Effect of bisphosphonates (Bis) combined with sunitinib (Su) on the response rate (RR), progression-free survival (PFS), and overall survival (OS) of patients (pts) with bone metastases (mets) from renal cell carcinoma (RCC).

Abstract

379 Background: Bis are used to prevent skeletal events of bone mets, and may exhibit anti tumor effects. We aimed to evaluate whether Bis can bring a RR, PFS, and OS benefit to pts with bone mets from RCC that are treated with Su. Methods: We performed a multicentre retrospective study of pts with bone mets from RCC who were treated with Su. Pts were divided into Bis users (group 1) and nonusers (group 2). The effect of Bis on RR, PFS and OS, was tested with adjustment for known prognostic factors using a chisquare test from contingency table and partial likelihood test from Cox regression model. Results: Between 2004–2011, 209 pts with metastatic RCC were treated with Su. 76 pts had bone mets, 35 group 1 and 41 group 2. The groups were balanced regarding the following known prognostic factors: past nephrectomy, clear cell/non clear cell histology, time from initial diagnosis to sunitinib treatment (tx), the presence of > 2 mets sites, the presence of lung/liver mets, ECOG performance status, anemia, calcium level >10 mg/dL, elevated alkaline phosphatase, platelets count, pre-tx neutrophil to lymphocyte ratio (NLR) >3, sunitinib induced HTN, and the use of angiotensin system inhibitors. They were also balanced with regard to past cytokines/targeted tx, and mean sunitinib dose/cycle. Objective response was partial response/stable disease 86% (n=30) vs 71% (n=29), and progressive disease 14% (n=5) vs 29% (n=12) (p=0.125, OR 2.48) in group 1 vs 2 respectively. Median PFS was 15 vs 5 months (HR 2.6, p < 0.0001), and median OS 21 vs 13 months (HR 2.1, p=0.029), in favor of group 1. In multivariate analysis of the entire pt cohort (n=76), factors associated with PFS were Bis use (HR 2.2, p=0.035) and pre-tx NLR >3 (HR 0.38, p=0.009). Factors associated with OS were Bis use (HR 2.8, p=0.008), elevated alkaline phosphatase level (HR 0.287, p=0.0003), and Su induced HTN (HR 5.57, p < 0.0001). Conclusions: Bis may improve the outcome of Su tx in RCC with bone mets. Whether this is generalizable to other TKIs is not known. This should be investigated prospectively, and if validated applied in clinical practice and clinical trials.