Increased lymphoblast-like cells following umbilical cord blood stem cell transplantation do not predict recurrent acute leukemia

The prognostic significance of hematogones in childhood B-cell acute lymphoblastic leukemia

BACKGROUND

Recent studies have demonstrated hematogones (HGs) expansion to be associated with favorable outcomes in hematological diseases, especially in patients with acute myeloid leukemia and patients undergoing hematopoietic stem cell transplantation. Acute lymphoblastic leukemia (ALL) is the most common form of cancer in children. As of now, minimal residual disease (MRD) remains the most compelling independent prognostic factor in childhood ALL. There is need for more prognostic tools for evaluating relapse risk.

PROCEDURE

The goal of this study was to assess the prognostic value of HGs on relapse-free survival (RFS) and overall survival (OS) in childhood ALL. In this prospective cohort study, a total of 122 subjects with definitive diagnosis of precursor B lymphoblastic leukemia were evaluated. Flow cytometric HG detection was performed in bone marrow aspirates after induction and consolidation therapy.

RESULTS

The median follow-up period of patients was 35.5 ± 9.4 (SD) months. Patients who had at least 1.0% HGs had a significantly better RFS (p = .023). Moreover, univariate and multivariate analyses confirmed that positive HGs were independently associated with longer RFS (unadjusted model: hazard ratio = 0.33, 95% CI = 0.12-0.91, p = .031; adjusted model: hazard ratio = 0.30, 95% CI = 0.11-0.82, p = .020).

CONCLUSIONS

Along with the role of MRD, our study shows the significance of HGs as an independent prognostic factor. The results indicate the independent prognostic value of HGs on RFS after adjustment for other prognostic factors, and can be beneficial for risk stratification and treatment modifications amongst pediatric B-cell ALL patients.

Impact of bone marrow hematogones on umbilical cord blood transplantation outcomes in patients with acute myeloid leukemia

Early after umbilical cord blood transplantation, patients show marked differences in bone marrow (BM) hematogone percentages. Little is known about whether these differences are clinically relevant. We hypothesized that early recovery of hematogones may be associated with improved transplantation outcomes. BM aspirates were assessed from 88 patients with acute myeloid leukemia by two independent reviewers at day 21 and 100 after umbilical cord blood transplantation. Interobserver variability for BM hematogone percentages at these time points showed correlation coefficients of 0.83 and 0.98, respectively (P ≤ .01 for both). A high percentage of hematogones at day 21 was associated with less acute graft-versus-host disease grade 3 to 4 (P = .01). At day 100, a high percentage of BM hematogones was associated with improved overall survival (P = .02) and lower treatment-related mortality (P ≤ .01). This study shows that BM hematogone percentages may be useful prognostic indicators in patients with acute myeloid leukemia after umbilical cord blood transplantation and should be routinely reported in BM differential counts.

Importance of day 21 BM chimerism in sustained neutrophil engraftment following double-unit cord blood transplantation

Delayed or failed engraftment remains a concern after cord blood transplantation (CBT) even when using double-unit grafts. Therefore, we analyzed the association between BM assessment performed approximately 21 days after transplantation, and the speed and success of sustained donor-derived neutrophil engraftment in 56 myeloablative double-unit CBT (DCBT) recipients. Overall, the cumulative incidence of sustained neutrophil engraftment was 95% (95% confidence intervals (CI): 89-100). Of the percentage of myeloid precursors, the BM cellularity and the total donor chimerism the total donor chimerism percentage had the most critical association with the speed and success of engraftment. DCBT recipients who were 100% donor achieved a 98% engraftment rate at a median of 22 days. This compared with 100% engraftment in patients who were 90-99% donor, but at a delayed median of 29 days and only 68% engraftment in patients <90% donor at a median of 37 days (P=0.001). Multivariate analysis was performed in the subgroup of patients who had not engrafted at the time the BM analysis was performed, the subgroup of most clinical concern. This confirmed donor chimerism was predictive of subsequent neutrophil recovery (P=0.004). These findings demonstrate the importance of the day 21 BM chimerism determinations after DCBT.