Abstract
BACKGROUND AND OBJECTIVE: Lung cancer, mainly non-small cell lung cancer (NSCLC), is a serious threat to human life. In particular, the prognosis for advanced patients is poor, with the 5-year survival rate being exceedingly low. In recent years, immune checkpoint inhibition has changed the pattern of the treatment of a variety of cancers, including lung cancer; however, not all patients can benefit from immunotherapy, and thus finding the right biomarkers is particularly important for guiding precise treatment. Programmed death-ligand 1 (PD-L1) expression is one of the most valuable biomarkers for predicting the efficacy of lung cancer immunotherapy. Several studies have confirmed that patients with high PD-L1 expression are more likely to benefit from immunotherapy, but there is a high proportion of people with negative PD-L1 expression constituting a patient population that cannot be ignored. This article reviews the distribution of PD-L1 expression, the methods for evaluating PD-L1, and the effectiveness of immunotherapy for advanced NSCLC with negative PD-L1 expression. METHODS: We performed a literature review to identify relevant data published until September 2022. In order to organize related information, we searched for literature in PubMed; abstracts and reports published in the American Society of Clinical Oncology (ASCO), the European Society for Medical Oncology (ESMO), the World Conference on Lung Cancer (WCLC), and other congresses; and clinical trial information registered on ClinicalTrials.gov. Information on the distribution of PD-L1 expression, detection of PD-L1, and immunotherapy efficacy for NSCLC with negative PD-L1 expression was collated and reviewed. KEY CONTENT AND FINDINGS: The incidence of PD-L1 expression in patients with stage IIIB/IV NSCLC is similar in all regions of the world, but PD-L1 expression level is associated with certain clinicopathological features. The expression of PD-L1 can be evaluated by various detecting methods. Some immunotherapy regimens have better efficacy than traditional chemotherapy in patients with negative PD-L1 expression. CONCLUSIONS: Patients with NSCLC and negative PD-L1 expression can receive better survival benefits under some immunotherapy types, and these may represent a better treatment option for this relatively small patient population.