Discovery of APO-50815, a potent WEE1 kinase inhibitor with exceptional efficacy against patient-derived colorectal cancer organoids

Herein, we report the discovery of APO-50815 (14), a potent and selective thietane-3-ol WEE1 inhibitor. When tested against TP53-mutated colorectal cancer (CRC) patient-derived organoids (PDOs) grown from peritoneal and liver metastases, 14 exhibited outstanding anticancer efficacy, surpassing previously reported branched alkane counterpart 3, as well as clinical candidates AZD1775 (1) and ZN-c3 (2). Against primary CRC organoids with diverse TP53, BRAF and KRAS mutation profiles compared with patient-matched normal colon organoids, 14 exhibited selectively potent activity, yielding exceptionally high TI values (129-238) that highlight a substantial therapeutic window for potential cancer treatment. Against primary CRC PDOs (TP53-WT, BRAF-V600E, KRAS-WT), 14 profoundly elevated DNA damage and replication stress compared to 1, while amplifying cellular apoptosis, confirming a broadly similar but superior mode of action. Owing to its highly selective and exemplary anticancer efficacy, 14 represents a valuable tool compound for drug testing investigations against primary and metastatic CRCs, especially in the context of PDOs.