Myositis - A common but underreported adverse effect of osimertinib: Case series and review of the literature.

Background: Lung cancer is the second most common cancer in both men and women and the leading cause of cancer death worldwide. The development of novel tyrosine kinase inhibitors (TKIs) represented a paradigm shift in the management of lung cancer and has resulted in markedly prolonged survival. Osimertinib is a TKI that was fast-tracked by the United States Food and Drug Administration in 2015 and subsequently approved for the treatment of metastatic epidermal growth factor receptor T790M mutation-positive non-small cell lung cancer.