Twenty Years of Unrelated Donor Bone Marrow Transplantation for Pediatric Acute Leukemia Facilitated by the National Marrow Donor Program

AbstractThe National Marrow Donor Program (NMDP) has facilitated unrelated donor hematopoietic cell transplants for more than 20 years. In this time period, there have been many changes in clinical practice, including improvements in HLA typing and supportive care, and changes in the source of stem cells. Availability of banked unrelated donor cord blood (incorporated into the NMDP registry in 2000) as a source of stem cells has become an important option for children with leukemia, offering the advantages of immediate availability for children with high-risk disease, the need for a lesser degree of HLA match, and expanding access for those with infrequent HLA haplotypes. Overall survival (OS) in children with acute leukemia transplanted with unrelated donor bone marrow (BM) is markedly better in more recent years, largely attributable to less treatment-related mortality (TRM). Within this cohort, 2-year survival was markedly better for patients with acute lymphoblastic leukemia (ALL) in first complete response (CR1) (74%) versus second complete response (CR2) (62%) or more advanced disease (33%). Similar findings are observed with patients with AML, suggesting earlier referral to bone marrow transplant (BMT) is optimal for survival. Notably, this improvement over time was not observed in unmodified peripheral blood stem cell (PBSC) recipients, suggesting unmodified PBSC may not be the optimal stem cell source for children

“No Wash” Albumin-Dextran Dilution for Double-Unit Cord Blood Transplantation is Safe with High Rates of Sustained Donor Engraftment

AbstractWashing cord blood (CB) grafts involves product manipulation and may result in cell loss. We investigated double-unit CB transplantation (CBT) using red blood cell (RBC)–depleted units diluted with albumin-dextran in patients with hematologic malignancies. One-hundred thirty-six patients (median age, 43 years; range, 4 to 71; median weight, 69 kilograms (kg); range, 24 to 111) underwent transplantation with a 4/6 to 6/6 HLA-matched graft. Patients ≤ 20 kg were excluded, as they only received washed units. Units were diluted a median of 8 fold to a median volume of 200 mL/unit. The median infused total nucleated cell doses were 2.7 (larger unit) and 2.0 (smaller unit) x 107/kg, respectively, and the median post-thaw recovery was 86%. Units were infused consecutively (median, 45 minutes/unit). While only 17 patients (13%) had no infusion reactions, reactions in the remaining 119 patients were almost exclusively mild-moderate (by CTCAE v4 criteria 12 grade 1, 43 grade 2, 63 grade 3) with only 1 patient (< 1%) having a severe (grade 4) reaction. Moreover, most were easily treated. Grade 2 to 3 hypertension was the most common in 101 (74%) patients. The cumulative incidence of sustained donor-derived neutrophil engraftment was high: 95% in myeloablative and 94% in nonmyeloablative CBT recipients. With appropriate supportive care, double-unit CBT with RBC-depleted grafts infused after albumin-dextran dilution is safe with high rates of engraftment in patients > 20 kg

Transplantation in Remission Improves the Disease-Free Survival of Patients with Advanced Myelodysplastic Syndromes Treated with Myeloablative T Cell-Depleted Stem Cell Transplants from HLA-Identical Siblings

AbstractFrom 1985 to 2004, 49 patients with advanced myelodysplastic syndromes (MDS) (≥5% blasts) or acute myeloid leukemia (AML) transformed from MDS underwent T cell depleted bone marrow or peripheral blood hematopoietic stem cell transplantation (HSCT) from HLA-identical siblings following conditioning with a myeloablative regimen that included total body irradiation (44 patients) or busulfan (5 patients). Thirty-six patients received chemotherapy (3 low dose and 33 induction doses) before conditioning, and 13 patients did not receive any chemotherapy. Prior to transplantation, 22 of the 36 treated patients were in hematologic remission; 4 were in a second refractory cytopenia phase (26 responders); 8 had failed to achieve remission; and 2 of the responders had progression or relapse of their MDS (10 failures). No post-transplantation pharmacologic prophylaxis for graft-versus-host disease (GVHD) was given. The median age was 48 yrs (range 13-61). Forty-five of the 49 patients engrafted; 2 had primary graft failure; and 2 died before engraftment. Only 3 patients developed acute GVHD (aGVHD) (grades I and III) and 1 chronic GVHD (cGVHD). At 3 yrs post-transplantation, the overall survival (OS) was 54% in the responders; 31% in the untreated group; and 0% in the failure group (P=.0004). The disease free survival (DFS) was 50%, 15% and 0% in each group respectively (P=.0008). In multivariate analysis, disease status before cytoreduction remained highly correlated with DFS (P<.001). The cumulative incidence (CI) of relapse at 2-yrs post-transplantation for the responders was 23%; for the untreated group was 38%; and for the failures was 50%. The CI of non-relapse mortality at 2-yrs post-transplantation, for the responders was 23%; for the untreated group was 38%; and for the failures was 40%. All survivors achieved a Karnofsky Performance Status (KPS) of ≥90. These results indicate that patients with advanced MDS who achieve and remain in remission or a second refractory cytopenia phase with chemotherapy before conditioning can achieve successful long-term remissions following a myeloablative T cell depleted allogeneic HSCT

