First patient dosed as Bambusa expands global development of its long-acting bispecific antibody targeting both IL-4Rα and IL-31

High-concentration subcutaneous formulation designed to combine BBT001's emerging profile of rapid, deep and durable clinical activity with convenient administration and the potential for infrequent maintenance dosing

Milestone demonstrates continued execution of Bambusa's strategy to bring together efficacy, durability and dosing convenience in a single differentiated therapy for patients with chronic inflammatory skin disease

BOSTON, Oct. 1, 2026 /PRNewswire/ -- Bambusa Therapeutics, Inc. (Bambusa), a clinical-stage biotechnology company advancing next-generation, long-acting bispecific antibodies for immunology and inflammation (I&I), today announced that the first patient has been dosed in the subcutaneous (SC) cohort of its ongoing global Phase 1 clinical trial of BBT001 at a clinical research center in New Zealand. BBT001 is Bambusa's half-life-extended, bispecific antibody engineered to block IL-4Rα and IL-31 signaling, with the goal of addressing both Type 2 inflammation and itch in patients with atopic dermatitis (AD) and other Type 2 inflammatory skin diseases. The initiation of SC dosing follows the potentially transformative preliminary proof-of-concept results already achieved with intravenously administered BBT001 and expands Bambusa's evaluation of a potentially more convenient treatment approach for chronic use in AD patients.

"Subcutaneous dosing represents an important step in advancing BBT001 as a differentiated, long-acting and convenient therapy for patients with atopic dermatitis," said Thang Ho, Ph.D., Co-Founder and Chief Development Officer of Bambusa Therapeutics. "The prolonged half-life observed in healthy volunteers and patients, together with the compelling clinical activity demonstrated in our intravenous proof-of-concept study and our high-concentration subcutaneous formulation, provides a strong foundation for the late-stage development of BBT001. We are now focused on translating BBT001's rapid, deep and durable clinical profile into a convenient subcutaneous therapy with the potential for infrequent maintenance dosing. This study represents an important part of our advancement of the BBT001 development program, with preparations for our Phase 2b study already underway."

Compelling Clinical Proof of Concept Data

In July 2026, Bambusa reported preliminary results from a randomized, double-blind, placebo-controlled proof-of-concept cohort enrolling biologic-naive patients with moderate-to-severe AD from New Zealand and the United States. After four weeks of treatment, BBT001 demonstrated rapid, deep and durable clinical activity:

• Rapid and deep skin responses: Statistically significant placebo-adjusted EASI improvement was observed beginning at Week 1 (35.6%; p=0.0012), deepening to 79.0% at Week 6 (p<0.0001), with a 64% placebo-adjusted EASI-75 response at Week 6. The placebo-adjusted EASI reduction deepened through Week 6 and remained sustained throughout the follow-up period.
• Rapid and progressively greater itch relief. BBT001 reduced PP-NRS scores as early as Day 1, with improvements deepening throughout treatment and remaining sustained for eight weeks after the last dose.
• Durable pharmacology: Type 2 inflammatory biomarkers, including TARC and IgE, were substantially suppressed, with effects sustained for eight weeks following the last dose.
• Favorable emerging profile: BBT001 was observed to be well tolerated, with no cases of conjunctivitis reported and low immunogenicity. An approximately 33-day half-life, together with sustained clinical and pharmacodynamic activity, support the potential for maintenance dosing as infrequently as once every three months.

About the BBT001-001 SC Cohort in AD Patients

The SC cohort is part of Bambusa's global Phase 1 BBT001-001 study and is evaluating 12 weeks of treatment with SC BBT001 in biologic-naive patients with moderate-to-severe AD. The cohort is currently enrolling up to 45 patients across the United States, Australia, Europe and New Zealand. Patients will receive five doses of BBT001 at either 360 mg or 720 mg, or the placebo, administered subcutaneously.

The primary endpoints are safety and tolerability. Secondary endpoints include pharmacokinetics, including half-life, and immunogenicity. Exploratory endpoints include pharmacodynamic measures and clinical activity, including change from baseline in Eczema Area and Severity Index (EASI) and Peak Pruritus Numerical Scale (PP-NRS) and the proportion of patients achieving a validated Investigator Global Assessment (vIGA-AD) score of 0 or 1.

About BBT001

Bambusa Therapeutics' lead clinical program, BBT001, is a potential first-in-class, multi-targeting, half-life-extended bispecific antibody engineered to block both IL-4Rα and IL-31 signaling. By simultaneously addressing core Type 2 inflammation and directly targeting pathways that drive itch, BBT001 is designed to provide faster, deeper, and more durable relief for patients with AD and other Type 2 inflammatory skin diseases.

Bambusa previously presented Phase 1 data in healthy volunteers and in AD patients that support favorable safety results, positive pharmacokinetic and pharmacodynamic activity, and the potential for quarterly maintenance dosing. Bambusa is currently evaluating BBT001 in multiple ongoing placebo-controlled clinical trials, including studies in patients with AD and chronic spontaneous urticaria.

About Bambusa Therapeutics

Bambusa Therapeutics is a clinical-stage biotechnology company developing a portfolio of next-generation, multi-targeting medicines designed to transform patient care across chronic immunology and inflammation diseases. We combine advanced protein engineering with half-life extension technology and high-concentration subcutaneous delivery to improve durability, convenience, and clinical differentiation. Bambusa's vision is to deliver transformative medicines for patients across every stage of life and help define the next era of I&I therapies.

• BBT001 is a half-life-extended bispecific antibody targeting interleukin-4 receptor alpha (IL-4Rα) and interleukin-31 (IL-31) with first-in-class potential. It is currently in development for atopic dermatitis and chronic spontaneous urticaria.
• BBT002 is a half-life-extended bispecific antibody targeting IL-4Rα and interleukin-5 (IL-5) with pipeline-in-a-molecule and first-in-class potential. It is currently in development for Type 2 inflammatory disorders including asthma, chronic obstructive pulmonary disease and chronic rhinosinusitis with nasal polyps.
• BBT003 and BBT004 are preclinical programs focused on gastroenterology and autoantibody-driven autoimmune diseases, respectively.

For more information, visit www.bambusatx.com.

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