Allogeneic Hematopoietic Cell Transplantation for Consolidation of VGPR or CR In Myeloma

Abstract 4581

Allogeneic hematopoietic cell transplantation (HCT) from HLA-identical siblings has been shown to prolong survival of patients with multiple myeloma in some studies. However, all published clinical trials of up front allogenic transplant for myeloma were conducted before thalidomide, lenalidomide and bortezomib became available; as such, less than 10% of the patients were in complete remission (CR) at time of transplantation. With contemporary therapy incorporating novel agents, more than 50% of patients achieve very good partial response (VGPR) or better (VGPR or CR). We summarize our experience with the safety and efficacy of allogeneic transplantation for patients achieving VGPR or better following induction therapy containing novel agent(s). Thirteen myeloma patients with first VGPR or CR received allogeneic HCT between July 2007 and January 2011. Median age at transplant was 45 years (range, 25 – 59), median time from initial therapy to transplant was 236 days (range, 122 – 410). Six patients (46%) have high-risk cytogenetics/FISH. Five patients received bortezomib plus lenalidomide induction therapy and eight patients received bortezomib-induction. Three patients (23%) underwent autologous HCT with melphalan plus bortezomib conditioning (melphalan 100 mg/m² for 2 days followed by bortezomib 1.3 mg/m²) subsequent to induction therapies to achieve further cytoreduction prior to allogeneic HCT. Median number of prior therapies was 2 (range, 1–2). Disease status at the time of allogeneic HCT was stringent CR (n=5), CR (n=3), and VGPR (n=5). All patients received unmanipulated peripheral blood stem cell grafts from HLA-matched sibling donors (n=5) and HLA-matched unrelated donors (n=8). Six patients received fludarabine 30 mg/m² for 4 days and melphalan 70 mg/m² for 2 days followed by a single dose of bortezomib 1.3 mg/m² (Flu/Mel/Vel). Seven patients received fludarabine 40 mg/m² for 4 days and melphalan 70 mg/m² for 2 days (Flu/Mel). Graft-versus-host disease (GVHD) prophylaxis constitutes tacrolimus/methotrexate (n=5), tacrolimus/mycophenolate mofetil (n=4), and tacrolimus/sirolimus (n=4). All patients achieved neutrophil engraftment after a median of 17 days (range, 11 – 19), and all patients achieved platelet engraftment after a median of 17 days (range, 12 – 21). All patients established stable donor cell chimerism. Best responses after allogeneic HCT were sCR (n=10), CR (n=2) and VGPR (n=1). The cumulative incidence of grades 2–4 acute GVHD at day 100 was 57% (95% CI 0.30 – 1.00) with Flu/Mel conditioning and 33% (95% CI 0.11 – 1.00) for Flu/Mel/Vel conditioning, respectively (p=0.24). This observation suggests that a single dose of bortezomib 48 hours before HCT may prevent GVHD. One patient died of GVHD complications, 1 had disease progression and 11 remain alive, progression free with a median follow-up of one year (range 4 months to 4 years). The one year progression-free survival estimate is 90% (95%CI 0.71 – 1.00). These initial data indicate that allogenic transplant for myeloma in VGPR or CR is well tolerated. Longer follow-up is required to assess the efficacy of allogeneic HCT in the era of novel agents in preventing progression of the disease.