Serum immune modulators associated with immune-related toxicities and efficacy of atezolizumab in patients with non-small cell lung cancer

Purpose Identifying patients at high risk of immune-related adverse events (irAEs) that impede the achievement of durable efficacy of programmed cell death 1 (PD-1)/programmed death ligand 1 (PD-L1) blockade therapy is important in improving their management. Identification of a novel predictive factor of therapeutic benefit is also important in improving patient selection for treatment with PD-1/PD-L1 inhibitors. Further determinants driving response and linking with irAEs are urgently required. Methods To address these unmet needs in the field, we explored whether 27 soluble checkpoint proteins and immunomodulatory proteins in serum at the therapy baseline and after week 3 were associated with irAE onset and therapeutic efficacy using MILLIPLEX Human Immuno-Oncology Checkpoint Protein Panel assays in a prospective, multicenter cohort of 81 patients with non-small cell lung cancer (NSCLC) receiving atezolizumab monotherapy. Results By competing-risks regression analysis, we identified that high levels of B cell-activating factor (BAFF) at baseline were a significant and strong risk factor of irAEs (hazard ratio, 5.61; 95% confidence interval, 2.43–12.96; P < 0.0001). We also identified that increased inducible T cell co-stimulator (ICOS) during the first therapeutic cycle was an independent factor associated with prolonged progression-free survival and overall survival. Conclusion These findings are in keeping with the reported mechanistic basis of these molecules and may provide potential guidance for clinical decision-making to improve patient care. Further validation studies are warranted. Trial registration UMIN000035616 (January 28, 2019)