Azathioprine effectively maintains remission in autoimmune pancreatitis
Treatment with azathioprine (AZA) appears to safely and effectively prevent autoimmune pancreatitis (AIP) relapses, according to a retrospective study.
The study included AIP patients who were treated with AZA (AZA+ group; n=23; mean age 54 years; 78 percent male) as maintenance therapy or did not receive maintenance therapy (AZA− group; n=97; mean age 45 years; 59.8 percent male). None of the patients had previous pancreatic surgery, other autoimmune diseases as indication for AZA treatment, and used immunosuppressants (IMs) other than AZA. Evaluations included drug safety and clinical and instrumental outcomes of patients in the AZA+ group.
Patient characteristic data showed that compared with those in the AZA− group, AZA+ group patients were significantly older (p=0.043), more likely to have type 1 AIP (87 vs 51 percent; p=0.006), higher sIgG4 (758 vs 311 mg/dl; p<0.001), other organ involvement (OOI; 83 vs 48 percent; p=0.002) and higher frequency of relapse prior to AZA treatment (78 vs 14 percent; p<0.001).
Drug discontinuation due to adverse events (AEs) was reported in three patients in the AZA+ group. Of the 20 patients available for outcome evaluation, six relapsed after 24 months (30 percent; five in pancreas and one on biliary tract). Those who relapsed received retreatment with steroids and continued AZA. Second relapse was reported in two patients (33 percent), occurring after 11 months (in pancreas and kidney) in one and after 22 months (in kidney) in the other.
Based on the present data, researchers said AZA use may be considered in relapsing type 1 AIP and/or in the presence of other organ’s involvement and elevated IgG4 at clinical onset.
Having unique histological features, AIP has two histological subtypes. Type 1 is characterized by periductal infiltration of lymphocytes, abundant IgG4-positive plasma cells in pancreatic parenchyma, storiform fibrosis and obliterative phlebitis. This AIP type is commonly diagnosed in elderly males and is associated with high IgG4 serum levels, extra pancreatic involvement (biliary tree, salivary glands, kidney, retroperitoneum) and frequent relapses. On the other hand, type 2 AIP is characterized by the presence of granulocytic epithelial lesions, whereas IgG4-positive plasma cells are rare or absent in pancreatic parenchyma. This AIP type commonly affects younger individuals, and inflammatory bowel disease is a common observation; relapses after steroids are rare. [Virchows Arch 2004;445:552–563; Pancreas 2010;39:549–554; Pancreas 2011;40:1172–1179; Gastroenterology 2010;139:140–148; Pancreatology 2012;12:276–283]