One dose of the novel agent, REGN1908-1909 (Regeneron Pharmaceuticals) resulted in a rapid and durable reduction in cat-allergen-induced bronchoconstriction in cat-allergic subjects with mild asthma.
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The finding, from a phase 2 randomized placebo-controlled study, is good news for the millions of people who are plagued by cat allergies, the investigators say.
The study, which was sponsored by Regeneron, was presented in a late breaking oral abstract session at the annual meeting of the American Academy of Allergy, Asthma, and Immunology, held virtually this year.
“REGN1908-1909 contains antibodies against Fel d 1, the major cat allergen, and here we show that it quickly and lastingly reduces acute bronchoconstriction in people with cat allergy,” lead author Frederic J. de Blay, MD, Strasbourg University Hospital, France, said in an interview.
Dr. de Blay admitted he is “quite excited” about the results.
“This study was performed in an environmental exposure chamber, and we clearly demonstrate that these antibodies decrease the asthmatic response to cat allergen within 8 days, and that these effects last 3 months. I never saw that in my life. I was a little bit skeptical at first, so to obtain such robust results after just 8 days, after just one injection, I was very surprised,” he said.
Dr. de Blay and his team screened potential participants to make sure they were cat allergic by exposing them to cat allergen for up to 2 hours while they were in the environmental exposure chamber. To be eligible for the study, participants had to show an early asthmatic response (EAR), defined as a reduction in forced expiratory volume in 1 second (FEV1) of at least 20% from baseline.
The participants were then randomized to receive either single-dose REGN1908-1909, 600 mg, subcutaneously (n = 29 patients) or placebo (n = 27 patients) prior to cat-allergen exposure in the controlled environmental chamber.
Dr. de Blay developed the chamber used in the study: the ALYATEC environmental exposure chamber.
“The chamber is 60 meters square, or 150 cubic meters, and can accommodate 20 patients. We are able to nebulize cat allergen, mice allergen, or whatever we wish to study so we can standardize the exposure. We can control the particle size and the amount so we know the exact amount of allergen that the patient has been exposed to,” he explained.
To test the efficacy of REGN1908-1909 in reducing acute bronchoconstriction, or EAR, the researchers measured FEV1 at baseline, and on days 8, 29, 57, and 85 in both groups. During each exposure, measurements were taken every 10 minutes for periods that lasted up to 4 hours.
They found that the probability of remaining in the chamber with no asthmatic response was substantially elevated in the group treated with REGN1908-1909.
Compared with placebo, REGN1908-1909 significantly increased the median time to EAR, from 51 minutes at baseline to more than 4 hours on day 8, (hazard ratio [HR], 0.36; P < .0083), day 29 (HR, 0.24; P < .0001), day 57 (HR, 0.45; P = .0222), and day 85 (HR, 0.27; P = .0003).
The FEV1 area under the curve (AUC) was also better with REGN1908-1909 than with placebo at day 8 (15.2% vs. 1.6%; P < .001). And a single dose reduced skin-test reactivity to cat allergen at 1 week, which persisted for up to 4 months.
In addition, participants who received REGN1908-1909 were able to tolerate a threefold higher amount of the cat allergen than those who received placebo (P = .003).
“We initially gave 40 nanograms of cat allergen, and then 8 days later they were able to stay longer in the chamber and inhale more of the allergen, to almost triple the amount they had originally been given. That 40 nanograms is very close to real world exposure,” Dr. de Blay noted.
Regeneron plans to start a phase 3 trial soon, he reported.