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

Abstract
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.