Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed AL amyloidosis

- Persistent or recurrent disease after 1 course of prior high-dose chemotherapy

- Previously treated with autologous stem cell transplantation

- Significant initial improvement in organ function after prior high-dose melphalan,
defined by at least 1 of the following:

- Complete hematologic remission (e.g., absence of monoclonal spike by
immunofixation in serum and urine AND less then 5% plasma cells in bone marrow
with no clonal predominance) OR partial hematologic response (e.g., any decrease
in serum or urine monoclonal protein OR decrease in bone marrow plasmacytosis)

- Greater than 50% reduction in proteinuria with preservation of creatinine
clearance

- Greater than 50% reduction in alkaline phosphatase OR at least 2 cm decrease in
liver size by physical exam

- Subjective neurologic improvement, as confirmed by neurologist

- Cardiac stabilization of disease confirmed by echocardiography defined as less
than 2 mm increase in mean wall thickness and/or less than 20 g increase in left
ventricular mass

- Improvement in performance status* NOTE: *This criteria alone does not
constitute significant improvement in organ function

- No myelodysplastic syndromes

- No abnormal bone marrow cytogenetics

- Prior stem cell yield must have been ≥ 2 x 10^6 CD34+ cells/kg

PATIENT CHARACTERISTICS:

Age

- 18 to 65

Performance status

- SWOG 0-2

Life expectancy

- More than 6 months

Hematopoietic

- See Disease Characteristics

Hepatic

- See Disease Characteristics

Renal

- See Disease Characteristics

Cardiovascular

- See Disease Characteristics

- LVEF ≥ 45% by MUGA or echocardiogram

Pulmonary

- DLCO ≥ 50%

Other

- Not pregnant or nursing

- Fertile patients must use effective contraception

- Acceptable toxicity from first transplantation, confirmed by the transplant team

- HIV negative

- No other concurrent malignancy except treated skin cancer

PRIOR CONCURRENT THERAPY:

Biologic therapy

- See Disease Characteristics

Chemotherapy

- See Disease Characteristics

- No chemotherapy after first transplantation

Endocrine therapy

- Not specified

Radiotherapy

- Not specified

Surgery

- Not specified