Inclusion Criteria:

- Biopsy-confirmed malignant melanoma

- Stage IV disease

- Cutaneous or mucosal origin

- Melanoma of unknown primary allowed

- No ocular melanoma

- Measurable or non-measurable disease

- No prior or concurrent brain metastases as confirmed by CT scan or MRI

- Zubrod performance status 0-1

- ANC ≥ 1,500/mm^3

- Platelet count ≥ 100,000/mm^3

- Hemoglobin ≥ 9 g/dL

- Serum bilirubin ≤ 1.5 times upper limit of normal (ULN) (including patients with
hepatic metastases)

- SGOT or SGPT ≤ 2.5 times ULN (≤ 5 times ULN in the presence of hepatic metastases)

- Serum creatinine ≤ 1.5 times ULN

- Not pregnant or nursing

- Fertile patients must use effective contraception

- No other prior malignancy except for adequately treated basal cell or squamous cell
skin cancer, in situ cervical cancer, adequately treated stage I or II cancer from
which the patient is currently in complete remission, or any other cancer from which
the patient has been disease-free for 5 years

- No prior therapy with a cyclin-dependent kinase inhibitor

- At least 14 days since prior radiotherapy

- At least 28 days since prior systemic chemotherapy

- At least 28 days since prior adjuvant systemic therapy

- At least 28 days since prior surgery

- No more than 1 prior systemic therapy regimen (chemotherapy, biologic/immunotherapy,
hormonal therapy, or a combination regimen) for stage IV melanoma and any side
effects must have resolved to ≤ grade 1

- Any number of prior adjuvant systemic therapy regimens allowed, including interferon
alfa-2b, GM-CSF, chemotherapy, and chemobiotherapy

- Therapy for stage IV resected free-of-disease will be considered adjuvant
therapy

- Prior radiotherapy allowed provided any side effects have resolved to ≤ grade 1

- Prior surgery (for both the primary and stage IV disease) allowed provided side
effects have resolved to ≤ grade 1

- No other concurrent or planned non-study treatment (including chemotherapy, hormonal
therapy, biologic therapy, or radiotherapy)

- No concurrent CYP3A4 inhibitors or inducers

- No concurrent grapefruit or grapefruit juice