Novel Antibody-Drug Conjugate Shows Promise for Pretreated UC

BL-B01D1, a potentially first-in-class EGFR x HER3 bispecific antibody-drug conjugate for locally advanced or metastatic urothelial carcinoma (la/mUC), has demonstrated safety and efficacy in a phase 1b/2 trial led by Ye Dingwei, MD, and presented at the European Society for Medical Oncology Congress 2024.

Thirty-two patients were enrolled in every-three-week treatment: 29 patients received 2.2 mg/kg, two patients received 2.5 mg/kg, and three patients received 2.75 mg/kg. The median prior line of systemic therapy was two.

Among those enrolled, 23 patients dosed at 2.2 mg/kg were evaluable for efficacy:

• Overall response rate (ORR): 43.5%
• Complete ORR: 34.8%
• Disease control rate: 91.3%
• Median progression-free survival: 5.5 months

The most common grade 3 or higher treatment-related adverse events at 2.2 mg/kg were:

• Anemia: 17%
• Leukopenia: 26%
• Thrombocytopenia: 26%
• Neutropenia: 44%
• Decreased appetite: 4%
• Decreased lymphocyte count: 4%

In patients with pretreated UC, BL-B01D1 demonstrated manageable safety with encouraging antitumor activity. Further evaluation of this population is ongoing.