Haematopoietic Stem Cell Transplantation (HSCT) for Primary Immune System Disorders in Children: A Single Centre Experience.

OBJECTIVE: To determine the outcomes of allogeneic HSCT in children with primary immune system disorders (PID).

STUDY DESIGN: Descriptive Cross-sectional study. Place and Duration of the Study: Armed Forces bone marrow transplant centre / National Institute of Bone Marrow Transplant (AFBMTC / NIBMT), Rawalpindi, Pakistan, from October 2012 to December 2021.

METHODOLOGY: Data of all cases undergoing HSCT for immune system disorders were analysed for variables affecting outcome and overall survival in the first 180 days after allogeneic HSCT. All patients presenting to AFBMTC / NIBMT with PID, age <12 years. Patients with organ dysfunction secondary to repeated infections were excluded from the study. Data of all patients and their donors undergoing HSCT for immune system disorders were analysed for variables affecting outcome and overall survival in the first 180 days after allogeneic bone marrow transplant. Neutrophil engraftment was defined as absolute neutrophil count ≥0.5 × 109/L for 3 consecutive days, while platelet engraftment as platelet count ≥20 × 109/L without platelet transfusion for one week. Overall survival (OS) was taken as time from the date of HSCT till day + 180 post-transplant.

RESULTS: A total of 42children including 29 boys and 13 girls underwent HSCT for PID. The mean age was 2.1±2.8 years. Underlying diagnosis was haemophagocytic lymphohistiocytosis (HLH), severe immune deficiency (SCID), leukocyte adhesion defect (LAD), X-linked agammaglobulinemia, chronic granulomatous disease (CGD) and Job's syndrome in 18 (42.9%), 16 (38.1%), 3(7.1%), 2 (4.8%), 2 (4.8%) and 1 (2.4%) patients respectively. Thirty-one (73.8%) children had fully HLA-matched donors while 11 (26.2%) had haplo-matched donors. Major immediate post-transplant complications were febrile neutropenia, mucositis and SOS/VOD in 31 (73.8%), 9 (21.4%) and 4 (10.0%) cases, respectively. Eight (19.0%) had CMV reactivation, acute GVHD was seen in 17 (40.4%) cases, while 1 (2.3%) case had chronic GVHD. Twelve (28.6%) patients died, out of which 5 had graft failure, 3 had VOD, 2 had pneumonia, 1 had severe GVHD, and 1 died due to seizures. Overall survival (OS) in this study was 71.4% with survival reaching up to 80.6% in fully matched HSCT.

CONCLUSION: HLH and SCID were the commonest immune disorders requiring HSCT. Graft failure leading to neutropenic sepsis was the commonest cause of mortality. OS was better in fully matched HSCT as compared to haplo-identical HSCT.

KEY WORDS: Immune deficiency, Severe combined immunodeficiency, Haematopoietic stem cell transplantation.