated false and misleading statements about the RGX-111 trial, a one-time gene therapy for the treatment of Mucopolysaccharidosis Type I (MPS I). On January 28, 2026, REGENXBIO announced that the FDA had placed a clinical hold on the RGX-111 trial after a participant developed an intraventricular CNS tumor. This news caused REGENXBIO's stock price to drop nearly 18%.

  • The class period covers February 9, 2022 to January 27, 2026.
  • REGENXBIO announced the FDA clinical hold on January 28, 2026.

The players

REGENXBIO, Inc.

A clinical-stage biotechnology company developing gene therapies, including the RGX-111 treatment for Mucopolysaccharidosis Type I.

Lesley F. Portnoy

An attorney at the Portnoy Law Firm, which is representing investors in the class action lawsuit against REGENXBIO.

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What they’re saying

“Investors are encouraged to contact attorney Lesley F. Portnoy, by phone 844-767-8529 or email: lesley@portnoylaw.com, to discuss their legal rights, or join the case via https://portnoylaw.com/regenxbio-inc.”

— Lesley F. Portnoy, Attorney

What’s next

Investors have until April 14, 2026 to file a lead plaintiff motion in the class action lawsuit.

The takeaway

This case highlights the importance of transparency and accurate disclosures from biotech companies, especially those developing high-risk, experimental therapies. Investors rely on this information to make informed decisions, and allegations of misleading statements can have serious consequences for both the company and its shareholders.