Rituximab in Hypersensitivity Pneumonitis refractory to conventional treatment: experience from two centers

<bold>Introduction:</bold> Standard treatments of Hypersensitivity Pneumonitis (HP) are antigen avoidance and, despite poor evidence, immunosuppression. In the absence of a response to these measures, therapeutic options to consider are scarce. Despite the limited scientific evidence to date, it is thought that rituximab could benefit patients with HP. <bold>Aims:</bold> To evaluate the effect of rituximab on FVC, FEV1 and DLCO and adverse events in patients with HP. <bold>Methods:</bold> Retrospective study that included all patients followed in Diffuse Lung Diseases clinic, at two hospital centers, with a diagnosis of HP, with progression despite previous therapies, and who underwent salvage therapy with rituximab, from january 2013 to december 2023. <bold>Results:</bold> <fig><object-id>erj;64/suppl_68/PA699/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig> <fig><object-id>erj;64/suppl_68/PA699/F2</object-id><object-id>F2</object-id><object-id>F2</object-id><graphic></graphic></fig> <bold>Conclusion:</bold> Treatment with rituximab seems to be associated with stabilization of respiratory function in patients with HP. Rituximab is a relatively safe and well-tolerated drug, despite its significant risk of respiratory infections requiring hospitalization. Studies in a larger sample size are needed to assess the real impact of this drug on the evolution of the disease.