B43-21 Basiliximab as Induction Therapy for Anti-MDA5 Dermatomyositis With Rapidly Progressive Interstitial Lung Disease

Abstract Introduction Anti-MDA5 dermatomyositis (DM) is associated with rapidly progressive interstitial lung disease (RP-ILD) and associated mortality approaching 50% at 6 months. Guidelines recommend combining multiple lines of immunosuppression in upfront “triple therapy,” with evidence that this may improve outcomes compared with step up therapy. We present a case of anti-MDA5 DM with RP-ILD treated with multiple lines of immunosuppression including basiliximab despite PJP infection and severe lymphopenia. Case Report A previously health 50-year-old male presented with three months of worsening shortness of breath, joint pain, and rash. He underwent rheumatologic evaluation and was started on prednisone for synovitis. He represented reporting no improvement along with weight loss, Raynaud’s, dysphagia, and lymphopenia. He was admitted and underwent bronchoscopy with transbronchial biopsy and bronchial alveolar lavage which revealed organizing pneumonia and PJP respectively. He was discharged on treatment-dose Bactrim and steroids but represented three weeks later with worsening dyspnea. Despite his incompletely treated infection and lymphopenia, on hospital day 1 he was given 1 g/day of solumedrol for 3 days, followed by a taper; on day 2 he received basiliximab and tacrolimus; on day 3 he was given 1 gram of rituximab; and on day 4 he started 2g/kg IVIG over 4 days. His condition worsened and on hospital day 5 he required admission to the ICU for HFNC. On hospital day 10 he was improved and able to leave the ICU. Prior to discharge, azathioprine was added to his immunosuppression regimen. He gradually improved and was discharged on hospital day 25 with CMV, fungal, and PJP prophylaxis. On discharge he required 2 L/min at rest and 6 L/min with exertion. At follow up 5 months after discharge he no longer required oxygen. PFTs also demonstrated improvement in FVC (table 1). Discussion Prompt recognition and treatment of MDA5 RP-ILD is imperative. Presentation with lymphopenia and PJP infection has been described and is associated with poor outcomes. Despite this, multiple lines of immunosuppression, including basiliximab, were initiated shortly after admission. Basiliximab is an anti-CD25 (alpha chain of IL-2 receptor) monoclonal antibody used to inhibit T cell activation after organ transplantation. In transplant, it achieves a state of therapeutic immunosuppression while maintenance immunosuppression is introduced. Given the severity of this patient’s presentation, basiliximab was used to similar effect while simultaneously administering tacrolimus, rituximab, steroids, and IVIG. Basiliximab may be a therapeutic option for patients with anti-MDA5 DM RP-ILD while initiating multimodal background immunosuppression. This abstract is funded by: none