Children with acute leukemia: a comparison of outcomes from allogeneic blood stem cell and bone marrow transplantation

Myeloid Cells Restrict MCMV and Drive Stress-Induced Extramedullary Hematopoiesis through STAT1

Cytomegalovirus (CMV) has a high prevalence worldwide, is often fatal for immunocompromised patients, and causes bone marrow suppression. Deficiency of signal transducer and activator of transcription 1 (STAT1) results in severely impaired antiviral immunity. We have used cell-type restricted deletion of Stat1 to determine the importance of myeloid cell activity for the defense against murine CMV (MCMV). We show that myeloid STAT1 limits MCMV burden and infection-associated pathology in the spleen but does not affect ultimate clearance of infection. Unexpectedly, we found an essential role of myeloid STAT1 in the induction of extramedullary hematopoiesis (EMH). The EMH-promoting function of STAT1 was not restricted to MCMV infection but was also observed during CpG oligodeoxynucleotide-induced sterile inflammation. Collectively, we provide genetic evidence that signaling through STAT1 in myeloid cells is required to restrict MCMV at early time points post-infection and to induce compensatory hematopoiesis in the spleen.

Partially CD3+-Depleted Unrelated and Haploidentical Donor Peripheral Stem Cell Transplantation Has Favorable Graft-versus-Host Disease and Survival Rates in Pediatric Hematologic Malignancy

Most children who may benefit from stem cell transplantation lack a matched related donor. Alternative donor transplantations with an unrelated donor (URD) or a partially matched related donor (PMRD) carry an increased risk of graft-versus-host-disease (GVHD) and mortality compared with matched related donor transplantations. We hypothesized that a strategy of partial CD3⁺/CD19⁺ depletion for URD or PMRD peripheral stem cell transplantation (PSCT) would attenuate the risks of GVHD and mortality. We enrolled 84 pediatric patients with hematologic malignancies at the Children's Hospital of Philadelphia and the Children's Hospital of Wisconsin between April 2005 and February 2015. Two patients (2.4%) experienced primary graft failure. Relapse occurred in 23 patients (27.4%; cumulative incidence 26.3%), and 17 patients (20.2%) experienced nonrelapse mortality (NRM). Grade III-IV acute GVHD was observed in 18 patients (21.4%), and chronic GVHD was observed and graded as limited in 24 patients (35.3%) and extensive in 8 (11.7%). Three-year overall survival (OS) was 61.8% (95% confidence interval [CI], 50.2% to 71.4%) and event-free survival (EFS) was 52.0% (95% CI, 40.3% to 62.4%). Age ≥15 years was associated with decreased OS (P= .05) and EFS (P= .05). Relapse was more common in children in second complete remission (P = .03). Partially CD3⁺-depleted alternative donor PSCT NRM, OS, and EFS compare favorably with previously published studies of T cell-replete PSCT. Historically, T cell-replete PSCT has been associated with a higher incidence of extensive chronic GVHD compared with limited chronic GVHD, which may explain the comparatively low relapse and NRM rates in our study cohort despite similar overall rates of chronic GVHD. Partial T cell depletion may expand donor options for children with malignant transplantation indications lacking a matched related donor by mitigating, but not eliminating, chronic GVHD.

Allogeneic Bone Marrow Transplantation versus Peripheral Blood Stem Cell Transplantation for Hematologic Malignancies in Children: A Systematic Review and Meta-Analysis

Peripheral blood stem cell transplantation (PBSCT) is being increasingly performed as an alternative to bone marrow transplantation (BMT); however, PBSCT has not been proven to have equivalent outcome to BMT. We conducted a meta-analysis to compare survival rates and treatment-related complications between PBSCT and BMT for pediatric hematologic malignancies. We searched Medline, Embase plus Embase classics, and the Cochrane Central Register of Controlled Trials for the terms "hematopoietic stem cell transplantation" AND "allogeneic transplantation" AND "children", including randomized controlled studies and cohort studies without language limitations. We identified 7 of 5368 studies for inclusion in our meta-analysis. The cohorts of these studies included a total of 4328 patients, 3185 who underwent BMT and 1143 who underwent PBSCT. Five-year overall survival was similar in the 2 groups (PBSCT, 56.2%; BMT, 63.5%; relative risk [RR], 1.17; 95% confidence interval [CI], .91 to 1.52), as was the 5-year event-free survival (PBSCT, 49.9%; BMT, 57.2%; RR, 1.14; 95% CI, .93 to 1.39). The incidences of nonrelapse mortality and chronic graft-versus-host disease were higher in the PBSCT group compared with the BMT group (RR, 1.73; 95% CI, 1.50 to 1.99 versus RR, 1.55; 95% CI, 1.18 to 2.03). This meta-analysis found insufficient evidence to conclude that peripheral blood stem cells are equivalent to bone marrow. The results indicate that bone marrow can still be a preferred donor source for pediatric hematologic malignancies.

