RATIONALE: Drugs used in chemotherapy use different ways to stop cancer cells from dividing so they stop growing or die. Combining more than one drug may kill more cancer cells.

PURPOSE: Phase II trial to study the effectiveness of combining arsenic trioxide and dexamethasone in treating patients who have recurrent or refractory stage II or stage III multiple myeloma.

OBJECTIVES:

• Determine the response rate of patients with recurrent or refractory stage II or III multiple myeloma treated with arsenic trioxide and dexamethasone.
• Determine the rates of overall and relapse-free survival in patients treated with this regimen.
• Determine the safety profile of this treatment regimen in these patients.

OUTLINE: Patients receive arsenic trioxide IV daily for 5 days during the first week only and then 2 days a week thereafter. Patients also receive IV or oral dexamethasone on days 1-4 every 4 weeks. Treatment continues in the absence of disease progression or unacceptable toxicity. Disease assessments are conducted every 4 weeks. Patients achieving complete response (CR) receive 2 additional courses of therapy after initial determination of CR.

Final assessments are conducted 4 weeks after the last study treatment and then annually thereafter.

PROJECTED ACCRUAL: A total of 55 patients will be accrued for this study.

DISEASE CHARACTERISTICS:

• Diagnosis of stage II or III multiple myeloma

• Refractory myeloma defined as progressive disease (more than 25% increase in M protein or in radiographic findings of nonsecretory myeloma) despite up to 3 courses of prior cytotoxic chemotherapy

  • No more than 3 prior cytotoxic regimens
  • No more than 1 prior high-dose cytotoxic regimen with stem cell transplantation

• History of disease progression after prior steroid antimyeloma therapy

• No smoldering myeloma

• Measurable disease based on presence of serum and urine M protein and/or measurable plasmacytoma

PATIENT CHARACTERISTICS:

Age:

• Over 18

Performance status:

• Karnofsky 70-100%

Life expectancy:

• At least 3 months

Hematopoietic:

• Absolute granulocyte count greater than 1,200/mm^3*
• Platelet count greater than 75,000/mm^3*
• Hemoglobin greater than 10 g/dL* NOTE: *Unless due to multiple myeloma

Hepatic:

• Bilirubin no greater than 2 times upper limit of normal (ULN)
• SGOT and SGPT no greater than 2 times ULN

Renal:

• Creatinine no greater than 1.5 times ULN

Cardiovascular:

• Absolute QT interval less than 460 msec in the presence of normal potassium and magnesium levels
• No significant underlying cardiac dysfunction
• No conduction defects
• No unstable angina
• No congestive heart failure
• No New York Heart Association class II-IV cardiac disease
• No myocardial infarction within the past 6 months

Other:

• No preexisting grade 2 or greater neurotoxicity/neuropathy
• No other malignancy within the past 5 years except curatively treated carcinoma in situ of the cervix or nonmelanoma skin cancer
• No uncontrolled diabetes mellitus
• No active serious infection uncontrolled by antibiotics
• No history of grand mal seizures (other than infantile febrile seizures)
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• See Disease Characteristics
• See Chemotherapy
• At least 28 days since prior biologic therapy

Chemotherapy:

• See Disease Characteristics
• At least 28 days since prior cytotoxic chemotherapy, including high-dose cytotoxic regimen with stem cell transplantation
• No other concurrent cytotoxic chemotherapy

Endocrine therapy:

• See Disease Characteristics

Radiotherapy:

• At least 28 days since prior radiotherapy except for focal radiation for symptom control

Surgery:

• Not specified