Multicenter phase 1 study of BL-B01D1 for locally advanced or metastatic solid tumors

BL-01D1 is a first-in-class EGFR-HER3 bispecific antibody-drug conjugate. A phase 1 study at 7 centers in China evaluated BL-01D1 in heavily pretreated adult patients with locally advanced or metastatic solid tumors. In phase 1a (n=25), the maximum tolerated dose was reached at 3.0 mg/kg on days 1 and 8 every three weeks and 6.0 mg/kg at day 1 every three weeks. In phase 1b (n=170), median follow-up was 6.9 months (IQR 4.5-8.9) and 34% of patients (95% CI 27-42) had an objective response. Grade 3 or worse treatment-related adverse events occurred in 71%; 27% had a dose reduction, and 3% discontinued treatment due to TRAEs. Treatment-related deaths occurred in 2%. The authors conclude that BL-B01D1 has an acceptable safety profile and preliminary antitumor activity in heavily pretreated patients with advanced solid tumors.