A single-center, observational, retrospective, case control study of rituximab for the treatment of interstitial pneumonia associated with autoimmune features.

Background: Patients with interstitial lung disease (ILD) and features of autoimmunity who do not meet the classification criteria for a specific autoimmune rheumatic disease are diagnosed with interstitial pneumonia with autoimmune features (IPAF). The treatment approach to ILD in this setting remains undefined. We conducted an observational retrospective study to examine the use of rituximab in IPAF. Methods: Patients from the Mount Sinai Respiratory Institute Interstitial Lung Disease Registry were included if they met the 2015 classification criteria for IPAF and were treated with at least one dose of rituximab. Clinical improvement was defined as improvement in four domains after the use of rituximab including pulmonary function tests, CT chest findings, need for respiratory related hospitalization and survival. Results: Of the 791 patients in the registry, 14 patients met the criteria for IPAF and received at least one dose of rituximab. Nineteen patients with IPAF were identified to serve as the control group. More patients in the rituximab group received immunosuppressive medications. The percentage of patients with improved, stable, or worsened pulmonary function tests was similar in both groups. Frequency of oxygen use, incidence of infection, respiratory related admissions and overall mortality was similar in both groups. Conclusion: The majority of patients with IPAF receiving rituximab showed improvement or stability in their pulmonary function. Although both groups had similar outcomes, more patients in the rituximab group were on baseline immunosuppressive therapy suggesting refractory ILD. We suggest rituximab is a treatment option for patients with moderate to severe IPAF who progress despite standard therapy.