A Phase 1b/2 Study of OMP-59R5 (Tarextumab) in Combination With Etoposide and Platinum Therapy

Inclusion Criteria: Subjects must meet all of the following criteria to be eligible for the study: 1. Histologically or cytologically documented extensive stage small cell lung cancer. 2. Adults of 18 years of age or older. 3. Performance Status (ECOG) of 0 or 1. 4. Formalin Fixed Paraffin Embedded (FFPE) tumor tissue. 5. Adequate organ function: 1. Adequate hematologic function (absolute neutrophil count \[ANC\] ≥ 1,500 cells/μL; hemoglobin ≥ 9 g/dL, platelets ≥ 100,000/μL). 2. Adequate renal function (serum creatinine ≤ 1.5 mg/dL or calculated creatinine clearance ≥ 60 mL/min using Cockcroft-Gault formula). 3. Adequate hepatic function (alanine aminotransferase \[ALT\] ≤ 3 x upper limit of normal \[ULN\], ALT may be ≤ 5 x ULN if due to liver metastases but cannot be associated with concurrent elevated bilirubin \>1.5 times the upper limit of normal (ULN) unless it is approved by the Sponsor's Medical Monitor). 4. Prothrombin Time (PT)/International Normalized Ration (INR) ≤1.5 × ULN, activated partial thromboplastin time (aPTT) ≤1.5 × ULN. 6. Written consent on an Institutional Review Board (IRB)/IndependentEthics Committee (IEC)-approved Informed Consent Form prior to any study-specific evaluation. 7. For women of child-bearing potential, negative serum pregnancy test at screening and use of physician-approved method of birth control from 30 days prior to the first study drug administration to 30 days following the last study drug administration or the last EP in the study, whichever is discontinued last. 8. Male subjects must be surgically sterile or must agree to use physician-approved contraception during the study and for 30 days following the last study drug administration or the last EP in the study, whichever is discontinued last. Exclusion Criteria: Subjects who meet any of the following criteria will not be eligible for participation in the study: 1. Limited stage small cell lung cancer appropriate for radical treatment with chemoradiation. 2. Prior therapy including radiation, chemotherapy or surgery for newly diagnosed extensive stage small cell lung cancer. 3. Presence of any serious or uncontrolled illness including, but not limited to: ongoing or active infection, symptomatic congestive heart failure unstable angina pectoris, uncontrolled cardiac arrhythmia, uncontrolled arterial thrombosis, symptomatic pulmonary embolism, and psychiatric illness that would limit compliance with study requirement. 4. History of myocardial infarction, acute coronary syndromes (including unstable angina), coronary angioplasty and/or stenting within 6 months prior to the first administration of study drug. 5. A history of malignancy with the exception of: 1. Adequately treated basal cell carcinoma, squamous cell carcinoma of the skin, or in situ cervical cancer 2. Adequately treated stage I cancer from which the subject is currently in remission, or 3. Any other cancer from which the subject has been disease-free for ≥ 3 years 6. Known human immunodeficiency virus (HIV) infection. 7. Females who are pregnant or breastfeeding. 8. Concurrent use of therapeutic warfarin (prophylactic low dose of warfarin, i.e., 1 mg daily for port catheter is allowed)