Single-agent GVHD prophylaxis with posttransplantation cyclophosphamide after myeloablative, HLA-matched BMT for AML, ALL, and MDS

High-dose, posttransplantation cyclophosphamide (PTCy) reduces severe graft-versus-host disease (GVHD) after allogeneic blood or marrow transplantation (alloBMT), but the impact of PTCy on long-term, disease-specific outcomes is unclear. We conducted a retrospective study of 209 consecutive adult patients transplanted for acute myeloid leukemia (AML, n = 138), myelodysplastic syndrome (n = 28), or acute lymphoblastic leukemia (ALL, n = 43) using PTCy as sole GVHD prophylaxis after myeloablative conditioning and HLA-matched-related or -unrelated T-cell-replete allografting. At alloBMT, 30% of patients were not in morphologic complete remission. The cumulative incidences of grades II to IV and III to IV acute GVHD at 100 days and chronic GVHD at 2 years were 45%, 11%, and 13%, respectively. Forty-three percent of patients did not require immunosuppression for any reason beyond PTCy. At 3 years, relapse cumulative incidence was 36%, disease-free survival was 46%, survival free of disease and chronic GVHD was 39%, and overall survival was 58%. Lack of remission at alloBMT, adverse cytogenetics, and low allograft nucleated cell dose were associated with inferior survival for AML patients. Minimal residual disease but not t(9;22) was associated with inferior outcomes for ALL patients. The ability to limit posttransplantation immunosuppression makes PTCy a promising transplantation platform for the integration of postgrafting strategies to prevent relapse.

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

PBSCs are increasingly being chosen as the mode of donation among unrelated donors. Pediatric patients, in particular, may receive very high CD34(+) and CD3(+) doses during unrelated PBSCT. In this work, we analyzed survival and GVHD outcomes in a cohort of 81 children who received unrelated PBSCT with uniform antithymocyte globulin (ATG)-based in vivo T-cell depletion for treatment of hematologic malignancy, with emphasis on the impact of cell dose on transplant outcomes. EFS was 61.5±5.6%, with higher CD34(+) dose (>10.0 × 10(6)/kg) and lower patient risk status predicting improved survival in multivariate study. Cumulative incidence of relapse was 30.2±5.2%; a low CD34(+) dose was the only significant factor for relapse. Neither CD34(+) nor CD3(+) dose was a significant determinant of acute or chronic GVHD. Importance of CD34(+) dose was reaffirmed in a subcohort of younger patients who received greater median cell doses than the overall cohort. In summary, for children who received unrelated PBSCT with ATG-based T-cell depletion for treatment of hematologic malignancy, the CD34(+) dose was the most important factor for relapse and EFS, and neither the CD34(+) nor the CD3(+) dose influenced incidence of acute or chronic GVHD.

Evaluation of risk for graft-versus-host disease in children who receive less than the full doses of mini-dose methotrexate for graft-versus-host disease prophylaxis in allogeneic hematopoietic stem cell transplantation

PURPOSE

The use of cyclosporine and mini-dose methotrexate (MTX) is a common strategy for graft-versus-host disease (GVHD) prophylaxis in allogeneic transplants. We investigated whether patients who receive fewer than the planned MTX doses are at increased risk for GVHD.

METHODS

The study cohort included 103 patients who received allogeneic transplants at the Department of Pediatrics of The Catholic University of Korea College of Medicine, from January 2010 to December 2011. MTX was administered on days 1, 3, 6, and 11 after transplant at a dose of 5 mg/m(2) each. Within the cohort, 76 patients (74%) received all 4 doses of MTX [MTX(4) group], while 27 patients (26%) received 0-3 doses [MTX(0-3) group].

