[Unexpected adverse events of immunotherapies in non-small cell lung cancer: About 2 cases].

Programmed death receptor 1 (PD1) checkpoint inhibitors are known for immune mediated toxicities such as colitis, endocrinopathies and pneumonitis. However, other rare adverse effects are reported in the literature. Nivolumab is an anti-PD1 immunotherapy used in the second line of non-small cell lung cancer (NSCLC). We report two cases of rare toxicities occurring under nivolumab in patients without a history of dysimmunity. A 79-year-old patient with a large-cell carcinoma showed a muscle weakness after the second course, revealing myositis with a CPK grade IV elevation as well as symptoms of myasthenia. The diagnosis of myositis was confirmed by a muscle biopsy. An 82-year-old patient followed for bronchial adenocarcinoma with EGFR mutation, presented with nivolumab shoulder and hip pain with extreme fatigue. After further investigations, the diagnosis of systemic erythematosus lupus was retained. Investigations led to the diagnosis of systemic lupus erythematosus. For both patients treatment was interrupted and systemic corticosteroid therapy was initiated permitting resolution of symptoms. The occurrence of symptoms of dysimmunity should attract the attention of the clinician, leading to discontinuation of anti-PD1 therapy and corticosteroid therapy. Retreatment after symptoms resolution must be collegially discussed if no alternative therapeutic is available.