Efficacy of Second-line Nivolumab Tyrosine Kinase Inhibitors for Renal Cell Carcinoma With Bone Metastases.

BACKGROUND/AIM: Combination therapy with immune checkpoint inhibitors has become the standard first-line treatment for metastatic renal cell carcinoma (mRCC), leading to changes in second-line treatment options, such as nivolumab or tyrosine kinase inhibitors (TKIs). However, very few studies have compared the efficacy of these drugs in patients with mRCC, particularly those with bone metastases (BM), which are associated with a poor prognosis. This study compared the efficacy of nivolumab and TKIs as second-line treatments for mRCC patients with BM and examined the microenvironments of primary tumors and BM lesions.

PATIENTS AND METHODS

This multi-institutional retrospective study included 87 mRCC patients with BM who received either nivolumab or TKIs as second-line treatments. We analyzed tumor-infiltrating immune cells expressing CD8 and CD20, along with PD-L1, HIF2α, c-MET, VEGFR2, and AXL, in primary tumors and BM sites using immunohistochemistry.

RESULTS

This analysis indicated that poor-risk classification, as per the International Metastatic RCC Database Consortium criteria (p<0.01), and elevated serum alkaline phosphatase levels (p=0.031) were significantly associated with poor prognosis. No significant difference in overall survival was observed between patients receiving nivolumab and those receiving TKIs. However, the objective response rate of patients with BM lesions was significantly higher when receiving TKIs than when receiving nivolumab (p=0.014). Immunohistochemistry revealed significantly higher VEGFR2 expression in BM lesions than primary tumors.

CONCLUSION

TKIs could be a promising second-line treatment option for mRCC patients with bone-limited metastases.