Datopotamab Deruxtecan, a Novel TROP2-directed Antibody-drug Conjugate, Demonstrates Potent Antitumor Activity by Efficient Drug Delivery to Tumor Cells.

Trophoblast cell surface antigen 2 (TROP2) is highly expressed on various epithelial tumors and correlates with poor prognosis. We developed the novel TROP2-directed antibody-drug conjugate (ADC), datopotamab deruxtecan (Dato-DXd, DS-1062a), with a potent DNA topoisomerase I inhibitor (DXd), and evaluated its antitumor activity and safety profiles in preclinical models.The pharmacologic activity and mechanism of action of Dato-DXd were investigated in several human cancer cell lines and xenograft mouse models including patient-derived xenograft (PDX) models. Safety profiles were also assessed in rats and cynomolgus monkeys.Dato-DXd bound specifically to TROP2 and was internalized into tumor cells followed by intracellular trafficking to lysosome and DXd release, which induced DNA damage and apoptosis in TROP2-expressing tumor cells in vitro. Dato-DXd exhibited in vivo antitumor activity with DNA damage induced by the accumulated DXd in TROP2-expressing xenograft tumors, but neither isotype control IgG-ADC nor anti-TROP2 antibody had this effect. Dato-DXd also showed potent antitumor activity with tumor regression in several TROP2-expressing xenograft tumors including NSCLC PDX models. Safety profiles of Dato-DXd in rats and cynomolgus monkeys were acceptable.Dato-DXd demonstrated potent antitumor activity against TROP2-expressing tumors by efficient payload delivery into tumors and acceptable safety profiles in preclinical models. These results suggest Dato-DXd could be a valuable treatment option for patients with TROP2-expressing tumors in the clinical setting.

Antidepressant-like behavior in brain-specific angiogenesis inhibitor 2-deficient mice.

Brain-specific angiogenesis inhibitor 2 (BAI2) is a transmembrane protein that is predominantly expressed in the brain. Although BAI2 is supposed to correlate with antiangiogenesis in the brain, its psychiatric function is still unclear. In this study, we examined the influence of BAI2 gene disruption on mood-related behavior using BAI2-deficient mice. BAI2-deficient mice showed significant antidepressant-like behavior in the social defeat test and in the tail suspension test compared with wild-type mice. On the other hand, BAI2-deficient mice had normal basal locomotor activity in the home cage and in the open field test, and normal learning ability and memory retention in the Morris water maze test. Additionally, we found that hippocampal cell proliferation in BAI2-deficient mice was higher than that in wild-type mice. These results indicate that BAI2 has an important role related to depression and influences the hippocampal neurogenesis. BAI2 may be a novel therapeutic target for mood-related disorders.

Brain-specific angiogenesis inhibitor 2 (BAI2) may be activated by proteolytic processing.

Brain-specific angiogenesis inhibitor 2 (BAI2) is a member of adhesion-G protein-coupled receptors (GPCRs). BAI2 is dominantly expressed in the brain and its physiological ligands and functions are still unclear. Adhesion-GPCRs, including BAI2, commonly have a long N-terminal extracellular region (ECR) containing the GPCR proteolysis site (GPS) and the cleavage of the ECR at the GPS domain is suspected to be important for their function. In this study, we analyzed the proteolytic processing of BAI2 and its activation mechanism. Several cleaved C-terminal fragments of BAI2 were identified in mouse hippocampus. We confirmed that mutation in the GPS domain caused inhibition of the proteolysis of BAI2, which indicated the possibility that BAI2 was cleaved at the GPS domain. The association of the ECR putatively cleaved at the GPS domain and the C-terminal seven-transmembrane (7TM) fragment was detected by co-immunoprecipitation. We also found that furin prohormone convertase cleaved BAI2 at another site in the ECR. Additionally, the C-terminal fragment cleaved at the GPS domain specifically activated the nuclear factor of activated T-cells (NFAT) pathway. These results suggest that BAI2 is a functional GPCR regulated by proteolytic processing and activates the NFAT pathway.