Early reversal of the lymphocyte‐to‐monocyte ratio after allogeneic‐hematopoietic stem cell transplantation is associated with reduced relapse and improved prognosis

Abstract

AbstractBackgroundThe early recovery of lymphocyte and monocyte cells is associated with a favorable prognosis after allogeneic stem cell transplantation (allo‐HSCT); however, it is not clear whether the balance of lymphocyte and monocyte recovery affects the post‐transplant prognosis.MethodsWe examined whether the time‐point at which the number of lymphocytes exceeded the number of monocytes, which we termed lymphocyte‐to‐monocyte ratio reversal (LMRR), affected the prognosis after allo‐HSCT. We retrospectively evaluated 235 patients who underwent their first allo‐HSCT at our institution.ResultsThe median number of days from HSCT to LMRR was 46 (range, 0–214), and the patients were divided into two groups according to the occurrence of LMRR by day 45 (LMRR45). In a multivariate analysis, early LMRR contributed favorably to overall survival (hazard ratio [HR] .519; 95% confidence interval [CI] .332‐.812; p = .004) with fewer post‐transplant relapses (HR .462; 95% CI, .274‐.777; p = .004). Differences in the timing of LMRR did not affect non‐relapse mortality (HR 1.477; 95% CI .779‐2.80; p = .23) or the incidence of grade II‐IV acute GVHD (LMRR45(+): 25.0% vs. LMRR45(−) 35.2%. p = .111). In subgroup analyses, LMRR45(+) was found to be a favorable factor for survival with less relapse, regardless of the disease risk, stem cell source, or the recovery of either lymphocyte or monocyte counts.ConclusionsAn early LMRR may be a novel factor that is associated with reduced relapse and improved survival after allo‐HSCT.