PKMYT1 is a targetable vulnerability in del(17p) high-risk multiple myeloma

Deletion of chromosome 17p [del(17p)] is among the most adverse cytogenetic abnormalities in multiple myeloma (MM). By integrating RNA sequencing data from cells of patients with MM with genetic dependency data from MM cell lines, we identified protein kinase membrane-associated tyrosine/threonine 1 (PKMYT1), a member of the WEE family, as a potential therapeutic target in MM cells harboring del(17p). Genetic suppression or pharmacological inhibition of PKMYT1 activity with the selective inhibitor RP-6306 triggered accumulation of DNA damage, micronucleus formation, and mitotic catastrophe, resulting in preferential cell death in del(17p) MM cells while largely sparing del(17p)- MM cells and healthy cells. RP-6306 also reduced tumor burden and extended survival in vivo in both xenograft and TP53-deficient syngeneic models. Collectively, our findings nominate PKMYT1 as an actionable target and support PKMYT1 inhibition as a biomarker-driven therapeutic strategy for patients with del(17p) or TP53-deficient MM.