NovaBridge Biosciences Reports Mature Phase 1b Data at ESMO 2026 Positioning Givastomig for Registrational Development (Form 6-K)

NovaBridge Biosciences Reports Mature Phase 1b Data at ESMO 2026 Positioning Givastomig for Registrational Development

Nearly 18 months of median follow-up, selection of the 8 mg/kg dose and FDA engagement strengthen the foundation for registrational development in first-line metastatic gastroesophageal adenocarcinoma

ROCKVILLE, Md., Oct. 25, 2026 -- NovaBridge Biosciences ("NovaBridge" or "Company") (Nasdaq: NBP) today announced the presentation of updated results from the ongoing Phase 1b study of givastomig, a CLDN18.2 x 4-1BB bispecific antibody, in combination with nivolumab and chemotherapy for patients with HER2-negative first-line metastatic gastroesophageal adenocarcinoma. The results were presented at the European Society for Medical Oncology (ESMO) Congress 2026 in Madrid, Spain.

Updated Clinical Dataset Strengthens Foundation for Registrational Development

The updated analysis includes data through August 6, 2026 and provides the most comprehensive assessment of givastomig generated to date. The dataset includes 71 patients across the 8 mg/kg and 12 mg/kg dose cohorts with nearly 18 months of median follow-up in the 8 mg/kg dose cohort and provides a more mature assessment of givastomig's clinical profile, substantially increasing confidence in the durability and consistency of clinical benefit while informing dose selection and registrational planning.

Among efficacy-evaluable patients treated at the selected 8 mg/kg dose:

Clinical activity was observed across CLDN18.2 expression levels, including:

"These updated data provide greater confidence in the durability of clinical benefit observed with givastomig and are encouraging given the persistent need for more effective first-line treatment options for patients with metastatic gastroesophageal adenocarcinoma," said Samuel J. Klempner, M.D., Associate Professor of Medicine at Massachusetts General Hospital. "What stands out in the updated analysis is not only the durability of benefit with longer follow-up, but also the strength and consistency of efficacy results across a

broad range of CLDN18.2 expression, including very low expression. The updated dataset provides a more mature view of givastomig's activity and supports its continued advancement to a Phase 3 trial."

Selected 8 mg/kg Dose Demonstrates Durable Activity and Manageable Safety

A key objective of the Phase 1b program was to identify the dose with the most appropriate overall benefit-risk profile for registrational development. Based on the totality of efficacy, safety and long-term follow-up data, NovaBridge selected the 8 mg/kg dose for the next stage of givastomig's development.

The safety profile of givastomig in the updated analysis from the ongoing Phase 1b study remained manageable and generally consistent with previous observations. No Grade 4 or Grade 5 treatment-related adverse events were attributed to givastomig. Immune-related adverse events were uncommon other than gastritis, the majority of which were Grade 2 events. The selected 8 mg/kg dose demonstrated a favorable overall benefit-risk profile and provides a strong foundation for registrational development.

Mature Phase 1b Dataset and FDA Engagement Support Registrational Development
Over the past year, NovaBridge has substantially expanded the clinical dataset for givastomig, gained a more mature understanding of the durability and safety profile of givastomig, selected the 8 mg/kg dose for potential registrational development, and achieved alignment with the FDA on a global registrational study protocol. Combined with the program's Orphan Drug Designation and Fast Track Designation, these accomplishments support NovaBridge's view that givastomig has evolved into a registrational-ready program.

NovaBridge's engagement with the FDA has informed key elements of the planned Phase 3 strategy, including the intended patient population, dose, and primary endpoints. Together with the more mature clinical dataset and regulatory designations, NovaBridge believes this progress establishes a clear regulatory pathway for registrational development of givastomig.

"The updated dataset provides a more mature view of givastomig's clinical profile, including longer follow-up, greater insight into durability and safety, and increased confidence in the 8 mg/kg dose, which has been selected for registrational development," said Phillip Dennis, M.D., Ph.D., Chief Medical Officer of NovaBridge. "Over the past year, we have significantly strengthened the clinical and regulatory foundation for the program through continued dataset maturation, dose selection, and productive engagement with the FDA, culminating in alignment on a Phase 3 study design. Together with the program's Orphan Drug and Fast Track Designations, we believe these advances position givastomig as a registrational-ready program."

