Belenos Announces Positive Phase 1b Interim Asthma Results for BEL512, a Long-Acting TSLP/IL-13 Bispecific Antibody

• BEL512 continues to demonstrate a favorable safety and tolerability profile, with adverse events balanced between treatment and placebo arms
• By Day 4 BEL512 produced rapid and deep reductions in FeNO of approximately a 48% change from baseline, and achieved sustained reductions with a mean decrease of 46 ppb by Week 8, a -65% change from baseline
• BEL512 produced rapid reductions in blood eosinophils, reaching levels approximately 26% lower than PBO at Day 4, and 50% lower than PBO by Week 5
• Clinically meaningful improvements among patients with moderate asthma in pre-bronchodilator FEV1 compared with placebo were observed, reaching 181 ml placebo-adjusted mean change from baseline by Day 4, and 330 ml placebo-adjusted mean change from baseline by Week 7
• BEL512 has now demonstrated clinical proof-of-concept in asthma, chronic rhinosinusitis with nasal polyps (CRSwNP) and atopic dermatitis
• Belenos plans to initiate global Phase 3 studies with BEL512 in CRSwNP in the first half of 2027 and asthma in the second half of 2027

SARASOTA, Fla.--(BUSINESS WIRE)--Belenos Biosciences, Inc. (“Belenos”), a clinical-stage biotechnology company developing long-acting bispecific antibodies for chronic inflammatory diseases, today announced positive interim results from its ongoing randomized, double-blind, placebo-controlled Phase 1b study of BEL512, an investigational long-acting bispecific antibody targeting thymic stromal lymphopoietin (“TSLP”) and interleukin-13 (“IL-13”), in patients with mild-moderate asthma.

Phase 1b Trial Design

Fifty participants with mild-to-moderate asthma were randomized to receive BEL512 or placebo (1:1 ratio) subcutaneously on Day 1 and Day 29 at approximately 20 clinical sites in the United States as part of a phase 1b trial. The study remains ongoing for long-term safety, pharmacokinetic and pharmacodynamic follow-up and these 50 participants are expected to complete their final safety assessments in the first quarter of 2027.

All enrolled patients were required to have fractional exhaled nitric oxide (FeNO) ≥25 ppb and pre-bronchodilator forced expiratory volume in one second (FEV1) between 60% and 90% of predicted normal.

The primary objective of the study is to evaluate the safety and tolerability of BEL512. The study also includes multiple exploratory pharmacodynamic and clinical efficacy endpoints, including FeNO, blood eosinophils count (BEC) and pre-bronchodilator FEV1.

Interim Safety Results

BEL512 was generally well tolerated as of the interim data cutoff. No serious or severe adverse events were reported, treatment emergent adverse events rates were similar to placebo, with no treatment related discontinuations.

BEL512 Reduces FeNO and BEC, and Improves Lung Function in Participants with Asthma

Significant reductions in FeNO reductions were observed on Day 4 and FeNO remained significantly reduced throughout the assessment period, with many participants achieving normal FeNO levels regardless of their baseline. Significant reductions in BEC were observed by Day 36. FeNO and BEC are key markers of inflammation that correlate with asthma exacerbations.

In the subgroup of patients with moderate asthma, BEL512 treatment was associated with early and clinically meaningful improvements in pre-bronchodilator FEV1 compared with placebo.

Importantly, there was evident concordance between FeNO and BEC reductions, and also between improvements in FeNO and FEV1 among the BEL512-treated patients. These exploratory findings provide encouraging evidence that the rapid pharmacodynamic effects of BEL512 on airway inflammation are accompanied by improvements in lung function in patients with moderate asthma.

“We are encouraged that the strong pharmacodynamic activity of BEL512 was accompanied by improvements in lung function in patients with moderate asthma, suggesting that the biological effects of dual pathway inhibition can translate into meaningful clinical benefit,” said Donnie McGrath, M.D., Chief Executive Officer of Belenos Biosciences. “Asthma is now the third indication in which BEL512 has demonstrated clinical proof-of-concept, following CRSwNP and atopic dermatitis. This consistency combined with a favorable tolerability profile and potential for dosing every three or six months, suggests BEL512 has the potential to offer a meaningfully differentiated profile as we advance into late-stage development.”

BEL512 Respiratory Development Program

Belenos plans to initiate two global Phase 3 respiratory programs with BEL512 in 2027, beginning with a Phase 3 program in CRSwNP in the first half of 2027, followed by a Phase 3 asthma program in the second half of 2027. Belenos also plans to initiate a global Phase 3 program in chronic obstructive pulmonary disease (COPD) in 2028.

In July 2026, Belenos’ partner Keymed Biosciences received Breakthrough Therapy Designation in China for BEL512, for the treatment of CRSwNP.

About BEL512

BEL512, known as CM512 in Greater China, is an investigational, long-acting bispecific antibody designed to simultaneously inhibit TSLP and IL-13. TSLP is an upstream epithelial-derived alarmin involved in the initiation and maintenance of inflammatory responses, while IL-13 is a central downstream effector cytokine involved in multiple features of type 2 inflammatory disease. By simultaneously targeting these complementary pathways, BEL512 is designed to provide broad and durable control of inflammation.

BEL512 is being developed for chronic inflammatory diseases characterized by epithelial-immune dysregulation, including CRSwNP, asthma, chronic obstructive pulmonary disease, and atopic dermatitis. Belenos holds development and commercialization rights to BEL512 outside Greater China. BEL512/CM512 has not been approved for marketing by any regulatory authority.

About Belenos Biosciences

Founded in 2024, Belenos Biosciences is a clinical-stage biotechnology company developing long-acting therapies designed to restore immune balance, improve clinical outcomes and ultimately achieve disease remission for patients with chronic inflammatory diseases. Belenos licensed ex-Greater China rights to BEL512 and BEL536 from Keymed Biosciences Ltd.

www.belenosbio.com