Regeneron Surges on FDA Delay as $0.77B Volume Ranks in Top 500

Regeneron Pharmaceuticals (REGN) saw a 3.36% rise on August 20, 2025, with a trading volume of $0.77 billion, marking a 55.76% increase from the previous day. The stock’s performance coincided with the announcement that the FDA has delayed key regulatory reviews for EYLEA HD, a high-dose aflibercept injection, to the fourth quarter of 2025. The extension affects submissions for a prefilled syringe format and expanded indications, including treatment of macular edema following retinal vein occlusion (RVO) and more flexible dosing schedules.

The delay follows an FDA inspection of Catalent Indiana LLC, a third-party manufacturer acquired by Novo Nordisk. Regeneron characterized the extension as a “major amendment” to its applications, necessitating additional review time. Novo Nordisk submitted a comprehensive response in early August to address the FDA’s observations. Despite the delay, EYLEA HD remains available in vial form, with existing dosing regimens for conditions such as wet AMD, DME, and DR unaffected. The prefilled syringe and expanded dosing options, however, face a temporary setback, impacting convenience and flexibility for patients.

Regeneron had previously disclosed the anticipated delay during its Q2 2025 earnings call, suggesting limited surprise among investors. The company emphasized that the FDA can expedite reviews once manufacturing issues are resolved. EYLEA HD, developed jointly with Bayer, is positioned to reduce injection frequency while maintaining efficacy compared to the standard EYLEA formulation. Regeneron retains exclusive U.S. rights to the product, with Bayer handling international marketing. The delay primarily affects near-term growth expectations for the prefilled syringe and dosing flexibility but does not alter the drug’s current market availability.

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