Bone metastasis is associated with poor prognosis in metastatic papillary renal cell carcinoma patients treated with first agent angiogenesis inhibitors

Objective: Papillary renal cell carcinoma (papRCC) is a rare (10%–15%) subtype of renal cancer. Few prognostic biomarkers have been described in metastatic papRCC (m-papRCC) patients treated with vascular endothelial growth factor receptor tyrosine kinase inhibitors (VEGFR-TKIs). We aimed to study the prognostic impact of bone metastases (BM) on response rate, progression-free and overall survival (PFS and OS) in patients with m-papRCC treated with first agent VEGFR-TKIs. Patients and methods: A multicentric, retrospective analysis of patient records was conducted. BM were detected by computed tomography and/or bone scintigraphy. The International Metastatic RCC Database Consortium (IMDC) score was calculated at start of first agent VEGFR-TKI treatment. Results: Forty-nine patients were included. Best objective response was partial response in 20%, stable disease in 60% and early progressive disease in 20% of patients. Median PFS (mPFS) was 6.0 months and median OS (mOS) 14.0 months after start of first agent VEGFR-TKI. The IMDC score correlated with mOS: 77.5 months in good, 17.0 months in intermediate and 8.0 months in poor risk patients (P = 0.002). Patients with BM had a poorer outcome compared to patients without BM: mPFS was 4.0 vs. 7.0 months (P = 0.006) and mOS 7.5 vs. 19.0 months (P = 0.002). On bivariate analysis, the presence of BM was independently associated with PFS (P = 0.02) and OS (P = 0.049), independent of the IMDC risk groups. Conclusion: In m-papRCC patients treated with first agent VEGFR-TKIs, the presence of BM is an unfavorable prognostic factor, associated with shorter PFS and OS.