Outcomes of second allogeneic stem cell transplantation and anti-relapse strategies in patients with relapsed/refractory acute myeloid leukemia: A unicentric retrospective analysis

Second allogeneic stem cell transplantation (allo-SCT2) represents a rescue option for selected patients (pts) with relapsed/refractory (r/r) acute myeloid leukemia (AML). Still, relapse rates post-allo-SCT2 remain high and effective anti-relapse strategies and predictive biomarkers remain to be defined. We here analyzed a cohort of 41 AML patients (pts) undergoing allo-SCT2 in our center. Allo-SCT2 induced a third hematologic complete remission (CR) in 37 pts, at costs of a 36% non-relapse mortality rate. Furthermore, 19 pts eventually relapsed post allo-SCT2. Addressing relapse after allo-SCT2, 14 pts (74%) underwent cell-based anti-relapse strategies, including third allogeneic transplantation (allo-SCT3; 3/14), donor lymphocyte infusions (DLIs) combined with either 5-azacytidin and venetoclax (4/14) or chemotherapeutic agents (7/14). Notably, six of seven pts (86%) who received either allo-SCT3 or a combination therapy of DLIs, 5-azacytidine and venetoclax achieved CR despite poor cytogenetics post-allo-SCT2 (e.g., TP53). Finally, 11 of 41 pts were alive at the last follow-up (seven CR2, three CR3, one partial remission) resulting in estimated 2- and 5-year overall survival of 35% and 25%, respectively.