A Study of LY2940680 in Small Cell Lung Cancer

Inclusion Criteria: * Histological or cytological diagnosis of Small Cell Lung Cancer (SCLC), including malignant pleural effusion that is extensive stage per the International Staging System * Performance status of 0 to 1 on the Eastern Cooperative Oncology Group (ECOG) performance status schedule * No prior systemic chemotherapy, immunotherapy, or biological therapy for SCLC * Prior radiation therapy allowed to \<25% of the bone marrow. Participants who have received prior radiation to the whole pelvis or chest for the treatment of SCLC are not eligible * At least 1 unidimensionally measurable lesion meeting Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 * Adequate organ function including the following: * Adequate bone marrow reserve: absolute neutrophil count (ANC) ≥1.5 x 10\^9/ liter (L), platelets ≥100 x 10\^9/L, and hemoglobin ≥9 grams/deciliter (g/dL) * Hepatic: bilirubin ≤1.5 times the upper limit of normal (ULN), alkaline phosphatase (AP), Serum alanine aminotransferase (ALT) and aspartate transaminase (AST) ≤3.0 x ULN (AP, AST, and ALT ≤5 x ULN is acceptable if liver has tumor involvement) * Renal: calculated creatinine clearance (CrCl) ≥50 milliliters per minute (mL/min) based on the standard Cockcroft and Gault formula * Estimated life expectancy of at least 12 weeks * For women: Must be surgically sterile, post-menopausal, or compliant with a medically approved contraceptive regimen during and for 6 months after the treatment period; must have a negative serum pregnancy test within 7 days before study enrollment. For men: Must be surgically sterile or compliant with a contraceptive regimen during and for 6 months after the treatment period * Availability of a tumor tissue sample * Able to swallow capsules Exclusion Criteria: * Currently enrolled in, or discontinued within the last 30 days from, a clinical trial involving an investigational product or non-approved use of a drug or device, or concurrently enrolled in any other type of medical research judged not to be scientifically or medically compatible with this study * Have previously participated in a study involving LY2940680 * Have previously received treatment with carboplatin or etoposide * Have a mixed histological diagnosis of SCLC and Non-Small Cell Lung Cancer (NSCLC) * Have a serious concomitant systemic disorder that, in the opinion of the investigator, would compromise the participant's ability to adhere to the protocol * Have an active infection \[≥38.5 degrees Celsius and/or receiving Intravenous (IV) antibiotic therapy\] * Have a serious cardiac condition * Have had a prior malignancy other than SCLC, carcinoma in situ of the cervix, or nonmelanoma skin cancer, unless that prior malignancy was diagnosed and definitively treated at least 5 years previously with no subsequent evidence of recurrence. Participants with a history of non-metastatic prostate cancer, including biochemical relapse only, will be eligible even if diagnosed less than 5 years previously * Symptomatic central nervous system (CNS) metastases and asymptomatic CNS metastases requiring concurrent corticosteroid therapy. Treated stable CNS metastases are allowed; the participant must be stable after radiotherapy for ≥2 weeks and off of corticosteroids for ≥1 week * Presence of clinically significant third-space fluid collections that cannot be controlled prior to study entry * Significant weight loss (that is, ≥10%) over the 6-week period prior to study entry * Concurrent administration of any other antitumor therapy. An exception will be made for non-metastatic prostate cancer participants continuing androgen blockade therapy only or breast cancer participants continuing adjuvant antiestrogen therapy only (for example, an aromatase inhibitor) * Females who are breastfeeding * Have corrected QT interval (QTc) of \>470 millisecond (msec) on screening electrocardiogram (ECG) * Have received medications that are strong inhibitors of Cytochrome P450 3A4 (CYP3A4) within 7 days prior to receiving study drug