Melphalan and Busulfan Followed By Donor Peripheral Stem Cell Transplant, Tacrolimus, and Methotrexate in Treating Patients With Multiple Myeloma

DISEASE CHARACTERISTICS:

* Diagnosis of multiple myeloma

  * Stage I disease with disease progression during the second of ≥ 2 lines of prior therapy
  * Stage II or III disease, meeting 1 of the following criteria:

    * Failed to achieve at least a partial response after ≥ 2 courses of prior therapy
    * Progressive disease after ≥ 2 courses of prior therapy
    * Presented with high-risk features at diagnosis, including any of the following:

      * Cytogenetic abnormality
      * Del 13 or 4,14 by fluorescent in situ hybridization (FISH)
      * Elevated lactic dehydrogenase
      * Beta 2 microglobulin \> 5.5
      * Circulating peripheral blood plasma cells
  * Any stage disease with disease progression \> 6 months after prior autologous stem cell transplantation
* Availability of an HLA-matched, related donor between 12 and 75 years of age\*

  * No bone marrow donors NOTE: \*Donors \> 75 years of age are eligible at the discretion of the principal investigator

PATIENT CHARACTERISTICS:

* Karnofsky performance status 70-100%
* Creatinine clearance \> 60 mL/min
* Bilirubin ≤ 2.5 mg/dL
* ALT/AST \< 2 times upper limit of normal
* Cardiac ejection fraction ≥ 49%
* DLCO ≥ 50% corrected
* FEV\_1 ≥ 60%
* Not pregnant or nursing
* Fertile patients must use effective contraception
* HIV negative
* No cirrhosis
* No chronic inflammatory or fibrotic liver disease

PRIOR CONCURRENT THERAPY:

* See Disease Characteristics
* At least 6 months since prior autologous transplantation