Recently developed anti-tumour therapies targeting immune checkpoints include 
tremelimumab and durvalumab. These agents have incompletely characterised side 
effect profiles. The authors report a 68-year-old man treated for non-small cell 
lung cancer (NSCLC) with a combination of tremelimumab and durvalumab. After 
treatment he developed diplopia, ptosis, fatigue, weakness, and an inflammatory 
myopathy affecting the extraocular muscles requiring hospitalisation. 
Electromyography (EMG) testing and muscle biopsy suggested inflammatory myopathy 
without sign of myasthenia. Within 1 month of withdrawal of cancer therapies and 
initiation of oral steroid therapy, ocular and systemic symptoms had resolved. 
This notable adverse effect has not been previously described for these drugs 
administered singly or in combination, and ophthalmologists should be aware of 
this presentation in patients treated with these agents.