Immunotransplantation for multiple myeloma using allogeneic peripheral blood stem cell transplantation

Abstract

17516 Background: Despite the improvement seen in patients with multiple myeloma (MM) treated with autologous hematopoietic cell transplantation (auto-HCT), most of the patients relapse or die of their disease. The objective of the study was to decrease toxicity of allogeneic HCT for MM patients while allowing the benefit of graft-versus-myeloma effect by using a non-myeloablative HCT (NM- HCT) approach. Methods: Newly diagnosed or previously treated myeloma patients of any stage were enrolled. All patients but one received VAD regimen prior to conditioning regimen which consisted of Fludarabine at 30 mg/m2/day on days -5, -4, -3 and Melphalan at 80 mg/m2 x 2 on days -2 and -1. Graft-versus-host disease (GVHD) prophylaxis included cyclosporine 3 mg/kg intravenously on day -2 and methotrexate at 10 mg/m2 intravenously on days 3, 6, and 11. Results: A total of 8 MM patients (4 IgG, 1 IgA, 1 light chain restriction, 2 non-secretory MM) with a median age of 46 years old (range, 35 to 57 years) have been enrolled. Only one patient received 3 regimens prior to NM-HCT. The initial responses to therapy prior to NM-HCT were: 2 CR, 1 nCR, and 5 PR. All patients received identical 6/6 HLA sibling donor stem cells. All patients but one attained CR (88%) after NM-HCT. The median time for ANC engraftment (≥ 500/mm3) was 12.5 days (range, 10–22 days). Four patients developed acute GVHD grade I-II (3 skin, 1 gastrointestinal); all of them responded well to methylprednisolone treatment. Four patients developed chronic GVHD (grade I-II). The 100-day mortality rate was 12% (1 patient died at day + 96 without evidence of MM). Post-transplant, all patients have reported a Karnofsky’s scale performance status between 80%-100%. Two patients relapsed after 31 months post-transplantation. After a median follow-up of 46 months, median survival has not been reached. Only 1 patient who relapsed has received treatment including auto-HCT. Conclusions: NM-HCT is a feasible treatment option in MM patients with a manageable toxicity profile and acceptable treatment-related mortality. Longer follow-up is needed to evaluate for graft-vs- myeloma effect using this approach. No significant financial relationships to disclose.