"The maturation of the givastomig dataset over the past year has significantly increased our confidence in the program," said Srishti Gupta, M.D., M.P.P., Chief Executive Officer of NovaBridge. "The updated efficacy, durability and safety findings, together with productive interactions with the FDA and important regulatory milestones, have advanced givastomig into a late-stage development program. We believe this represents an important inflection point for givastomig and its potential to make a meaningful difference for patients with metastatic gastroesophageal adenocarcinoma."

ESMO Congress 2026 Presentation Materials and Supplemental Data

The ESMO Congress 2026 poster presentation and supplemental analyses based on the August 2026 data cutoff are available on NovaBridge's investor relations website and can be accessed here.

NovaBridge to Host Webcast to Discuss Updated Givastomig Data and Path to Registrational Development

NovaBridge will host a webcast on November 2, 2026, at 8:00 a.m. ET to discuss the updated results presented at ESMO, the clinical rationale for selection of the 8 mg/kg dose and the implications of the mature Phase 1b dataset for givastomig's registrational readiness. The event will feature Samuel J. Klempner, M.D., Associate

Professor of Medicine at Massachusetts General Hospital, who will discuss the clinical significance of the updated data, the unmet need in first-line gastric and gastroesophageal cancers, and the potential role of givastomig in CLDN18.2-positive disease. Company management will also discuss the maturation of the clinical dataset, regulatory progress, ongoing FDA interactions and the considerations informing future development planning for the program. A question-and-answer session will follow the formal presentations.

Webcast Details

Title: Givastomig: Mature Clinical Data and Path to Registrational Development

Date: November 2, 2026

Time: 8:00 a.m. EST

Featured Speaker: Samuel J. Klempner, M.D., Associate Professor of Medicine at Massachusetts General Hospital and lead investigator of the Phase 1b givastomig study

Format: Live webcast followed by Q&A

Registration and webcast details are available on the Investor Relations section of the NovaBridge website and can be accessed here.

About Givastomig

Givastomig (TJ033721 / ABL111), a potential first-in-class Conditional T-cell Engager and Immune Amplifier (CTIA), is a Claudin 18.2 x 4-1BB bispecific antibody. Givastomig conditionally activates T cells via the 4-1BB signaling pathway in the tumor microenvironment where Claudin 18.2 is expressed. Givastomig is being developed for the potential treatment of gastroesophageal carcinoma, its current lead indication. Givastomig also has potential applicability across other Claudin 18.2-positive gastrointestinal malignancies, including biliary tract cancer and pancreatic ductal adenocarcinoma.

Givastomig is being evaluated in a global, randomized Phase 2 study (NCT07432295), following positive topline results from a Phase 1b, multicenter, open-label study in first-line metastatic gastroesophageal carcinoma. The U.S. Food and Drug Administration (FDA) has granted Fast Track Designation to givastomig for the treatment of previously untreated HER2-negative advanced or metastatic gastroesophageal adenocarcinoma in combination with nivolumab and chemotherapy.

About NovaBridge Biosciences

NovaBridge Biosciences ("NovaBridge") (NASDAQ: NBP) is a global biotechnology company advancing a portfolio of therapeutic programs in oncology and ophthalmology. The Company identifies differentiated therapeutic opportunities, generates value-defining clinical evidence, and applies the development, financing and partnering strategy best suited to each program.

NovaBridge's portfolio is led by givastomig, a Claudin 18.2 × 4-1BB bispecific antibody being developed for the potential treatment of gastrointestinal malignancies, and Visara, its majority-owned ophthalmology subsidiary. Through Visara, NovaBridge is building a diversified ophthalmology franchise designed to address unmet needs across diseases of the front and back of the eye.

NovaBridge's objective is to build a sustainable biotechnology company by repeatedly identifying differentiated innovation, advancing it efficiently, and bringing novel therapies to patients through the path best suited to each opportunity.

For more information, please visit www.novabridge.com and follow us on LinkedIn.