Inclusion Criteria:

- Written informed consent granted prior to initiation of any study-specific screening
procedures, given with the understanding that the patient has the right to withdraw
from the study at any time, without prejudice

- Histologic or cytologic diagnosis of SCLC (Note: patients with mixed histology are
not eligible)

- Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1

- Presence of measurable disease defined as >= 1 lesion whose longest diameter can be
accurately measured as >= 20 mm with conventional techniques or as >= 10 mm with
spiral computed tomography (CT)

- Previously treated SCLC with only one prior treatment regimen
(cyclophosphamide/doxorubicin/vincristine [CAV] alternating with etoposide/cisplatin
[EP] is acceptable)

- Resolution of all acute toxic effects of prior chemotherapy, radiotherapy, hormonal
therapy, or surgery to National Cancer Institute (NCI)-Common Terminology Criteria
for Adverse Events (CTCAE) version 4.0 grade 1, except for diarrhea (which must be
grade 0 without supportive antidiarrheal medications) and alopecia (any grade)

- Platelet count >= 100 x 10^9/L

- Hemoglobin (Hgb) >= 9 gm/dL

- Absolute neutrophil count (ANC) >= I 500/uL

- Serum creatinine =< 1.5 mg/dL or creatinine clearance > 45 mL/min; use either
measured or calculated with Cockroft and Gault formula

- Serum total bilirubin >= 1.5 x upper limit of normal (ULN)

- Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) 3 x ULN or 5 x
ULN if caused by liver metastasis

- Women of childbearing potential must have a negative pregnancy test performed within
seven days prior to the start of study drug; male and female subjects of
child-bearing potential must agree to use double-barrier contraceptive measures, or
avoidance of intercourse during the study and for 90 days after last investigational
drug dose received

Exclusion Criteria:

- Previous anti-cancer chemotherapy, immunotherapy or investigational agents < 4 weeks
(6 weeks for nitrosoureas or mitomycin C) prior to the first day of study defined
treatment; palliative radiation < 2 weeks, biological therapy within 2 weeks,
hormonal therapy within 1 week prior to day I cycle 1

- Prior treatment with a topoisomerase-I inhibitor (e.g., topotecan, irinotecan)

- Prior malignancy except for non-melanoma skin cancer and carcinoma in situ, unless
diagnosed and definitively treated more than 5 years prior to enrollment

- Substance abuse, medical, psychological or social conditions that may, in the opinion
of the Investigator, interfere with the patient's participation in the study or
evaluation of the study results

- Known human immunodeficiency virus (HIV) infection

- Pregnancy or breast-feeding

- Concurrent administration or received cytochrome P450 3A4 (CYP3A4) inducers or
inhibitors within 2 weeks prior to the first day of study drug treatment

- Patients with chronic or acute gastrointestinal (GI) disorders resulting in diarrhea
of any severity grade; patients who are using chronic anti-diarrheal supportive care
(more than 3 days/week) to control diarrhea in the 28 days prior to study entry

- Major surgery < 4 weeks or minor surgery (e.g. talc pleurodesis, excisional biopsy,
etc) < 2 weeks prior to the first day of study defined treatment

- Have central nervous system (CNS) metastases (unless the patient has completed
successful local therapy for CNS metastases and has been off corticosteroids for at
least 4 weeks before starting study therapy); brain imaging is required in
symptomatic patients to rule out brain metastases, but is not required in
asymptomatic patients

- Uncontrolled intercurrent illness including, but not limited to, ongoing or active
infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac
arrhythmia, or psychiatric illness/social situations that would limit compliance with
study requirements

- Unwilling or unable to follow protocol requirements