Panitumumab Regimen Evaluation in Colorectal Cancer to Estimate Primary Response to Treatment

Inclusion Criteria:

* Diagnosis of metastatic adenocarcinoma of the colon or rectum
* Available paraffin-embedded tumor tissue
* Failure of first line treatment containing fluoropyrimidine and oxaliplatin based chemotherapy with bevacizumab for mCRC
* Measurable disease
* Adequate hematologic, renal, hepatic and metabolic function

Exclusion Criteria:

* Radiotherapy ≤ 2 weeks prior to Day 1 of Cycle 1
* Unresolved toxicity(ies) from prior anti cancer therapy that, in the opinion of the investigator, precludes the subject from study enrollment
* Prior irinotecan therapy, anti epidermal growth factor receptor (EGFr) therapy, or vaccine for the treatment of mCRC
* CYP3A4 enzyme inducers, inhibitors, and substrates (eg, phenytoin, phenobarbital, carbamazepine, ketoconazole, rifampin, rifabutin, and St. John's Wort) ≤ 2 weeks prior to Day 1 of Cycle 1
* Infection requiring systemic anti infectives completed ≤ 2 weeks prior to Day 1 of Cycle 1
* Clinically significant cardiovascular disease
* History of interstitial lung disease (eg, pneumonitis or pulmonary fibrosis)
* Pulmonary embolism, deep vein thrombosis, or other significant thromboembolic event ≤ 8 weeks prior to Day 1 of Cycle 1
* Any significant bleeding ≤ 6 weeks prior to Day 1 of Cycle 1, per the investigator's judgement
* Gastroduodenal ulcer(s) determined by endoscopy to be active or uncontrolled gastrointestinal ulcer ≤ 4 weeks prior to Day1 of Cycle 1
* Any co-morbid disease or condition that could increase the risk of toxicity (eg, dihydropyrimidine deficiency, significant ascites, or pleural effusion)
* Major surgery (requiring general anesthesia), open biopsy, or significant traumatic injury ≤ 4 weeks prior to Day1 of Cycle 1. Subjects must have recovered from surgery and have no significant complications