IC50: 20 μM (ubiquitin-activating enzyme UBA1)

PYZD-4409 (10 mg/kg; intraperitoneal injection; daily on alternate days; for 16 days; male severe combined immunodeficient mice) decreases tumor weight and volume without untoward toxicity. Animal Model: Male severe combined immunodeficient (SCID) mice with MDAY-D2 murine leukemia cells Dosage: 10 mg/kg Administration: Intraperitoneal injection; daily on alternate days; for 16 days Result: Delayed tumor growth and decreased tumor weight without untoward toxicity.

PYZD-4409 (10-40 μM; 72 hours; myeloma, leukemia, and solid tumor cell lines, primary AML cells and normal hematopoietic cells) induces cell death with a LD 50 less than 10 μM in 5 of 8 leukemia and myeloma cell lines. In contrast, solid tumor cell lines were less sensitive with an LD 50 of approximately 15 to 20 μM. PYZD-4409 is preferentially cytotoxic to malignant cells over normal hematopoietic cells. PYZD-4409 (50 μM; 4 hours; K562 leukemia cells) treatment blocks the E1-dependent conjugation of ubiquitin to the E2 enzyme cdc34. PYZD-4409 (0-25 μM; 24 hours; K562 leukemia cells) significantly increases both mRNA and protein levels of Grp78 and Hsp70. In addition, PYZD-4409 increases levels of phospho-JNK and phospho-p38 mitogen-activated protein kinase, which have also been linked to ER stress and the unfolded protein response. Cell Cytotoxicity Assay Cell Line: Myeloma, leukemia, and solid tumor cell lines, primary AML cells and normal hematopoietic cells Concentration: 10 μM, 20 μM, 30 μM, 40 μM Incubation Time: 72 hours Result: Induced cell death with a LD 50 less than 10 μM in 5 of 8 leukemia and myeloma cell lines. In contrast, solid tumor cell lines were less sensitive with an LD 50 of approximately 15 to 20 μM. Western Blot Analysis Cell Line: K562 leukemia cells Concentration: 50 μM Incubation Time: 4 hours Result: Blocked the E1-dependent conjugation of ubiquitin to the E2 enzyme cdc34. RT-PCR Cell Line: K562 cells Concentration: 0 μM, 10 μM, 25 μM Incubation Time: 24 hours Result: Significantly increased both mRNA and protein levels of Grp78 and Hsp70.

PYZD-4409 是 ubiquitin-activating enzyme UBA1 的特异性抑制剂，其 IC50 值为 20 μM。PYZD-4409 能诱导恶性细胞死亡，并优先抑制原发性急性髓性白血病细胞的生长。