Phase 2, Randomized, Double Blind, Placebo-Controlled Dose and Schedule Finding Trial to Evaluate the Safety and Efficacy of AMG 531 For Treatment of Chemotherapy-Induced Thrombocytopenia in Subjects With Advanced Non-Small Cell Lung Cancer Already Receiving Gemcitabine and Platinum.

Inclusion Criteria:

- Histologically or cytologically confirmed locally advanced or metastatic stage IIIB
or stage IV NSCLC receiving Q21 day gemcitabine/carboplatin or gemcitabine/cisplatin

- Life expectancy > or = 12 weeks at the time of screening

- Thrombocytopenia as evidenced by a platelet count < or = 50 x 10^9/L during the
qualifying cycle of chemotherapy, OR platelet count < 100 x 10^9/L on Day 22 of the
qualifying cycle (for eligibility inclusion: ability to receive the same dose of
chemotherapy on study), this criteria ensures that the subject must be dose delayed
for platelet recovery

- Ability to receive the same dose and schedule of chemotherapy during the first
on-study treatment cycle as was given in the qualifying cycle (except Day 8
gemcitabine)

- ANC > or = 1,000/µL, Hgb > or = 9.5 g/dL, and platelet count > or = 100 x 10 ^9/L on
Day 1 of the first on study chemotherapy treatment cycle

- ECOG performance status of 0 to 2 at the time of screening

- Adequate Liver function; AST and ALT < 3.0 x ULN (except for subjects with a
confirmed diagnosis of Gilbert's Syndrome)

- Adequate renal function; serum creatinine < 1.5 x ULN

Exclusion Criteria:

- Receipt of > 1 prior systemic chemotherapy regimen

- Sepsis, disseminated coagulation or any other condition (i.e. ITP, TTP, HUS) that may
exacerbate thrombocytopenia

- History of unstable angina, CHF, uncontrolled hypertension (diastolic > 100mmHG),
uncontrolled cardiac arrhythmia, or recent (within 1 year of screening ) MI

- History of arterial thrombosis (e.g., stroke or transient ischemic attack) within 1
year of screening

- History of pulmonary embolism or other venous thrombosis within 1 year of screening
(except for catheter-related clots)

- Use of any nitrosourea or mitomycin-C within 6 weeks of screening

- Have received any thrombopoietic growth factor or related substance

- Have received granulocyte macrophage colony stimulating factor (GM-CSF) within the
last 4 weeks prior to screening

- Have received any experimental therapy within 4 weeks prior to screening

- Have ever received a bone marrow or peripheral blood stem cell infusion (within 1
year of screening)

- Known hypersensitivity to any recombinant E. coli-derived product