Regeneron
Pune, India | September 11, 2025
Regeneron shared encouraging results from two Phase 3 clinical trials testing new therapies for cat and birch pollen allergies. These treatments utilize monoclonal antibodies that directly neutralize allergens. Instead of only reducing symptoms, this approach targets the root cause of allergic reactions. If confirmed, it could mark a breakthrough in allergy care.
In the cat allergy trial, researchers studied two antibodies, REGN1908 and REGN1909. These antibodies block Fel d 1, the main allergen responsible for triggering cat allergies. The study included 64 participants, with 33 receiving treatment and 31 taking a placebo. One week after a single dose, patients in the treatment group showed significant progress. They reported a 52 percent reduction in eye itching, a 39 percent decrease in redness, and a 44 percent drop in skin test reactions. The improvements were even stronger in patients whose symptoms were linked mostly to Fel d 1.
The birch pollen trial showed similar success. This study tested two antibodies, REGN5713 and REGN5715, which target Bet v 1, the leading birch pollen allergen. Of the 54 participants, 27 received the therapy and 27 received a placebo. After one week, the treatment group reported a 51 percent drop in eye itching, a 46 percent decline in redness, and a 44 percent improvement in skin test results. These outcomes closely matched the results of the cat allergy trial, showing the strength of this method across allergens.
Both treatments proved safe and well-tolerated. No serious adverse events occurred, and no patients left the study due to side effects. This clean safety profile makes the therapies strong candidates against conventional treatments such as antihistamines, corticosteroids, and allergy shots. Many patients need to use these standard options for months or years, and they often fail to provide complete relief.
Regeneron now plans the next stage of development. Confirmatory Phase 3 studies for the cat allergy therapy are expected in early 2026. Birch pollen therapy trials are expected to begin before the end of 2025. These studies will measure long-term safety and lasting symptom relief. Early research suggested that a single dose could keep symptoms under control for three months. The same studies also reported relief for nasal and respiratory issues, not just eye irritation, hinting at even wider benefits.
Allergies affect millions worldwide. In the United States, more than 20 million people live with cat allergies, and about 10 million face moderate to severe birch pollen allergies. Many patients in these groups cannot find enough relief in current treatments. Regeneron’s new therapies could close that gap. By attacking allergens directly, these antibodies introduce a new model of care. Patients may no longer need daily tablets or years of allergy shots. A single injection could deliver lasting results.
Regeneron developed these antibody therapies through its own VelocImmune® platform. This advanced technology also powers several of the company’s approved medicines. It enables accurate targeting of allergens, increasing both precision and effectiveness. Applied to allergy care, the platform could provide a safer and more convenient option compared to existing standards.
The success of these Phase 3 trials marks a major moment in allergy research. If future confirmatory trials confirm the results, Regeneron could launch an entirely new class of treatments into clinics. For millions living with persistent allergies, this may translate into faster, longer-lasting, and more reliable relief.
About the Author
