RATIONALE: Antineoplastons are naturally-occurring substances that may also be made in the laboratory. Antineoplastons may inhibit the growth of cancer cells.

PURPOSE: This phase II trial is studying how well antineoplaston therapy works in treating patients with neuroendocrine tumor that is metastatic or unlikely to respond to surgery or radiation therapy.

OBJECTIVES:

• Provide treatment with antineoplastons A10 and AS2-1 for patients with metastatic or incurable neuroendocrine tumors.
• Describe response, tolerance to, and side effects of this regimen in these patients.

OUTLINE: This is an open-label study.

Patients receive gradually escalating doses of antineoplastons A10 and AS2-1 by intravenous injection 6 times daily until the maximum tolerated dose is reached.

Treatment continues for at least 2 months in the absence of unacceptable toxicity or disease progression. Patients achieving complete response (CR) continue treatment for an additional 8 months after reaching CR.

Tumors are measured every 2 months for 1 year and then every 3 months for 1 year.

PROJECTED ACCRUAL: Approximately 20-40 patients will be accrued for this study.

• Merkel Cell Carcinoma
• Islet Cell Carcinoma
• Neuroendocrine Carcinoma
• Pituitary Tumor

• Drug: antineoplaston A10
• Drug: antineoplaston AS2-1
• Procedure: alternative product therapy
• Procedure: biological therapy
• Procedure: biologically based therapies
• Procedure: cancer prevention intervention
• Procedure: complementary and alternative therapy
• Procedure: differentiation therapy

DISEASE CHARACTERISTICS:

• Histologically confirmed incurable neuroendocrine tumor that is unlikely to respond to existing therapy, meeting 1 of the following criteria:
• Metastatic disease
• Disease that is not curable with surgery or radiotherapy
• Measurable disease by MRI or CT scan
• Tumor must be at least 2 cm

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• Karnofsky 60-100%

Life expectancy:

• At least 2 months

Hematopoietic:

• WBC at least 2,000/mm^3
• Platelet count at least 50,000/mm^3

Hepatic:

• No hepatic insufficiency
• Bilirubin no greater than 2.5 mg/dL
• SGOT and SGPT no greater than 5 times upper limit of normal

Renal:

• No renal insufficiency
• Creatinine no greater than 2.5 mg/dL
• No history of renal conditions that contraindicate high dosages of sodium

Cardiovascular:

• No uncontrolled hypertension
• No history of congestive heart failure
• No history of other cardiovascular conditions that contraindicate high dosages of sodium

Pulmonary:

• No serious lung disease, such as chronic obstructive pulmonary disease

Other:

• Not pregnant or nursing
• Fertile patients must use effective contraception during and for 4 weeks after study participation
• No active infection
• No concurrent nonmalignant systemic disease
• Not a high medical or psychiatric risk

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• At least 4 weeks since prior immunotherapy
• No concurrent immunomodulating agents

Chemotherapy:

• At least 4 weeks since prior chemotherapy (6 weeks for nitrosoureas)

Endocrine therapy:

• Concurrent corticosteroids allowed

Radiotherapy:

• At least 8 weeks since prior radiotherapy

Surgery:

• Recovered from prior surgery

Other:

• Prior cytodifferentiating agents allowed
• No prior antineoplastons
• No other concurrent antineoplastic agents