This trial was halted prematurely for business reasons and low enrollment.

The purpose of this adaptive trial is to compare the progression-free survival of participants with metastatic rectal carcinoma when treated with intravenous (IV) dalotuzumab (MK-0646) + irinotecan therapy relative to participants treated with IV cetuximab + irinotecan. The primary hypothesis is that administration of dalotuzumab in combination with irinotecan to participants with wild-type KRAS metastatic rectal carcinoma with high insulin growth factor (IGF)-1/low IGF-2 expression levels improves progression-free survival compared to patients treated with cetuximab in combination with irinotecan.

Inclusion Criteria:

• Has metastatic colorectal cancer with primary tumor originating from the rectum
• Has an available archival (recent or remote) tumor, or newly obtained formalin-fixed tissue available for analysis for biomarker studies
• Has at least one measurable lesion greater than or equal to 10 mm
• Disease has progressed after treatment with both irinotecan- and oxaliplatin-containing regimens and should have progressed on or within 3 months of completing their last line of therapy
• Has a performance status 0-1 on the Eastern Cooperative Oncology Group (ECOG) Performance Scale

Exclusion Criteria:

• Has poorly-controlled diabetes
• Has received chemotherapy or biological therapy within 2 weeks prior to initial dosing on this study, or whose toxicities from agents administered 2 weeks earlier have not resolved to at least grade 1 or baseline, or who is within 3 weeks from a prior surgery
• Has received radiotherapy within 2 weeks prior to initial dosing on this study, unless the radiotherapy was for management of pain
• Is currently participating or has participated in a study with an investigational compound or device within 30 days or 5 half-lives of the investigational agent, whichever is longer, of initial dosing on this study
• Was unable to complete previous course of irinotecan due to intolerable toxicity, other than discontinuation due to fatigue following prolonged administration (>4 months exposure)
• Has prior exposure to insulin-like growth factor 1 receptor (IGF-1R) inhibitors or epidermal growth factor receptor (EGFR) inhibitors
• Has a known central nervous system (CNS) metastases and/or carcinomatous meningitis
• Has primary CNS tumor
• Has a history of a prior malignancy with the exception of cervical intraepithelial neoplasia; basal cell carcinoma of the skin; adequately treated localized prostate carcinoma; potentially curative therapy with no evidence of that disease for 5 years, deemed low risk for recurrence by treating physician.
• Is human immunodeficiency virus (HIV)-positive
• Has active hepatitis B or C infection and is receiving antiviral treatment regimens
• Has symptomatic ascites or pleural effusion
• Is concurrently using growth hormone (GH), or growth hormone inhibitors

The SPONSOR must have the opportunity to review all proposed abstracts, manuscripts, or presentations regarding this study 60 days prior to submission for publication/presentation.