Refractory Pediatric Autoimmune Enteropathy Successfully Treated with Hematopoietic Stem Cell Transplant

Rationale Both allogeneic and autologous hematopoietic stem cell transplant (HSCT) have utility in refractory autoimmune diseases. We report a pediatric case of autoimmune enteropathy (AIE) that was successfully treated with haploidentical SCT and post-transplant cyclophosphamide. Methods A 4 year old male with chronic diarrhea, multiple food allergies, eczema, recurrent infections, failure to thrive and TPN dependence was diagnosed as AIE with biopsy proven anti-enterocyte antibodies. Immune evaluation revealed no mutation for immunodysregulation polyendocrinopathy enteropathy X-linked and cytotoxic T-lymphocyte-associated protein 4 sequencing. T cell function and primary immunodeficiency panel were normal. He failed conventional treatments with TNF blockade, calcineurin inhibitors, mTOR inhibitors, and costimulatory blockade (abatacept). A haplo-HSCT was performed with rituximab 375 mg/m2 day (D) -14, fludarabine 150 mg/m2 D -11 to D -7, thiotepa 10 mg/kg D -7, melphalan 140 mg/m2 D -6, Thymoglobulin 10 mg/kg D -5 to D -2, along with post-transplant cyclophosphamide 100 mg/kg D +3 to D +4. Results The patient engrafted on D +16 with neutrophils above 500 mcL on three consecutive CBCs, and he was platelet transfusion independent after D+19 to maintain platelets above 50,000 mcL. He resumed regular diet on day + 46 post haplo-HSCT without any gastrointestinal symptoms and is gaining weight at the time of this report. Post-transplant course was complicated by grade II acute skin graft versus host disease that responded to prednisolone and tacrolimus, and HHV6 reactivation which resolved after starting ganciclovir. Conclusion This is a case of a pediatric patient with refractory AIE who is now asymptomatic post haplo-HSCT after failing treatment with extensive immune modulators. This treatment may prove to be helpful for similar challenging patients with AIE.