A phase 1b/2a study evaluating the combination of MM-151 + nal-IRI + 5-FU + Leucovorin in RAS/RAF wild-type Metastatic Colorectal Cancer.

Part 1: Patients will be enrolled to determine the maximum tolerated dose, safety and tolerability of MM-151 + nal-IRI + 5-FU + LV in patients with mCRC that are RAS/RAF wild-type.

Part 2: Patients will be enrolled at the maximum tolerated dose of MM-151 in combination with nal-IRI + 5-FU + LV to characterize initial efficacy in conjunction with levels of irinotecan and SN-38 measured in tissue.

Inclusion Criteria:

• Patients must be greater than 18 years of age
• Patients must be able to provide informed consent
• Patients must have KRAS/NRAS/BRAF wild-type colorectal cancer
• Willing to abstain from sexual intercourse or to use an effective form of contraception during the study and for 120 days following the last dose of any study therapy). This applies to women of childbearing potential as well as fertile men and their partners

Exclusion Criteria:

• Patients who have had previous pelvic radiation treatment
• Patients who are pregnant or lactating
• Patients who have untreated (primary) or uncontrolled Central Nervous System (CNS) (primary or metastatic) malignancies; patients with CNS metastases who have undergone surgery or radiotherapy or who have been on a stable dose of corticosteroids for at least 2 weeks and whose disease is stable prior to the first scheduled day of dosing will be eligible for the trial.
• History of any second malignancy in the last 3 years; patients with prior history of in-situ cancer or basal or squamous cell skin cancer are eligible.
• Patients who have received other recent antitumor therapy including any standard chemotherapy or radiation within 14 days and bevacizumab within 28 days (and having passed the time of any actual or anticipated toxicities) prior to the first scheduled dose of the study treatment