Pharmacoeconomic Impact of Upfront Use Plerixafor for Autologous Stem Cell Mobilization in Multiple Myeloma Patients

Abstract 2075

The most commonly employed agent for upfront stem cell mobilization is granulocyte-colony-stimulating factor (G-CSF), which is associated with about 25% of unsuccessful mobilization. Plerixafor was granted FDA approval based on improved rate of successful mobilization as an upfront mobilizing agent. However, because of its cost, it is often reserved for patients who failed previous standard mobilization. This strategy can increase the number of apheresis and potentially delay treatment.

This retrospective study, performed between January 2008 and April 2011, included 50 adult patients with multiple myeloma (MM) who underwent ASCT. Twenty-five patients received plerixafor, in combination with G-CSF, and 25 patients received G-CSF alone as an upfront mobilization therapy. Plerixafor was given as 0.24mg/kg/day SC in the evening for up to 4 days, starting on day 4 of G-CSF. For stem cell collection, G-CSF was given as 10mcg/kg/day SC in the morning for 5 days. Targets of collection were minimal 5 x10⁶ and optimal 10⁷ CD34+ cells/kg. After ASCT, G-CSF was given as 5mcg/kg/day IV from day 0 until engrafted. In April 2010, a practice change was instituted to delay initiation of G-CSF from day 0 to day +5 following ASCT. Simultaneously, plerixafor was used, in combination with G-CSF, as an upfront mobilization therapy for autologous stem cell mobilization in MM patients. The primary objective of this study was to assess pharmacoeconomic impact of using plerixafor as an upfront mobilization therapy in patients with MM. There were no differences in age (mean, 57.4±8.7 yrs vs. 56.4±6.3 yrs; p=NS), weight (mean, 74.6±15.9kg vs. 75±19.7kg; p=NS), number of previous SCT (mean, 0±0.2 vs. 0.1±0.3; p=NS), patients with relapsed disease (16% vs. 16%; p=NS) or melphalan dose (mean, 192.8±19.9mg vs. 192.8 ±19.9mg; p=NS) between plerixafor group and the control. Compared with the control, plerixafor mobilizations yielded higher CD34+ cell content [mean (x10⁶ CD34+ cells/kg), 16.1±9.7 vs. 8.4±4.6; p=0.0007], higher number of CD 34+cells infused [mean (x10⁶ CD34+ cells/kg), 7.6±4.6 vs. 4.4±1.7; p=0.0017], required fewer number of G-CSF doses for both stem cell collection (mean, 5.9±1.1 vs. 7.1±1; p=0.0001) and for neutrophil recovery (mean, 8±1.8 vs. 11.8±1.1; p<0.0001), and required fewer number of apheresis (mean, 1.9±1.1 vs. 3.1±1; p=0.0001). The plerixafor group had a longer time to neutrophil engraftment compared with the control (mean, 10.8±0.9 days vs. 9.8±0.9 days; p<0.0001); however, this did not translated to longer days of hospitalization post-ASCT (mean, 15.2±2.7 days vs. 14.1±3.1 days; p=NS). The plerixafor group required fewer G-CSF doses for both mobilization and neutrophil recovery, and fewer apheresis sessions. Therefore, this group had a lower cost of G-CSF per patient for both stem cell collection (mean, $2,212±572 vs. $2,765±487, p=0.0006) and for stem cell recovery (mean, $1,677±521 vs. $2,653±1,125, p=0.0003), and also lower cost of apheresis per patient (mean, $889±517 vs. $1,476±479; p=0.0001). The mean number of plerixafor doses per patient was 1.8±1, with a cost per patient of $9,081.6±5,220. Based on our interim data for overall cost analysis, the plerixafor group had similar cost for blood products per patient (mean, $2,803±3,049 vs. $2,332±1,160, p=0.49), overall cost of medications (mean, $19,461±5,307 vs. $22,442±5,451, p=0.13), overall cost of hospitalization (mean, $60,646±13,981 vs. $61,474±10,464, p=0.84), and cost of hospitalization and apheresis combined per patient (mean, $61,632±14,163 vs. $62,949±10,298, p=0.75).

This data suggests that using plerixafor for upfront autologous stem cell mobilization in patients with MM significantly improves success rate of mobilization, decreases the number of apheresis sessions, and does not have a substantial pharmacoeconomic impact.