A Study of ABT-888 in Combination With Temozolomide for Colorectal Cancer

Inclusion Criteria: * Histologically proven colorectal cancer with measurable or evaluable disease * Progression on or intolerance of or ineligibility for all standard therapies (including regimens containing fluoropyrimidine, oxaliplatin, irinotecan, bevacizumab, and an anti-EGFR antibody (where appropriate)) * Age \> = 18 years * ECOG performance status 0-2 * Subjects with no brain metastases or a history of previously treated brain metastases who have been treated by surgery or stereotactic radiosurgery at least 4 weeks prior to enrollment and have a baseline MRI that shows no evidence of active intercranial disease and have not had treatment with steroids within 1 week of study enrollment * At least 21 days since prior anti-cancer therapy, including chemotherapy, biological therapy, radiation therapy or any investigational agent within 4 weeks before starting ABT-888 and temozolomide * Adequate hepatic, bone marrow, and renal function * Partial thromboplastin time (PTT) must be \</= 1.5 x the upper limit of institution's normal range and INR \< 1.5. Subjects on anticoagulant will have PTT and INR as determined by the investigator. * Subject's with significant fluid retention, including ascites or pleural effusion, may be allowed at the discretion of the PI * Life expectancy \> 12 weeks * Women of childbearing potential must have a negative serum pregnancy test within 14 days prior to initiation of treatment and/or postmenopausal women must be amenorrheic for at least 12 months to be considered of non-childbearing potential. * Subject is capable of understanding and complying with parameters as outlined in the protocol and able to sign and date the informed consent approved by the IRB prior to the initiation of any screening or study-specific procedures. Exclusion Criteria: * CNS metastases which do not meet the criteria outlined in inclusion criteria * Active severe infection or known chronic infection with HIV, hepatitis B virus, or hepatitis C virus * Cardiovascular disease problems including unstable angina, therapy for life-threatening ventricular arrhythmia, myocardial infarction, stroke or congestive heart failure within the last 6 months * Life threatening visceral disease or other severe concurrent disease * Women who are pregnant or breastfeeding * Anticipated patient survival under 3 months * The subject has had another active malignancy within the past five years except for cervical cancer in site, in situ carcinoma of the bladder or non-melanoma carcinoma of the skin. * Clinically significant and uncontrolled major medical conditions including but not limited to: active uncontrolled infection, symptomatic congestive heart failure, Unstable angina pectoris or cardiac arrhythmia, psychiatric illness/ social situation that would limit compliance with study requirements; any medical condition, which in the opinion of the study investigator places the subject at an unacceptably high risk for toxicities