CD34 and breast cancer: Although the relative contributions of alloreactive or tumor-specific T cells to tumor control in PBMC-engrafted models are difficult to determine, the results suggest an overall enhancement of the T-cell response following exposure to feladilimab and are further supported by antitumor responses observed in a CD34+ HPSC-engrafted patient-derived xenograft model of breast cancer (BR1126; Supplementary Fig. S9).