RGNX's "Transformational" Promise Became a $2.40 Loss for Investors

Lawsuit alleges REGENXBIO hid safety risks of its gene therapy candidate RGX-111

Published on Mar. 5, 2026

Got story updates? Submit your updates here. ›

REGENXBIO, Inc. (NASDAQ: RGNX) faced a sharp stock drop of 17.8% after revealing that a CNS tumor was discovered in a trial participant for its gene therapy candidate RGX-111, leading the FDA to place a clinical hold on the program. The lawsuit alleges that REGENXBIO repeatedly touted RGX-111 as a "potentially transformational medicine" with "very promising results" despite internal awareness of underlying safety problems that were not disclosed to investors.

Why it matters

This case highlights the risks and challenges facing gene therapy companies as they navigate the complex regulatory landscape and balance the promise of their treatments with the need to fully disclose safety concerns to investors. The significant stock drop underscores the financial impact that such issues can have on shareholders.

The details

REGENXBIO revealed that a routine brain MRI identified an intraventricular CNS tumor in an asymptomatic five-year-old participant who had received RGX-111 four years earlier. Preliminary genetic analysis detected an AAV vector genome integration event linked to overexpression of a proto-oncogene (PLAG1), leading the FDA to place clinical holds on both RGX-111 and the related RGX-121 program.

  • On January 28, 2026, REGENXBIO disclosed the CNS tumor discovery and FDA clinical hold.
  • In November 2023, REGENXBIO de-prioritized RGX-111, which the lawsuit alleges reflected internal awareness of safety problems.
  • In January 2025, REGENXBIO described RGX-111 as a "potentially transformational medicine" with "very promising results."

The players

REGENXBIO, Inc.

A biotechnology company focused on the development of gene therapies.

RGX-111

REGENXBIO's gene therapy candidate that was placed on clinical hold by the FDA after a CNS tumor was discovered in a trial participant.

Nippon Shinyaku Co., Ltd.

A Japanese pharmaceutical company that partnered with REGENXBIO on RGX-111 and RGX-121 in January 2025.

Joseph E. Levi, Esq.

An attorney at Levi & Korsinsky, LLP, the law firm representing shareholders in the lawsuit against REGENXBIO.

Got photos? Submit your photos here. ›

What they’re saying

“Companies that make specific promises to investors about future performance have an obligation to disclose known risks to those projections. When a gene therapy candidate is repeatedly described as transformational while serious safety signals allegedly go undisclosed, the gap between promise and reality can be measured in shareholder losses.”

— Joseph E. Levi, Esq., Attorney, Levi & Korsinsky, LLP (SueWallSt.com)

What’s next

The lead plaintiff deadline for the lawsuit is April 14, 2026, and the firm is encouraging affected RGNX shareholders to contact them about recovering their investment losses.

The takeaway

This case highlights the importance of transparency and full disclosure from biotechnology companies, especially those developing promising but high-risk gene therapies. Investors rely on accurate information to make informed decisions, and the alleged gap between REGENXBIO's public statements and internal knowledge of safety issues raises concerns about the company's accountability to its shareholders.