LAUSR

Programmed cell death 1 (PD‐1) blockade has rapidly emerged as an effective therapy for a wide variety of metastatic malignancies. It has been associated with multiple immune‐related adverse effects, including cutaneous eruptions. We describe two patients with clinical and histological findings that were consistent with subacute cutaneous lupus erythematosus (SCLE) after receiving PD‐1 inhibitor therapy for metastatic lung cancer. We successfully treated our first patient with systemic and topical steroids, photoprotection and hydroxychloroquine. However, he subsequently developed dermatomyositis after continuing PD‐1 inhibitor therapy. Our second patient presented with a protracted course of a cutaneous eruption in spite of discontinuation of anti‐PD‐1 therapy and treatment with systemic corticosteroids and infliximab. This patient's SCLE resolved after the addition of topical steroids and photoprotection and discontinuation of anti‐tumour necrosis factor therapy. She and her oncology team decided to pursue non‐PD‐1 inhibitor treatment for lung cancer owing to a lack of tumour response. We add SCLE and dermatomyositis to the growing list of autoimmune complications of PD‐1 blockade. Our cases raise a number of questions, particularly in relation to the viability of continuing anti‐PD‐1 therapy after developing SCLE and the role of immunosuppressive therapy in patients with PD‐1 inhibitor‐associated connective tissue disease.