Bambusa Therapeutics Presents Positive Preliminary Phase 1 BBT002 Data at American Thoracic Society 2026 (ATS 2026) International Conference and Announces First Patient Dosed in Phase 1b/2a CRSwNP Trial

- BBT002 is a next-generation, long-acting bispecific antibody targeting two clinically and commercially validated targets, IL-4Rα and IL-5 -

- Preliminary Phase 1 data demonstrated rapid, deep, and sustained effects on key biomarkers for at least 8 weeks following a single dose, including pSTAT6 inhibition, TARC reduction, and eosinophil depletion -

- BBT002 exhibited ~29.4-day half-life, supporting the potential for extended dosing intervals -

- Topline data from ongoing Phase 1b/2a trials evaluating BBT002 in patients with COPD and CRSwNP anticipated by year-end 2026 and first half of 2027, respectively -

BOSTON, May 18, 2026 /PRNewswire/ -- Bambusa Therapeutics, Inc. (Bambusa Therapeutics), a clinical-stage biotechnology company advancing next-generation, long-acting bispecific antibodies for immunology and inflammation, today announced the presentation of preliminary data from the single ascending dose (SAD) cohorts of the Phase 1 trial evaluating BBT002 in healthy volunteers at the American Thoracic Society 2026 (ATS 2026) International Conference, taking place from May 17-20, 2026 in Orlando, Florida.

The Company also announced dosing of the first patient in the Phase 1b/2a trial evaluating BBT002 in patients with chronic rhinosinusitis with nasal polyps (CRSwNP), expanding the ongoing clinical development of BBT002 across Type 2 inflammatory respiratory diseases, beyond chronic obstructive pulmonary disease (COPD).

"We are excited to present the first clinical data from BBT002 in an oral presentation at ATS 2026. These data support the potential for BBT002 to deliver rapid and durable biologic activity providing the opportunity for more complete clinical outcomes compared to currently approved medicines," said Thang Ho, Ph.D., Chief Development Officer at Bambusa Therapeutics. "The Phase 1 SAD data demonstrate BBT002's potential to serve as a platform-in-a-molecule designed for respiratory and other Type 2 inflammatory diseases in which eosinophils play an important pathogenic role."

The ATS 2026 oral presentation, titled "Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of BBT002, a Novel Bispecific IL-4Rα/IL-5 Antibody: Results from the Single Ascending Dose Healthy Volunteers Portion of a Phase 1 Study" highlights the following data:

Percent Change in Eosinophil (EOS) Levels: EOS is a clinically established biomarker of Type 2 airway inflammation and IL-5 pathway activity, with elevated levels associated with disease severity and exacerbation risk across multiple respiratory diseases.

• BBT002 demonstrated rapid, robust, and sustained depletion of EOS for more than 8 weeks following a single dose compared to baseline.

Percent Change in Thymus and Activation-Regulated Chemokine (TARC): TARC is a key Type 2 inflammatory chemokine that is associated with Th2-driven immune responses and is strongly correlated with disease activity across multiple respiratory inflammatory diseases.

• BBT002 demonstrated dose-dependent, rapid, deep, and sustained reduction in TARC for at least 8 weeks following a single dose compared to baseline.

Percent Change in Phosphorylated STAT6 (pSTAT6): pSTAT6 is a key downstream mediator of Type 2 inflammation in respiratory inflammation disease when assessing IL-4Rα pathway activity.

• BBT002 achieved rapid, complete, and sustained inhibition of pSTAT6 for at least 8 weeks following a single dose compared to baseline.

Pharmacokinetics (PK): BBT002 exhibited prolonged PK with a half-life of approximately 29.4 days at or above target exposure following a single dose, supporting the potential for extended dosing intervals.

Safety and Tolerability: BBT002 was observed to be well-tolerated across all doses evaluated in the SAD cohorts throughout the trial.

Immunogenicity: The incidence of anti-drug antibodies (ADA) was low, with no apparent impact on safety or PK.

"We believe the clinical progress of BBT002 further validates the breadth and versatility of Bambusa's bispecific antibody platform and our strategy of developing differentiated, long-acting therapies for significant immunology and inflammatory disease markets," said Shanshan Xu, M.D., Ph.D., Founder & Chief Executive Officer of Bambusa Therapeutics. "With encouraging early Phase 1 PK, PD, and safety data, the advancement of BBT002 into patients with CRSwNP, and multiple upcoming clinical milestones including topline data from our ongoing COPD trial, we continue to demonstrate our ability to rapidly advance innovative bispecific antibodies that address complementary, clinically and commercially validated pathways within a single molecule. Together, BBT001 and BBT002 highlight our pipeline-in-a-program approach, which we believe has the potential to drive more complete clinical outcomes, enhanced dosing convenience enabled through prolonged half-life, and meaningful differentiation across multiple large inflammatory diseases."

The Company also expects to present data from the MAD cohorts of the BBT002 Phase 1 trial in healthy volunteers at European Academy of Allergy & Clinical Immunology (EAACI) Annual Congress 2026, taking place June 12-15, 2026, in Istanbul, Turkey. In parallel to the Phase 1 SAD and MAD trial in healthy volunteers, BBT002 is being evaluated in ongoing Phase 1b/2a trials in patients with COPD and CRSwNP, with topline results anticipated by year-end 2026 and the first half of 2027, respectively.

The BBT002 Phase 1 trial presentation from ATS 2026 is available in the "Publications" section on Bambusa's website, www.bambusatx.com.

About the Phase 1 SAD/MAD trial of BBT002

Bambusa Therapeutics' single- and multiple-ascending-dose Phase 1 clinical trial in healthy volunteers is a randomized, blinded, placebo-controlled trial designed to evaluate the safety, tolerability, pharmacokinetics, immunogenicity, and pharmacodynamic profile of BBT002.

About BBT002

Bambusa Therapeutics' second clinical program, BBT002, is a first-in-class, multi-targeting, half-life extended bispecific antibody engineered to inhibit both IL-4Rα and IL-5 signaling. Designed as a platform-in-a-molecule, BBT002 simultaneously targets the IL-4/IL-13 pathway through IL-4Rα and the IL-5/eosinophil axis within a single therapy. The Company believes this differentiated approach has the potential to address multiple respiratory and other Type 2 inflammatory diseases, improve clinical outcomes, and provide greater dosing convenience through extended maintenance dosing intervals. BBT002 has demonstrated a favorable safety profile and strong pharmacokinetics in healthy volunteers, supporting its advancement into multiple clinical trials in patients with COPD and CRSwNP.

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 (I&I) diseases. The Company's bispecific antibody platform combines 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 first-in-class, half-life-extended bispecific antibody targeting IL-4Rα and IL-31 with best-in-disease potential. It is currently in Phase 1b/2a proof-of-concept development for atopic dermatitis (AD) and chronic spontaneous urticaria (CSU).
• BBT002 is a first-in-class, half-life-extended bispecific antibody targeting IL-4Rα and IL-5 with platform-in-a-molecule potential. It is currently in Phase 1b/2a proof-of-concept development for Type 2 inflammatory disorders, including COPD and CRSwNP.
• BBT003 and BBT004 are preclinical programs focused on gastroenterology and rheumatology, respectively.

For more information, please visit www.bambusatx.com. Follow Bambusa on LinkedIn.

SOURCE Bambusa Therapeutics, Inc.