Efficiency of second allogeneic HSCT in the children with acute leukemias with relapses after first transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is effective treatment in high risk hematological malignancies.Nevertheless, the relapse rates after allo-HSCT range from 10% to 70%.There are no optimal strategy of the relapse therapy after allo-HSCT.Possible therapeutic options include re-induction chemotherapy, immunoadoptive therapy (DLI), target drugs, immunotherapy (CAR-T) and second allo-HSCT.The presented study is a retrospective single-institution experience of second allo-HSCT in the patients (pts) with acute leukemia relapses or graft failure in high-risk cases.The aim of our study was to analyze the outcomes after second allo-HSCT in 50 children with hematological malignancies, i.e., ALL (n=24), AML (n=15), MPDs/MDS (n=11). ResultsForty-four patients achieved engraftment, with median neutrophil engraftment time of 21 days (12 to 41).Remission was achieved in 44 pts (88%).Median follow-up period was 3 years 7 months.Overall survival (OS), according to Kaplan-Meier method, was 48% in the whole group.Relapse-free survival (RFS) was 60%.The fiveyear OS in ALL group was 46.2%; in AML group, 53.3%; in MPDs/MDS, 44.4%.Causes of death were as follows: relapse/progression in 65% (n=17), transplant-related mortality (TRM), in 18% (n=9; 95%CI, 8.8%-29.8%);cumulative relapse rate was 34% (95% CI, 21.6%-48%). ConclusionSecond allo-HSCT is an effective treatment option in cases of relapse after 1 st allo-HSCT.The patients that achieved remission or even blast cytoreduction prior to 2 nd allo-HSCT had better outcome.Clinical manifestations of acute and chronic GVHD can significantly improve the OS.Results of 2 nd allo-HSCT were comparable when using RIC or MAC conditioning regimens.Posttransplant therapy is required to improve results after 2 nd HSCT.