Life Threatening Hyperhemolysis in Two Children with Beta-Thalassemia Major (β-TM) Treated with Stem Cell Transplantation (SCT)
Authors: Russell Susan J , O'Brien Tracey , Mondy Philip , Williams Gary D 
Published: October 2019

Abstract
Hyperhaemolysis is a rare, poorly understood complication of red cell transfusion. We report the outcomes of SCT in 2 boys of Middle Eastern origin who developed life-threatening hyperhaemolysis each following their third transfusion for β-TM at the ages of 2.5 and 4 years. The diagnosis of hyperhaemolysis was based on laboratory evidence for haemolysis, post-transfusion haemoglobin (Hb) levels lower than pre-transfusion, positive Coomb’s tests and no allo-antibody able to be identified. Haemolysis was intravascular, extravascular and severe. Precipitous drops in Hb made transfusion unavoidable. The first boy responded to prednisolone, intravenous immunoglobulin (IVIG) and splenectomy. Haemosidderosis and fibrosis were present on liver biopsy, he was therefore regarded as a Class 3 thalassaemia patient and received hydroxyurea, azathioprine, erythropoietin, desferrioxamine, busulfan, cyclophosphamide and fludarabine conditioning prior to an HLA identical sibling SCT. He is alive and well 7 years post BMT with 30% stable donor chimerism and a normal Hb. The second child’s hyperhaemolysis failed to respond to prednisolone, IVIG, rituximab and splenectomy. Provision of the large number of suitably matched red cell units required was problematic. After receiving hydroxyurea, azathioprine, desferrioxamine, busulfan, cyclophosphamide, fludarabine, thiotepa and antithymocyte globulin (ATG) preparation for a CD3/CD19 depleted maternal haplotype peripheral blood SCT, the haemolysis finally stopped. Post-transplant severe veno-occlusive disease and multi-organ failure (MOF) required dialysis and ventilation. The maternal graft was rejected so 28 days after the first transplant he received a 4/6 mismatched unrelated cord blood transplant (UCBT) following further fludarabine and ATG, which fully engrafted. He recovered from MOF and was discharged from hospital 47 days after the UCBT, transfusion independent. On day +86 he contracted Respiratory Syncytial Virus chest infection with acute intravascular haemolysis necessitating transfusions. Fulminant liver failure developed, presumably due to iron toxicity, and death occurred on day +102, having received 112 transfusions in the 12 months since presentation. In conclusion, avoiding red cell transfusion is not always possible in hyperhaemolysis, especially in β-TM. Patients may quickly become classified as Class 3 in terms of predicting BMT outcome. Immune modulation therapy and SCT was effective in 1 case but only temporarily stopped haemolysis in the other, despite full engraftment ultimately being achieved with a mismatched UCBT. SCT should be considered early in cases of hyperhaemolysis in β-TM because it can potentially cure both and result in transfusion independence.

Disclosures
Off Label Use: Intravenous immunoglobulin and rituximab for treatment of haemolytic anaemia; hydroxyurea, azathioprine, fludarabine, erythropoeitin, busulphan, cyclophosphamide, thiotepa and antithymocyte globulin for use in stem cell transplantation in children with thalassaemia.