Artificial intelligence analysis of advanced breast cancer patients from phase I trial of Trastuzumab Deruxtecan: HER2 and histopathology features as predictors of clinical benefit

Human epidermal growth factor receptor 2 (HER2) immunohistochemistry (IHC) testing, and the corresponding ASCO/CAP (American Society of Clinical Oncology/College of American Pathologists) guidelines are routinely used to identify breast cancer patience that benefit from HER2-targeting therapies.

• These tests, however, are not optimized for identifying patients who might be eligible for HER2 targeted antibody-drug conjugates (ADC).

Trastuzumab druxtecan (T-Dxd), a novel HER2-Target antibody-drug conjugate (ADC), demonstrated clinical benefit in HER2-positive (IHC3+, IHC 2+/ISH+) and a portion of HER2-negative/HER2low (IHC2+/ISH-, IHC 1 +) advanced stage breast cancer patients as part of the DS8201-A-J101 phase 1 two-part, multicenter, non-randomized, open-label trial.

• Patients were enrolled based on local HER2 results and HER2 status was centrally confirmed based on an FDA approved test using 2013 ASCO/CAP guidelines. This HER2 Low population is traditionally categorized as HER2-negative according to ASCO/CAP guidelines.