Immunotherapy with Rituximab after Peripheral Blood Stem Cell Transplantation for Multiple Myeloma.

Introduction: autologous stem cell transplantation is a potentially curative or may augment the time to progression in Multiple Myeloma (MM) patients. The immunotherapy with rituximab may help control the minimal residual disease after high dose chemotherapy. Twenty percent (20%) of Multiple Myeloma patients express the CD20+ protein and can be target for immunotherapy.

Objective: The aim of this study was to evaluate the use of rituximab after autologous stem cell transplantation for Multiple Myeloma.

Patients and Methods: eight patients (4 male) with a median age of 53 (range 43–59) years diagnosed with MM. All of them had received at least one previous regimen were enrolled in the protocol study. All patients signed the consent form. Patients in relapse received a salvage regimen with C-VAD n=2 (cyclofosfamide 4 g/m² e vincristine 0.4 mg/d (d 1–4), doxorrubicin 0.9 mg/m2 (d1-4) e dexametasone 40 mg (d1-4; 9-12; 17–22) or cyclofosfamide (1OO mg/kg, n=7) followed by stem cell harvesting. The preparative regimen was Busulfan 12 mg/kg and cyclofosfamide 120 mg/kg or Melphalan 200mg/m². Rituximab at a dose of 375mg/m² weekly x 4 was given every 6 months for 2 years after SCT. The clinical characteristics of the patients are shown on Table 1.

Results: the median time to ANC and platelets engraftment was 11 (range 8–12) and 26 (range 17–35) days. Patients have been in CR at a median time of 11 months follow-up. Minor Rituximab-associated toxicities were seen:rigor, fever and short of breath that were controlled with acetaminophen and diphenidramine.

Conclusion: the Rituximab given after autologous stem cell transplantation is safe in Multiple Myeloma patients and may prolong time to disease progression. A randomized study is required to evaluate the role of rituximab after ASCT.

Table 1 - Clinical Characteristics of Patients