Combining Sorafenib with standard cytotoxic fluoropyrimidine therapy for advanced colorectal cancer may provide clinical benefit when no other treatment remains.

The Raf/MEK/ERK pathway is an important mediator of responses to growth factors, and a strong inducer of genes involved in tumorigenesis, angiogenesis, apoptosis, and tumorigenesis in metastatic colorectal cancer (mCRC). Inhibition of this pathway has been previously proven to be highly clinically beneficial for patients with this disease. It has also been clearly demonstrated that the inhibition of VEGF, when coupled with cytotoxic therapy and/or continued beyond initial response, can improve clinical outcomes and survival in this same cohort of patients. Safety and pharmacokinetic data have already been established for this novel doublet oral chemotherapy. This study is intended to determine the activity of a combination of oral fluoropyrimidine plus sorafenib in an advanced mCRC patient population for whom limited treatment options remain.

Inclusion Criteria:

• Histologically or cytologically proven adenocarcinoma of the colon or rectum.
• Metastatic disease that is not amenable to potentially curative treatment.
• Measurable disease (as per RECIST 1.1 criteria).
• At least one prior chemotherapeutic regimen for metastatic disease. Patients must have progressed following oxaliplatin based therapy (in either the adjuvant or metastatic setting) and irinotecan based therapy (in the metastatic setting).
• Adequate bone marrow, liver and renal function.
• Patients receiving anti-coagulation treatment with an agent such as warfarin or heparin may be allowed to participate, provided stability in anticoagulation therapy is documented at the treating provider's discretion. For patients on warfarin, the INR should be measured prior to the initiation of study treatment and should be monitored at least weekly, or as defined by the local standard of care, until INR is stable.
• Women of childbearing potential must have a negative serum pregnancy test performed within 7 days prior to the start of treatment.
• Women of childbearing potential and men must agree to use adequate contraception (barrier method of birth control) prior to study entry and for the duration of study participation. Men should use adequate birth control for at least three months after the last administration of sorafenib.
• Patients may have had a history of other (non-colorectal) malignancies if there is no current evidence of persistent or recurrent disease and they are not undergoing any active therapy (including hormonal).
• Patients should have paraffin-embedded tissue from initial diagnosis or prior colorectal cancer surgery available for molecular analysis.
• Patients must consent to participate in the study and must have signed and dated an IRB-approved consent form conforming to federal and institutional guidelines. Consent must be obtained prior to any study specific procedures.

Exclusion Criteria:

• Prior therapy with a tyrosine kinase inhibitor.
• Age < 18 years
• ECOG Performance Status > 2
• Less than 28 days elapsed from prior radiation therapy, surgery or chemotherapy to the time of registration.
• History of known brain metastasis. Patients with neurological symptoms must undergo a CT scan/MRI of the brain to exclude brain metastasis.
• History of clinically significant cardiac disease (severe/unstable angina pectoris, NYHA class III or IV congestive heart failure, symptomatic coronary artery disease) or myocardial infarction, cerebrovascular accident or transient ischemic attack within the last 12 months.
• Cardiac ventricular arrhythmias requiring anti-arrhythmic therapy. Uncontrolled hypertension defined as systolic blood pressure > 140 mmHg or diastolic pressure > 90 mmHg, as measured on 3 consecutive pre-enrollment assessments, despite optimal medical management.
• Known human immunodeficiency virus (HIV) infection or chronic Hepatitis B or C.
• Active clinically serious infection > CTCAE Grade 2.
• Pulmonary hemorrhage/bleeding event > CTCAE Grade 2 within 4 weeks of first dose of study drug.
• Any other hemorrhage/bleeding event > CTCAE Grade 3 within 4 weeks of first dose of study drug.
• Pulmonary embolism or any other uncontrolled thromboembolic event within 3 months prior to registration or occurrence of deep vein thrombosis within 4 weeks of registration.
• Serious non-healing wound, ulcer, or bone fracture.
• Evidence or history of a clinically significant bleeding diathesis or coagulopathy (without vitamin K antagonist therapy).
• Use of St. John's Wort or rifampin (rifampicin).
• Known or suspected allergy to sorafenib or capecitabine.
• Any condition that impairs patient's ability to swallow whole pills.
• Any known malabsorption problem.
• History of chronic or inflammatory bowel disorders, clinically significant chronic diarrhea refractory to medical management, or unresolved bowel obstruction.

Adults with metastatic colorectal cancer who had previously received two or more lines of systemic therapy.