Interstitial lung disease induced by apalutamide therapy for castration‐resistant prostate cancer: A report of a rare case

INTRODUCTION: Apalutamide is a new second‐generation anti‐androgen agent approved in 2019 for the treatment of metastatic, castration‐sensitive, and non‐metastatic, castration‐resistant prostate cancer. We herein report a case of apalutamide‐induced interstitial lung disease. CASE PRESENTATION: A 74‐year‐old Japanese male patient with non‐metastatic, castration‐resistant prostate cancer commenced hormonal therapy with apalutamide (240 mg/day orally) after 46 months of maximal androgen blockade therapy with bicalutamide and leuprorelin. Thirty‐five days following therapy initiation with apalutamide, he was hospitalized because of dyspnea. Chest computed tomography showed diffuse bilateral interstitial infiltrates and ground‐glass opacities in the upper and lower lobes of the lungs. Following a diagnosis of drug‐induced interstitial lung disease resulting from apalutamide treatment, the treatment with apalutamide was stopped. Steroid therapy was initiated, and the dyspnea resolved. CONCLUSION: Clinicians should be aware that apalutamide, and other drugs in general, can cause drug‐induced interstitial lung disease within 3 months.