Enhancement of anti-PD-L1 antibody plus anlotinib efficacy due to downregulation of PD-L1 in the micro-conduit endothelium within the tumor: a randomized double-blind trial

The possible enhancing effect of anlotinib on programmed death receptor ligand (PD-L1) antibody and the efficacy-predicting power of PD-L1 in micro-conduit endothelium, including lymphatic endothelial cells (LECs) and blood endothelial cells (BECs), were determined to identify patients who would benefit from this treatment. PD-L1 positivity in LECs, BECs, and tumor cells (TCs) was assessed using paraffin sections with multicolor immunofluorescence in an investigator's brochure clinical trial of TQB2450 (PD-L1 antibody) alone or in combination with anlotinib in patients with non-small cell lung cancer. Progression-free survival (PFS) with different levels of PD-L1 expression was compared between the two groups. Among 75 patients, the median PFS (mPFS) was longer in patients who received TQB2450 with anlotinib [10 and 12 mg (161 and 194 days, respectively)] than patients receiving TQB2450 alone (61 days) [hazard ratio (HR) = 0.390 (95% confidence interval {CI}, 0.201-0.756), = 0.005; HR = 0.397 (0.208-0.756), = 0.005]. The results were similar among 58 patients with high PD-L1 expression in LECs and TCs [159 and 209 82 days, HR = 0.445 (0.210-0.939), = 0.034; HR = 0.369 (0.174-0.784), = 0.009], and 53 patients with high PD-L1 expression in BECs and TCs [161 and 209 41 days, HR = 0.340 (0.156-0.742), = 0.007; HR = 0.340 (0.159-0.727), = 0.005]. No differences were detected in the mPFS between the TQB2450 and combination therapy groups in 13 low/no LEC-expressing and 18 low/no BEC-expressing PD-L1 cases. Mono-immunotherapy is not effective in patients with high PD-L1 expression in LECs and/or BECs. Anlotinib may increase efficacy by downregulating PD-L1 expression in LECs and/or BECs, which is presumed to be a feasible marker for screening the optimal immune patient population undergoing anti-angiogenic therapy.