S1697 Autologous Hematopoietic Stem Cell Transplantation (autoHSCT) for Crohn’s Disease

Introduction: Despite available therapies, a subset of patients with Crohn’s disease (CD) have a refractory course. The profound immune suppression from preparative regimens prior to autologous hematopoietic cell transplantation (autoHCT) induces depletion of self-reactive T- and B-cells, consequently attenuating the inflammatory process and resetting the dysbalanced immune response. AutoHCT uses a patient’s own hematopoietic stem cells and has been used to treat CD. We present interim results of our ongoing study using autoHCT for treating medically refractory CD. Methods: This is a prospective observational case series of adult patients with medically refractory CD who underwent autoHCT at our institution. Clinical, laboratory, radiographic, and endoscopic data were collected before, during, and at different intervals post-autoHCT. Peripheral blood hematopoietic stem cells were collected after mobilization with filgrastim ± plerixafor. Then, patients were admitted to the BMT unit. Conditioning regimen included cyclophosphamide 50 mg/kg/day (days -5 to -2) and rabbit anti-thymocyte globulin 0.5 mg/kg on day -5, followed by 1.5 mg/kg/day (days -4 to -1). Autologous stem cells were CD34+ selected in all patients and infused on day 0. Infection prophylaxis and treatment followed established institutional guidelines. All patients underwent a preemptive surveillance approach to identify cytomegalovirus (CMV) and Epstein-Barr virus (EBV) reactivation weekly until day +60. CD was reassessed at day +90, with noninvasive biomarkers, imaging and/or endoscopy. Results: Five patients underwent autoHCT with no life threatening adverse events. CD healing response rates as measured by biochemical, clinical, radiographic, and endoscopic, among these patients varied. Conclusion: In our series, autoHCT was safe and associated with relatively low morbidity. Side effects included volume overload during hydration for cyclophosphamide, 1 episode of bacteremia, and 1 readmission for persistent nausea/vomiting. No flares of CD occurred during the transplant process. No EBV or CMV reactivations occurred. Regarding CD, there was improvement of symptoms, reduction of inflammatory markers and improvement in quality of life. All patients recovered from the autoHCT and 1 patient remained free of CD directed therapy for 12 months post-transplant. High dose immune ablation with autologous transplantation remains a promising therapy for refractory CD.