T-SN38 A

T-SN38 A is an **antibody-drug conjugate (ADC)** composed of the monoclonal antibody trastuzumab covalently linked to the cytotoxic agent SN38, the active metabolite of irinotecan. This conjugate is designed to target **HER2-positive cancer cells** via trastuzumab’s binding to the HER2 receptor, delivering SN38 directly to tumor cells. The conjugation is achieved through specific linkers (e.g., stable ester, carbonate bond, PEG-carbonate), with T-SN38 A representing one of three variants with a drug-antibody ratio of approximately 3.7. In preclinical studies, T-SN38 A demonstrated markedly greater cytotoxicity against HER2-positive ovarian cancer cell lines, with a significantly lower IC50 compared to free SN38 and free trastuzumab. It also led to robust tumor growth inhibition in HER2-positive human ovarian cancer xenograft mouse models[1].