• Written informed consent and HIPAA authorization for release of personal health information. NOTE: HIPAA authorization may be included in the informed consent or obtained separately.

• Age \>= 18 years at the time of consent.

• ECOG Performance Status of 0-1 within 14 days prior to registration (Appendix A of Protocol).

• Histological or cytological confirmed small cell lung carcinoma

• Extensive stage disease

• Patient must be considered suitable to receive a platinum-based chemotherapy as 1st line treatment for ES-SCLC. Chemotherapy must contain either Carboplatin or Cisplatin in combination with Etoposide.

• Measurable disease according to RECIST v1.1 for solid tumors within 28 days prior to registration.

• Prior treatment must be completed within the following number of days prior to registration:

⁃ -Palliative radiation: for painful bony lesion must be completed prior to registration and recovered from significant bone marrow toxicity. For patients who received WBRT, 14 days washout is required prior to study therapy. Patient's must be off steroids without worsening of symptoms related to brain metastases. Patient should be on stable doses of anti-convulsant.

• Demonstrate adequate organ function as defined in the protocol; all screening labs to be obtained within 14 days prior to registration

‣ Hematological

• Absolute Neutrophil Count (ANC) \>/= 1500/mm\^3

∙ Platelet \>/= 100,000/mm\^3

∙ Hemoglobin (Hgb) \>/= 9 g/dL

⁃ Renal

• Creatinine \</= 1.5 x ULN

∙ Calculated creatinine clearance \>/= 50 mL/min using the Cockcroft-Gault formula if creatinine is more than 1.5 x ULN (60 mL/min if receiving Cisplatin)

⁃ Hepatic

• Bilirubin \</= 1.5 x upper limit of normal (ULN), \</= 3 x ULN if history of Gilbert Syndrome

∙ Aspartate aminotransferase (AST) \</= 2.5 x ULN (if liver metastases then \</= 5 x ULN)

∙ Alanine aminotransferase (ALT) \</= 2.5 x ULN (if liver metastases then \</= 5 x ULN)

• Female subjects of childbearing potential and non-sterilized male subjects who intend to be sexually active during the study must agree to use a highly effective method of contraception from the time of screening, throughout the total duration of the drug treatment, and for 6 months after the last dose of study drug treatment.

• Evidence of post-menopausal status or negative urinary or serum pregnancy test for female pre-menopausal patients. Women will be considered post-menopausal if they have been amenorrheic for 12 months without an alternative medical cause. The following age-specific requirements apply:

‣ Women \<50 years of age would be considered post-menopausal if they have been amenorrheic for 12 months or more following cessation of exogenous hormonal treatments and if they have luteinizing hormone and follicle-stimulating hormone levels in the post-menopausal range for the institution or underwent surgical sterilization (bilateral oophorectomy or hysterectomy).

⁃ Women ≥50 years of age would be considered post-menopausal if they have been amenorrheic for 12 months or more following cessation of all exogenous hormonal treatments, had radiation-induced menopause with last menses \>1 year ago, had chemotherapy-induced menopause with last menses \>1 year ago, or underwent surgical sterilization (bilateral oophorectomy, bilateral salpingectomy or hysterectomy).

• As determined by the enrolling physician or protocol designee, ability of the subject to understand and comply with study procedures for the entire length of the study

• Ability to swallow and retain oral medication

• Must have a life expectancy of at least 12 weeks