Allogeneic Lymphocytes Induce Tumor Regression of Advanced Metastatic Breast Cancer

Purpose Allogeneic T lymphocytes can induce regression of metastatic breast cancer through an immune-mediated graft-versus-tumor (GVT) effect in murine models. To determine if a clinical GVT effect exists against metastatic breast cancer, allogeneic lymphocytes were used as adoptive cellular therapy after a reduced-intensity chemotherapy conditioning regimen and allogeneic hematopoietic stem-cell transplantation (HSCT) from human leukocyte antigen–matched siblings. Patients and Methods Sixteen patients with metastatic breast cancer that had progressed after treatment with anthracyclines, taxanes, hormonal agents, and trastuzumab, received allogeneic HSCT. The reduced-intensity transplant conditioning regimen consisted of cyclophosphamide and fludarabine. To distinguish an immunological GVT effect from any antitumor effect of cytotoxic chemotherapy in the transplant-conditioning regimen, allogeneic T lymphocytes were removed from the stem-cell graft and were subsequently administered late postallogeneic HS...