This phase II trial is studying how well imatinib mesylate works in treating patients with stage III or stage IV melanoma that cannot be removed by surgery. Imatinib mesylate may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth.

PRIMARY OBJECTIVES:

I. Determine the overall objective response rate (complete response and partial response) in patients with inoperable stage III or IV melanoma harboring somatic alterations in c-KIT treated with imatinib mesylate.

SECONDARY OBJECTIVES:

I. Determine the time to progression in patients treated with this drug. II. Determine if c-KIT mutational status by DNA sequencing, DNA copy number status by fluorescent in situ hybridization (FISH) or comparative genomic hybridization, and/or protein expression by immunohistochemistry (IHC) can best predict clinical benefit from imatinib mesylate.

TERTIARY OBJECTIVES:

I. To evaluate tumors resistant to small molecule inhibitors of Kit for the development of secondary Kit mutations or for changes in Kit copy number.

II. To evaluate for changes in Ki-67, phospho-Akt, phospho-MEK, phospho-S6, phospho STAT3, cleaved caspase 3, IGF-1R, and Kit expression in paired tumor samples obtained from patients treated with a small molecule inhibitor of Kit.

III. To analyze baseline and post-resistance blood samples for soluble cKIT levels, soluble VEGFR1, soluble VEGFR2, VEGF, PlGF, FGF, and melanoma inhibitory activity (MIA) levels, and circulating tumor cells.

IV. To analyze concomitant samples of blood and tumor for imatinib levels in patients treated with imatinib.

OUTLINE: This is a multi-center study. Patients are stratified according to true amplification of c-KIT by FISH vs mutations by DNA sequencing.

Patients receive oral imatinib mesylate twice daily for up to 12 weeks in the absence of disease progression or unacceptable toxicity.

Tumor tissue samples or unstained tissue slides/paraffin blocks may be collected. c-KIT is evaluated by IHC and comparative genomic hybridization.

After completion of study treatment, patients are followed up periodically.

Inclusion Criteria:

• Histologically or cytologically confirmed inoperable stage III or IV melanoma that began on acral skin or mucosa

  • Patients with cutaneous melanoma that began on sun exposed sites of the skin and whose pathology demonstrates signs of sun damage (solar elastosis) involving the skin surrounding their primary melanoma are eligible

• Must have sufficient tumor tissue available for FISH and DNA sequencing

  • Patients must have either a true amplification of 4q12 or a detectable mutation of c-KIT
  • If no banked tumor tissue is available, or if the available banked tumor tissue is insufficient for the necessary testing, then a repeat biopsy procedure will be required to collect the necessary tumor sample

• Measurable disease according to Response Evaluation Criteria in Solid Tumors (RECIST) criteria

• No known untreated brain or epidural metastases

  • Brain metastases that have been treated and deemed stable are allowed

• ECOG performance status (PS) 0-2 OR Karnofsky PS 60-100%

• Life expectancy greater than 3 months

• WBC ≥ 3,000/mm³

• ANC ≥ 1,500/mm³

• Platelet count ≥ 100,000/mm³

• Bilirubin ≤ 1.5 times upper limit of normal (ULN)

  • Patients with unexplained hyperbilirubinemia that is clinically consistent with an inherited disorder of bilirubin metabolism (e.g., Gilbert's syndrome) may be eligible

• AST and ALT ≤ 2.5 times ULN (5 times ULN if hepatic metastases are present)

• Creatinine ≤ 1.5 times ULN

• PT and PTT ≤ 1.5 times ULN

• Not pregnant or nursing

• Negative pregnancy test

• Fertile patients must use effective contraception before and during study participation

• No history of allergic reactions attributed to compounds of similar chemical or biological composition to imatinib mesylate

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

  • Ongoing or active infection
  • Symptomatic congestive heart failure
  • Unstable anginapectoris
  • Cardiac arrhythmia resulting in hemodynamic instability
  • Intestinal malabsorption disorders
  • Psychiatric illness or social situations that would limit study compliance

• Recovered to grade 1 from all prior therapies with the exception of alopecia

• At least 2 weeks since prior radiotherapy (≤ 3,000 cGy to fields including substantial marrow)

• At least 2 weeks since prior isolated limb infusion or perfusion (must have evidence of progression despite this therapy)

• At least 2 weeks since prior chemotherapy

• No more than 2 prior chemotherapy regimen for metastatic melanoma

• Prior therapies with vaccines, targeted agents not believed to affect the kit proteins, cytokines, interferon-α, or intratumoral injections will NOT be considered prior therapy unless administered with a chemotherapy drug

• No prior therapy with an inhibitor of the kit protein

• No other concurrent investigational agents

• No other concurrent anticancer agents or therapies

• No concurrent antiretroviral therapy for HIV-positive patients

• No concurrent inhibitors of CYP3A4, including any of the following:

  • Fluconazole, itraconazole, ketoconazole, macrolide antibiotics (azithromycin, clarithromycin, erythromycin, troleandomycin),midazolam, nifedipine, verapamil, diltiazem, terfenadine, cyclosporine and cisapride

  • Herbal extracts and tinctures with CYP3A4 inhibitory activity, including the following:

    • Hydrastis canadensis (goldenseal), Hypericum perforatum (St. John's wort),Uncaria tomentosa (cat's claw), Echinacea angustifolia roots, Trifolium pratense(wild cherry), Matricaria, chamomilla (chamomile), Glycyrrhiza glabra (licorice), dillapiol, hypericin, and naringenin

• No concurrent inducers of CYP3A4, including any of the following:

  • Carbamazepine, phenobarbital, phenytoin, and rifampin