Steep Neutrophil Recovery Following Unrelated Bone Marrow Transplantation Is a Major Risk Factor for the Development of Acute Graft-Vs-Host Disease

Background:

Neutrophil recovery following allogeneic hematopoietic cell transplantation (allo-HCT) varies widely among patients. Some cases have a rapid increase in neutrophils and early engraft, while others show slow increase after neutrophils appearance and take time until engraftment. Such differences in neutrophil recovery may reflect the composition of the graft and affect the complications or prognosis after allo-SCT, though it has not been well documented in the literature. In this study, we retrospectively analyzed the influence of the slope of neutrophil recovery (N slope) following allo-HCT on post-transplant complications and prognosis.

Methods:

This study was a retrospective analysis of 120 patients with hematopoietic diseases who undergone first unrelated bone marrow transplantation at Jichi Medical University between January 2009 and December 2018. Patients who failed to achieve engraftment or did not receive granulocyte-colony stimulating factor were excluded. The N slope was defined as the increase of neutrophil counts from the last day of lowest neutrophil count after transplantation to the date of neutrophil engraftment. We evaluated the predictive value of N slope for acute graft-versus-host disease (GVHD) using the area under the receiver operating characteristic (ROC) curve and determined the cut-off value to maximize the sum of the sensitivity and specificity.

Results:

The median N slope was 205.5 /µL/day (range 26.4-7574). An ROC analysis showed that a cut-off value of N slope for grade II-IV acute GVHD was 207.5 /µL/day (sensitivity 0.73, specificity 0.6, AUC = 0.67, 95 % confidence interval (CI) = 0.59-0.79). Then, we classified patients into the low (n = 59) and high (n = 61) N slope groups according to the cut-off value of 200 /µL/day. The high N slope group correlated with older patients, RIC regimen, higher infused CD34+ cells ≥ 1.5 × 10⁶/kg, and former transplantation between 2009 and 2013 compared with the low N slope group (p = 0.028, p = 0.003, p = 0.036 and p = 0.025, respectively). Cumulative incidence of grade II-IV acute GVHD at day 100 was significantly higher in the high N slope group than the low N slope group (44.3 % vs. 16.9%, p = 0.0007). With regard to the risk factors for grade II-IV acute GVHD, male, donor age ≥ 40 years, N slope ≥ 200 /µL/day and former transplantation between 2009 and 2013 were significant in univariate analysis. In multivariate analysis, donor age ≥ 40 years, N slope ≥ 200 /µL/day and former transplantation were identified as significant independent risk factors (hazard ratio (HR) 3.6, 95%CI 1.7-7.7, p = 0.001; HR 2.8, 95%CI 1.5-5.3, p = 0.002; HR 3.0; 95%CI 1.5-6.1, p = 0.02;, respectively). Cumulative incidence of grade III-IV acute GVHD at day 100 and chronic GVHD at 2 years did not differ in the high and low N slope groups (10.8 % vs. 5.1 %, p = 0.328; 63.3 % vs. 50.1 %, p = 0.12, respectively). In addition, there was no difference in relapse, non-relapse mortality and overall survival between the two groups (p = 0.76, p = 0.32, p = 0.65, respectively).

Conclusion:

The current study showed that a steeper slope of neutrophil recovery following HCT was associated with increased acute GVHD, though it did not affect relapse, NRM and OS. Early diagnosis and therapeutic intervention for acute GVHD may improve the outcome of patients with rapid neutrophil recovery.