RATIONALE: Herpesvirus is found in the lesions of most patients with Kaposi's sarcoma, and may have a role in causing Kaposi's sarcoma. Valganciclovir is an antiviral drug that acts against many types of herpesviruses and may be an effective treatment for Kaposi's sarcoma.

PURPOSE: This clinical trial is studying how well valganciclovir works in treating patients with classic non-HIV-associated Kaposi's sarcoma.

OBJECTIVES:

Primary

• Determine the antitumor activity of valganciclovir in patients with classic non-HIV-associated Kaposi's sarcoma (KS).

Secondary

• Determine the effect of this drug on lytic and latent human herpesvirus-8 gene expression in KS lesions of these patients.
• Determine the effect of this drug on the markers of angiogenesis in KS lesions of these patients.
• Determine the safety and tolerability of this drug in these patients.

OUTLINE: This is a pilot study.

Patients receive oral valganciclovir twice daily for 3 weeks and then once daily for 21 weeks in the absence of disease progression or unacceptable toxicity.

All patients are followed for 1 month after completion of therapy. Patients with responding disease are followed monthly for up to 1 year.

PROJECTED ACCRUAL: A total of 15 patients will be accrued for this study within 1 year.

DISEASE CHARACTERISTICS:

• Histologically confirmed classic Kaposi's sarcoma (KS) involving the skin

  • Non-HIV-associated disease

    • HIV negative

• Measurable disease

  • At least 8 KS lesions with ≥ 5 marker lesions measurable in 2 dimensions AND ≥ 3 other lesions measuring ≥ 1 cm in diameter

    • Two 3 mm punch biopsies of a non-marker lesion entirely composed of KS

  • Irradiated cutaneous lesions may not be used as indicator lesions

• No known active visceral KS or symptomatic KS-related edema that would preclude function or require cytotoxic chemotherapy

PATIENT CHARACTERISTICS:

Age

• 18 and over

Performance status

• Karnofsky 70-100%

Life expectancy

• At least 12 months

Hematopoietic

• Hemoglobin ≥ 8 g/dL
• Absolute neutrophil count ≥ 1,500/mm^3
• Platelet count ≥ 100,000/mm^3

Hepatic

• Bilirubin ≤ 1.5 times upper limit of normal (ULN)
• AST and ALT ≤ 3 times ULN

Renal

• Creatinine clearance ≥ 50 mL/min

Other

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective barrier contraception during and for 3 months after study participation
• No hypersensitivity to valganciclovir or ganciclovir
• No other neoplasia requiring cytotoxic therapy

PRIOR CONCURRENT THERAPY:

Biologic therapy

• More than 4 weeks since prior biological therapy for KS
• No concurrent immunotherapy

Chemotherapy

• More than 4 weeks since prior chemotherapy for KS
• No concurrent chemotherapy

Endocrine therapy

• No concurrent corticosteroid treatment except for replacement doses (equivalent to 20 mg of hydrocortisone per day)

Radiotherapy

• See Disease Characteristics
• More than 4 weeks since prior radiotherapy for KS
• No concurrent radiotherapy

Surgery

• Not specified

Other

• More than 14 days since prior acute treatment for infection (other than oral thrush or genital herpes) or other serious medical illness
• More than 60 days since prior local therapy for any KS indicator lesion unless the lesion showed documented progression since treatment
• More than 4 weeks since prior local therapy for KS
• More than 4 weeks since prior investigational agents
• More than 4 weeks since other prior antineoplastic therapy for KS
• No other concurrent antiviral therapy
• No other concurrent investigational agents
• No other concurrent systemic therapy for KS