Regeneron’s allergen-blocking antibodies have reduced the symptoms of cat and pollen allergies in a pair of phase 3 studies.
One of these studies saw 64 patients with cat allergy receive either placebo or a combination of two FelD1-blocking antibodies, dubbed REGN1908 and REGN1909. FelD1 is the most dominant cat allergen, according to Regeneron.
The trial hit its primary endpoint of reducing itchy eyes with a “high degree of statistical significance” one week after treatment, the pharma said. Specifically, itchiness was reduced by 52%, while conjunctival redness and skin prick reactivity— the two secondary endpoints—were reduced by 39% and 44%, respectively.
The other trial enrolled 54 patients with an allergy to birch pollen, a trigger for hay fever, who received a separate antibody combination or placebo. The treatment consisted of REGN5713 and REGN5715, monoclonal antibodies that both block BetV1, the dominant allergenic protein for birch pollen.
Itchy eye was reduced by 51%, hitting the trial’s primary endpoint. Conjunctival redness and skin prick reactivity were also reduced by 46% and 44%, respectively, compared to placebo.
The trials involved patients receiving the allergen—in the form of cat dander or birch pollen—directly in their eye eight days after receiving a single subcutaneous dose of the relevant allergen-blocking antibodies.
Both treatments were generally well tolerated, according to Regeneron, with no serious treatment-related adverse events reported.
Following the results, Regeneron said further phase 3 development for the birch pollen treatment is planned for later this year, with the cat allergy program to be pushed forward in the first half of 2026.
The treatments were produced by the same VelocImmune antibody technology that Regeneron used to create its Sanofi-partnered autoimmune blockbuster Dupixent and the skin cancer drug Libtayo.
Regeneron Chief Scientific Officer George Yancopoulos, M.D., Ph.D., put this morning’s results in the context of “burdensome” allergy desensitization shots that patients can take “several times a week for several years … often with disappointing results.”
“We wondered whether we could instead manufacture and directly provide allergen-blocking antibodies,” Yancopoulos, who is billed as a “co-inventor of this new approach to allergy,” said in the release.
“These recent phase 3 allergen challenge trials, together with our earlier phase 2 trials, provide compelling evidence that our first-in-class approach can have the potential to provide profound allergy relief—rapidly and durably after a single treatment—decreasing ocular, nasal and even asthma measures,” Yancopoulos added.