Comparative Overview of Azathioprine and Rituximab for Gastrointestinal IgG4 Disease

IgG4-related disease (IgG4-RD) is a chronic inflammatory condition marked by the infiltration of IgG4-positive plasma cells. The pancreas and biliary systems are commonly involved. Glucocorticoids (GCs) have been the mainstay of treatment for IgG4-RD, achieving a high initial response rate. Many patients experience relapses when the GC dose is reduced or discontinued, necessitating the need for effective steroid-sparing agents. Rituximab, a monoclonal antibody targeting CD20 on B-cells, has emerged as a promising alternative for patients with IgG4-RD. Similarly, other immunosuppressive agents such as Tacrolimus and Azathioprine are being evaluated for their potential to manage IgG4-RD. The studies for this review have been carried out in Italy, Sweden, Minnesota (USA), and Japan. Relapse rates were 21%, 0% (smaller number of patients), and 11% in the Rituximab trials, compared to 19% in the Azathioprine group, indicating similar results. Remission rates were not reported in the Azathioprine group, but remission rates in Rituximab studies were 89%, 99% (66 complete and 33 partial), and 86%, indicating high efficacy of Rituximab in inducing remission. Azathioprine shows promise as a maintenance therapy, lowering relapse rates compared to steroids alone, while Rituximab exhibits high remission rates but also a moderate relapse rate, especially in multi-organ involvement. The review concludes that while Rituximab is a good choice for steroid-resistant or intolerant cases, Azathioprine requires more research. However, Rituximab also had a higher incidence of adverse reactions, which mostly included infections, including a case of tuberculosis and borrelia, whereas Azathioprine had benign effects, including nausea, vomiting, and elevated transaminases.