TJ-C64B

**TJ-C64B** is an investigational **bispecific antibody** developed by **I-Mab** for **CLDN6-positive solid tumors**, with ovarian cancer and gastric cancer reported as active development indications. It is designed to bind **claudin 6** on tumor cells and **tumor necrosis factor receptor superfamily member 9** on immune cells, thereby **conditionally activating 4-1BB costimulatory signaling only in the presence of CLDN6-expressing tumor tissue**. This tumor-localized 4-1BB agonism is intended to enhance antitumor T-cell activity while reducing the systemic toxicity historically associated with non-targeted 4-1BB agonists. Publicly available pipeline sources describe it as a preclinical or early-development oncology immunotherapy with IND-level progress reported.