Nonmyeloablative allogeneic stem cell transplantation (NST) has considerable activity in patients with metastatic renal cell carcinoma (RCC), although there are limited long-term follow-up data. Between February 1999 and May 2003, 18 patients with metastatic RCC underwent 19 matched-sibling NSTs after conditioning with fludarabine and cyclophosphamide with tacrolimus and mycophenolate mofetil as posttransplant immunosuppression. Among the four objective responses, all were partial and have relapsed with a median response duration of 609 days ( range, 107 - 926). All responders are alive at a median of 41 months. Median overall survival for the entire cohort was 14 months. There were four early treatment-related deaths and one late treatment-related death. Eight patients died from progressive disease and five (28%) from treatment-related mortality. Stratifying transplant outcome as early death, intermediate ( no response, no early death), or response, the combination of pre-treatment anemia and decreased performance status, was associated with adverse outcome ( P = 0.015) and reduced survival (HR 5.4, 95% confidence interval of 1.4 to 21, P = 0.007). Responders demonstrated prolonged survival compared to nonresponders ( P = 0.002). NST leads to durable responses in a minority of metastatic RCC patients. Appropriate patient selection is paramount. Anemia and decreased performance status may enable risk stratification.
