Impact of achieving CR1 with one vs two induction courses on allo-HSCT outcomes with PTCy prophylaxis in AML

A retrospective, multicenter study evaluated the impact of the number of induction chemotherapy courses required to achieve first complete remission (CR1) on outcomes after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in 677 adults with acute myeloid leukemia (AML) receiving post-transplant cyclophosphamide (PTCy)-based graft-versus-host disease (GvHD) prophylaxis. The study endpoints were leukemia-free survival (LFS), overall survival (OS), relapse incidence (RI), non-relapse mortality (NRM), incidence of engraftment, acute GvHD (aGvHD), chronic GvHD (cGvHD) and GvHD-free, relapse-free survival (GRFS). Results were published in Bone Marrow Transplantation by Nagler et al.

Key data: Among all patients, 77% achieved CR1 after one induction course and 23% after two induction courses. In multivariate analysis, patients requiring one induction course had a lower 2-year cumulative RI than those requiring two courses (19.3% vs 27.0%; hazard ratio [HR], 1.75; 95% confidence interval [CI], 1.21–2.53; p = 0.003). No differences were observed in OS (HR, 1.27; 95% CI, 0.92–1.75; p = 0.14), LFS (HR, 1.24; 95% CI, 0.91–1.68; p = 0.168), GRFS (HR, 1.18; 95% CI, 0.9–1.54; p = 0.239), or NRM (HR, 0.72; 95% CI, 0.41–1.25; p = 0.241) between patients requiring one vs two induction courses.

Key learning: In this study, requiring two induction courses to achieve CR1 was associated with higher RI after allo-HSCT with PTCy-based GvHD prophylaxis than requiring one induction course, while no differences were observed in OS, LFS, GRFS, or NRM. The authors suggest that PTCy may partially mitigate the survival disadvantage traditionally associated with delayed remission; however, further evaluation is needed.