FDA Rejection Clouds Path For REGENXBIO's Rare Disease Treatment

Core Viewpoint - The FDA has issued a Complete Response Letter (CRL) for RGX-121, raising concerns about study eligibility criteria and surrogate endpoints, which may complicate the path to approval for this gene therapy targeting MPS II [2][4]. Regulatory Developments - The FDA accepted the RGX-121 Biologics License Application (BLA) under the accelerated approval pathway, but the Prescription Drug User Fee Act (PDUFA) goal date has been extended from November 9, 2025, to February 8, 2026 [1]. - The CRL outlines several potential paths forward, including conducting a new study, treating additional patients, and using an untreated control arm, which poses challenges in the ultra-rare disease population [2]. Company Actions - REGENXBIO plans to request a Type A meeting to discuss the CRL and aims to resubmit the BLA with additional evidence from global experts to clarify the neuronopathic patient population [3]. - The BLA for RGX-121 was supported by positive biomarker, functional, and safety data from the CAMPSIITE I/II/III trial, demonstrating good tolerability across all patients [3]. Analyst Insights - Analysts note that the CRL reflects structural reasons for not approving the gene therapy rather than safety issues related to a clinical hold [4]. - The FDA's cautious approach indicates a preference for placebo-controlled data before granting accelerated approvals [4]. Market Performance - REGENXBIO's stock carries a Buy Rating with an average price target of $31.38, despite facing regulatory challenges [5]. - The stock showed strong momentum, outperforming the broader market, although it experienced a decline of 10.99% to $9.17 during premarket trading [5][6]. - Recent analyst ratings include Buy from Chardan Capital with a target of $52.00, and Stifel raised its target to $45.00 [6].