This is an open-label, multicenter, ascending multiple dose study of REGN1400 alone and in combination with erlotinib or cetuximab administered to patients with certain types of cancer.

Inclusion Criteria include, but are not limited to, the following:

1. Confirmed diagnosis of certain unresectable or metastatic cancers
2. Adequate Eastern Cooperative Oncology Group (ECOG) performance status
3. Adequate hepatic, renal and bone marrow function
4. Resolution of toxicity from prior therapy to grade less than/ = to 1

Exclusion Criteria include, but are not limited to, the following:

1. Active brain metastases
2. Thromboembolic events < 6 months prior to study
3. Patients with a recent history (within 5 years) of another malignancy.
4. Investigational or any antitumor treatment with a maximum of 4 half-lives or administered 30 days prior to the initial administration of REGN1400
5. Patients who are pregnant or nursing
6. Prior treatment with ErbB3 inhibitors