4769 Purpose: Evaluate the efficacy and safety of a bone-targeted regimen consisting of zoledronate, thalidomide, and gamma IFN in patients with renal cell carcinoma and bone metastases. Patients and Methods: Fifteen patients were enrolled on the study between 11/14/02 and 11/7/03. Impending pathological fractures or spinal cord compressions were controlled by surgery or radiation therapy prior to study. Zoledronate (4 mg) was given intravenously once every 4 weeks. Thalidomide (300 mg) was taken orally once every day. Gamma IFN (100 mcg) was given subcutaneously once every week. Patients were evaluated for the presence of calcification in osteolytic metastases, time to skeletal-related events, and levels of bone formation and resorption markers (i.e., bone-specific alkaline phosphatase, urine N-telopeptide and deoxypyridinoline). Results: Twelve patients had previously received surgery, radiation, or embolization for their bone metastases. Eleven patients had multiple (more than three) sites of bone involvement. Nine patients also had non-osseous metastases in the lungs, liver, lymph node, pancreas, and/or adrenal gland. The median time to progression was 8.3 weeks (range, 2.1–48 weeks). The median time to skeletal-related event was 13.7 weeks (range, 3.1 - 46.4 weeks). Two patients discontinued treatment because of adverse drug reactions (deep venous thrombosis or myocardial infarction). Two patients had pain improvement and developed calcification in the osseous metastases. They also had increased bone formation marker or decreased bone resorption marker. Conclusions: A bone-targeted regimen combining zoledronate, thalidomide, and gamma IFN is well tolerated and may provide clinical benefit for selected patients with renal cell carcinoma and bone metastases. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration AstraZeneca, Merck, Pfizer Celgene, Eli Lilly, Novartis