Long-term follow-up of metastatic renal cancer patients undergoing reduced-intensity allografting

SCT from an HLA-compatible sibling donor is an adoptive immunotherapy for cytokine-refractory, metastatic clear-cell renal cell cancer (RCC). However, the recent introduction of targeted therapy compounds has reduced the interest in this therapeutic strategy. We have reanalyzed our series with the aim to assess long-term benefit from allografting. Twenty-five RCC patients received a reduced-intensity allograft from an HLA-identical sibling donor. All patients received a thiotepa, fludarabine and CY conditioning regimen, and a cyclosporine-based GVHD prophylaxis. Best response to allograft was evaluable in 24 patients: 1 CR, 4 PR, 12 minor response/stable disease, 7 progressive disease. One-year survival was 48%, and five-year survival was 20%. At a median observation time of 65 months, five patients are alive, one in CR, one in PR and three with stable disease. By multivariate analysis, C-reactive protein value before transplant, the number of CD34+ infused cells and disease status at day +90 significantly correlated with survival. Survival of patients at favorable/intermediate-risk according to the MSKCC score that underwent allografting was better in comparison to the survival predicted by historical controls. We conclude that 20% of cytokine-refractory RCC patients are alive long-term after allografting. Transplantation is able to induce long-term disease control in a fraction of relapsed RCC patients.