Bambusa Therapeutics Reports Potentially Transformative Preliminary Proof-of-Concept Results for BBT001 in Atopic Dermatitis, Reinforcing Its Best-in-Disease Potential

BBT001 delivered highly statistically significant and clinically meaningful improvement in EASI beginning at Week 1, with responses continuing to improve over time

Fast-onset and potent itch relief was observed as early as Day 1 after the first dose alongside robust and durable suppression of Type 2 inflammatory biomarkers

Favorable safety, extended half-life and low immunogenicity findings support BBT001's potential best-in-disease profile and infrequent maintenance dosing

Additional topline data from ongoing BBT001 studies in atopic dermatitis and chronic spontaneous urticaria expected in 1H 2027

BOSTON, July 27, 2026 /PRNewswire/ -- Bambusa Therapeutics, Inc. (Bambusa Therapeutics or Bambusa), a clinical-stage biotechnology company developing next-generation, long-acting bispecific antibodies designed for immunology and inflammation (I&I), today announced compelling preliminary data of bio-naïve patients with moderate-to-severe atopic dermatitis (AD) who received four weeks of treatment in its ongoing global Phase 1 clinical trial of BBT001. BBT001 is a half-life-extended bispecific antibody targeting interleukin-4 receptor alpha (IL-4Rα) and interleukin-31 (IL-31).

Study design:

This proof-of-concept AD study is part of a global, randomized, double-blind, placebo-controlled Phase 1 clinical trial (NCT06808477) evaluating both intravenous (IV) and subcutaneous (SC) formulations of BBT001 in healthy volunteers and patients with AD.

In this study, patients with moderate-to-severe AD who have received neither biologics targeting the same pathways as BBT001 nor JAK inhibitors were randomized 2:1 to receive either 450 mg IV of BBT001 or placebo once every two weeks during a four-week treatment period at clinical sites in New Zealand and the United States. This study's primary endpoints are safety and tolerability. Exploratory efficacy and biomarker endpoints include percentage changes from baseline in the Eczema Area and Severity Index (EASI), Peak Pruritus Numerical Rating Scale (PP-NRS) score, and Type 2 inflammatory biomarkers.

Key preliminary findings:

As of the June 8, 2026 data cutoff date, 17 patients were enrolled with 12 patients randomized to receive BBT001 treatment and 5 patients to receive placebo.  Key baseline characteristics can be found in Table 1.

Table 1: Key Baseline Patient Characteristics*

• Fast-onset, statistically significant and clinically meaningful improvement in EASI. BBT001 produced a highly statistically significant placebo-adjusted EASI reduction beginning at Week 1. The placebo-adjusted EASI reduction deepened through Week 12 and remained sustained throughout course of treatment for patients followed.
• 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.
• Robust and durable suppression of Type 2 inflammatory biomarkers. BBT001 produced early and substantial reductions in key biomarkers, including thymus and activation-regulated chemokine (TARC) and immunoglobulin E (IgE), that were sustained for eight weeks after the last dose, demonstrating durable inhibition of Type 2 inflammation.
• Favorable safety findings. BBT001 was observed to be well tolerated, with no cases of conjunctivitis reported, consistent with prior findings in healthy volunteers.
• Extended half-life supporting infrequent dosing. BBT001 demonstrated an extended half-life in patients with AD, consistent with prior observations in healthy volunteers, supporting the potential for maintenance dosing as infrequently as once every three months.
• Low immunogenicity. BBT001 demonstrated a low incidence of treatment-emergent anti-drug antibodies, with low titers and no apparent evidence of neutralizing activity, consistent with prior findings in healthy volunteers.

Table 2: EASI Reduction*

Table 3: Additional Exploratory Endpoints*

"Despite important advances in atopic dermatitis treatment, patients and physicians are still looking for therapies that provide more complete control of both skin lesions and itch without the burden of frequent dosing," said Eric Simpson, M.D., M.C.R. Professor of Dermatology and Director of Clinical Research at Oregon Health & Science University and a member of Bambusa's Scientific Advisory Board. "The rapid onset and depth of response observed with BBT001 in this study, together with its favorable safety results and potential for extended dosing intervals, make BBT001's emerging profile particularly compelling. If these findings are confirmed in larger and longer studies and if BBT001 is approved, it could meaningfully raise the standard of care for patients with moderate-to-severe atopic dermatitis."

"I had the opportunity to enroll several patients with severe atopic dermatitis in this study and saw firsthand the substantial burden this disease placed on their lives," said Michael Cameron, M.D., Co-founder and CEO of Equity Medical and Assistant Clinical Professor at Mount Sinai Health System, Principal Investigator in the BBT001-001 study.  "The speed, depth and consistency of clinical improvement observed with BBT001 exceeded my expectations, particularly given the short treatment duration and severity of disease among the participants. I am grateful to our patients and proud that our site contributed to the advancement of a potential novel therapy that, if approved, could reshape the treatment landscape for atopic dermatitis."

"We founded Bambusa to create medicines that could redefine the standard of care, rather than deliver incremental improvement," said Shanshan Xu, M.D., Ph.D., Co-Founder and Chief Executive Officer of Bambusa Therapeutics. "These results provide compelling clinical validation of our strategy: combining two commercially validated and complementary targets with a long-acting bispecific antibody to deliver a potentially differentiated treatment experience. We believe BBT001 has the opportunity to bring together the attributes that matter most to patients and physicians—fast onset, powerful control of both skin disease and itch, a favorable safety profile and infrequent dosing—in a single therapy. This milestone strengthens our conviction not only in BBT001, but also in the broader potential of Bambusa's bispecific platform. As a physician, drug developer and mother of a young daughter who has experienced eczema, this mission is deeply personal to me. We are advancing BBT001 with urgency for patients and families—including families like my own—who are waiting for better treatment options."

Next Steps:

Bambusa plans to present the full results at an upcoming medical conference. Based on the compelling clinical signal, the Company intends to rapidly advance BBT001 into a Phase 2b trial in patients with moderate-to-severe AD, evaluating a maintenance dosing regimen of up to once every three months. BBT001 is also being evaluated in additional ongoing randomized, double-blind, placebo-controlled Phase 1 and Phase 2a clinical studies, in both IV and SC formulations. The Company plans to report additional topline IV data in the first half of 2027 from bio-naïve and bio-experienced patients with moderate-to-severe AD treated with twelve weeks of BBT001 and patients with chronic spontaneous urticaria (CSU) treated with fourteen weeks of BBT001. Together, these studies are designed to inform dose and formulation selection and support the subsequent advancement of BBT001 into registrational development across multiple Type 2 inflammatory diseases.

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 has previously presented Phase 1 healthy volunteer data supporting a potential best-in-disease profile for BBT001, including favorable safety results, positive pharmacokinetic and pharmacodynamic activity, and the potential for maintenance dosing of up to every three months. Bambusa is currently evaluating BBT001 in multiple ongoing placebo-controlled clinical trials, including studies in patients with AD and CSU.

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 best-in-disease and first-in-class potential. It is currently in Phase 1b/2a proof-of-concept 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 Phase 1b/2a proof-of-concept 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.

Contact:
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SOURCE Bambusa Therapeutics