Incidence, Risk Factors, Characteristics, and Outcome of Chronic Graft Versus Host Disease in Children Undergoing Haploidentical Peripheral Blood Stem Cell Transplant With Post-transplant Cyclophosphamide.

AIM: Chronic graft versus host disease (cGVHD) is a major cause of morbidity postallogeneic peripheral blood stem cell transplant (PBSCT). There is paucity of literature describing incidence, risk factors, characteristics, and outcome of cGVHD in children undergoing haploidentical PBSCT with post-transplant cyclophosphamide (PTCy). Here, we describe our experience from our center regarding the same. METHODS: All children who underwent haploidentical PBSCT with PTCy between January 2016 and December 2021 at our center and survived beyond day+100 post-transplant were included in this retrospective study. Conditioning regimens used were: Thiotepa-Fludarabine-Cyclophosphamide with 2 Gy single fraction total body irradiation, Thiotepa-Busulfan-Fludarabine, Fludarabine-total body irradiation and Fludarabine-Melphalan. Peripheral blood was used as stem cell source in all patients. GVHD prophylaxis was PTCy 50 mg/kg on day +3 and +4, Mycophenolate mofetil and Calcineurin inhibitors. Clinical and laboratory data was electronically retrieved and analyzed based on National Institute of Health Consensus Criteria-2014 at regular intervals. Impact of various patient, donor, and transplant-related factors on development of cGVHD were analyzed. Incidence of relapse, event free survival (EFS) and overall survival (OS) were calculated and compared between cGVHD and no cGVHD groups. Patients with rejection were excluded from risk factor analysis for cGVHD but were considered for survival analysis. RESULTS: Fifty-one children included in this study. Median age of transplant of our cohort was 7.5 years with male:female=1.6:1. Eight patients had rejection with autologous recovery. History of acute GVHD (aGVHD) was present in 15/51 (Grade III to IV in 7/51). cGVHD developed in 19/51 patients (mild-9/51, moderate-6/51, and severe-4/51). Skin was the most common organ involved (100%) followed by gastrointestinal tract (47.4%), liver (36.8%), eyes (21%), lungs (21%), mouth (15.7%), and joints (5.2%). Advanced donor age (>30 y) and previous aGVHD were found to be significantly associated with increased risk of developing cGVHD. At last follow-up, complete response and partial response of cGVHD was seen in 6/19 and 4/19 patients, respectively. Overall mortality was 15/51 (cause of mortality was relapse of cancer 8/15, cGVHD-3/15, other 4/15). EFS and OS of full cohort was 55% and 70.6%, respectively. Compared with patients without cGVHD, patients with cGVHD demonstrated a lower relapse (18.2% vs. 40%, P =0.2333), higher EFS (68.4% vs. 53.1%, P =0.283), and higher OS (73.7% vs. 68.8%, P =0.708). CONCLUSION: Incidence of cGVHD was high in children undergoing haploidentical PBSCT with PTCy. Other than PBSC graft source; donor age and previous aGVHD were the risks factors for development of cGVHD. Patients with cGVHD had lower incidence of relapse translating into better survival but this difference was not statistically significant.

Fatal Severe Cytokine Release Syndrome Post-haploidentical Stem Cell Transplant With Post-transplant Cyclophosphamide in an Infant With Severe Combined Immunodeficiency and Disseminated Bacille Calmette-Guérin Infection.

