A case of dupilumab-induced eosinophilic pneumonia

Introduction: Eosinophilic pneumonia is a condition defined by eosinophilic infiltration of the lung parenchyma. Eosinophilic pneumonia is a known side effect of Dupilumab, a monoclonal antibody targeting the alpha chain of interleukin-4 (IL-4) that is used to treat moderate to severe atopic dermatitis and asthma by its inhibition of IL-4 and IL-13, which are key drivers in the TH2 response. We present a case of a patient presenting with eosinophilic pneumonia ten weeks after being started on Dupilumab. Case report: A 55-year-old female with history of asthma, bullous pemphigoid and chronic dermatitis who was started on Dupilumab (Dupixant) by her rheumatologist for treatment of her dermatitis and bullous pemphigoid ten weeks prior to presentation. Patient presented to the pulmonary clinic with four weeks history of worsening cough, shortness of breath, generalized body aches, lowgrade fevers, chills, chest pains and non-drenching night sweats. She had been treated by primary physician with a course of antibiotics without improvement in her symptoms. Outpatient chest computed tomography (CT chest) showed extensive bilateral reticular nodular opacities and scattered ground glass opacities (Panel A) for which she was admitted to the hospital for further evaluation. Patient was hypoxic and required 4 liters/minute oxygen by nasal cannula. Her laboratory testing showed normal leucocyte count 9.57 X 103/uL with eosinophilia of 17% (total eosinophilic count 17,000). Her immunoglobulin E was 2096 U/mL. Covid testing was negative. Rheumatologic workup was negative. Patient underwent fiberoptic bronchoscopy with bronchoalveolar lavage (BAL) which showed 29% eosinophil count (Panel B) and was negative for bacterial and fungal cultures.Following BAL results, Dupilumab was discontinued and patient received single dose 60mg intravenous methylprednisone then oral prednisone 40 mg daily, resulting in rapid improvement in her symptoms, oxygen requirements and complete resolution of peripheral eosinophilia. She was discharged on oral prednisone taper. Discussion: Drug induced eosinophilic pneumonias are reported with medications such as non-steroidal anti-inflammatory drugs (NSAIDS), and antibiotics. There are very few described cases of Dupilumab-induced eosinophilic pneumonia in the medical literature. Eosinophilic pneumonia and eosinophilic conditions are listed side effects of Dupilumab which inhibits Th2 pathway by inhibiting IL-4 and IL-13 and should in theory decrease tissue eosinophilia, eosinophil degranulation, and reduce eosinophil survival. This case illustrates Dupilumab-induced eosinophilic pneumonia, suggesting that despite the drug's effect on Th2 cytokines, it can cause eosinophilic tissue infiltration and eosinophilia which if promptly identified and treated can lead to excellent outcomes. .