YO35 - Gefitinib induced movement disorder - a Case report

Case summary

Background - Epidermal growth factor receptors have been commonly associated with rash, diarrhoea and nail changes

Case details - A 57 year female, a known case of EGFR positive metastatic Adenocarcinoma of the lung with Pleural, liver and bone involvement, who had been started on Gefitinib 250 mg once daily upfront eight months ago presented with complaints of involuntary movements involving the jaw and neck since the past 15 days. She had to take resort to clenching her teeth tightly in an attempt to control the movements which interfered with mastication and activities of daily living. They were not suppressed during sleep. She also reported bite marks on the lips and tongue along with mucosal ulcerations. The movements did not involve the upper or lower extremity. There was a positive history of reduced oral intake, however she did not report any difficulty upon swallowing. There were no signs of intracranial metastasis. She had also undergone ICD insertion for right sided malignant pleural effusion and had received palliative radiotherapy for vertebral metastasis (L1-L5). CT scan done at the time of presentation was suggestive of a right hilar mass with pleural, hepatic and bone involvement. Response assessment CT (performed after seven months of upfront EGFR Tyrosine kinase inhibitor) was suggestive of significant interval change in the Lung mass with reduction in size and number of liver lesions. MRI performed after development of abnormal movements was not suggestive of any intracranial pathology. The patient had been started on Gabapentin for targeting the neuropathic component of her bone pain, so a diagnosis of Gabapentinoid induced movement disorder was also considered. She was referred to the medical oncologist, where her EGFR Tyrosine kinase inhibitor was discontinued.

Discussion - She reported an improvement in her symptoms after the discontinuation of the Gefitinib (small cell transformation was suspected). A WHO-UMC category of possible/likely causation and score of 3 was obtained on Naranjo’s algorithm (possible Adverse drug reaction). Gabapentinoids were continued on the subsequent visit. This is one of the first reports of a movement disorder due to a EGFR tyrosine kinase inhibitor.

Clinical trial identification

Editorial acknowledgement