https://orcid.org/0000-0003-4098-8968
Key Points
In patients who achieve CR following post-HSCT AML relapse, DLI and HSCT2 are not associated with improved OS, RFS, or relapse rates.
Patients with donor chimerism <90% or MRD-positivity had inferior OS, representing subgroups in which DLI/HSCT2 should be studied further.
Acute myeloid leukemia (AML) relapse after allogeneic hematopoietic stem cell transplantation (HSCT) portends a dismal prognosis. One approach for reinvigorating a graft-vs-leukemia response is consolidation with donor lymphocyte infusions (DLI) or second HSCT (HSCT2). However, the role of DLI/HSCT2 in patients who achieve complete remission (CR) after salvage therapy is unclear. In this retrospective study we evaluated the outcomes of 464 patients with post-HSCT AML relapse, focusing on those who achieved CR prior to consolidation with cellular therapy. In multivariable analysis (MVA), achieving CR after post-HSCT1 relapse was associated with improved survival (OS), HR 0.42, p<0.0001. Of 133 patients (29%) who achieved CR after post-transplant AML relapse and before cellular therapy; 64 received DLI, 28 underwent HSCT2, and 41 received neither. Four-year outcomes from CR for the entire cohort (N=133) were: OS 29%, relapse-free survival (RFS) 22%, cumulative incidence of relapse (CIR) 58%, and non-relapse mortality (NRM) 20%. In MVA, there was no association between receipt of DLI (HR 0.87, p=0.59) or HSCT2 (HR 1.08, p=0.83) and OS. Furthermore, we did not identify a benefit with DLI or HSCT2 with respect to RFS, relapse, or NRM. Patients with donor chimerism <90% at the time of CR had reduced 4-year OS (20% vs 32%, p=0.03), as did MRD-positive patients (17% vs 62%, p=0.024). Our results question the benefit of consolidation with DLI or HSCT2 in patients with AML who achieve CR, and we identify high-risk subgroups that should be the focus of future studies with larger cohorts.
