Toxicity with small molecule and immunotherapy combinations in non-small cell lung cancer

Treatment stratification in stage IV NSCLC is guided by identification of oncogene driver mutations. Actionable mutations with current licenced therapeutic agents include epidermal growth factor receptor (EGFR), rearrangements of anaplastic lymphoma kinase (ALK), ROS-1 and BRAF V600. Alongside progress with small molecule therapy, developments in immune checkpoint inhibitors (CPIs) have transformed the landscape of stage III and stage IV NSCLC. The success of CPIs has led to evaluation with small molecule therapy in both concurrent and sequential settings. In this review we summarise recent results of combination CPIs and tyrosine kinase inhibitors (TKIs) in stage IV NSCLC, detailing significant toxicity and its potential mechanisms with both concurrent and sequential approaches. As more therapeutic targets are being discovered it is becoming increasingly important for clinicians to correctly sequence therapy for delivery of safe and effective treatment. In addition to stage IV disease we suggest that comprehensive molecular profiling of key NSCLC drivers, particularly in stage III disease, will help to inform optimal treatment sequencing and minimise potential toxicity.