h3B7A-LDM, a novel anti-mesothelin antibody-drug conjugate with the potential to induce antitumor immunity, shows potent efficacy against solid tumors.

Antibody-drug conjugates (ADCs) are a promising class of cancer therapeutics that enable the targeted delivery of highly cytotoxic payloads to cancer cells. Mesothelin (MSLN) is an attractive therapeutic target in cancer treatment. Lidamycin (LDM), an enediyne-containing antibiotic with potent antitumor effects, has potential as ADC payload. To generate an ADC targeting MSLN, we first produced a novel anti-MSLN antibody, 3B7A, using hybridoma technology. We then obtained the humanized version, h3B7A, via complementarity-determining region (CDR) grafting. This was followed by fusion with LDM through genetic recombination and molecular assembly to create the ADC h3B7A-LDM. h3B7A-LDM undergoes efficient internalization and lysosomal trafficking in MSLN-positive cancer cells. It demonstrates strong tumor-targeting capability and long-term persistence in tumor-bearing mice. In vitro, it exhibits potent antitumor effects, suppressing the proliferation and migration of cancer cells with sub-nanomolar half maximal inhibitory concentration (IC50) values. Mechanistically, h3B7A-LDM induces cell cycle arrest and apoptosis, triggers immunogenic cell death (ICD), and may elicit antitumor immunity. In vivo, h3B7A-LDM significantly inhibits tumor growth in multiple cancer xenograft models. Together, these findings support h3B7A-LDM as a promising drug candidate for treating MSLN-positive cancer.