Maintenance Treatment of Multiple Myeloma (MM) After Autologous Peripheral Blood Transplant (PBSCT) Using Polyethylene Glycol alpha2B Interpheron (PEG-INTRON)

* Multiple myeloma accounts for approximately 1% of all cancers and 10% of hematologic malignancies. Between 50 and 70% of symptomatic patients presented response to induction chemotherapy. The rate of complete responses (CR) achieved with standard induction of these treatments is less than 5% of cases and the median event-free survival between 2 and 3 years although most of the patients died from the disease. * High dose chemotherapy with autologous stem cell transplant has improved the response rate and survival of patient with MM. However eventually all patients relapse with a median EFS between 40-50 months post-transplant. * To improve these results and sustain remission, various maintenance treatment have been proposed as is the case of Interpheron alpha2b s.c. (Intron A) that has shown benefits in a meta-analysis. * Intron A s.c. need administration of 3 days per week and is not well tolerated * Recently a new formulation of Interpheron alpha2b is available. Conjugated with polietilenglicol (Pegintron) that need only one dose weekly and has not been tested in MM. * The purpose of this study is to evaluate the role of Pegintron as maintenance after autologous transplant in MM