I-Mab (NASDAQ: IMAB) announced it has entered into a definitive agreement to acquire 100% ownership of Bridge Health Biotech Co., Ltd. for $1.8 million upfront plus potential milestone payments up to $3.875 million. The strategic acquisition provides I-Mab with upstream rights to the Claudin 18.2 (CLDN18.2) parental antibody used in its lead bispecific antibody candidate givastomig, while eliminating all royalty obligations and reducing future milestone payments.
Strategic Value of the Acquisition
"Advancing givastomig is I-Mab's top priority. The strategic acquisition of Bridge Health emphasizes I-Mab's focus on enhancing the value of givastomig," said Sean Fu, PhD, MBA, Chief Executive Officer of I-Mab. "With this transaction, I-Mab has further enriched the potential value of givastomig by strengthening upstream intellectual property rights, reducing future milestone payments, and unencumbering givastomig of future royalties."
The acquisition grants I-Mab rights to bispecific and multi-specific applications, including bispecific and multi-specific antibodies and antibody drug conjugates (ADCs), based on the CLDN18.2 parental antibody. The CLDN18.2 parental antibody utilized in givastomig has been observed to show higher affinity to human CLDN18.2 than other antibodies, including antibodies used in approved CLDN18.2-directed therapies. Additionally, the antibody exhibits stronger binding affinity to cell lines expressing high, medium and even low levels of CLDN18.2.
Promising Clinical Results Drive Confidence
Recent positive Phase 1b dose escalation data presented at the European Society for Medical Oncology Gastrointestinal Cancers Congress (ESMO GI 2025) showed an 83% objective response rate (ORR) in the doses selected for dose expansion cohorts, with favorable overall tolerability. The study evaluated givastomig in combination with nivolumab (an anti-PD-1 checkpoint inhibitor) plus chemotherapy in 17 patients with first-line metastatic gastric cancer.
"Positive Phase 1b dose escalation data recently presented at ESMO GI 2025 has enhanced our confidence that givastomig has the potential to be a best-in-class CLDN18.2-directed therapy for gastric cancers and beyond," Fu stated. The responses were observed in patients with low PD-L1 and CLDN18.2 expression and were characterized as rapid, durable and deepening over time.
Accelerated Development Timeline
The clinical momentum has enabled faster than expected enrollment in the Phase 1b dose expansion cohorts. Enrollment in the first dose expansion cohort (n=20) finished ahead of schedule, and enrollment in the second dose expansion cohort (n=20) is nearly complete. I-Mab now expects to provide topline readout from the Phase 1b dose expansion combination study in Q1 of 2026.
Mechanism of Action and Development Strategy
Givastomig (TJ033721 / ABL111) is a bispecific antibody targeting CLDN18.2-positive tumor cells that conditionally activates T cells through the 4-1BB signaling pathway in the tumor microenvironment where CLDN18.2 is expressed. The drug is being developed for first-line metastatic gastric cancers, with potential to expand into other solid tumors.
In Phase 1 trials, givastomig has shown promising anti-tumor activity attributable to a potential synergistic effect of proximal interaction between CLDN18.2 on tumor cells and 4-1BB on T cells in the tumor microenvironment, while minimizing toxicities commonly seen with other 4-1BB agents.
Transaction Details
Under the terms of the agreement, I-Mab will pay Bridge Health shareholders an upfront payment of $1.8 million and non-contingent payments of $1.2 million through 2027. Bridge Health shareholders may receive future milestone payments of up to $3.875 million, subject to the achievement of certain development and regulatory milestones. The transaction is expected to close in Q3 of 2025, with Sidley Austin LLP serving as legal advisor to I-Mab.
Givastomig is being jointly developed through a global partnership with ABL Bio, in which I-Mab is the lead party and shares worldwide rights equally with ABL Bio, excluding Greater China and South Korea.
