The goal of this study was to determine the effect on overall survival and progression free survival by adding iniparib (BSI-201/SAR240550) to the combination of gemcitabine/carboplatin in adult patients with triple negative breast cancer (estrogen receptor (ER)-negative, progesterone receptor (PR)-negative, and human epidermal growth factor receptor 2 (HER2)-negative).

Based on data generated by BiPar/Sanofi, it is concluded that iniparib does not possess characteristics typical of the poly (ADP-ribose) polymerase (PARP) inhibitor class. The exact mechanism has not yet been fully elucidated, however based on experiments on tumor cells performed in the laboratory, iniparib is a novel investigational anti-cancer agent that induces gamma-H2AX (a marker of DNA damage) in tumor cell lines, induces cell cycle arrest in the G2/M phase in tumor cell lines, and potentiates the cell cycle effects of DNA damaging modalities in tumor cell lines. Investigations into potential targets of iniparib and its metabolites are ongoing.

Participants were treated for 21-day cycles until disease progression, unacceptable toxicity, or consent withdrawal. After treatment discontinuation, participants were followed until end of study or death or receipt of new anticancer therapy, whichever was first.

Inclusion Criteria:

- Histologically documented breast cancer (either primary or metastatic site) that is ER-negative, PR-negative, and HER2 non-overexpressing by immunohistochemistry (0, 1) or fluorescence in situ hybridization (FISH).

Triple-negative tumors were defined by the following criteria:

• HER2-non-overexpressing: FISH-negative (defined by ratio <2.2) or, immunohistochemical (IHC) 0, IHC 1+ or, IHC 2+ or IHC 3+ and FISH-negative.

• ER- and PR-negative: <10% tumor staining by immunohistochemistry (IHC).

  • Never having received chemotherapy for metastatic disease or, having received 1 or 2 prior chemotherapy regimens in the metastatic setting (Prior adjuvant/neoadjuvant therapy was allowed);
  • Metastatic breast cancer (Stage IV) with measurable disease by RECIST 1.1 criteria;
  • Female, ≥18 years of age;
  • Eastern Cooperative Oncology Group (ECOG) performance status of 0-1;
  • Organ and marrow function as follows: absolute neutrophil count (ANC) ≥1500/mm3, platelets ≥100,000/dL, hemoglobin ≥9 g/dL, bilirubin ≤1.5 mg/dL, serum creatinine ≤1.5 mg/dL or creatinine clearance ≥60 mL/min, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤2.5 times the upper limit of normal if no liver involvement or ≤5 times the upper limit of normal with liver involvement;
  • Radiation therapy completed at least 14 days before study dosing on day 1; radiated lesions may not have served as measurable disease;
  • Central nervous system metastases allowed if subject did not require steroids, whole brain radiation therapy (XRT), gamma/cyber knife, and brain metastases were clinically stable without symptomatic progression;
  • For women of child bearing potential, documented negative pregnancy test within two weeks of study entry and agreement to acceptable birth control during the duration of the study therapy;
  • Tissue block (primary or metastatic) or readily available fresh frozen tumor tissue for PARP expression and other pharmacogenomic studies recommended (although its absence will not exclude subjects from participating);
  • No other diagnosis of malignancy (with exception of non melanoma skin cancer or a malignancy diagnosed ≥5 years ago);
  • Obtained informed consent;
  • Capability to understand and comply with the protocol and signed informed consent document.

Exclusion Criteria:

• Systemic anticancer therapy within 14 days of the first dose of study drug;
• Prior treatment with gemcitabine, carboplatin, cisplatin or iniparib
• Had not recovered to grade ≤1 from adverse events (AEs) per National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) v3.0 or to within 10% of baseline values due to investigational drugs or other medications administered more than 30 days prior to study enrollment;
• Major medical conditions that might have affected study participation (e.g. uncontrolled pulmonary, renal, or hepatic dysfunction, uncontrolled infection, cardiac disease);
• Concurrent radiation therapy intended to treat primary tumor not permitted throughout the course of the study; palliative radiation was acceptable;
• Leptomeningeal disease or brain metastases requiring steroids or other therapeutic intervention;
• Pregnancy or breastfeeding;
• Inability or unwillingness to abide by the study protocol or cooperate fully with the investigator or designee.