Allogeneic Hematopoietic Cell Transplantation for Aggressive NK-cell Leukemia. A CIBMTR Analysis

Abstract

Aggressive NK-cell leukemia (ANKL) is an exceedingly rare form of leukemia and carries a poor prognosis with a median survival of only 2-months. Using the Center for International Blood and Marrow Transplant Research database, we evaluated outcomes of allogeneic hematopoietic cell transplantation (alloHCT) in patients with ANKL. Twenty-one patients with a centrally confirmed diagnosis of ANKL were included. Median patient age was 42-years and 15 patients (71%) were Caucasian. Fourteen patients (67%) were in complete remission (CR) at the time of alloHCT, while 5 patients had active disease. Median follow-up of survivors was 25 months (range: 12–116). The 2-year estimates of non-relapse mortality, relapse/progression, progression-free (PFS) and overall survival (OS) were 21%, 59%, 20% and 24%, respectively. The 2-year PFS of patients in CR at the time of alloHCT was significantly better than that of patients with active disease at transplantation (30% vs. 0%; p=0.001). The 2-year OS in similar order was 38% vs. 0% (p<0.001). In conclusion, this registry analysis that included majority non-Asian patient population shows that alloHCT can provide durable disease control in a subset of ANKL patients. Achieving CR before transplantation appears to be a prerequisite for successful transplantation outcomes.