Haploidentical Stem Cell Transplantation With Post-transplant Cyclophosphamide for Pediatric Acute Leukemia is Safe and Effective.

BACKGROUND: Haploidentical family donor is universally available and is fast emerging as an alternative donor choice for children with leukemia needing hematopoietic stem cell transplant (HSCT). Here we describe our experience of treating children with acute leukemia by haploidentical HSCT with posttransplant cyclophosphamide (PTCy). METHODS: We retrospectively analyzed the outcome data of 17 children with acute leukemia who underwent related haploidentical HSCT. Fifteen were in complete remission (CR) before HSCT: CR1-6, CR2-7, and CR3-2 and 2 were not in remission. Donors were mobilized with granulocyte colony stimulating factor. The conditioning was nonmyeloablative in 4 and myeloablative in 13. All received PTCy 50 mg/kg on days 3 and 4 as graft-versus-host disease (GVHD) prophylaxis along with tacrolimus or cyclosporine and mycophenolate mofetil. A median of 8.94 million of CD34+ cells/kg was infused. RESULTS: All patients were engrafted for neutrophil and platelets, except 1 child with refractory acute myeloid leukemia disease who relapsed before engraftment. Five children relapsed (4 died and 1 child with CD20-positive leukemia is disease free after Rituximab therapy). There was 1 transplant-related mortality due to grade IV GVHD. Remaining 11 patients are in CR. Acute GVHD was seen in 4 patients. Of 4, 3 children later developed chronic GVHD and all are alive and disease free. Three of 4 children who received nonmyeloablative conditioning have relapsed. Overall survival is 70.5% and event-free survival is 64.7%. Median follow-up of all patients was 393 days. CONCLUSION: Haploidentical HSCT with PTCy is a safe and effective therapy for children with acute leukemia. Myeloablative conditioning and chronic GVHD lead to improved disease-free survival.

Successful Haploidentical Stem Cell Transplant With Posttransplant Cyclophosphamide for Hemophagocytic Lymphohistiocytosis.

Allogeneic hematopoietic stem cell transplant (HSCT) has been known to be a curative therapy for patients with hemophagocytic lymphohistiocytosis (HLH) but donor availability is an issue. Haploidentical HSCT with posttransplant cyclophosphamide (PTCy) has been investigated as a feasible option for various malignant and nonmalignant conditions with reduced incidence of acute graft versus host disease (GVHD) and graft rejection. However, its use has not been described in children with HLH and here we describe 2 boys who underwent successful haploidentical HSCT with PTCy. None had acute GVHD and 1 had limited chronic GVHD. Both are alive and disease-free at follow-up of 912 and 239 days, respectively. Haploidentical HSCT with PTCy is a feasible option for children with HLH lacking a matched sibling donor.

Reduced-toxicity alternate-donor stem cell transplantation with posttransplant cyclophosphamide for primary immunodeficiency disorders.

We describe here the outcomes of reduced-toxicity alternate-donor stem cell transplant (SCT) with posttransplant cyclophosphamide (PTCy) for primary immunodeficiency disorders (PIDs) in eight children (haploidentical-seven and matched unrelated donor-one). The conditioning was with serotherapy (alemtuzumab-3/rabbit-anti-thymoglobulin-5); fludarabine, cyclophosphamide, and total body irradiation-5 (additional thiotepa-3); fludarabine and treosulfan-2; and fludarabine and busulfan-1. All received PTCy 50 mg/kg on days 3 and 4 as graft versus host disease prophylaxis along with tacrolimus and mycophenolate. Mean CD34 dose was 13.8 × 106 /kg. Two children died because of PIDs. Acute graft versus host disease up to grades I and II was seen in three children. All six survivors are fully donor and disease free at median follow-up of 753 days. Alternate donor SCT with PTCy is feasible in PID and has good outcomes.

Successful Nonmyeloablative Allogeneic Stem Cell Transplant in a Child With Emberger Syndrome and GATA2 Mutation.

Emberger syndrome with underlying guanine-adenine-thymine-adenine 2 (GATA2) mutation is a rare disorder and very few successful nonmyeloablative allogeneic hematopoietic stem cell transplants (HSCTs) have been reported. We report a case of Emberger syndrome with GATA2 mutation in a 9-year-old girl who presented with congenital sensorineural deafness, warts, lymphedema, and Myelodysplastic syndrome. Her sister had died of a similar illness. She underwent a nonmyeloablative matched related donor peripheral blood HSCT with rabbit antithymoglobulin (5 mg/kg), fludarabine (160 mg/m), cyclophophamide (29 mg/kg), and total body irradiation (2 Gray). Graft versus host disease prophylaxis consisted of tacrolimus and mycophenolate moefetil. She had neutrophil engraftment on day+15 and fully donor chimerism by day+30. She developed limited chronic skin graft versus host disease on tapering off immunosuppression. She is disease free on day+475. The review of literature showed a total of 28 patients with GATA2 mutation have undergone HSCT mostly nonmyeloablative and overall survival is 75%. Nonmyeloablatove HSCT is feasible and safe for the patients with GATA2 mutation.

Successful Reduced Intensity Conditioning Alternate Donor Stem Cell Transplant for Wiskott-Aldrich Syndrome.

There are very few reports of reduced intensity conditioning (RIC) hematopoietic stem cell transplant (HSCT) with alternate donor for Wiskott-Aldrich syndrome (WAS) and there is no report of RIC with posttransplant cyclophosphamide (PTCy) in WAS. There is only 1 report of T cell receptor αß and CD19-depleted haploidentical HSCT for WAS. Here we report successful outcome in 3 children with WAS who underwent successful RIC alternate donor HSCT of whom 2 (matched unrelated donor and T-cell replete haploidentical) received PTCy and 1 underwent T cell receptor αß and CD19-depleted haploidentical HSCT. We modified conditioning used by Luznik for haploidentical HSCT by adding thiotepa 8 mg/kg and Campath or rabbit antithymoglobulin for 2 cases who received PTCy. In third case we gave fludarabine, thiotepa, and treosulfan-based conditioning. The mean duration of follow-up for these patients was 23.6 months posttransplant (range, 21 to 26 mo). All 3 patients are transfusion independent. Acute graft versus host disease (GVHD) grade I occurred in 1 and none had chronic GVHD. Chimerism of all 3 was fully donor (>95% donor) at D+30 and D+100 posttransplant. All are alive, healthy, and doing well. Our 3 cases highlight that with newer conditioning and GVHD prophylaxis approach alternate donor HSCT in WAS can become a safe and effective treatment option.