Indirect comparison between immunotherapy alone and immunotherapy plus chemotherapy as first-line treatment for advanced non-small cell lung cancer: a systematic review

OBJECTIVES: Use of immune checkpoint inhibitors as first-line treatment for advanced (stage IIIB/IV) non-small cell lung cancer (NSCLC) remains controversial. Clinical trials comparing single-drug immunotherapy (IO) with immunotherapy plus chemotherapy (IC) are lacking. We aimed to compare the efficacy of IO alone with that of IC as first-line treatment for advanced NSCLC. DESIGN: Systematic review. DATA SOURCES: PubMed, the Cochrane Library and Embase for related studies on NSCLC; ClinicalTrials.gov, American Society of Clinical Oncology Meeting Library and World Conference on Lung Cancer for relevant conference abstracts (to July 2019). ELIGIBILITY CRITERIA: Articles meeting the following criteria were selected: (1) randomised controlled trials on NSCLC treatment, (2) all individuals in the studies had not received treatment previously and (3) research on IO monotherapy using programmed death-1/programmed death ligand-1 (PD-L1) inhibitors or IC. DATA EXTRACTION AND SYNTHESIS: After reading the original literature, two reviewers independently extracted the relevant information. The primary outcomes were progression-free survival (PFS), overall survival (OS) and objective response rate (ORR). We also extracted data on treatment-related adverse events and immune-related adverse events (irAEs). RESULTS: Overall, 10 randomised controlled clinical trials (n=5765) were included. As first-line treatment for advanced NSCLC, IC tended to yield better PFS, OS and ORR than did IO. Furthermore, IC yielded significantly better PFS than IO when tumour PD-L1 expression was at least 50% (HR: 1.81, 95% CI: 1.18 to 2.78) and yielded a better OS and PFS when tumour PD-L1 expression was at least 1%; IO resulted in fewer adverse events than did IC. However, the incidence of irAEs was higher for IO than for IC. CONCLUSIONS: The findings of the indirect comparison indicate that IC as first-line treatment for advanced NSCLC is significantly more effective than IO in patients with PD-L1 expression in at least 50% of tumour cells. TRIAL REGISTRATION NUMBER: CRD 42018116589.