Inclusion Criteria

DISEASE CHARACTERISTICS:

- Diagnosis of multiple myeloma (MM) according to the Durie and Salmon criteria

- Refractory to or in early relapse after standard chemotherapy with or without stem
cell transplantation

- Measurable disease

- Quantifiable IgM, IgG, or IgA paraprotein in serum AND/OR

- Bence-Jones protein in urine

- No plasma cell leukemia (more than 20% plasma cells in peripheral blood and an
absolute plasma cell count of at least 2,000/mm3)

- No nonsecretory MM

- No spinal cord compression

PATIENT CHARACTERISTICS:

Age:

- 18 and over

Performance status:

- ECOG 0-2

Life expectancy:

- More than 6 months

Hematopoietic:

- No clinical symptoms of hyperviscosity

Hepatic:

- Not specified

Renal:

- Creatinine no greater than 2 times upper limit of normal

- Calcium no greater than 11 mg/dL

Other:

- No other prior malignancy within the past 5 years except basal cell carcinoma of the
skin or carcinoma in situ of the cervix

- No severe allergy to fish or seafood

- No medical condition that would interfere with intake and/or absorption of study
medication (e.g., gastrectomy or major intestinal resection)

- No significant medical or psychiatric condition that would preclude study
participation

- Not pregnant

- Negative pregnancy test

- Fertile patients must use adequate contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

- See Disease Characteristics

- No prior history of treatment with thalidomide for more than 14 days duration

- At least 4 weeks since prior biological therapy for MM

- Concurrent epoetin alfa allowed

Chemotherapy:

- See Disease Characteristics

- At least 4 weeks since prior chemotherapy for MM

Endocrine therapy:

- At least 4 weeks since prior steroid therapy for MM

- No prednisone maintenance therapy

Radiotherapy:

- At least 4 weeks since prior radiotherapy

- No concurrent palliative or curative radiotherapy

Surgery:

- Not specified

Other:

- At least 28 days since other prior shark cartilage products

- At least 28 days since other prior experimental therapeutic agents

- Concurrent monthly bisphosphonate (pamidronates) infusions allowed

- No other concurrent anticancer treatment

- No other concurrent shark cartilage products

- No other concurrent therapies for MM