Allogeneic Stem Cell Tranplantation (allo-SCT) for Adult Patients with Active Refractory/Relapsed Hematological Malignancies: a Survey From the Societe Française De Greffe De Moelle Et De Therapie Cellulaire (SFGM-TC).

Abstract 3456

Patients with active refractory/relapsed hematological diseases have a very poor outcome. Best supportive care or investigational therapies in phase 1 trials are usually proposed to these patients. However, some previous data suggested that allo-SCT might be an efficient therapy even in the setting of chemorefractory disease, because long-term immune-mediated disease control can be achieved in some patients after allo-SCT. The aim of this study was to evaluate on a large series the outcome of adult patients with active refractory/relapsed hematological diseases at time of allo-SCT and to determine which sub-group would most benefit from such approach.

Between 2005 and 2009, 861 patients with various hematological diseases (AML, n=323; ALL, n=43; MDS, n=129, CMML, n=12; MPS, n=110; CML, n=28; NHL, n=100; HL, n=40; myeloma, n=36; CLL, n=24; and other, n=16) were treated with allo-SCT, and reported to the SFGM-TC Registry. Per study criteria, all patients presented with active refractory or relapsed disease at time of transplant. This series included 517 males (60%) and 344 females (40%). The median age at transplant was 50 (range, 16–71) years. The median interval between diagnosis and transplant was 17 (range, 1–99) months. 32% of patients failed at least one prior SCT (Autologous or allogeneic prior to allo-SCT). 350 (41%) patients received allo-SCT from an HLA-matched sibling donor, while the remaining 59% received an allogeneic graft from a matched unrelated or mismatched donor. The stem cell source was mainly peripheral blood stem cells (n=617; 72%). Bone marrow was used in 139 patients (16%), and cord blood in 107 patients (12%). Myeloablative conditioning regimen was used in 328 patients (38%), and various reduced-intensity regimens were used in other cases (62%).

With a median follow-up of 290 (range, 1–1854) days after allo-SCT, engraftment was observed in 88% of cases. Grade II-IV and grade III-IV acute GVHD occurred in 35% (n=301) and 17% (n=144) of patients, respectively. Chronic GVHD was observed in 185 patients (21%; limited: n=77; extensive: n=82; missing data: n=24). At last follow-up, 347 patients (40%) were still alive (of whom 297 were in CR; 86%). 246 patients (28.5%) died of disease progression, and 232 patients died of transplant-related causes (NRM: 27%). The Kaplan-Meier (KM) estimates of overall survival (OS) at one and 2 years were 39% (95%CI, 36–43%) and 31% (95%CI, 28–35%), respectively. Of note, in patients with lymphoma (n=140), OS at 1 and 2 years were 57% (95%CI, 48–66%) and 49% (95%CI, 40–58%) versus 36% (95%CI, 32–40%) and 27% (95%CI, 23–31%), respectively, in all other diagnoses (P=0.00004). In a Cox multivariate analysis accounting for relevant factors, a diagnosis of lymphoma (NHL or Hodgkin) was the most significant factor associated with improved survival (RR=1.68; 95%CI, 1.3–2.2; P=0.0001).

Despite its retrospective nature and the inherent selection biases, in case of availability of suitable donor, this data support the use of allo-SCT in adult patients with active refractory/relapsed hematological diseases, especially in patients with lymphomas. Results are expected to be further improved with the advent of novel conditioning regimens and maintenance therapies after transplant that are currently tested as part of prospective studies.