I-Mab and ABL Bio Inc. announced that the U.S. Food and Drug Administration (FDA) has approved the Investigational New Drug (IND) application for initiating phase 1 trial for bispecific antibody TJ-CD4B/ABL111. The phase 1 clinical trial will evaluate the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of TJ-CD4B/ABL111 in advanced or metastatic solid tumors. TJ-CD4B/ABL111 is a novel bispecific antibody that works through binding to a tumor antigen Claudin 18.2 (CLDN18.2) which is selectively expressed in several cancers and to 4-1BB, a co-stimulatory molecule expressed on T cells, to activate immune response within tumor for better anti-tumor activity.

Preclinical studies demonstrate that TJ-CD4B/ABL111 has superior anti-tumor property as compared to the two monoclonal antibodies when acting alone or in combination. This superior anti-tumor activity is achieved locally on tumor site, thus minimizing the risk of liver and systemic side effects commonly associated with 4-1BB antibody when used alone. The phase 1 clinical study will be a multi-center, dose escalation study in the U.S.I-Mab also plans to conduct dose expansion studies for TJ-CD4B/ABL111 in patients with gastric cancers, gastro-esophageal junction adenocarcinoma, esophageal adenocarcinoma and pancreatic ductal adenocarcinoma in China later this year.

TJ-CD4B, also known as ABL111, is a Claudin 18.2 and 4-1BB bispecific antibody capable of binding to tumor cells expressing Claudin 18.2, i.e., gastric cancer and pancreatic cancer cells, and stimulating intra-tumoral T cells by the 4-1BB arm designed to be activated only upon tumor engagement whilst silent elsewhere. TJ-CD4B effectively maintains a strong tumor binding property and anti-tumor activity attributable to a synergistic effect of both Claudin 18.2 antibody and 4-1BB antibody while it avoids or minimizes liver toxicity and systemic immunotoxicity commonly seen with 4-1BB antibodies as a drug class. TJ-CD4B is being developed under collaboration between I-Mab and ABL.