CD276 and breast neoplasm: Encouraged by the sensitivity of orthotopic breast tumors derived from aggressive breast cancer cell lines, next we tested m276-SL-PBD against four CD276+, triple-negative orthotopic breast cancer patient-derived xenograft (PDX) models previously developed at the Baylor College of Medicine (BCM) (Figures 6A, 6B, and S7A).52 Immunodeficient NRG mice were initially challenged with BCM-5471 or BCM-3204 tumors.