(P-BT-10) Early Post-Transplant Outcomes Support Generic Plerixafor Is As Effective as (and in Subgroup More Effective Than) Brand As Adjunct Peripheral Blood Stem-Cell Mobilization Agent for Multiple Myeloma

Until recent approval of generic plerixafor, widespread use of plerixafor for peripheral blood stem cell (PBSC) mobilization was limited by cost in the United States (US). Real-world data from US of mobilization efficacy and early engraftment outcomes of generic versus brand plerixafor is needed to assess operational and clinical benefits of widespread use of generic plerixafor among multiple myeloma (MM) patients.

Study

Design/Methods:

Two cohorts of patients with MM who underwent PBSC mobilization before (n=64) and after (n=61) the switch from brand-name to generic plerixafor were included. All were mobilized with filgrastim at 10 µg/kg/day for 4 days, with plerixafor given subcutaneously either upfront in the evening of day 4 prior to starting collection on day 5 or added just in time on day 5 following low peripheral blood CD34 counts or collection yields. Injections and apheresis collections continued until 2-3 × 10e6 or 4-6 × 10e6 CD34+ cells/kg for single and double transplant candidates, respectively, were collected. Cohorts were followed for early engraftment outcomes. Survival curves are estimated and compared using Kaplan-Meier method.

Results/Findings:

The two cohorts had no significant difference in sex (P=.70), median age (P=.30), mean weight (P=.20), previous radiation therapy (P=.59), previous number of therapy lines (P=.70), and upfront (vs just-in-time) plerixafor use (P=.25). Patients required a lower median number of plerixafor doses and collection days in generic arm versus brand arm (P< .05). Only 31% of patients in generic arm required more than 1 dose versus 59% of patients in brand arm (P< .05). There is a significantly higher post plerixafor day-1 yield (10e6 CD34+ cells/kg) in generic versus brand cohort (4.79 vs 3.78, respectively; P< .05). There were no significant differences in median overall cumulative total yield (brand, 5.91; generic, 5.80; P=.5). Ninety-one percent in brand and 85% in generic cohort underwent transplantation (P=0.42). All achieved platelet and neutrophil engraftment. There is a trend towards shorter median time to platelet engraftment for generic versus brand cohort (generic, 17 days; brand, 19 days; P=0.08). Among female subgroup, median time to platelet engraftment is significantly shorter for generic (17 days) versus brand (19 days) cohort (P=0.028, Log-rank), Table 1. There is an insignificant trend towards fewer patients within generic versus brand arm requiring platelet transfusion within first 30 days post-transplant (P=0.11). The cohorts had comparable median time to neutrophil engraftment (12 days) and red cell transfusions during first 30 days post-transplant.

Conclusions: Generic plerixafor, as compared to brand-name plerixafor, produced similar cumulative collection yields with fewer doses and collection days, and comparable early engraftment outcomes with significantly earlier platelet engraftment among female subgroup in MM patients.