Outcomes of Hematopoietic Cell Transplantation in Acute Promyelocytic Leukemia – a Single Institution Experience

Abstract

<h3>Background</h3> Outcomes of patients with acute promyelocytic leukemia (APL) have improved; however, a significant number of patients still relapse despite receiving all-trans-retinoic acid (ATRA) and arsenic-based therapies. We present single institution outcomes of autologous (auto) and allogenic (allo) hematopoietic cell transplantation (HCT) in patients with relapsed APL. <h3>Methods</h3> Outcomes in patients with relapsed APL who underwent either auto- or allo- HCT at Moffitt Cancer Center from 1990 to 2018 were reviewed utilizing the clinical data obtained from BMT Research & Analysis Information Network (BRAIN). Survival data were analyzed using Kaplan-Meier estimates. <h3>Results</h3> <b>Autologous HCT Cohort:</b> A total of 15 received auto-HCT with a median age at HCT of 39 (range, 21-60) years. Only 3/8 patients with known disease risk at time of diagnosis had high risk disease (high=3, low=5). Disease status at HCT were first complete remission (CR1) in 5 (33%) and CR2 in 10 (67%). All 8 patients who had minimal residual disease evaluation had negative PCR for PML-RARA. The median progression-free survival (PFS) for auto HCT was 12.9 (95% confidence interval (CI): 1.2-24.8) years. With a median follow up of 45.1 months for surviving patients, overall survival (OS) for auto HCT was 12.9 (95%CI: 0-27.8) years. <h3>Allogeneic HCT Cohort</h3> A total of 9 patients received allo HCT with a median age at HCT of 43 (range, 22-56) years. All six patients with known disease risk at time of diagnosis were either intermediate (n=2) or high risk disease (n=4). Disease status at allo HCT was CR2 in 1, CR3 in 6, and two had refractory disease. Two patients had prior auto HCT. 5/6 patients who had minimal residual disease evaluation had negative PCR for PML-RARA. Donor type was HLA-identical sibling=5; one antigen-mismatched sibling=1; HLA-matched unrelated donor=2; related haploidentical=1. Conditioning regimen intensity was myeloablative in six and reduced intensity in three of the patients. Six patients received tacrolimus-based graft-versus-host disease (GVHD) prophylaxis. The median PFS for allo HCT was 11.9 (95%CI: 0-24.1) months. With a median follow up of 48.2 months for surviving patients, OS for allo HCT was 14.2 (95%CI: 6.5-21.9) months. <h3>Conclusions</h3> In our single center analysis, auto HCT resulted in a durable remission and prolonged survival. Outcomes after allo HCT were suboptimal primarily due to their heavily pretreated condition and chemotherapy resistant disease.