Cyclophosphamide With or Without Veliparib in Patients With Locally Advanced or Metastatic Breast Cancer

Inclusion Criteria:

• Phase I: Patients must have histologically confirmed breast cancer (MBC) that is HER2/neu negative (as determined by local pathology or reference laboratory), and have disease that is metastatic (stage IV [TxNxM1]) or locally advanced and not amenable to potentially curative surgical resection (eg, clinical stage IIIB-C) Phase II: Patients must have histologically confirmed breast cancer (MBC) that is ER positive and/or PR positive, and HER2/neu negative (as determined by local pathology or reference laboratory), and have disease that is metastatic (stage IV [TxNxM1]) or locally advanced and not amenable to potentially curative surgical resection (eg, clinical stage IIIB-C)
• HER2/neu negative disease (performed on primary tumor and/or metastatic lesion using commercially available/approved assay in local institutional or reference laboratory), according to American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guidelines
• ER/PR expression (by standard immunohistochemical assay) on primary tumor and/or metastatic lesion known, and classified as ER and/or PR-positive according to ASCO/CAP guidelines (including 1-9%expression)
• National Comprehensive Cancer Network (NCCN) guidelines recommend for metastatic breast cancer "…biopsy documentation of first recurrence, if possible, and determination of hormone receptor status (ER and PR) and HER2 status…."; therefore, histologic and/or cytologic confirmation of metastatic disease is encouraged whenever feasible, but not required; in some circumstances, histologic confirmation may not be feasible (eg, bone metastases not amenable to biopsy and elevated CA27-29 tumor marker); for patients who have had histologic confirmation of metastatic disease, it is required that the biopsy confirm that the metastatic tumor is ER and/or PR positive, and HER2/neu negative; for patients in whom biopsy confirmation of metastatic disease is not feasible, it is required that the primary tumor be ER and/or PR-positive and HER2/neu negative
• Measurable disease (Response Evaluation Criteria in Solid Tumors [RECIST] 1.1) or non-measurable disease, with measurement obtained within 4 weeks of registration
• Phase I: Patients must have received at least one prior chemotherapy regimen for metastatic disease Phase II: Patients must have received two or more prior chemotherapy regimens for metastatic disease, which must have included an antitubulin agent (eg, paclitaxel, docetaxel, vinorelbine, ixabepilone) and capecitabine; there should be at least a 4 week interval between the last chemotherapy dose and registration (one week for capecitabine, 2 weeks for weekly paclitaxel in the presence of disease progression), and the patient should have recovered from acute toxicity related to prior therapy; no prior treatment with veliparib or other PARP inhibitors (eg, BSI 201)
• Patients must have had progressive disease after at least one line of endocrine therapy for metastatic disease (includes relapse while receiving endocrine therapy); there should be at least 1 week interval between the last endocrine treatment for an aromatase inhibitor and at least 2 weeks for tamoxifen or fulvestrant
• Eastern Cooperative Oncology Group (ECOG) performance status 0, 1, or 2 (Karnofsky >= 60%)
• Leukocytes >= 3,000/mcL
• Absolute neutrophil count >= 1,500/mcL
• Platelets >= 100,000/mcL
• Hemoglobin > 9g/dl (per manufacturer recommendation)
• Total bilirubin within normal institutional limits (unless isolated indirect hyperbilirubinemia due to Gilbert's disease)
• Aspartate aminotransferase (AST) (serum glutamic oxaloacetic transaminase [SGOT])/alanine aminotransferase (ALT) (serum glutamate pyruvate transaminase [SGPT]) =< 2.5 × institutional upper limit of normal
• Creatinine within normal institutional limits OR creatinine clearance >= 60 mL/min/1.73 m^2 for patients with creatinine levels above institutional normal
• Patients with a history of brain metastases are eligible if they have been treated with radiation and have stable brain metastases at least 3 months after radiation and must also be off steroids
• Patients must be able to swallow whole capsules and tolerate oral medications
• Women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation; being not of childbearing potential is defined as: (1) prior hysterectomy, or (2) no menstrual period for at least 24 months
• Ability to understand and the willingness to sign a written informed consent document

Exclusion Criteria:

• Patients who have radiotherapy within 3 weeks prior to entering the study or those who have not recovered from adverse events due to systemic agents administered more than 3 weeks earlier
• Patients may not be receiving any other investigational agents
• Patients with known brain metastases with active symptoms or requiring anticonvulsive medications, or steroids should be excluded from this clinical trial
• History of allergic reactions attributed to compounds of similar chemical or biologic composition to veliparib (ABT-888) or cyclophosphamide used in the study
• Evidence of complete or partial bowel obstruction or other unable to take oral medications
• Patients with malabsorption syndrome or other condition that would interfere with intestinal absorption
• Patients unable to swallow whole capsules
• Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements
• Pregnant (positive pregnancy test) or lactating women will be excluded from the study; also, unwillingness to use effective means of contraception in subjects with child-bearing potential will be excluded from the study; women of child-bearing potential must use two forms of contraception (i.e., barrier contraception and one other method of contraception) at least 4 weeks prior to study entry, for the duration of study participation
• Patients with active severe infection; known infection with human immunodeficiency virus (HIV), hepatitis B virus, hepatitis C virus, or severe concurrent illness will be excluded from the study; HIV-positive patients on combination antiretroviral therapy are ineligible
• Patients with a history of seizure disorder requiring antiepileptics who have had a seizure episode within the last 6 months
• Prior treatment with veliparib (ABT-888) or other PARP inhibitors (e.g., olaparib)