Immunotherapy efficacy and safety of programmed cell death 1 (PD-1) versus programmed death ligand-1 (PD-L1) inhibitors in pan-cancer: A systematic review and meta-analysis.

e14113 Background: Immune checkpoint inhibitors (ICIs) that target programmed cell death 1 (PD-1) and its ligand (PD-L1) have led to a paradigm shift in cancer treatment, while whether PD-1 and PD-L1 inhibitors deliver different clinical outcomes remains obscure. Here we carried out a systematic review and meta-analysis to compare the efficacy and safety profile of PD-1 and PD-L1 inhibitors in pan-cancer patients. Methods: We systematically searched PubMed, Cochrane library, and Embase from January 2000 to December 2018 for randomized controlled trials that compared PD-1/PD-L1 inhibitors with standard treatment in patients with solid tumors. We also reviewed abstracts and presentations from all major conference proceedings. Retrospective studies and trials that compared anti-PD-1/PD-L1 with other immunotherapies were excluded. The primary outcome was the difference in overall survival (OS). Studies were stratified into comparison groups upon studies mirrored with trial design and patient characteristics. Effect size in each comparison group was pooled first, the difference in overall survival was estimated, and the overall effect sizes was pooled using a random-effects model. Results: A total of 3864 publications were retrieved through initial literature search, 17 randomized controlled trials involving 9549 patients with solid tumors were included for this meta-analysis. PD-1 inhibitors exhibited significantly improved OS over PD-L1 inhibitors either in overall population (HR 0.75, 95% CI 0.64-0.87), as monotherapy (HR 0.79, 95% CI 0.65-0.96), or combination with chemotherapy (HR 0.66, 95% CI 0.53-0.82). PD-1 inhibitors also showed improved progression free survival (PFS) over PD-L1 inhibitors in overall population (HR 0.70, 95% CI 0.53-0.94). No significant difference was observed for safety profile between PD-1 inhibitors and PD-L1 inhibitors as monotherapy. PD-1 inhibitors plus chemotherapy have less Grade 3-5 adverse events than PD-L1 inhibitors plus chemotherapy (overall RR 0.84, 95% CI 0.75-0.93). Sensitivity analysis presented a satisfactory consistency of the overall estimates across these analyses. Conclusions: PD-1 inhibitors exhibited better clinical performance for survival outcome and safety profile over PD-L1 inhibitors. Future studies and explorations of the underlying mechanisms are needed for the further optimization of treatment strategies in clinical practice.