Matched Unrelated Donor Stem Cell Transplantation for Patients with Diffuse Large Cell B Cell Lymphoma: A Retrospective Analysis of 118 Patients Registered through the European Group for Blood and Marrow Transplantation (EBMT).

Matched unrelated donor stem cell transplantation (MUD-SCT) may provide a treatment option for patients with diffuse large B cell lymphoma (DLBC) who have failed other conventional therapies and do not have a compatible sibling donor available. We present data of 118 DLBC patients, 69 males and 49 females, aged 18 to 66 years (median 43 years), treated with a MUD-SCT between January 1997 and July 2005 and reported to the EBMT registry. Median time from diagnosis to MUD-SCT was 25 months (range, 3 – 205), and 64% of the cases had failed a previous autologous transplant (ASCT). At allogeneic transplantation, 25% of the patients had chemorefractory disease. Peripheral blood was the source of hematopoietic stem cells in 70% of the cases and reduced intensity conditioning regimens (RIC) were used in 52% of the cases. After a median follow up of 26 months, the estimated 2-year non-relapse mortality (NRM), relapse rate (RR), progression free survival (PFS) and overall survival (OS) for the whole series were 29%, 35%, 36% and 43%, respectively. Grade II–IV acute graft-versus-host-disease developed in 32% of patients. Patients selected for RIC protocols were older (median age of 44 years vs 38 years, p = 0.02) and more heavily pre-treated; 75% had failed a previous autograft compared with 53% in the conventionally treated group (CC) (p = 0.01). Despite these unfavorable factors, the 2-yr NRM for RIC patients was significantly lower than in CC patients: 19% vs 39% (p = 0.03). Unfortunately, this advantage was offset by an increased RR in this group of patients (2-yr RR: 46% vs 24%, p = 0.2), resulting in a very similar PFS and OS for both types of conditioning regimens. The prognostic factor with highest impact on PFS was refractory disease at transplantation (RR = 1.8; 95%CI 1.1 −3.1, p = 0.02). The 2-year PFS for patients transplanted with sensitive disease was 40% irrespective of the conditioning regimen used. In sensitive patients undergoing a RIC transplant, the NRM was significantly lower with respect to CC regimen (14% vs 38%, p = 0.02), resulting in an improved PFS and OS (41% vs 37% and 50% vs 46% respectively). PFS in patients transplanted with refractory disease was generally poor (25% at 2 years). However, CC seemed to provide a better outcome than RIC (2-yr PFS of 35% vs 16%). In conclusion, MUD-SCT constitutes a treatment option for patients with DLBCL failing other conventional treatments, particularly for those patients being allografted in sensitive disease. The high RR observed with reduced intensity protocols does not allow to demonstrate a clear long-term benefit of this approach in this setting.