Inclusion Criteria:

- Histologically or cytologically confirmed small cell lung cancer

- Extensive stage disease

- Recurrent disease

- Measurable disease

- Chemotherapy-sensitive disease, defined as:

- No progression during first-line chemotherapy

- No disease recurrence < 2 months after completion of first-line chemotherapy

- Must have received prior platinum-based chemotherapy

- No symptomatic or progressive brain metastases

- Patients with previously treated brain metastases who are clinically and
radiographically stable or improved and have been off steroids ≥ 14 days are
eligible

- ECOG performance status 0-2

- Life expectancy > 12 weeks

- Leukocytes ≥ 3,000/μL

- ANC ≥ 1,500/μL

- Platelet count ≥ 100,000/μL

- Total bilirubin < 1.5 mg/dL

- AST and ALT ≤ 2.5 times upper limit of normal

- Serum creatinine ≤ 1.5 mg/dL OR creatinine clearance ≥ 60 mL/min

- Hemoglobin > 8 g/dL

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception before, during, and for 30 days
after completion of study therapy

- Able to take oral medications on a regular basis

- Willing to provide blood samples for mandatory correlative studies

- No condition that impairs the ability to swallow and retain R-(-)-gossypol tablets,
including the following:

- Gastrointestinal tract disease resulting in an inability to take oral medication
or a requirement for IV alimentation

- Active peptic ulcer disease

- No malabsorption syndrome or disease significantly affecting gastrointestinal
function

- No ulcerative colitis, inflammatory bowel disease, or a partial or complete small
bowel obstruction

- No uncontrolled concurrent illness including, but not limited to, any of the
following:

- Ongoing or active infection

- Symptomatic congestive heart failure

- Unstable angina pectoris

- Cardiac arrhythmia

- Psychiatric illness or social situations that would limit compliance with study
requirements

- No symptomatic hypercalcemia > grade 2

- No requirement for routine use of hematopoietic growth factors (including G-CSF,
GM-CSF, or IL-11) or platelet transfusions to maintain ANC or platelet counts

- No history of allergic reactions attributed to compounds of similar chemical or
biologic composition to R-(-)-gossypol

- No HIV positivity

- Recovered from all prior therapy, including prior surgical procedures

- No prior surgical procedures affecting absorption

- No prior resection of the stomach or small bowel

- No more than one prior chemotherapy regimen

- No prior racemic gossypol or R-(-)-gossypol

- At least 4 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin C)

- At least 4 weeks since prior radiotherapy, hormonal agents, or biologic response
modifiers

- At least 4 weeks since prior and no concurrent investigational agents or devices

- No concurrent prophylactic hematopoietic growth factors (including filgrastim
[G-CSF], sargramostim [GM-CSF], or interleukin-11 [IL-11]) during course one

- No concurrent combination antiretroviral therapy for HIV-positive patients