• Reduction in pain from index lesion 4 weeks following the completion of radiotherapy, assessed using Brief Pain Inventory. [ Time Frame: 7 weeks ] [ Designated as safety issue: No ]
  

• reduction in pain in index lesion at study termination assessed using Brief Pain Inventory [ Time Frame: 12 weeks ] [ Designated as safety issue: No ]
  
• acute toxicity of palliative radiotherapy and sorafenib together [ Time Frame: 12 weeks ] [ Designated as safety issue: Yes ]
  
• acute toxicity of sorafenib alone [ Time Frame: 1 week ] [ Designated as safety issue: Yes ]
  
• biologic response of the index lesion to radiotherapy and sorafenib assessed using FDG-PET-CT [ Time Frame: 7 weeks ] [ Designated as safety issue: No ]
  
• disease-free survival [ Time Frame: greater than 3 months ] [ Designated as safety issue: No ]
  

Drug: Sorafenib
Dose level 1: sorafenib 200mg PO OD on Days 1-84 Dose level 2: sorafenib 400mg PO OD on Days 1-84
Radiation: external beam radiotherapy
3000cGy in 10 fractions

Inclusion Criteria:

• Eligible patients must have histologically or cytologically confirmed metastatic RCC that is judged to be incurable with standard therapy.
• Patients must have at least one radiographically-evident symptomatic (> 2/10 on the Brief Pain Inventory) bone metastasis that is amenable to palliative radiation. If more than one symptomatic bone metastasis is identified, one will be chosen as the index lesion.
• No planned change in analgesic medications.
• No planned increase in regular analgesic medications.
• No prior surgery to the index lesion, although previous surgery for other metastatic disease is permissible if > 4 weeks prior to study registration.
• Patients may have had up to two previous lines of systemic treatment for metastatic RCC, including prior treatment with sorafenib or another similar multi-targeted tyrosine kinase inhibitor.
• Patients may not have had previous radiotherapy to the index lesion. Patients may have had previous radiotherapy to other metastases if completed > 4 weeks prior to study registration. Patients must have recovered from the acute side effects of radiotherapy prior to study registration.
• Age >18 years.
• Life expectancy of greater than 3 months.
• ECOG performance status < 2 (Karnofsky > 60).

• Patients must have normal organ and marrow function as defined below:

  • Absolute neutrophil count >1.5 x109 /L
  • Platelet count >100 x109 /L
  • Total bilirubin < 1.5 x ULN
  • AST (SGOT) / ALT (SGPT) <= 2.5 × institutional ULN
  • Creatinine <1.5 x ULN or
  • Creatinine clearance > 60 mL/min/1.73 m2
  • International Normalized Ratio (INR) <= 1.5
  • Hemoglobin value Hb > 10 mg/dL
  • Serum phosphate level > 2.0 mg/dL
  • Serum lipase, normal values (range of 5-208 U/L)
  • Serum amylase, normal values (range 30-110 U/L)
• Ability to understand and the willingness to sign a written informed consent document.
• The effects of sorafenib on the developing human fetus at the recommended therapeutic dose are unknown. Women of child-bearing potential must agree to use adequate contraception prior to study entry and for the duration of study participation. Effective methods of birth control would include a barrier method (e.g. condoms, diaphragm) combined with spermicide, or an intrauterine device (IUD). Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately.

Exclusion Criteria:

• Serious medical condition that might be aggravated by treatment, including but not limited to: myocardial infarction within 6 months, congestive heart failure, unstable angina, active cardiomyopathy, unstable ventricular arrhythmia, uncontrolled hypertension, uncontrolled psychotic disorders, serious infections, active peptic ulcer disease, active liver disease, or cerebrovascular disease with previous stroke.
• Patients may not be receiving any other investigational agent concurrently or within 4 weeks of study registration. Patients receiving other molecularly-targeted treatments for RCC off of study, including inhibitors of angiogenesis or mTOR, will be eligible for this study after a 1 week wash-out period.
• Patients with clinical or radiological evidence of spinal cord compression are ineligible.
• Patients who are at high risk of pathologic fracture and appropriate for surgical intervention are ineligible.
• Patients who are planned for palliative surgical intervention to the index lesion or adjacent bone are ineligible.
• Pregnant or lactating women are excluded from this study because the safety of sorafenib has not been established in these circumstances.
• Patients with immune deficiency are at increased risk of lethal infections when treated with marrow-suppressive therapy. Therefore, HIV-positive patients receiving combination anti-retroviral therapy are excluded from the study because of possible pharmacokinetic interactions with sorafenib.
• Patients with other active malignancies other than non-melanoma skin cancer are excluded.
• Patients who have had significant surgical procedures requiring a general anaesthetic (for example, open laparotomy or thoracotomy) within the past month
• Patients who possess unhealed wounds or ulcers
• Patients with any bleeding or clotting disorder
• Patient taking greater than 325mg of aspirin per day
• Patients with diabetes mellitus will be ineligible for the PET-CT components of the study, but will remain eligible to receive sorafenib.