HSK41959

HSK41959 is an orally bioavailable, methylthioadenosine (MTA)-cooperative inhibitor of protein arginine methyltransferase 5 (PRMT5), developed by Haisco Pharmaceutical Group. It is specifically designed to target tumor cells harboring methylthioadenosine phosphorylase (MTAP) deletions, a genetic alteration found in approximately 10–15% of solid tumors. In MTAP-deleted cells, the metabolite MTA accumulates and binds to PRMT5, creating a unique binding pocket. HSK41959 selectively binds to this PRMT5-MTA complex to induce synthetic lethality while sparing PRMT5 function in normal, MTAP-proficient cells. This selective mechanism aims to provide a wider therapeutic window and reduce the hematological toxicities, such as anemia and thrombocytopenia, commonly associated with non-selective PRMT5 inhibitors. Preliminary clinical data from Phase I studies have demonstrated safety and antitumor activity in patients with MTAP-deleted advanced solid tumors, including non-small cell lung cancer.