Early response of bone metastases can predict tumor response in patients with non-small-cell lung cancer with bone metastases in the treatment with nivolumab

The effect of nivolumab and the relation between bone response and tumor control in patients with non-small-cell lung cancer (NSCLC) with bone metastases are not clear. The outcome of nivolumab monotherapy was investigated, and whether the response of bone metastases is useful as an early predictor of tumor control in patients with NSCLC with bone metastases was examined. The participants included 15 patients who received nivolumab monotherapy for NSCLC with bone metastases in our institution between 2015 and 2017. Tumor control was defined using Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST1.1). Response of bone metastases was assessed by the MD Anderson response criteria (MDA criteria). Responses according to RECIST1.1 and the MDA criteria were classified as responder (complete response or partial response) and non-responder [progressive disease (PD) or stable disease]. Progression-free survival (PFS) was investigated using the Kaplan-Meier method. With RECIST1.1, the overall response rate was 20%. Multivariate analysis showed that the MDA criteria were the only risk factor for patients with PD (RECIST1.1). Median PFS was 1.9 months, with PFS of 20% at 6 months. Univariate analysis showed that being a non-responder according to the MDA criteria was the only risk factor for PFS. In patients who were responders (MDA criteria) within 3 months, PFS was 83 and 50% at 3 and 6 months, respectively, though all non-responder (MDA criteria) patients converted to PD (RECIST1.1) within 3 months. Response according to RECIST1.1 was significantly correlated with response according to the MDA criteria (P<0.05). In patients who were both responders according to RECIST1.1 and the MDA criteria, time to response with the MDA criteria (1.4-2.0 months) was earlier than with RECIST1.1 (2.8-3.0 months) in all patients. In conclusion, application of the MDA criteria within 2 months of nivolumab monotherapy is useful for early prediction of response and prognosis in patients with NSCLC with bone metastases.