Regeneron Advances Phase 3 Antibody Trial in Birch Pollen Eye Allergy: What Investors Should Know

Regeneron Pharmaceuticals (REGN) announced an update on their ongoing clinical study.

Study Overview
Regeneron Pharmaceuticals has launched a new Phase 3 trial titled “A Randomized, Double-Masked, Placebo-Controlled, Phase 3 Study to Assess the Efficacy and Safety of Bet v 1 Monoclonal Antibodies in Participants With Allergic Conjunctivitis Due to Birch Pollen Allergy.” The study aims to test whether new antibody drugs can safely and effectively reduce red, itchy eyes in teens and adults who suffer from birch pollen–related eye allergies. This is important because seasonal eye allergies are common, often under-treated, and represent a large, recurring market.

Intervention/Treatment
The trial is testing two injectable antibody drugs, REGN5713 and REGN5715. Each targets the birch pollen allergen (Bet v 1) to block the body’s allergy response. Patients will receive either REGN5713 alone, REGN5715 alone, both together, or a placebo. The goal is to see which option best eases eye symptoms while maintaining a clean safety profile.

Study Design
This is a randomized study, meaning participants are assigned by chance to one of the treatment groups or placebo. It follows a parallel design, so each group stays on its assigned treatment throughout the trial. The trial is “double-masked” (quadruple-masked in formal terms), so patients, doctors, study staff, and those assessing results do not know who is getting the real drug or placebo. The main purpose is treatment: to show whether these drugs work better than placebo for eye allergies.

Study Timeline
The study was first submitted on December 17, 2025, and is currently listed as “Not Yet Recruiting,” so enrollment has not started. A primary completion date has not yet been posted, but investors should assume readouts several years after enrollment begins, in line with typical Phase 3 timelines. The most recent update was submitted on December 29, 2025, confirming the protocol and signaling that Regeneron is moving the program toward active recruitment.

Market Implications
This update highlights Regeneron’s push to expand beyond its core eye and immunology franchises into seasonal allergy, a large and durable market now largely served by antihistamine drops, steroids, and allergen immunotherapy. A successful program could add a high-value, biologic option for patients with more severe or persistent eye symptoms, supporting long-term revenue diversification. For investors, the move reinforces Regeneron’s strategy of leveraging antibody platforms into new allergy niches, complementing its existing pipeline. Near term, the impact on the stock is likely modest because the trial is early and still pre-enrollment. However, the start of a Phase 3 program in a broad indication can support sentiment by underscoring pipeline depth versus peers in immunology and allergy. Competitors in allergy care, mainly generic eye drop makers and immunotherapy players, may not face immediate pressure, but a positive late-stage readout could eventually shift share toward higher-priced biologics in more severe cases. Overall, the update is a mild positive for long-term holders focused on pipeline optionality rather than near-term earnings.

The study is ongoing in the setup phase and has been recently updated, with further details available on the ClinicalTrials portal.

To learn more about REGN’s potential, visit the Regeneron Pharmaceuticals drug pipeline page.