RESULTS

Although there was no difference in neutrophil engraftment between the 2 groups, platelet engraftment was significantly faster in the MTX(4) group (median, 15 days), compared to the MTX(0-3) group (median, 25 days; P=0.034). The incidence of grades II-IV acute GVHD was not different between the MTX(4) and MTX(0-3) groups (P=0.417). In the multivariate study, human leukocyte antigen mismatch was the most significant factor causing grades II-IV acute GVHD (P=0.002), followed by female donor to male recipient transplant (P=0.034). No difference was found between the MTX(4) and MTX (0-3) groups regarding grades III-IV acute GVHD, chronic GVHD, and disease-free survival.

CONCLUSION

Our results indicate that deviations from the full dose schedule of MTX for GVHD prophylaxis do not lead to increased incidence of either acute or chronic GVHD.

PBSCT is associated with poorer survival and increased chronic GvHD than BMT in Japanese paediatric patients with acute leukaemia and an HLA-matched sibling donor

BACKGROUND

Peripheral blood stem cells (PBSC) may be used as an alternative to bone marrow (BM) for allogeneic transplantation. Since peripheral blood stem cell bank from unrelated volunteer donor has been started in Japan, use of PBSC allografts may be increased. Therefore we surveyed the outcomes of Japanese leukemia children after PBSC and BM transplantation.

PROCEDURE

This retrospective study compared the outcomes of 661 children (0-18 years) with acute lymphoblastic leukaemia (ALL) or acute myeloid leukaemia (AML) who received their first allogeneic peripheral blood stem cell transplantation (PBSCT; n = 90) or bone marrow transplantation (BMT; n = 571) from HLA-matched siblings between January 1996 and December 2007.

RESULT

Neutrophil recovery was faster after PBSCT than after BMT (ALL: P < 0.0001; AML: P = 0.0002), as was platelet recovery (ALL: P = 0.0008; AML: P = 0.0848). However, the cumulative incidence of chronic graft-versus-host disease (GvHD) was higher after PBSCT than after BMT (ALL: 26.0% vs. 9.9%, P = 0.0066; AML: 41.6% vs. 11.1%, P < 0.0001). The 5-year disease-free survival (DFS) was lower after PBSCT than after BMT for ALL (40.6% vs. 57.1%, P = 0.0257). The 5-year overall survival (OS) was lower after PBSCT than after BMT for ALL (42.4% vs. 63.7%, P = 0.0032) and AML (49.8% vs. 71.8%, P = 0.0163). Multivariate analysis revealed the use of PBSC was a significant risk factor for DFS and OS. PBSCT and BMT did not differ in relapse rate, acute GvHD for ALL and AML, or in DFS for AML.

CONCLUSION

PBSC allografts in Japanese children engraft faster but are associated with poorer survival and increased chronic GvHD.

Risk of complications during hematopoietic stem cell collection in pediatric sibling donors: a prospective European Group for Blood and Marrow Transplantation Pediatric Diseases Working Party study

We investigated prospectively factors influencing the safety of hematopoietic stem cell (HSC) collection in 453 pediatric donors. The children in the study donated either BM or peripheral blood stem cells (PBSCs) according to center policy. A large variability in approach to donor issues was observed between the participating centers. Significant differences were observed between BM and PBSC donors regarding pain, blood allotransfusion, duration of hospital stay, and iron supplementation; however, differences between the groups undergoing BM vs PBSC donation preclude direct risk comparisons between the 2 procedures. The most common adverse event was pain, reported mainly by older children after BM harvest, but also observed after central venous catheter (CVC) placement for PBSC collection. With regard to severe adverse events, one patient (0.7%) developed a pneumothorax with hydrothorax after CVC placement for PBSC collection. The risk of allotransfusion after BM harvest was associated with a donor age of < 4 years and a BM harvest volume of > 20 mL/kg. Children < 4 years were at higher risk than older children for allotransfusion after BM harvest and there was a higher risk of complications from CVC placement before apheresis. We conclude that PBSC and BM collection are safe procedures in children.