Inclusion Criteria:
* Subject must have cytologically or histologically confirmed non-small cell lung cancer
* Subject must have brain metastases demonstrated on a magnetic resonance imaging (MRI) brain scan.
* Subject must be eligible for treatment with WBRT
* Subject must have had adequate hematologic, renal, and hepatic function.
Exclusion Criteria:
* Subject is diagnosed with brain metastases greater than 28 days prior to Day 1
* Subject received any prior form of cranial radiation and/or neurosurgery for their brain metastases
* Subject's last dose of anti-cancer therapy or investigational therapy was less than or equal to 7 days prior to Day 1
* Subject has a Karnofsky Performance Score of less than 70
* Subject has significant dyspnea requiring supplemental oxygen therapy
* Subject has liver metastases (restaging is not required for known liver metastases)
* Subject has more than 2 sites (organ systems) of metastases from non-small cell lung cancer with the exception of intra-cranial sites of metastases from non-small cell lung cancer, thoracic sites of metastases from non-small cell lung cancer and bone metastases
* Subject has leptomeningeal metastases or subarachnoid spread of tumor
* Subject has unresolved or unstable, serious toxicity from prior administration of another investigational drug and/or prior anti-cancer treatment
* Subject has a known seizure disorder that is uncontrolled, or has seizures occurring greater than or equal to 3 times a week over the past month. Subjects presenting with symptoms of seizures from the brain metastases are eligible; however he/she should receive adequate anti-seizure medication prior to study treatment
* Subject is pregnant or lactating
* Subject has previously been treated with a poly-(ADP-ribose)-polymerase inhibitor as an investigational agent
* Subject has clinically significant and uncontrolled major medical condition(s)
* Subject has a history of another active cancer within the past 5 years except: cervical cancer in situ, in situ carcinoma of the bladder, basal or squamous cell carcinoma of the skin or other cancer in situ that is considered cured
