HMGB1 assists the predictive value of tumor PD-L1 expression for the efficacy of anti-PD-1/PD-L1 antibody in NSCLC.

Background: The expression of anti-programmed cell death ligand-1 (PD-L1) in tumors is widely used as a biomarker to predict the therapeutic efficacy of anti-programmed cell death-1(PD-1)/PD-L1 antibodies. However, the predictive accuracy of this method is limited. High-mobility group box 1 (HMGB1) is known to modulate cancer immunity. Therefore, we investigated the potential of circulatory HMGB1 in combination with PD-L1 expression to predict the efficacy of anti-PD-1/PD-L1 antibody monotherapy.

Patients and methods: This multicenter retrospective study analyzed blood samples collected from 114 patients with non-small cell lung cancer (NSCLC) prior to anti-PD-1/PD-L1 antibody monotherapy at two university hospitals (Hiroshima University Hospital and Kawasaki Medical School Hospital) between December 2015 and October 2020. We evaluated the association of serum HMGB1 levels with tumor response and progression-free survival (PFS).

Results: Serum HMGB1 levels were significantly higher in patients with complete or partial response than in those with stable or progressive disease. Using receiver operating characteristic analysis, the cut-off level of serum HMGB1 to predict tumor response was determined to be 3.83 ng/mL. PFS was significantly longer in the HMGB1^high group than that in the HMGB1^low group in the entire cohort (4.3 months vs. 2.3 months) and in patients with NSCLC with PD-L1 tumor proportion score (TPS) ≥ 50% (12.4 months vs. 4.4 months), but not in those with PD-L1 TPS < 50% or unknown.

Conclusion: HMGB1 may serve as a predictive biomarker for the efficacy of anti-PD-1/PD-L1 antibody therapy in the patients with NSCLC, especially in those with PD-L1 TPS ≥ 50%.