Clinical status and perspective on the application of immunotherapy combined with chemotherapy in advanced non-small cell lung cancer: a review

The therapeutic landscape of advanced non-small cell lung cancer (NSCLC) has been significantly improved by developing immunotherapy represented by programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) immune checkpoint inhibitors (ICI). Furthermore, immunotherapy combined with chemotherapy is an essential treatment strategy for driver-negative advanced NSCLC, especially in a population with PD-L1 <50%, and leads to long-term survival in the entire population regardless of the PD-L1 expression status. However, specific challenges must be overcome, including how to use immunotherapy with chemotherapy in clinics. Furthermore, the application of immunotherapy with chemotherapy in populations such as elderly patients and patients with brain metastases, oligometastases, epidermal growth factor receptor (EGFR) gene mutation, anaplastic lymphoma kinase (ALK) gene rearrangements, and other driver gene-positive populations must be further explored. The biomarkers associated with immunotherapy and chemotherapy are still unclear, and the search for predictive biomarkers can contribute toward more precise and personalized immunotherapy. Furthermore, treatment strategies after immunotherapy and chemotherapy resistance are of significant focus clinically, and clinical studies with multiple combination therapy strategies are ongoing. Therefore, based on the reported status of immunotherapy combined with chemotherapy for advanced NSCLC, this study conducted a comprehensive literature review by searching keywords "PD-1 and PD-L1, immune checkpoint inhibitor (ICI), and NSCLC" in MEDLINE, major conferences, and major clinical research projects to elucidate the therapeutic efficacy of immunotherapy combined with chemotherapy as the current first-line treatment approach for various types of NSCLC patients. Additionally, it addresses several pressing challenges associated with immunotherapy combined with chemotherapy, including enhancing treatment response and survival rate in specific patient populations and identifying potential biomarkers.