Interest of Non-Myeloablative Allogeneic Stem Cell Transplantation in Mantle Cell Lymphoma: A Multicenter Retrospective Study.

MCL is a relatively rare, but aggressive subtype of non-Hodgkin’s lymphoma. The current standard therapeutic approach for MCL combines rituximab–containing chemotherapy, followed by autologous stem cell transplantation. Using such approach, most patients will achieve complete remission (CR). However, almost all patients will experience relapse with MCL being an uncurable disease. With this background, and given its curative potential, reduced intensity conditioning allogeneic stem cell transplantation (RIC-allo-SCT) may represent an attractive strategy in MCL. Here, we report a large multicenter retrospective analysis including 60 MCL patients who underwent RIC-allo-SCT. In this series, 43 patients were males. All patients but one, received at least one line of chemotherapy prior to RIC-allo-SCT including auto-SCT in 37 cases. The median number of previous therapies was 2 (range, 0–5). At time of RIC-allo-SCT, 26 patients were in CR, 20 in PR, while 14 were in stable/progressive or refractory disease. Median age at time of transplantation was 56 years (range, 33–67). Median time between diagnosis and transplantation was 3.5 years (range, 0.5–10). PBSCs were used in the majority of cases (n=56). HLA-identical sibling donors were used in 25 cases. HLA-mismatched or HLA-matched unrelated donors were used in the remaining 35 cases. Different RIC regimens were also used: fludarabine-busulfan-ATG in 17 cases, fludarabine and low-dose TBI in 10 cases, fludarabine-melphalan-ATG-rituximab in 6 cases, and other various regimens in 27 cases. In all, the RIC regimen included low-dose TBI in 14 cases, fludarabine in 56 cases and ATG in 34 cases. The median follow-up for surviving patients was 2 years (range, 0.1–8.5). Fifteen patients died of non-relapse-related causes, while 6 patients did not engraft. Disease-related deathes accounted for 6 cases. The 3-years OS estimate was 47% (95%CI, 31–60). According to disease status at transplantation, the 3-years OS estimates for patients who reached CR were 59% (95%CI, 34–77) as compared to 36%(95%CI, 8–65.5) for patients who reached PR and 17% (95%CI, 1– 49) for all others (P=0.001). According to disease status at transplantation (excluding those patients who failed to engraft), the 3-years EFS estimates for patients who reached CR were 68.5% (95%CI, 42–85) as compared to 45% (95%CI, 15–72) for patients who reached PR and 21% (95%CI, 1–57) for all others (P=0.005). Interestingly, the number of lines of chemotherapy administered prior to RIC-allo-SCT had no significant impact on OS and EFS Despite its retrospective nature, and the heterogeneity of the patients included in this analysis, these results suggest that RIC-allo-SCT may be an effective therapy in MCL, especially in those patients with a chemo-sensitive disease at time of transplantation, irrespective of the number of lines of prior therapy.