A Study to Assess the Safety and Preliminary Efficacy of PT-523 in Patients With Advanced Non-Small Cell Lung Cancer (NSCLC)

Inclusion Criteria: * Age ≥ 18 years * Histologically or cytologically confirmed NSCLC which is stage III or stage IV, or recurrent disease, and failed therapy with a standard first line (Phase I/II) as well as second line chemotherapy regimen (Phase I), or be intolerant of standard chemotherapy. Receipt of one additional prior chemotherapy regimen for neoadjuvant, adjuvant, or neoadjuvant plus adjuvant is allowable. A prior epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TK) antagonist is allowable (Phase II). * Asymptomatic or treated brain metastases (including steroids) if last therapy was received \> 4 weeks from study entry and is deemed by the investigator to have a low likelihood of rapid deterioration. * ECOG performance status 0 - 2. * Adequate organ function and bone marrow reserve. * Use of appropriate contraceptive method. * Signed patient informed consent. Exclusion Criteria: * Investigational agents within 30 days prior to Day 1 of study. * Known symptomatic or uncontrolled brain metastases. * Uncontrolled intercurrent illness. * Known human immunodeficiency virus (HIV), hepatitis A, B, C, D and E. * Patient has uncontrolled pleural effusions. * Patient has received nitrosoureas or mitomycin-C within 6 weeks or other chemotherapy or radiation therapy within 3 weeks before study entry.