Inclusion Criteria:

- Either non-small cell lung cancer, hormone-refractory prostate cancer, colorectal
cancer, breast cancer, or squamous cell cancer of the head and neck that is
refractory to standard treatment or for which no effective treatment exists. The
patient must have a life expectancy of 12 weeks or longer.

- Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1

Exclusion Criteria:

- Received any anticancer medications in the 28 days prior to receiving their first
dose of study medication

- Evidence of venous thrombosis by flow Doppler examination at Screening

- A history of thrombosis or a coagulation disorder

- Patients with a contraindication to use of low dose warfarin and/or aspirin.

- Any unresolved toxicity greater than grade 2 from previous anticancer therapy, except
for stable chronic toxicities not expected to resolve

- Brain metastases or spinal cord compression

- Impaired renal function

- Inadequate bone marrow reserve