Neoadjuvant immunotherapy in non-small cell lung cancer: a narrative review on mechanisms, efficacy and safety.

Background and Objective: Immune checkpoint inhibitors and immunotherapy have been shown to improve survival rates, especially in non-small cell lung cancer (NSCLC) patients. More recently, several trials have evaluated the clinical roles of immunotherapy as neoadjuvant settings for NSCLC. There trials suggested that neoadjuvant immunotherapy may effectively reduce the risk of the local recurrence and metastasis of cancer, and significantly improved overall survival and cure rates. Here we conducted a review to summarize the possible mechanism, clinical development, and research progress of neoadjuvant immunotherapy in NSCLC. Methods: Relevant articles for this review were retrieved from Google Scholar, Clinicaltrials.gov., and PubMed using the terms "non-small-cell lung cancer", "NSCLC", "neoadjuvant", "immunotherapy", "immune checkpoint inhibitors", "mechanisms", and "toxicity". The primary focus was placed on clinical studies and conference abstracts measuring the safety and efficacy of neoadjuvant immunotherapy in NSCLC until May 2022. Key Content and Findings: After reviewing the preclinical and clinical trial, the preclinical study showed that neoadjuvant immune checkpoint inhibitor promotes antitumor immunity through the enhancement of T cell effector function and the induction of long-term memory. The initial results of preliminary early-phase trials suggested that neoadjuvant immunotherapy is a promising therapeutic strategy for resectable NSCLC patients, with long-term response and modest toxicity, many of these regimens are currently being evaluated by randomized phase III trials. In addition, the major pathologic response of neoadjuvant immunotherapy ranged up to 45% in these studies when used alone, and up to around 83-86% when used in combination with chemotherapy, therefore it has been seen as a rather potent tumor debulking agent. Conclusions: Neoadjuvant immunotherapy has been shown to be a novel integral component of NSCLC care. However, there are also several research questions that requires further investigation, such as the side effects, the optimally treated patients, and the time of preoperative immunotherapy.