Melphalan and Amifostine Followed By One or Two Autologous or Syngeneic Stem Cell Transplants and Maintenance Therapy in Treating Patients With Stage II-III Multiple Myeloma

Inclusion Criteria:

* Patients who have MM undergoing autologous or syngeneic hematopoietic transplantation
* Patients must meet Salmon and Durie criteria for initial diagnosis of MM
* Transplant will be offered to patients with stage II or III MM
* Measurable disease, defined as serum monoclonal protein \>= 0.2 g/dl or Bence Jones protein \>= 200 mg/24 h
* Karnofsky \>= 70 or Eastern Cooperative Oncology Group (ECOG) 0-2
* Life expectancy is not severely limited by concomitant illness
* Left ventricular ejection fraction \>= 50%
* No uncontrolled arrhythmias or symptomatic cardiac disease
* Forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and diffusion capacity of carbon monoxide (DLCO) \>= 50%
* No symptomatic pulmonary disease
* Human immunodeficiency virus (HIV) negative
* Bilirubin \< 2 mg/dl
* Serum glutamic pyruvate transaminase (SGPT) \< 2.5 x normal
* Creatinine clearance \>= 60 cc/min, estimated or measured
* Signed informed consent

Exclusion Criteria:

* Pregnant or lactating females
* Uncontrolled infection
* Planned tandem autologous/reduced intensity allograft
* Insufficient PBSC for an autologous transplant (\< 3.0 x 10\^6 CD34+ cells/kg total)
* Prior autologous transplant
* Non-secretory myeloma and patients who are in a complete response or near complete response after conventional therapy
* Patients unwilling to practice adequate forms of contraception if clinically indicated
* Male patients on study need to be consulted to use latex condoms, even if they have had a vasectomy, every time they have sex with a woman who is able to have children
* Patients with history of seizures
* Patients receiving antihypertensive therapy that cannot be stopped for 24 hours preceding amifostine treatment