Patients with acute myeloid leukemia (AML) who exhibit complete response (CR) at haploidentical stem cell transplantation (haploSCT) can proceed with transplant, as clinical transplant outcomes appear to be similar regardless of measurable residual disease (MRD) status, according to results from a retrospective study published in the American Journal of Hematology.
Researchers evaluated the effects of pretransplant disease status on post-transplant outcomes in 143 consecutive patients with AML who underwent haploSCT with fludarabine and melphalan conditioning and post-transplant cyclophosphamide for graft-versus-host-disease prophylaxis between February 2009 and October 2018.
Median follow-up was 29 months, and 2-year progression-free survival (PFS) across all patients was 41%. Patients with active disease (29 patients) or complete remission with incomplete count recovery (CRi; 39 patients) at transplant experienced inferior PFS compared with patients who experienced CR. For patients with active disease, the hazard ratio (HR) for PFS was 3.5 (95% CI, 2.05-6.1; P <.001); for patients with CRi, the HR was 2.3 (95% CI, 1.3-3.9; P =.002).
MRD was assessed in patients with morphologic CR at transplant (65 patients) using validated methods, including reverse transcriptase quantitative polymerase chain reaction, cytogenetics, multiparametric flow cytometry, fluorescence in situ hybridization, and next-generation sequencing.
In patients with CR at transplant, there was no difference in PFS between patients who were MRD-positive (24 patients) and MRD-negative (41 patients; HR, 1.85; 95% CI, 0.9-4.0; P =.1). Multivariate analysis indicated age was the only factor predictive of outcomes in patients in CR.
These results suggest haploSCT with fludarabine and melphalan conditioning and post-transplant cyclophosphamide is potentially protective and may attenuate the poorer outcomes that come with MRD positivity in AML. Furthermore, patients in CR with MRD positivity may benefit from proceeding immediately to haploSCT as this does not seem to negatively affect the outcomes of transplant.
- Srour SA, Saliba RM, Bittencourt MCB, et al. Haploidentical transplantation for acute myeloid leukemia patients with minimal/measurable residual disease at transplantation [published online October 8, 2019]. Am J Hematol. doi:10.1002/ajh.25647