Second- and Third-Line Salvage Chemotherapy Followed by Allogeneic Stem Cell Transplantation Leads to High Survival Rates in Primary Refractory AML-A Population-Based Study.

Refractory acute myeloblastic leukemia (AML) is poorly studied. In this study, we characterized primary refractory AML and investigated treatment and outcome in a population-based setting. Based on all AML patients receiving intensive induction therapy at 12 Swedish hospitals from 2011 to 2018 (N = 1221), we identified 306 patients that failed to achieve composite complete remission (CRc) after first-line therapy. Two-hundred-sixteen (71%) of these patients received salvage treatment with intensive chemotherapy (ICT), of which 126 (58%) achieved CRc and 85 (39%) underwent allogeneic stem cell transplantation (HSCT). One- and 3-year overall survival (OS) in patients receiving salvage ICT were 56.8% and 28.9%, respectively. Secondary AML and adverse ELN risk were associated with worse OS after salvage ICT, while fludarabine-based FAIDA versus amsacrine-based ACE salvage and HSCT were associated with better OS. Three-year OS after first or second salvage chemotherapy, followed by HSCT were 55% and 71%, respectively. Refractory patients responding to salvage ICT showed only a nonsignificant trend toward inferior OS compared to patients in CRc after the first cycle. In conclusion, refractory AML patients eligible for further intensive therapy have a reasonable chance of obtaining remission and long-term survival when followed by HSCT. The results can serve as a basis for evaluation of new treatments in refractory AML.