ALTM0230

ALTM0230 is an antibody-drug conjugate (ADC) targeting G6B (also known as MPIG6B), a cell-surface antigen that is selectively overexpressed in mutant hematopoietic stem and progenitor cells (HSPCs) in patients with myeloproliferative neoplasms (MPNs). The overexpression of G6B is observed across various MPN driver mutations, including JAK2, CALR, and MPL. ALTM0230 consists of a G6B-directed antibody conjugated to the topoisomerase I inhibitor payload, exatecan. By binding to G6B, the ADC is internalized, delivering the cytotoxic payload specifically to the mutant clone while sparing normal hematopoiesis and platelets. Preclinical studies have demonstrated that ALTM0230 induces potent and selective cytotoxicity in patient-derived cells and human marrow organoids, and shows significant tumor growth inhibition and survival benefits in xenograft models of myelofibrosis and acute myeloid leukemia (AML).