Adverse impact of bone metastases on clinical outcomes of patients with advanced non-small cell lung cancer treated with immune checkpoint inhibitors

Background Bone metastasis (BoM) is common in patients with advanced non-small cell lung cancer (NSCLC) and considered as one of the negative prognostic factors. However, the impact of BoM on clinical outcomes of patients with advanced NSCLC treated with immune checkpoint inhibitors (ICIs) remains unclear. Methods A total of 103 patients treated with ICI monotherapy and 101 patients treated with ICIs combined with chemotherapy or antiangiogenesis therapy were retrospectively analyzed. The differences in progression-free survival (PFS), overall survival (OS) and objective response rate (ORR) between BoM+ and BoM- were investigated. Results Of those 101 patients who received combination therapy, no significant difference between BoM- and BoM+ in terms of both median PFS and median OS (median PFS, 10.1 vs. 12.1 months,P= 0.6; median OS, NR vs. 24.6 months,P= 0.713) was determined. In contrast, of the 103 patients who received ICI monotherapy, BoM+ patients had an inferior PFS (4.2 vs. 6.7 months,P= 0.0484) and OS (12.5 vs. 23.9 months,P= 0.0036) compared with BoM- patients. The univariate and multivariate analysis in the ICI monotherapy group also identified BoM as an independent factor attenuating the efficacy of ICI monotherapy. Of all BoM+ patients who received ICI monotherapy, neither palliative radiotherapy nor bisphosphonate drugs improved OS (palliative radiotherapy: 12.5 vs. 16.7 months,P= 0.487; bisphosphonate drugs: 12.5 vs. 9.7 months,P= 0.568). Conclusions BoM attenuated the efficacy of ICI monotherapy in patients with advanced NSCLC. Of BoM+ patients who received ICI monotherapy, neither palliative radiotherapy nor bisphosphonate drugs improved OS. Other therapeutic strategies are needed for patients with BoM.