Promising treatment of autoimmune hepatitis with 6-thioguanine after adverse events on azathioprine

The use of corticosteroids in autoimmune hepatitis is an established therapy. To avoid the possible serious side effects of corticosteroids, immunosuppression with azathioprine is often warranted. Azathioprine, a purine analogue, is frequently used to taper or replace corticosteroids. However, approximately 10% of the patients are intolerant to azathioprine. Alternative therapies using mycophenolate, tacrolimus, budesonide, cyclosporine and 6-mercaptopurine have been studied, with variable results. The use of 6-thioguanine, an agent more directly leading to the down-stream active metabolites of azathioprine (6-thioguanine nucleotides) in inflammatory bowel disease patients intolerant to azathioprine or 6-mercaptopurine showed conflicting results. We report three patients with autoimmune hepatitis who could not tolerate azathioprine but tolerated 6-thioguanine 0.3 milligram per kilogram daily well. All three patients improved clinically. Therapeutic drug monitoring was performed. The prospective evaluation of 6-thioguanine as a possible immunosuppressive drug in autoimmune hepatitis patients is warranted.