Regenxbio Soars 7.2% on FDA Acceptance of Groundbreaking Gene Therapy for Hunter Syndrome

Shares of Regenxbio Inc (NASDAQ: RGNX) saw an impressive uptick in premarket trading, gaining 7.2%, following a pivotal announcement from the U.S. Food and Drug Administration (FDA). The regulatory body has accepted the company’s Biologics License Application (BLA) for RGX-121, a promising gene therapy aimed at addressing Mucopolysaccharidosis II (MPS II), commonly referred to as Hunter syndrome.

The FDA's decision to prioritize the review of this therapy indicates robust investor sentiment, especially with a target action date set for November 9, 2025. RGX-121 stands poised to make history as the first one-time gene therapy for MPS II, potentially revolutionizing the treatment landscape for this condition.

Curran M. Simpson, President and CEO of Regenxbio, expressed enthusiasm about this milestone, emphasizing the therapy’s potential to significantly ameliorate both neurological and systemic manifestations of Hunter syndrome. The company has presented optimistic biomarker data and promising long-term outcomes, which point towards RGX-121’s capability to ease the burden currently endured by patients reliant on weekly enzyme replacement therapies.

Enhancing Regenxbio's strategic positioning in the market, a partnership with Nippon Shinyaku was forged earlier in January 2025, positioning its subsidiary, NS Pharma, to spearhead the commercialization of RGX-121 in the U.S. contingent upon FDA approval. Furthermore, should RGX-121 secure the green light, it may be eligible for a Priority Review Voucher (PRV), with Regenxbio retaining the right to any profits generated from its sale.

Notably, RGX-121 has garnered multiple designations from the FDA, including Orphan Drug Product, Rare Pediatric Disease, Fast Track, and Regenerative Medicine Advanced Therapy (RMAT), along with advanced therapy medicinal products (ATMP) classification from the European Medicines Agency. These accolades underscore its critical significance in addressing MPS II.

In light of this significant news, market reactions have been favorable, reflecting a high level of confidence in both the therapy's market viability and the company's strategic initiatives in the commercialization and production realms. The FDA's acknowledgment of the BLA marks a crucial advancement for Regenxbio, as it endeavors to deliver this groundbreaking therapy to the MPS II patient population.