Gefitinib Related Movement Disorder: A Case Report

Abstract

Background: Tyrosine kinase inhibitors targeting the Epidermal growth factor receptor have been used in treatment of Non small cell lung cancer and Head and neck cancer. Gefitinib is a first generation tyrosine inhibitor associated with a relatively favourable toxicity profile (as compared to chemotherapy). Gefitinib usage has been shown to be associated with rare, but life threatening adverse effects like Interstitial lung disease, symptomatic corrected QT interval prolongation and severe transaminitis, which may warrant drug discontinuation. EGFR tyrosine kinase inhibitors have been shown to cause symptomatic improvement and delay disease progression in those with central nervous system involvement. The following case report is one of the first instances of a patient presenting with a movement disorder with the prolonged uninterrupted use of an EGFR tyrosine kinase inhibitor. Case details: A 57 year female, known case of EGFR mutation positive adenocarcinoma lung with pleural, liver and bone metastasis, taking Gefitinib 250 mg once daily since the past eight months, presented with complaints of movements involving the jaw and neck since the past 15 days. These involuntary movements interfered with activities of daily living and were not suppressed during sleep. The movements did not involve the upper or lower extremity. She did not complain of headache, vomiting, early morning nausea or blurring of vision. She had undergone ICD insertion for right sided pleural effusion and received palliative radiotherapy for vertebral metastasis (L1-L5). Response assessment CT was suggestive of significant interval change in the Lung mass with reduction in size and number of liver lesions. MRI Brain was not suggestive of any intracranial psathology. She was referred to the medical oncologist, where her EGFR Tyrosine kinase inhibitor was discontinued. An improvement in her symptoms was noted after the discontinuation of the Gefitinib. Discussion: A WHO-UMC category of possible/likely causation and score of 3 was obtained on Naranjo’s algorithm (possible adverse drug reaction). Conclusion: Development of movement disorder affecting activities of daily living might constitute an indication for discontinuation of Gefitinib therapy.