The Easix Score Is Associate with Overall Survival and Non-Relapse Mortality after Ex-Vivo CD34+-Selected Allogeneic HCT.

Background The EASIX (Endothelial Activation and Stress Index) score has been shown to be associated with NRM and overall survival (OS) after reduced intensity alloHCT. We aimed to validate EASIX in patients who underwent a calcineurin-inhibitor (CNI)-free alloHCT using ex-vivo CD34-selection. Design We included 364 adult patients who underwent first CD34-selected alloHCT between July 2006-December 2016 using the CliniMACS CD34 Reagent System (Miltenyi Biotech) as GVHD prophylaxis. The EASIX score (LDH*Creatinine/platelet counts) was calculated at several timepoints (pre-HCT [day -30 to day -10], day 30, day 100 and onset of acute GVHD). For EASIX scores post-HCT, a landmark analysis was conducted at the given timepoint. A log transformation using base 2 (log2) was applied to all EASIX variables to reduce skew. The Kaplan-Meier and cumulative incidence methods were used to estimate OS and NRM/acute GVHD, respectively. Cox models (cause-specific for NRM and acute GVHD) were used to evaluate differences in outcomes. Relapse and death or relapse, were considered competing risks for NRM and acute GVHD, respectively. Results Median age was 55 years (range 19-73). Most patients had myeloid diseases (47% AML, 28% MDS and 4% CML) and all patients received myeloablative conditioning (MAC). With a median follow-up among survivors of 4.7 years (range, 0.7-11.8), 1 and 3-year OS was 78.6% (95% confidence interval [CI], 74.0-82.4) and 61.8% (95% CI, 56.5-66.7), respectively. The cumulative incidence of NRM at 1 and 3 years was 15.1% (95% CI, 11.7-19.0) and 24.2% (95% CI, 19.9-28.8), respectively. The 1-year cumulative incidences of grades 1-4, 2-4, and 3-4 acute GVHD were 40.1% (95% CI, 35.1-45.1), 29.4% (95% CI, 24.8-34.1) and 11.0% (95% CI, 8.0-14.5), respectively. Pre-HCT EASIX was not significantly associated with OS, NRM, or acute GVHD. A higher day 30 EASIX score was significantly associated with increased risk of death (HR=1.35 [95% CI, 1.19-1.52], p<0.001) and NRM (HR=1.56 [95% CI, 1.35-1.80], p<0.001; Table 1, Figures 1-2). A higher day 100 EASIX score similarly resulted in an increased risk of NRM and death (p<0.001) Conclusions EASIX score at day 30 and at day 100 post- ex-vivo CD34-selected alloHCT is associated with higher NRM and inferior OS. Despite a CNI-free platform, endothelial injury is an important contributor to poorer outcomes after MAC. EASIX provides a simple, complimentary tool to predict allo-HCT outcomes in these patients.