BGB-43395-101 (NCT06120283) is a Phase 1a/1b, open-label, dose-escalation and expansion trial of BGB-43395, a selective CDK4 inhibitor, as monotherapy and in combination with fulvestrant, letrozole, or elacestrant in patients with hormone receptor-positive (HR+)/HER2-negative metastatic breast cancer and other advanced solid tumors.