Allogeneic Stem Cell Transplantation (allo-SCT) for Isolated and Leukemic Myeloid Sarcoma (GS): a Survey on Behalf of the Acute Leukemia Working Party (ALWP) of EBMT.

Abstract 4558

Myeloid Sarcoma (MS) is a rare malignant disorder usually presenting as an extramedullary myeloid cell tumor proliferation. MS can be observed in 3 to 7% of AML cases (called “leukemic” MS, LMS hereinafter). MS prognosis is rather poor with overall survival (OS) not exceeding 2 years. We have previously shown, that allo-SCT following an AML-like chemotherapy is likely the best available therapeutic option for patients with LMS (J Clin Oncol 2008). However, it is still unclear whether allo-SCT is a valid therapeutic option for patients with isolated MS (IMS). The aim of this analysis was to assess the role of allo-SCT in patients with IMS as compared to patients with LMS.

We retrospectively analysed the outcome of 99 MS patients with a median age of 40 years (range: 18–70), including 30 cases of IMS and 69 cases of LMS, reported to the EBMT registry between January 1991 and June 2009. The majority of patients were in complete remission (CR) at time of transplant (IMS: first CR n=14, second CR or beyond n=7 vs. LMS: first CR n=38, second CR or beyond n=21, P=0.20). In this series, patients received either a standard (IMS, n=24 vs. LMS, n=55, P=NS) or a reduced-intensity conditioning regimen (IMS, n=6 vs. LMS, n=14, P=NS) prior to allo-SCT from a matched-related (IMS n=21 vs. LMS, n=48, P=NS) or unrelated donor (IMS, n=9 vs. LMS, n=21, P=NS).

After allo-SCT, engraftment was observed in all patients. The incidences of grade 2–4 and grade 3–4 acute GVHD were 32% and 9%, respectively. The incidence of chronic GVHD at 2 years was 45%. With a median follow-up of 48 (range: 6–213) months, the 5-years OS, and leukaemia-free survival (LFS), and the cumulative incidences of relapse (RI), and non-relapse mortality (NRM) were 48%, 36%, 40% and 19%, respectively. When comparing the two sub-groups (IMS vs. LMS), there were no significant differences in term of outcomes: neutrophils recovery (15 vs 18.5 days), grade 2–4 acute GVHD (27% vs 35%), chronic GVHD (54% vs 41% at 2 years), 5-year OS (33% vs. 48%), 5-year LFS (30% vs. 38%), 5-year RI (45% vs. 38%) and 5-year NRM (19% vs. 17%).

In all, we conclude that allo-SCT is an effective treatment for patients with MS. The current data suggest that patients with isolated or leukemic MS have similar outcome after allo-SCT. Therefore, allo-SCT is likely to be considered as the optimal therapy for both isolated and leukemic MS.