Impact of PD1 and PDL1 immunotherapy on non-small cell lung cancer outcomes: a systematic review

Introduction Despite comprising many cancer diagnoses, few treatments are suitable for patients with advanced non-small cell lung cancer (aNSCLC). Trials suggest blockade of programmed death 1 (PD1) or its ligand (PDL1) may be effective for these patients. However, this therapy's impact on outcomes other than survival, and outcomes of patients not in trials, remains largely unknown. Therefore, we compared the effectiveness of PD1 and PDL1 immunotherapy to chemotherapy and placebo across multiple clinical outcomes. Methods Six databases were searched on 12-13 October 2019 for randomised controlled trials (RCTs) and observational studies investigating nivolumab, pembrolizumab, atezolizumab or durvalumab. Study selection was performed independently by two reviewers. Data for overall survival, progression-free survival, adverse effects (AEs) and quality of life (QoL) were descriptively and meta-analysed. Factors impacting treatment outcomes, including PDL1 expression, were explored. The similarity between RCT and observational data was assessed. Results From 5423 search results, 139 full texts and abstracts were included. Immunotherapy was associated with a lower risk of death than both comparators. In RCTs, the incidence of treatment-related AEs was approximately 20% lower among patients using immunotherapy compared with chemotherapy. However, no other consistent benefits were observed. Progression-free survival results were inconsistent. Improvements to QoL varied according to the instrument used; however, QoL was not recorded widely. Survival results were similar between study designs; however, AEs incidence was lower in observational studies. Discussion Among patients with aNSCLC, immunotherapy improved overall survival and incidence of treatment-related AEs compared with chemotherapy. Benefits to progression-free survival and QoL were less consistent. PROSPERO registration number CRD42019153345.