The effect of tumor size and metastatic extent on the efficacy of first line pembrolizumab monotherapy in patients with high PD-L1 expressing advanced NSCLC tumors

•Baseline SLD and NMO did not predict tumor response on 1L pembro monotherapy in high PD-L1 NSCLC.•Baseline SLD by RECIST v1.1 below 90 mm was associated with improved PFS and OS.•Therapies, e.g., chemo, aimed to reduce tumor size may be considered in high tumor burden patients.•Prospective studies such as PAULIEN are needed to investigate this hypothesis.