Introduction: Connective tissue disease-related interstitial lung disease (CTD-ILD) are a collection of systemic autoimmune disorders associated with lung abnormalities. Understanding CTD-ILD onset and progression is essential to improve patient?s survival by tailoring personalize treatments avoiding adverse events. The aim of this work was to analyse the progression of these patients treated with rituximab (RTX).

Methods: Retrospective study of a cohort of 29 CTD-ILD patients treated with RTX for clinical-functional impairment (2015-2022). Comorbidities, radiological pattern, functional evolution and treatments were analysed.

Results: Mean age was 62±11 years, 66% were women. One third had ?3 points in Charlson index. Most prevalent CTD-ILD were: 38% rheumatoid arthritis,15% interstitial pneumonia with autoimmune features and 15% Overlap Sjögren's syndrome-Scleroderma. The 31% at diagnosis had a radiological pattern of UIP. 97% received steroid and 18% antifibrotic drugs; among the immunosuppressants used prior to RTX, the most used were methotrexate (45%) and mycophenolate (38%). Mean number of RTX doses was 3.31±2.11 and only 38%(11) had adverse effects, most of which were mild, with only 1 exacerbation and 5 admissions for infections. At 12 months, there was an improvement in mean FVC (+121 ml/4%), stabilisation of DLCO and better exercise tolerance (+44 metres in WT6M). Currently, 11 patients have home oxygen, 1 is on waiting list for lung transplant and 10 have died.

Conclusion: RTX treatment in patients with CTD-ILD contributes to functional stabilisation with mild adverse effects, favouring improvement in quality of life and survival.