RITUXIMAB RESCUE IN TREATMENT REFRACTORY HYPERSENSITIVITY PNEUMONITIS

Abstract

SESSION TITLE: Tuesday Medical Student/Resident Case Report Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/22/2019 01:00 PM - 02:00 PM INTRODUCTION: Evidence for successful management of patients with hypersensitivity pneumonitis (HP) refractory to or intolerant of glucocorticoid therapy is extremely limited (1,2). We report 2 cases of HP that failed contemporary treatment but demonstrated the excellent clinical response to the anti-CD20 monoclonal antibody rituximab (RTX). CASE PRESENTATION: Case #1: A 59-year-old lady presented with dyspnea that began while installing a below-ground pool at home. Baseline Forced Vital Capacity (FVC) was 86% of predicted and Diffusing capacity (DLCO) was 47%. Chest computerized tomography (CT) scan reported a mosaic pattern. Bronchoalveolar lavage (BAL) differential showed lymphocytic predominance (48%), and biopsies demonstrated granulomatous inflammation. HP was diagnosed and Prednisone started, but her dyspnea and hypoxemia worsened. She didn’t tolerate azathioprine (AZA) and responded poorly to mycophenolate mofetil (MMF). PFTs progressively worsened (FVC 62%, DLCO 47%) as did hypoxemia. Her symptoms improved slightly once she moved out of her house. She was eventually treated with RTX and responded dramatically. Repeat FVC was 92% and DLCO 65%. Home oxygen was discontinued, and she returned to her previous active lifestyle. Case #2: A 60-year-old female with a severe cough but normal FVC (79%) and DLCO (87%) developed respiratory failure and was hospitalized. Her CT chest showed diffuse ground glass infiltrates and mosaicism. She confirmed exposure to a horse and barn with moldy hay. BAL differential revealed 53% lymphocytes, with a lymphocytic interstitial infiltrate on transbronchial biopsies. HP was diagnosed and she was discharged on oxygen. Her pulmonary function steeply declined (FVC 45%, DLCO 34%). She was persuaded to sell her horse and started on Prednisone and AZA. She developed transaminitis and AZA was switched to MMF, but she failed to respond. She remained physiologically unimproved (FVC 43%, DLCO 36%). RTX was then introduced, which significantly alleviated her dyspnea and hypoxemia. Repeat FVC was 48% and DLCO 52%. DISCUSSION: The evidence in the medical literature to guide the management of HP patients’ refractory to or intolerant of corticosteroids and cytotoxic agents is extremely limited. A single case is reported where the use of RTX reversed worsening hypoxemia and progressive impairment of pulmonary function (1). Our 2 cases clearly responded to RTX where other treatments had failed. CONCLUSIONS: This experience adds to the very small body of literature describing the use of RTX in refractory HP. Further studies with larger numbers of patients are needed to confirm the efficacy of RTX in such patients. Reference #1: Lota HK, Keir GJ, Hansell DM, et al. Novel use of rituximab in hypersensitivity pneumonitis refractory to conventional treatment. Thorax. 2013;68(8):780-781. Reference #2: Keir GJ, Maher TM, Ming D, et al. Rituximab in severe, treatment-refractory interstitial lung disease. Respirology. 2014;19(3):353-359. DISCLOSURES: No relevant relationships by Udhayvir Grewal, source=Web Response Principal investigator in clinical trial relationship with Boehringer ingelheim Please note: $1-$1000 Added 03/16/2019 by Aman Pande, source=Web Response, value=No fees Principal investigator in clinical trial relationship with Galecto Biotech AB Please note: $1-$1000 Added 03/16/2019 by Aman Pande, source=Web Response, value=And accommodation overnight Principal investigator in clinical trial relationship with Galecto Biotech AB Please note: $1-$1000 Added 03/16/2019 by Aman Pande, source=Web Response, value=Travel