12 Months Report from a Phase 3 Study of Plerixafor+G-CSF Vs. Placebo+G-CSF for Mobilization of Hematopoietic Stem Cell for Autologous Transplant in Patients with Multiple Myeloma

Introduction: We previously reported that plerixafor + G-CSF was as safe as and more effective than placebo + G-CSF in mobilizing hematopoietic stem cell for autologous transplant in patients with multiple myeloma (MM) through 100 days follow-up (DiPersio ASH 2007). We report herein the 12 months data. Methods: This is a phase 3, multi-center, randomized (1:1), double-blind, placebocontrolled study. Multiple myeloma patients requiring an autologous hematopoietic stem cell transplant, in first or second complete or partial remission were eligible. Patients received G-CSF (10μg/kg/day) subcutaneously for up to 8 days. Beginning on evening of Day 4 and continuing daily for up to 4 days, patients received either plerixafor (240μg/kg) or placebo subcutaneously. Starting on Day 5, patients began daily apheresis for up to 4 days or until ≥ 6 x 106 CD34+cells/kg were collected. We report herein the 12 months graft durability and hematology data. Results: As reported previously, the primary endpoint of collecting ≥ 6 x 106 CD34+ cells/kg in ≤ 2 days of apheresis was met in 106/148 (71.6%) patients in the plerixafor group and 53/154 (34.4%) patients in the placebo group, p<0.001. 142 (96%) patients in plerixafor group and 136 (88%) patients in placebo group underwent transplantation. Median time to PMN and PLT engraftment was similar in both groups. Through 12 months follow-up, there were no differences in graft durability and hematology profiles between groups (Table 1). Over the 12 months, 6/142 (4.2%) patients in the plerixafor group and 5/136 (3.7%) patients in the placebo group died. Of the patients who died, 2 patients in the plerixafor group and 2 patients in the placebo grouped died due to disease progression. Plerixafor + G-CSF Placebo + G-CSF Hematology data presented as mean ± SD and n=number of patients with available data P values were NS for all variables at all time points between groups aAll patients who underwent transplantation bAll patients who underwent transplantation and had laboratory data at the study visit Graft durability (n, %) 100 daysa 140/142 (98.6%) 133/136 (97.8%) 6 monthsb 133/135 (98.5%) 125/127 (98.4%) 12 monthsb 127/128 (99.2%) 119/120 (99.2%) Platelet (x 109/L) 100 days 226 ± 80 (n=90) 210 ± 88 (n=87) 6 months 218 ± 67 (n=95) 209 ± 89 (n=93) 12 months 204 ± 69 (n=53) 205 ± 80 (n=54) Neutrophils (x 109/L) 100 days 3.3 ± 2.3 (n=88) 3.0 ± 1.7 (n=80) 6 months 3.4 ± 1.6 (n=90) 3.5 ± 1.8 (n=88) 12 months 3.1 ± 1.1 (n=52) 3.6 ± 2.1 (n=52) Hemoglobin (mg/dL) 100 days 12.5 ± 1.5 (n=89) 12.6 ± 1.3 (n=86) 6 months 12.7 ± 1.4 (n=94) 12.7 ± 1.6 (n=92) 12 months 12.9 ± 1.8 (n=53) 13.1 ± 1.5 (n=54) Conclusions: The addition of plerixafor to G-CSF resulted in higher CD34+ cell collection in fewer days of apheresis than G-CSF alone. Importantly, this 12 months report showed that transplants with cells collected with plerixafor resulted in graft durability rates that were similar to cells collected with G-CSF alone.