Purpose: To evaluate the feasibility of allogeneic peripheral-blood progenitor-cell (PBPC) transplantation and to assess graft-versus-tumor effects in patients with metastatic breast cancer.
Patients and methods: Ten patients with metastatic breast cancer that involved the liver or bone marrow were treated with high-dose chemotherapy and allogeneic PBPC transplantation. The median age was 42 years (range, 29 to 55). The median number of metastatic sites was three (range, one to five). The conditioning regimen was cyclophosphamide (6,000 mg/m2), carmustine (BCNU; 450 mg/m2), and thiotepa (720 mg/m2) (CBT regimen). Patients received graft-versus-host disease (GVHD) prophylaxis using cyclosporine- or tacrolimus-based regimens.
Results: All patients had engraftment and hematologic recovery. Three patients developed grade > or = 2 acute GVHD and four patients had chronic GVHD. After transplantation, one patient was in complete remission (CR), five achieved a partial remission (PR), and four had stable disease (SD). In two patients, metastatic liver lesions regressed in association with skin GVHD after withdrawal of immunosuppressive therapies. The median follow-up time was 408 days (range, 53 to 605). The median progression-free survival duration was 238 days (range, 53 to 510).
Conclusion: We conclude that allogeneic PBPC transplantation is a feasible procedure for patients with poor-risk metastatic breast cancer. The regression of tumor associated with GVHD provides suggestive clinical evidence that graft-versus-tumor effects may occur against breast cancer. Compared with autologous transplantation, allogeneic PBPC transplantation is associated with the additional risks of GVHD and related infections. Allogeneic transplantation should only be performed in the context of clinical trials and its ultimate role requires demonstration of improved progression-free survival.