INTRODUCTION: Severe Combined Immunodeficiency (SCID) is a primary immunodeficiency disorder characterized by absent or dysfunctional T lymphocytes, leading to defective cellular and humoral immunity requiring urgent hematopoietic stem cell transplantation (HSCT). We report a case of SCID with disseminated Bacille Calmette-Guérin (BCG) infection who developed cytokine release syndrome (CRS) and possible Immune reconstitution inflammatory syndrome (IRIS) after Haploidentical HSCT with post-transplant cyclophosphamide. METHODS: Data were retrospectively retrieved from electronic medical records. RESULT: A 5-month-old male infant was referred with fever, cough, and generalized maculopapular rash for 15 days, and had pallor without hepatosplenomegaly or lymphadenopathy. He had a history of previous male sibling death at 6 months of age due to pneumonia. Investigations: hemoglobin: 4.7 g/dL, TLC-6.37×103/uL, absolute lymphocytes: 0.98×103/uL, platelets: 319×103/uL, bilateral patchy opacities in both lung fields, and low immunoglobulin levels. Lymphocyte subset analysis revealed T-, B+, NK- SCID. Genetic analysis showed a hemizygous mutation in IL2RG (c.314A>G). The child received intravenous (IV) antibiotics, antifungal, antitubercular drugs, irradiated blood products, and IV immunoglobulins. Urgent haploidentical HSCT from the mother was planned. Conditioning was Fludarabine-40 mg/m2/d for 4 days, cyclophosphamide: 14.5 mg/kg/d for 2 days. He received peripheral blood hematopoietic stem cells with CD34- 15×106 cells/kg and CD3- 805×106 cells/kg. Within 2 hours of stem cell infusion, he developed respiratory distress, fever, shock, and flaring of rash. Methylprednisolone was started in view of CRS. On day+2, he had sudden desaturation and bradycardia needing mechanical ventilation and inotropes. His inflammatory markers were elevated (Ferritin: 3640 ng/mL, IL-6:5000 pg/mL, CRP:255 mg/L). In view of high-grade CRS, he received an injection of tocilizumab 8 mg/kg on day +2 and day +4. He received post-transplant cyclophosphamide 5 mg/kg on day +3. The endotracheal secretion GeneXpert was positive for Mycobacterium supporting the diagnosis of disseminated tuberculosis. Our patient had disseminated BCG infection which could also be contributory in the initiation of IRIS as the mother was immunized with the BCG vaccine in childhood so she must be having cytotoxic T cells specific for BCG, which were transferred to the infant with peripheral blood stem cell product. He succumbed to severe acute respiratory distress syndrome and multiorgan dysfunction on day +5 post-transplant. CONCLUSIONS: In haploidentical HSCT of SCID, post-transplant course can be complicated by CRS and IRIS as these patients are inefficient in mounting any response to infused donor lymphocytes resulting in their unregulated growth.

Impact of Conditioning Regimen and Graft-versus-Host Disease Prophylaxis on The Outcome of Haploidentical Peripheral Blood Stem Cell Transplantation for High-Risk Severe Aplastic Anemia in Children and Young Adults: A Report from the Pediatric Severe Aplastic Anemia Consortium of India.

Allogenic hematopoietic cell transplantation (HCT) is the best curative approach for patients with severe aplastic anemia (SAA). The outcomes of HCT from haploidentical family donors (HFDs) have improved, making it a feasible option for patients lacking an HLA-identical donor. However, data on HFD-HCT for younger patients with SAA is sparse. In this multicenter retrospective study, we evaluated the outcomes of 79 patients undergoing HFD-HCT for SAA. All the patients were heavily pretransfused, the median time to HCT was >12 months, and 67% had failed previous therapies. Conditioning was based on fludarabine (Flu)-cyclophosphamide (Cy)-antithymocyte globulin (ATG)/total body irradiation (TBI) with or without thiotepa/melphalan (TT/Mel). Post-transplantation Cy (PTCy) and calcineurin inhibitors (CNIs)/sirolimus were used as graft-versus-host disease (GVHD) prophylaxis with or without abatacept. The rate of primary graft failure (PGF) was 16.43% overall, lower in patients conditioned with TT/Mel. The incidences of acute and chronic GVHD were 26.4% and 18.9%, respectively. At a median follow-up of 48 months, the overall survival (OS) and event-free survival (EFS) were 61.6% and 58.1%, respectively. Both OS and EFS were better in the TT/Mel recipients and with abatacept as GVHD prophylaxis. On multivariate analysis, the use of abatacept was found to favorably impact the outcome variables, including GVHD and EFS. Our study suggests that PTCy-based HFD-HCT is a reasonable option for young patients with high-risk SAA, in whom optimization of conditioning and GVHD prophylaxis might further improve outcomes.

Diagnosis and Management of Acquired Aplastic Anemia: Consensus Statement of Indian Academy of Pediatrics.

