Autologous hematopoietic stem cell transplantation for severe/refractory intestinal Behcet disease

Behcet disease is a chronic inflammatory disorder of unknown etiology characterized by recurrent oral aphthous ulcers, genital ulcers, skin lesions, and uveitis.¹  It has long been postulated that immunologic abnormalities, which are possibly triggered by microbial pathogens in genetically susceptible individuals (strong association with HLA-B51), are important in its pathogenesis.²  Recent findings have better defined the nature of inflammation, revealing the central role of T-cell–mediated immunity. Histopathologic and laboratory investigations have demonstrated mainly T-cell–dominated perivascular infiltrates in involved tissue, with presence in the blood of aberrant oligoclonal polarized Th1 T-cell population (in particular, γδ T cells producing tumor necrosis factor α [TNFα]).^3,4  To date, Behcet disease is recognized as a multisystem vasculitis, which can also affect all types and sizes of blood vessels in joints, lungs, central nervous system, and gut.² 

Few patients with Behcet disease have gastrointestinal ulceration. Such patients, in particular those with diffuse ulceration, are very difficult to treat and have higher mortality as a result of severe complications.⁵  Surgery is required in cases involving complications (perforation) and failed medical treatment (persistent bleeding), but it is often palliative, with postsurgical recurrence occurring in about 75% of patients.⁶  We describe the successful treatment of a child with severe/refractory intestinal Behcet disease, by lymphocyte-depleted autologous stem cell transplantation (ASCT) following high-dose immunosuppressive therapy (HDIT). The rationale for HDIT lies on the hypothesis that a vigorous immunoablative regimen can delete the autoaggressive lymphocyte clones, thus allowing the “reset” of the immune system, with recapitulation of ontogenesis and, potentially, development of tolerance toward self antigens. However, as complete eradication of autoimmunity has yet to be proven, a less ambitious and more realistic hypothesis is that an intensive immunosuppressive regimen may, through modulation of the immune response, induce prolonged remission and favorably affect the natural course of the disease.

A 4-year-old girl presented with recurrent episodes of fever, aphtoid oral ulcers, papulopustolar and Sweet syndrome–like skin lesions, arthralgias, conjunctivitis, and gastrointestinal symptoms (abdominal pain, bloody diarrhea, and weight loss). Pathergy test was positive. Autoantibodies were negative. Colonoscopy revealed serpiginous and aphtoid ulceration in descending, transverse, and ascending colon, as well as shallow ulcers in the terminal ileum. Biopsies demonstrated chronic inflammatory infiltrate in the lamina propria and submucosa with focal lymphoid aggregates, without granulomas. For 2 years the child underwent several medical therapeutic attempts consisting of total parenteral nutrition with bowel rest, intravenous bolus of high-dose metyl-prednisolone and oral prednisone associated with sulfasalazine, azathioprine, cyclosporin, tacrolimus, methotrexate, and cyclophosphamide. Unfortunately, disease recurrence occurred after each attempt to reduce the dose of oral steroid. Faced with refractory symptoms, we tried to induce remission with 4 cycles of anti-TNFα monoclonal antibody infliximab,⁷  but the result was disappointing with transient response. Given the high risk of developing complications and the poor prognosis associated with diffuse intestinal involvement, we decided to intensify immunosuppression with high-dose chemotherapy followed by ASCT.⁸  Recent studies have shown that conditioning regimens for severe autoimmune disease using high-dose cyclophosphamide alone (200 mg/kg) are not myeloablative and do not necessarily require stem cell rescue.⁹  However, in view of the extreme refractoriness of the disease, we decided to use a more powerful immunoablative regimen, followed by infusion of hematopoietic stem cells, able to accelerate hematologic recovery, thus reducing the risk of infectious complications.

Moreover, due to the peculiar presence of oligoclonal aberrant T cells in peripheral blood of patients with Behcet disease, we reasoned that an immunologic “purging” of lymphocytes contained in the autograft would be expected to significantly diminish the risk of reinfusion of such autoreactive cells and, thus, of disease relapse. After the patient had received cyclophosphamide at a dose of 2 g/m² and granulocyte colony-stimulating factor (G-CSF) at a dose of 8 μg/kg per day for 5 days, we collected stem cells, which were subsequently enriched ex vivo for CD34⁺ cells (positive selection). The conditioning regimen consisted of cyclophosphamide 100 mg/kg, fludarabine 160 mg/m², and antithymocyte globulin (ATG) 60 mg/kg. The total number of CD34⁺ cells infused was 11 × 10⁶/kg, whereas the residual T and B lymphocytes infused were 3 × 10³/kg and 4 × 10⁴/kg, respectively. Neutrophil (> 0.5 × 10⁹/L) and platelet (> 50 × 10⁹/L) engraftment occurred on day +9 and day +14, respectively. The posttransplant course was substantially uneventful. Monitoring of Epstein-Barr virus and cytomegalovirus reactivation by polymerase chain reaction and antigenemia, respectively, always resulted negative. The patient immune function was monitored over time; after having profound immune impairment during the first 4 months after transplantation, the patient progressively recovered both lymphocyte number and function (Table 1). Despite discontinuation of therapy with prednisone, the child experienced a marked improvement of her general well-being, with complete resolution of all signs and symptoms. Coloscopy revealed complete healing of the lesions. Two years after undergoing transplantation, the child is still in complete, medication-free remission. Although the follow-up is relatively short, we may conclude that highly immunosuppressive, lymphocyte-depleted ASCT is a useful and safe therapy for the intractable form of intestinal Behcet disease.