Safety and Immunogenicity of the Live Attenuated Varicella Vaccine Following T Replete or T Cell-Depleted Related and Unrelated Allogeneic Hematopoietic Cell Transplantation (alloHCT)

There are limited studies assessing the live attenuated varicella vaccine following allogeneic hematopoietic cell transplantation (alloHCT). Because of the morbidity of varicella acquired after childhood, we immunized and retrospectively analyzed the safety and immunogenicity of this vaccine in 46 varicella zoster virus (VZV) seronegative patients <20 years old at HCT who achieved a CD4 cell count ≥200/μL, were off immunosuppression, and responded to ≥1 post-HCT vaccines. Two vaccinated patients lacking follow-up titers were excluded from analysis. Stem cells were derived from an HLA-matched sibling (n = 18) or an alternative (HLA mismatched related or unrelated) donor (n = 26). Median time to vaccination was 4 years. Sixty-four percent of patients seroconverted following 1 immunization. There was no significant difference in response between recipients of a matched related or alternative donor graft (P = .2) or between those given a T cell-depleted or T-replete alternative donor graft (P = .27). Three of 44 patients developed a self-limited varicella-like rash within 2.5 weeks of immunization. With a median follow-up of 29.1 (range: 6.9-167.1) months, there were no subsequent cases of varicella-like rashes. No patient developed shingles. This study suggests that this vaccine is safe and immunogenic when given according to preset clinical and immunologic milestones, warranting larger prospective studies in patients ≥24 months following HCT as outlined in current post-HCT vaccine guidelines

Excellent leukemia control after second hematopoietic cell transplants with unrelated cord blood grafts for post-transplant relapse in pediatric patients

BackgroundPatients with leukemia relapse after allogeneic hematopoietic cell transplant (HCT) have poor survival due to toxicity and disease progression. A second HCT often offers the only curative treatment.MethodsWe retrospectively reviewed our bi-institutional experience (MSKCC-USA; Utrecht-NL) with unrelated cord blood transplantation (CBT) for treatment of post-transplant relapse. Overall survival (OS) and event-free survival (EFS) were evaluated using the Kaplan-Meier method, treatment-related mortality (TRM) and relapse were evaluated using the competing risk method by Fine-Gray.ResultsTwenty-six patients age &lt; 21 years received a second (n=24) or third (n=2) HCT with CB grafts during the period 2009-2021. Median age at first HCT (HCT1) was 11.5 (range: 0.9-17.7) years and all patients received myeloablative cytoreduction. Median time from HCT1 to relapse was 12.8 (range 5.5-189) months. At CBT, median patient age was 13.5 (range 1.4-19.1) years. Diagnoses were AML: 13; ALL: 4, MDS: 5, JMML: 2; CML: 1; mixed phenotype acute leukemia: 1. Sixteen patients (62%) were in advanced stage, either CR&gt;2 or with active disease. Median time from HCT1 to CBT was 22.2 (range 7-63.2) months. All patients engrafted after CBT. Thirteen patients developed acute GvHD; 7 had grade III or IV. With a median survivor follow-up of 46.6 (range 17.4-155) months, 3-year OS was 69.2% (95% CI 53.6-89.5%) and 3-year EFS was 64.9% (95% CI 48.8-86.4%). Eight patients died, 3 of AML relapse and 5 due to toxicity (respiratory failure [n=4], GvHD [n=1]) at a median time of 7.7 (range 5.9-14.4) months after CBT. Cumulative incidence of TRM at 3 years was 19.2% (95% CI 4.1-34.4%). Notably, all TRM events occurred in patients transplanted up to 2015; no toxicity-related deaths were seen in the 16 patients who received CBT after 2015. Cumulative incidence of relapse was 15.9% (95% CI 1.6-30.2%) at 3 years, remarkably low for these very high-risk patients.ConclusionsSurvival was very encouraging following CB transplants in pediatric patients with recurrent leukemia after first HCT, and TRM has been low over the last decade. CBT needs to be strongly considered as a relatively safe salvage therapy option for post-transplant relapse