I-Mab Acquires Bridge Health for $6.8M to Secure Upstream Rights to CLDN18.2 Bispecific Antibody Givastomig

On July 17, I-Mab announced that it had entered into a definitive agreement to acquire 100% of the equity interests in Bridge Health. This transaction will secure upstream rights to the CLDN18.2 parent antibody used in its CLDN18.2×4-1BB bispecific antibody, Givastomig, for bispecific and multispecific applications (including bispecific antibodies, multispecific antibodies, and ADCs), thereby further strengthening the intellectual property moat surrounding Givastomig.

Under the terms of the agreement, Tianjing Biotechnology will pay Bridge Health shareholders an upfront payment of $1.8 million and a total of $1.2 million in non-contingent payments by 2027; furthermore, Bridge Health shareholders may receive milestone payments of up to $3.875 million upon the achievement of specific development and regulatory milestones. (The total transaction value is approximately $6.8 million, equivalent to approximately RMB 48.82 million.)

Givastomig is the core pipeline asset of Tianjing Biotechnology, a bispecific antibody targeting CLDN18.2-positive tumor cells. Its unique mechanism lies in the conditional activation of T cells through interaction with the 4-1BB receptor exclusively within the tumor microenvironment expressing CLDN18.2. This design not only enhances the anti-tumor activity of T cells at the tumor site but also avoids systemic toxicities associated with conventional 4-1BB therapies, such as cytokine release syndrome. The product is currently under development for first-line treatment of metastatic gastric cancer and other solid tumors.

Recently, Tianjing Biotechnology announced positive data from its Phase 1b dose-escalation trial evaluating givastomig in combination with a PD-1 inhibitor and chemotherapy as first-line treatment for gastric cancer at the 2025 European Society for Medical Oncology Gastrointestinal Cancers Congress (ESMO GI 2025). Key findings included an overall objective response rate (ORR) of 71%, with 12 out of 17 patients achieving partial response. In the recommended dose cohorts of 8 mg/kg and 12 mg/kg, the ORR reached 83% (10/12). The disease control rate was 100% across all three dose levels.

Givastomig demonstrated activity across patients with varying expression levels. In patients with CLDN18.2 expression <75%, the ORR was 80%, reaching 100% in the recommended dose group. This indicates that even patient populations with low expression can derive benefit from it.

In terms of durability, as of the data cutoff date, 8 out of 17 treated patients were still receiving the study treatment. The longest duration of treatment reached 11.3 months, demonstrating favorable treatment durability.

From a safety perspective, no dose-limiting toxicities were observed in the study. Common treatment-related adverse events were mostly Grade 1–2, including nausea, vomiting, and fatigue, while Grade ≥3 adverse events were rare.

Overall, the 71% overall ORR is higher than that of the currently marketed zolbetuximab monoclonal antibody (approximately 40–50%), and no cytokine release syndrome, commonly associated with 4-1BB agents, was observed in terms of safety.

It is worth noting that the results released this time are from the Phase 1b dose-escalation stage involving 17 patients. According to I-Mab’s clinical development plan, the dose-expansion phase is currently underway, with data from a larger sample size expected to be announced in the first half of next year. This will include the complete results for the recommended dose group, which demonstrated an 83% overall response rate (ORR). If subsequent data maintain this level of efficacy, it will further validate the clinical value of Givastomig.

CLDN18.2 is a tight junction protein specifically overexpressed in gastrointestinal tumors such as gastric and pancreatic cancers, and has emerged as a prominent target for oncology targeted therapy. Currently, competition surrounding the CLDN18.2 target in gastric cancer is intense; in addition to the already marketed zolbetuximab, multiple antibody-drug conjugate (ADC) candidates are under development.

Astellas’ CLDN18.2-targeting monoclonal antibody, zolbetuximab (brand name: Vyloy), has been approved for marketing in select countries and regions for the first-line treatment of locally advanced unresectable or metastatic gastric/gastroesophageal junction adenocarcinoma that is CLDN18.2-positive and HER2-negative. Clinical studies have demonstrated that zolbetuximab combined with chemotherapy yields an objective response rate (ORR) of approximately 40–50%, surpassing the efficacy of conventional chemotherapy. However, zolbetuximab primarily targets patients with high CLDN18.2 expression and may cause certain safety concerns during treatment, such as adverse reactions including nausea and vomiting.

In the field of antibody-drug conjugates (ADCs), numerous CLDN18.2-targeting ADCs—including Amgen/BeiGene’s Zanidatamab Zovodotin (HER2×CLDN18.2 ADC), AstraZeneca/Daiichi Sankyo’s DS-9606, Eli Lilly’s SYSA1801 (licensed to Zai Lab), and Kelun-Biotech’s SKB315—are at various stages of clinical development, making this one of the most actively pursued research areas currently.

Tianjing Biotechnology’s givastomig, with its unique “conditional activation” mechanism and overall ORR of 71% and ORR of 83% in the recommended dose cohort, has to some extent demonstrated the value of its differentiated technological approach, showcasing its potential to become a best-in-class CLDN18.2-targeted therapy.

This acquisition strengthens I-Mab’s rights to givastomig. According to reports, Bridge Health, the acquired entity, holds the parental CLDN18.2 antibody required for the development of givastomig. This antibody from Bridge Health is considered key to the success of givastomig.

Tianjing Biotechnology pointed out in the press release that the CLDN18.2 parental antibody demonstrated stronger binding affinity to cell lines with high, medium, and even low levels of CLDN18.2 expression. These characteristics provide givastomig with core differentiated advantages as a potential best-in-class bispecific antibody for the treatment of Claudin 18.2-positive cancers.

Currently, givastomig is being co-developed in collaboration with South Korea’s ABL Bio, with Tianjing Biotechnology serving as the lead partner and sharing global rights equally with ABL Bio, excluding Greater China and South Korea.

Dr. Fu Hai’an, Chief Executive Officer of Tianjing Biotechnology, stated in the press release that enrollment in the Phase 2 trial of givastomig is expected to proceed faster than anticipated. Through this transaction, Tianjing Biotechnology has strengthened its upstream intellectual property rights, reduced future milestone payments, and eliminated future royalties on givastomig, thereby further enhancing the potential value of the asset. The positive data from the Phase 1b dose-escalation trial, recently presented at the 2025 ESMO Gastrointestinal Cancers Congress (ESMO GI 2025), have reinforced our confidence that givastomig has the potential to become a best-in-class CLDN18.2-targeted therapy for gastric cancer and other malignancies.

China has the world’s largest population of gastric cancer patients, with approximately 400,000 new cases annually, accounting for nearly half of the global total. Given the substantial patient base and unmet medical needs, Givastomig holds significant potential market opportunity in the future.