This is a Phase 1/1b open-label study evaluating the safety, pharmacokinetics (PK), and preliminary efficacy of ABT-165 when administered as monotherapy and in combination with paclitaxel or 5-fluoruracil, folinic acid and irinotecan (FOLFIRI) or ABBV-181 with/without paclitaxel in subjects with advanced solid tumors. Enrollment to Cohorts A, B were completed and for Cohorts C and D are recruiting.

Inclusion Criteria:

• Subject must have advanced solid tumor that is not amenable to surgical resection or other approved therapeutic options that have demonstrated clinical benefit.
• Subject has adequate bone marrow, renal, hepatic and coagulation function.
• Subject must have measurable disease per Response Evaluation Criteria In Solid Tumors (RECIST) version 1.1 or disease evaluable by assessment of tumor antigens including but not limited to cancer antigen (CA-125) and prostate-specific antigen (PSA).
• Women of childbearing potential must have a negative serum pregnancy test at the screening visit and a negative urine pregnancy test at baseline prior to the first dose of study drug. Female subject considered not of childbearing potential must be documented as being surgically sterile or post-menopausal for at least 1 year. Women of childbearing potential and men must agree to use adequate contraception.
• Subjects in the combination therapy cohorts must meet the above inclusion criteria and be eligible to receive paclitaxel or FOLFIRI per most current prescribing information, or at the discretion of the Investigator. Subjects in the combination therapy cohorts who are to receive ABBV-181, an anti-PD1 antibody, must also meet other criteria described in the Protocol.

Exclusion Criteria:

• Subject has received anticancer therapy including chemotherapy, radiation therapy, immunotherapy, biologic, or any investigational therapy within a period of 21 days or anti-cancer herbal therapy within 7 days prior to Cycle 1 Day 1 of ABT-165.
• Subject has uncontrolled metastases to the central nervous system (CNS).
• Subject has unresolved clinically significant toxicities from prior anticancer therapy, defined as any Common Terminology Criteria for Adverse Events (CTCAE) Grade 2 or higher.
• Subject has history (within previous 5 years) of clinically significant pulmonary hypertension, uncontrolled systemic hypertension or hypertensive crisis, symptomatic heart failure, cardiomyopathy, myocardial infarction, unstable/severe angina pectoris, cardiac arrhythmia requiring medication, coronary/peripheral artery bypass graft, aneurysm or aneurysm repair, angioplasty, cerebrovascular accident, transient ischemic attack or the left ventricular ejection fraction (LVEF) less than 50%.
• Subjects enrolled on the combination therapy phase must not meet the above exclusion criteria and must be eligible to receive paclitaxel or FOLFIRI per most current prescribing information, or at the discretion of the Investigator. Subjects receiving ABBV-181 must not meet other exclusion criteria described in the Protocol.