The association of PD-L1 expression with the efficacy of anti- PD-1/PD-L1 immunotherapy and survival of non-small cell lung cancer patients: a meta-analysis of randomized controlled trials

Lung cancer is the most frequent cause of cancer related mortality worldwide, and non-small cell lung cancer (NSCLC) accounts for approximately 85% of the lung cancers. Most patients already have advanced-stage or metastatic (stage III or IV) disease at the time of the first diagnosis. The long-term survival of patients with lung cancer was not optimistic, for which the 5-year survival rate was 18%, and only 4% for patients with metastatic disease (stage IV) (1,2). Platinum-based doublet chemotherapy has long been the standard of care for first-line therapy for patients with no oncogenic driver, with ORR ranging from 25–35%, while 5-year OS rates were only about 2%. In addition, chemotherapy is also associated with significant side effects (3). In recent years, the application of targeted therapies brings new hope to lung cancer patients. Patients with an oncogenic driver who received a targeted agent had a median survival of 3.5 years, which was longer than patients with no actionable drivers (4). However, the acquired resistance to tyrosine kinase inhibitors (TKI) inevitably develops. On the other hand, most patients do not have an actionable driver and may not benefit from targeted treatment (5). In this challenging clinical setting, immunotherapy is gradually changing the treatment pattern of NSCLC with improved response rates and impressive efficacy (6)