Inclusion Criteria:

- Female patients with a histologically confirmed diagnosis of metastatic ovarian
cancer

- Measurable disease according to Response Criteria for Solid Tumors (RECIST)

- Prior treatment with platinum-based therapy

- Platinum-sensitive or platinum-resistant disease

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

- Life expectancy of ≥3 months

- Adequate organ and marrow function

- Signed informed consent

- No other malignancies within 5 years

Exclusion Criteria:

- Radiation to ≥25% of bone marrow within 30 days of XL999 treatment

- Use of an investigational drug or cytotoxic chemotherapy within 30 days of XL999
treatment

- Prior anticancer therapy targeting VEGF (eg, bevacizumab, sorafenib, or sunitinib)

- More than two prior systemic non-platinum cytotoxic chemotherapy regimens

- Subject has not recovered to grade ≤1 or to within 10% of baseline from adverse
events due to other medications administered >30 days prior to study enrollment

- History of or known brain metastases, current spinal cord compression, or
carcinomatous meningitis

- Uncontrolled and/or intercurrent illness

- Patients who are pregnant or breastfeeding

- Known human immunodeficiency virus (HIV)