Inclusion Criteria:

- Histologically confirmed NSCLC and Stage 3b or 4 NSCLC (Phase 1 only), Stage 3b or 4
NSCLC (Phase 2 only)

- Documented progressive disease following a prior RECIST response to monotherapy with
erlotinib OR documented progressive disease following stable disease of at least 6
months on monotherapy with erlotinib (Phase 2 only)

- Must have tolerated erlotinib at the maximal dose that will be administered in Phase
2 only (or at a higher dose) for a minimum of 6 weeks

- Measurable disease per RECIST (Phase 2 only)

- At least 18 years old

- ECOG performance status of 0 or 1

- Adequate organ and marrow function

- Sexually active subjects must agree to use medically accepted methods of
contraception during the course of the study and for 3 months following
discontinuation of study treatment (excluding women who are not of child bearing
potential and men who have been sterilized).

- Female subjects of childbearing potential must have a negative pregnancy test at
enrollment

- No other diagnosis of malignancy (unless non-melanoma skin cancer, carcinoma in situ
of the cervix or malignancy diagnosed ≥ 2 years previously, and currently with no
evidence of disease).

- Capable of understanding and complying with the protocol, and written informed
consent

Exclusion Criteria:

- Received anti-cancer treatment within 4 weeks, except erlotinib, prior to first dose
(Phase 1 only)

- In Phase 2 only: the subject has received:

- Small molecule inhibitors of VEGFR2/KDR OR

- An investigational anti-cancer agent within 4 weeks of the first dose of study
drug OR

- An investigational agent that targets EGF or EGFR at any time OR

- An approved agent that targets EGF or EGFR (with the exception of erlotinib and
gefitinib) at any time unless approved by Exelixis OR

- Anti-cancer therapy within 4 weeks (with the exception of gefitinib and
erlotinib) of the first dose of study drug OR

- Prior therapy with a c-Met inhibitor

- Not recovered to NCI CTCAE v.3 Grade ≤1 from clinically significant adverse events
due to antineoplastic agents, investigational drugs, or other medications
administered prior to study enrollment

- Symptomatic or uncontrolled brain metastases requiring current treatment, including
steroids and anticonvulsants

- History of significant hematemesis or recent history of hemoptysis

- Presence of cavitation, central lesion, or lesion abutting a major blood vessel

- Intercurrent illness such as hypertension or cardiac arrhythmias or recent history of
significant disease such as congestive heart failure

- Pregnant or breastfeeding

- Active bacterial or viral infection requiring systemic treatment

- Allergy or hypersensitivity to components of either the XL184 or erlotinib
formulations

- Incapable of understanding and complying with the protocol or unable to provide
informed consent

- History of idiopathic pulmonary fibrosis or interstitial lung disease