Abstract

BACKGROUND/METHODS: Long-term survivors with Philadelphia chromosome-negative myeloproliferative neoplasms (Ph-neg MPNs) can eventually develop acute myeloid leukemia (AML, i.e. blast transformation). Allogeneic hematopoietic stem cell transplantation (allo-HSCT) can be the only curative treatment for such patients. To clarify its outcome, we retrospectively studied the cases with AML transformed from Ph-neg MPNs using the national registry data of JSHCT. The cases transplanted after 2000 were collected.

RESULTS: Thirty-nine cases were extracted (male, n=21; female, n=18). Median age was 57 years (range, 22-71). Underlying Ph-neg MPNs included essential thrombocythemia (ET, n=21), primary myelofibrosis (PMF, n=11) and polycythemia vera (PV, n=7). FAB classification was M0 (n=4), M1 (n=4), M2 (n=10), M3 (n=0), M4 (n=1), M5 (n=3), M6 (n=0), M7 (n=1) and unknown (n=16). Median value of WBC at diagnosis of AML was 8300/uL (250-338000). Karyotype at diagnosis of AML was normal (n=6), complex (n=12), others (n=17) and unknown (n=4). Thirty-two cases (82%) were not in remission at the time of allo-HSCT (1st relapse, n=7; primary induction failure, n=18; untreated, n=12). Median duration between diagnosis of AML and allo-HSCT was 134 days (range, 24-369). The donors were related bone marrow or related mobilized peripheral blood stem cell (rBM/rPBSC, n=8), unrelated bone marrow (uBM, n=15) and unrelated umbilical cord blood (uCB, n=16). Myeloablative conditioning regimens (MAC) were used in 15 cases, and the remaining 24 cases were conditioned by reduced-intensity regimens (RIC), according to CIBMTR definition (Giralt S, et al, 2009). Cumulative incidence of neutrophil engraftment was 74.4% at day 60 (patients engrafted, n=29; death before day 60, n=6; relapse before day 60, n=4). At 2 years after transplant, overall survival (OS) was 29.2%. The median duration of follow up of survivors was 1989.5 days (range, 285-3270). In univariate analysis, age (>57 vs. <57, p=0.87), underlying MPNs (PMF vs. ET vs. PV, p=0.16), disease status at allo-HSCT (CR vs. non-CR, p=0.09), conditioning regimen (MAC vs. RIC, p=0.95) and donor selection (rBM/PBSC vs. uBM vs. uCB, p=0.10) had no impact on OS. The only variable that influenced on OS was chromosome at diagnosis of AML (normal vs. others vs. complex, p=0.02). The cumulative incidence of relapse and non-relapse mortality at 3 years was 34.4% and 38.1%, respectively.

CONCLUSION: Although the prognosis of AML transformed from Ph-neg MPNs is dismal in general, the study suggested a promising result that there were curable patients with allo-HSCT.

Disclosures

No relevant conflicts of interest to declare.

Author notes

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Asterisk with author names denotes non-ASH members.