Protocol Amendment 1: This study did not begin under the original protocol. Sites needed to obtain amendment approval before study initiation. The purpose of this amendment was to: ● Revise study design such that subjects randomized to the placebo arm will receive a fluorouracil bolus (400 mg/m^2) prior to the 46-hr (2400 mg/m^2 ) infusion, i.e., these subjects will receive the standard FOLFIRI regimen. This change was made in response to FDA's comments. ● Add new information regarding unblinded site pharmacy personnel responsible for the preparation of a fluorouracil or saline bolus in response to FDA's comments. ● Clarify that a female subject must be postmenopausal for at least 1 yr. ● Update the informed consent inclusion criterion in the Synopsis and Section 5.2.2 and remove the references to the "subject's legally acceptable representative" as subjects in the study are required to consent for themselves. ● Clarify a discrepancy in the Main Exclusion Criteria of the synopsis to indicate that subjects must be disease-free from previous or concurrent malignancies for a minimum of 3 yrs. ● Clarify a discrepancy in the Main Exclusion Criteria of the synopsis and Section 5.2.2 to indicate that "symptomatic congestive heart failure" is an exclusion criterion for all subjects, not only subjects receiving bevacizumab. ● Clarify that leucovorin will be administered for 90 minutes concurrently with irinotecan per National Comprehensive Cancer Network (NCCN) Guidelines. ● Increase frequency of radiographic tumor assessments to ensure adequate evaluation of subjects and maintain consistency throughout the duration of the study. ● Update Clinical Experience Section 3.8 to include the rationale for excluding the 5-fluorouracil (5-FU) bolus with veliparib treatment based on published Phase 1 trial data. ● Move Benefits and Risks Section 3.9 to the end of the Introduction to improve overall clarity.

Protocol Amendment 1, continued: ● Update the Benefits and Risks Section 3.9 to include potential risk of excluding fluorouracil bolus from the veliparib arm. ● Add an exclusion criterion to the Synopsis and Section 5.2.2 to exclude subjects that have received an investigational product within the 28 days prior to Screening. ● Add an exclusion criterion to the Synopsis and Section 5.2.2 to cover local laws and regulations where certain patient groups would be prohibited from participation. ● Update Table 2 Excluded Medications for clarity to specify the appropriate patient population. ● Clarify in Section 5.3.1.1 that body weight measurement is not a necessary component for every physical exam, only for those visits as indicated in Table 4. ● Update Table 4 Study Assessments to include Adverse Event (AE) assessments and Prior and Concomitant Therapy assessments. ● Clarify in Section 5.3.1.1 that radiographic tumor assessments may be performed up to 4 days before scheduled date, but not after, and should be performed prior to the next cycle of FOLFIRI to ensure subjects are evaluated before receiving additional chemotherapy. ● Add in Section 5.3.1.1 that AbbVie may require sites to electronically transfer copies of CT or MRI scans to facilitate third party review of disease progression. ● Update Section 5.3.1.1 to remove the statement that Australia should select "Europe" in the Interactive Response Technology (IRT) system at randomization as the IRT system only includes "Rest of World" and "North America" classifications. ● Clarify in Table 5 that the subject's morning dose of veliparib on the pharmacokinetic (PK) sampling days of C2D1 and C3D1 should be taken on site. ● Clarify the timing of the safety data analysis in Section 5.3.4. ● Provide additional clarity in Section 5.4.1 and Section 8.1.2.2 for subjects that undergo surgical resection while on the study.

Protocol Amendment 1, continued: ● Clarify in Section 5.5.9 that AbbVie must be notified before the blind is broken by the Investigator. ● Add Section 8.1.7, Interim Analysis, to indicate that AbbVie will perform at least 2 efficacy and 2 safety interim analyses to ensure subject safety and assess efficacy of veliparib. ● Clarify language in Completion of Study Section 13.0. ● Revise guidelines for dose reduction and toxicity management (Appendix G and Appendix I) for fluorouracil to adjust for inclusion of the bolus in the placebo arm. ● Add the central back-up phone number under Section 6.7 Adverse Event. ● Reporting as required per the current version of the protocol template. ● Incorporate minor linguistic and administrative changes throughout the document for clarification.

Protocol Amendment 2: The purpose of this amendment was to: ● Update contact information for the AbbVie Study Designated Physician. ● Provide timing windows around the infusion duration of fluorouracil, irinotecan, leucovorin and bevacizumab. ● Section 1.2, Synopsis, add bevacizumab as a reference therapy in the table. ● Section 1.2, Synopsis, and Section 5.2.2, Exclusion Criteria, clarify that Exclusion Criterion 3 pertains to neoadjuvant chemotherapy in addition to adjuvant therapy and change "prior to colorectal cancer recurrence" to "prior to C1D–2." ● Section 1.2, Synopsis, and Section 5.2.2, Exclusion Criteria, add a definition to symptomatic congestive heart failure. ● Section 3.8, Clinical Experience, correct inaccurate adverse event frequencies from Study M10-977, Phase 1 dose escalation study. ● Section 5.1, Overall Study Design and Plan: Description, update Figure 1 to reflect that subjects will receive either fluorouracil or saline bolus and illustrate that the 46-hour fluorouracil infusion will continue into Day 3. ● Section 5.1, Overall Study Design and Plan: Description, and Section 5.4.5, Timing and Collection of Survival and Post-Treatment Cancer Information, clarify that the survival information and post-treatment cancer information will be collected beginning 4 weeks after the last clinical assessment. ● Section 5.3.1, Efficacy and Safety Measurements Assessed and Flow Chart, remove physical exam requirement at C1D1. ● Section 5.3.1.1, Study Procedures, clarify that RAS, BRAF and MSI status only need to be captured in Medical History if known. ● Section 5.3.1.1, Study Procedures, Table 7, Clinical Laboratory Tests, update clinical chemistry terminology. ● Section 5.3.2.1, Blood Samples for Pharmacokinetic Analysis, update the information that is to be captured. ● Section 5.3.2.2, Measurement Methods, revise "non-GLP" to "non-validated."

Protocol Amendment 2, continued: ● Section 5.3.2.3, Blood Samples for Pharmacogenetic Analysis, revise the label for the pharmacogenetic sample collection tube from "PG-DNA" to "PG-DNA blood." ● Section 5.3.7, Pharmacodynamic Variables, and Section 5.4, Removal (Discontinuation) of Subjects from Protocol Therapy and Study Visits, update storage and retention language for the pharmacodynamics samples. ● Section 5.4, Removal (Discontinuation) of Subjects from Protocol Therapy and Study Visits, update language regarding consent withdrawal and the pharmacodynamic samples. ● Section 5.5.1, Protocol Therapy Administered, specify that sites can use their own method for calculating body surface area (BSA), and dose re-calculations must be made if a subject's weight increases or decreases by more than 10%. ● Section 5.5.1, Protocol Therapy Administered, update protocol therapy administration to allow for sequential infusion of irinotecan followed by leucovorin. ● Section 5.5.9, Blinding, update language regarding unblinded AbbVie study personnel. ● Section 6.7, Adverse Event Reporting, update information regarding reporting SAEs if the site does not have access to Electronic Data Capture (EDC) or the system is not operable and update the 24-hour AbbVie Medical Escalation Hotline information. ● Section 7.0, Protocol Deviations, update language regarding intentional/prospective deviations from the protocol. ● Section 8.1.7, Interim Analysis, update interim analysis plan. ● Appendix I, Toxicity Management Guidelines for Protocol Therapy, update language regarding dose modifications and unresolved toxicity. ● Additional minor corrections and clarifications.