Pune, India | September 11, 2025
Regeneron has released promising data from two Phase 3 clinical studies targeting cat and birch pollen allergies. These trials assessed the effectiveness of first-in-class monoclonal antibody treatments that neutralize allergens at the source. By addressing the root cause of allergic responses, this new approach offers a potential breakthrough in allergy treatment.
In the cat allergy trial, Regeneron tested a combination of two monoclonal antibodies—REGN1908 and REGN1909. These antibodies specifically target FelD1, the primary allergen produced by cats. The study included 64 participants, with 33 receiving the treatment and 31 receiving a placebo. Just one week after a single dose, treated patients experienced a 52% reduction in eye itching, a 39% decrease in eye redness, and a 44% drop in skin test reactivity. Patients whose symptoms were mainly triggered by Fe D1 showed even stronger responses.
For birch pollen allergies, the company evaluated REGN5713 and REGN5715—antibodies that target Bet v 1, the key birch allergen. This trial involved 54 participants, evenly divided between the treatment and placebo groups. One week after receiving the injection, patients reported a 51% improvement in eye itching, a 46% reduction in redness, and a 44% decrease in skin prick test response. These findings align closely with the cat allergy results, further demonstrating the potential of this approach.
Participants responded well to both treatments. No one experienced serious adverse effects, and all participants completed the trials without dropping out due to side effects. The strong safety profile supports continued research and suggests these therapies could serve as alternatives to traditional treatments such as antihistamines, corticosteroids, and allergy shots.
Regeneron plans to move forward with more Phase 3 confirmatory trials. The company will launch additional studies for the cat allergy treatment in early 2026. Trials for the birch pollen therapy are scheduled to begin before the end of 2025. These upcoming studies will focus on evaluating long-term safety and the duration of symptom relief.
These Phase 3 trials build on earlier research showing that a single dose could provide relief for at least three months. Previous studies also demonstrated improvements in nasal and respiratory symptoms, suggesting that the therapy may offer broader benefits beyond just eye-related reactions.
Millions of people around the world suffer from allergies. In the U.S. alone, more than 20 million individuals experience cat allergies, while over 10 million deal with moderate to severe birch pollen allergies. Many patients continue to struggle with symptoms despite using current medications. Regeneron’s new antibody-based therapies may help close this treatment gap by providing a more targeted and lasting solution.
The VelocImmune® platform played a central role in developing these monoclonal antibodies. Regeneron’s proprietary technology also powers several of its approved therapies and enables precise targeting of allergens, enhancing both efficacy and specificity.
By attacking allergens directly, Regeneron introduces a novel approach to allergy management. Patients may no longer need daily pills or long-term immunotherapy. A single injection could offer substantial relief. If upcoming trials confirm these early findings, this new class of treatment could change the standard of care for allergy sufferers.
The positive results from these Phase 3 studies mark an important milestone. Regeneron now stands on the threshold of delivering innovative allergy therapies from the lab to clinical settings. If successful in future trials, these treatments could provide rapid, long-lasting relief to millions living with allergic conditions.
