Impact of CD34+ cell dose in children who receive unrelated PBSCT with in vivo T-cell depletion for hematologic malignancies

Efficacy of low dose antithymocyte globulin on overall survival, relapse rate, and infectious complications following allogeneic peripheral blood stem cell transplantation for leukemia in children

Antithymocyte globulin (ATG) and anti-T lymphocyte globulin (ATLG) have been widely used to prevent graft-versus-host disease (GvHD), each with distinct properties and noninterchangeable doses. However, the optimal dose of ATG in children undergoing allo-PBSCT for leukemia has not yet been established. Therefore, the impact of ATG dose on overall survival (OS), relapse, GvHD, and infectious complications was investigated. Patients administered high dose (unrelated: 7.5 mg/kg, haploidentical: 10.0 mg/kg) and low dose (unrelated: 3.75 mg/kg, haploidentical: 5.0 mg/kg) ATG during two consecutive time periods were compared. There were 78 (39.8%) patients in the low dose group and 118 (60.2%) in the high dose group. OS was superior in the low dose group compared to the high dose group (P = 0.017), and relapse incidence was significantly lower in the low dose group (P = 0.022). Cumulative incidences of acute and chronic GvHD were similar between the groups (P = 0.095 and P = 0.672, respectively). Cytomegalovirus reactivation (70.3% vs. 51.3%, P = 0.007), Epstein-Barr virus reactivation (81.4% vs. 39.7%, P < 0.001), and invasive bacterial infections (12.7% vs. 0%, P = 0.001) post transplant were more frequent in the high dose group compared to the low dose group. Therefore, low dose ATG is more optimal in pediatric allo-PBSCT providing better OS while lowering the risk of relapse and infectious complications.

Relationship of Cell Compositions in Allografts with Outcomes after Haploidentical Transplantation for Acquired Severe Aplastic Anemia: Effects of CD34+ and CD14+ Cell Doses

Background

The dose of certain cell types in allografts affects engraftment kinetics and clinical outcomes after allogeneic stem cell transplantation (SCT). Hence, the present study investigated the association of cell compositions in allografts with outcomes after unmanipulated haploidentical SCT (haplo-SCT) for patients with acquired severe aplastic anemia (SAA).

Methods

A total of 131 patients with SAA who underwent haplo-SCT were retrospectively enrolled. Cell subsets in allografts were determined using flow cytometry. To analyze the association of cellular compositions and outcomes, Mann-Whitney U nonparametric tests were conducted for patient age, sex, weight, human leukocyte antigen mismatched loci, ABO-matched status, patient ABO blood type, donor-recipient sex match, donor-recipient relationship, and each graft component. Multivariate analysis was performed using logistic regression to determine independent influence factors involving dichotomous variables selected from the univariate analysis.

Results

A total of 126 patients (97.7%) achieved neutrophil engraftment, and 121 patients (95.7%) achieved platelet engraftment. At 100 days after transplantation, the cumulative incidence of II-IV acute graft-versus-host disease (GVHD) was 32.6%. After a median follow-up of 842 (range: 124-4110) days for surviving patients, the cumulative incidence of total chronic GVHD at 3 years after transplantation was 33.7%. The probability of overall survival at 3 years was 83.0%. Multivariate analysis showed that higher total doses of CD14⁺ (P = 0.018) and CD34⁺ cells (P < 0.001) were associated with a successful platelet engraftment. A successful platelet was associated with superior survival (P < 0.001). No correlation of other cell components with outcomes was observed.

Conclusions

These results provide evidence and explain that higher doses of CD34⁺ and CD14⁺ cells in haploidentical allografts positively affect platelet engraftment, contributing to superior survival for patients with SAA.

Treatment and response of autoimmune cytopenia occurring after allogeneic hematopoietic cell transplantation in children

Background

Autoimmune cytopenia (AIC) is a rare complication of allogeneic hematopoietic cell transplantation (HCT). In this study, we reviewed the diagnosis, treatment and response to therapy for pediatric patients with post-HCT AIC at our institution.

Methods

Of the 292 allogeneic HCTs performed from January, 2011 to December, 2015 at the Department of Pediatrics, The Catholic University of Korea, seven were complicated by post-HCT AIC, resulting in an incidence of 2.4%.

Results

All seven patients with post-HCT AIC had received unrelated donor transplant. Six of seven patients had a major donor-recipient blood type mismatch. The subtypes of AIC were as follows: immune thrombocytopenia (ITP) 2, autoimmune hemolytic anemia (AIHA) 2, Evans syndrome 3. Median time from HCT to AIC diagnosis was 3.6 months. All but one patient responded to first line therapy of steroid±intravenous immunoglobulin (IVIG), but none achieved complete response (CR) with this treatment. After a median duration of treatment of 15.3 months, two patients with ITP achieved CR and five had partial response (PR) of AIC. Five patients were treated with rituximab, resulting in the following response: 2 CR, 2 PR, 1 no response (NR). Median time to response to rituximab was 26 days from first infusion. All patients are alive without event.

Conclusion

Post-HCT AIC is a rare complication that may not resolve despite prolonged therapy. Rapid initiation of second line agents including but not limited to B cell depleting treatment should be considered for those that fail to achieve CR with first line therapy.