JUSTIFICATION: In India, there is a lack of uniformity of treatment strategies for aplastic anemia (AA), and many children are managed only with supportive care due to non-availability of hematopoietic stem cell transplantation (HSCT). PROCESS: Eminent national faculty members were invited to participate in the process of forming a consensus statement in Hyderabad in July, 2016. Draft guidelines were circulated to all members, and comments received in a online meeting in October, 2020 were incorporated into the final draft. These were approved by all experts. Objective: To facilitate appropriate management of children with acquired aplastic anemia. RECOMMENDATIONS: Key recommendations are: i) A bone marrow biopsy is must to make a diagnosis of AA; ii) Rule out inherited bone marrow failure syndromes (IBMFS), connective tissue disorders, viral infections, paroxysmal nocturnal hemoglobinuria (PNH), drug or heavy metal induced marrow suppression in all cases of AA; iii) Conservative approach to transfusions should be followed, with a target to keep hemoglobin >6 g/dL in children with no co-morbidities; iv) HLA-matched sibling donor HSCT is the preferred choice of treatment for newly diagnosed very severe/ severe AA; v) In absence of HLA-matched family donor, a matched unrelated donor (MUD) transplant or immunosuppressive therapy (IST) should be considered as alternate choice based on physician expertise; vi) Fludarabine, cyclophos-phamide and anti-thymocyte globulin (ATG) based conditioning with cyclosporine and methotrexate as graft versus host disease (GvHD) prophylaxis is the preferred regimen; vii) Horse ATG and cyclosporine are the recommended drugs for IST. One should wait for 3-6 months for the response assessment and consideration of next line therapy.

DOT1L activity in leukemia cells requires interaction with ubiquitylated H2B that promotes productive nucleosome binding.

DOT1L methylates histone H3 lysine 79 during transcriptional elongation and is stimulated by ubiquitylation of histone H2B lysine 120 (H2BK120ub) in a classical trans-histone crosstalk pathway. Aberrant genomic localization of DOT1L is implicated in mixed lineage leukemia (MLL)-rearranged leukemias, an aggressive subset of leukemias that lacks effective targeted treatments. Despite recent atomic structures of DOT1L in complex with H2BK120ub nucleosomes, fundamental questions remain as to how DOT1L-ubiquitin and DOT1L-nucleosome acidic patch interactions observed in these structures contribute to nucleosome binding and methylation by DOT1L. Here, we combine bulk and single-molecule biophysical measurements with cancer cell biology to show that ubiquitin and cofactor binding drive conformational changes to stimulate DOT1L activity. Using structure-guided mutations, we demonstrate that ubiquitin and nucleosome acidic patch binding by DOT1L are required for cell proliferation in the MV4; 11 leukemia model, providing proof of principle for MLL targeted therapeutic strategies.

Successful Haploidentical Stem Cell Transplant With Posttransplant Cyclophosphamide for Isolated Central Nervous System Blast Crisis in a Child With Chronic Myeloid Leukemia.

Chronic myelogenous leukemia (CML) is a myeloproliferative disorder. The extramedullary blast crisis (BC) is a known complication of CML, but it usually accompanies a systemic disease. However, an isolated central nervous system (CNS) BC at relapse is very rare and has a very poor prognosis. Salvage is even more difficult for patients who relapse with a CNS BC after an allogeneic stem cell transplant (SCT). Here, we report successful treatment of an isolated CNS BC of CML in a 14-year-old boy who relapsed with isolated a CNS BC after matched sibling donor SCT by haploidentical SCT with posttransplant cyclophosphamide.

Successful Haploidentical Stem Cell Transplant With Posttransplant Cyclophosphamide in Wiskott-Aldrich Syndrome With Myeloablative Conditioning.

Hematopoietic stem cell transplant (HSCT) is the only curative treatment modality for Wiskott-Aldrich syndrome. Haploidentical HSCT with posttransplant cyclophosphamide (PTCy) is an upcoming option in children with nonmalignant conditions. However, only few cases have been reported for Wiskott-Aldrich syndrome HSCT with PTCy approach. Here we report a 4-year-old boy, treated successfully by haploidentical HSCT with myeloablative conditioning (busulfan, fludarabine, and thiotepa) and PTCy. Posttransplant chimerism was fully donor. Of 13 cases (current case and other 12 published cases) 10 are alive and disease free after haploidentical HSCT with PTCy. Haploidentical HSCT with PTCy using myeloablative conditioning is feasible and safe.

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.

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.

Isolated bilateral uveitis in child with hypereosinophilic syndrome.

The ocular involvement has rarely been described in hypereosinophilic syndrome (HES). We report an 8-year-old girl with HES and isolated bilateral uveitis as end-organ damage. Almost 20 months after detection of persistent asymptomatic eosinophilia, she developed complete loss of vision in right eye due to retinal detachment and decreased vision in left eye. We treated this organ-threatening condition with prednisolone and imatinib mesylate, although she was negative for FIP1L1-PDGRFA fusion gene. The vision in her left eye returned to normal. At present, the child is on alternate-day low-dose prednisolone and daily imatinib. Early recognition and aggressive treatment is essential in HES with ocular involvement to save vision. Imatinib is a useful adjuvant drug even in PDGRFA/FIP1L1-negative HES.