SAN FRANCISCO—Combining a bisphosphonate with sunitinib may improve progression-free survival (PFS) and overall survival (OS) in patients with bone metastases from renal cell carcinoma (RCC), that are treated with sunitinib, according to a multicenter, retrospective study presented at the 2012 Genitourinary Cancer Symposium.

Bisphosphonates can prevent skeletal events related to bone metastases, but the findings from this study suggest bisphosphonates also may have anti-tumor effects in this patient population, said lead investigator Daniel Keizman, MD, head of the Genitourinary Oncology Service at Meir Medical Center in Kfar-Saba, Israel, who presented the study findings.

For this investigation, he and his colleagues evaluated whether a bisphosphonate can improve the response rates, PFS, and OS in patients with RCC and bone metastases treated with sunitinib.  Patients were divided into bisphosphonate users (Group 1) and non-users (Group 2). 

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From 2004-2011, 209 patients with metastatic RCC were treated with sunitinib. Of these, 76 patients had bone metastases (35 patients in Group 1 and 41 in Group 2). The groups were balanced in terms of known prognostic factors. The patients were also balanced with regard to past cytokines/targeted treatments, and mean sunitinib dose/cycle. Objective response was partial response/stable disease in 30 patients (86%) in Group 1 compared with 29 patients (71%) in Group 2. Moreover, disease refractory to sunitinib treatment occurred in five patients (14%) of Group 1 compared with 12 patients (29%) of Group 2. The median PFS was 15 months for Group 1 compared with five months for Group 2. Median OS was not reached (with a median follow-up of 45 months) for group 1 versus 14 months for group 2.

“We found that the use of bisphosphonates decreased the risk of disease progression by 45% and of dying by approximately 60%,” Dr. Keizman said.