The purpose of this study is to determine the dose regimen of Ispinesib in combination with capecitabine in patients with solid tumors. Ispinesib is dosed by 1-hour intravenous infusion every 3 weeks and capecitabine is dosed orally, twice a day for 14 days with a 1 week rest period. A patient may continue to receive treatment as long as they are benefiting from the treatment. Blood samples will be taken at specific times to measure the amount of both drugs in your body at specific times after the drug is given. Blood samples will also be taken for lab tests such as complete blood counts and clinical chemistries. Physical exams will be performed before each treatment with Ispinesib. During the treatment phase, the patients will undergo regular assessments for safety and clinical response.

Inclusion criteria:

• Histologically or cytologically confirmed diagnosis of an advanced solid tumor malignancy that is not responsive to standard therapies or for which there is no standard therapy.
• ECOG (Eastern Cooperative Oncology Group) Performance Status of 0-2.
• Bone marrow function: - ANC greater than 1500/mm3.
• Platelet count greater than or equal to 100,000/mm3.
• Hemoglobin greater than 9 g/dL.
• Renal function: - Calculated creatinine clearance greater than or equal to 50 mL.min.
• Total bilirubin greater than 1.5 mg/dL.
• AST/ALT less than 2.5 X upper limit of normal.

Exclusion criteria:

• Females who are pregnant or nursing.
• Pre-existing hemolytic anemia.
• Pre-existing peripheral neuropathy greater than or equal grade 2.
• Known deficiency in dihydropyrimidine dehydrogenase (DSD).