Plerixafor Plus G-CSF Compared to Chemotherapy Plus G-CSF for Mobilization of Autologous CD34+ Cells Resulted in Similar Cost but More Predictable Days of Apheresis and Less Hospitalization.

Plerixafor plus G-CSF has been shown to mobilize more CD34+ cells than G-CSF alone for autologous (auto) hematopoietic stem cell transplant (HSCT). However, many centers use chemotherapy followed by G-CSF to mobilize CD34+ cells prior to HSCT. Comparing the effectiveness of CD34+ cell mobilization, cost, logistical issues, and clinical outcomes between plerixafor/G-CSF and chemotherapy/G-CSF mobilized pts may help better define optimal mobilization regimens.

Patients and Methods: We performed a retrospective study of pts who participated in the expanded access program (EAP) of plerixafor/G-CSF for upfront mobilization of CD34+ cells, and compared the costs of mobilization and clinical outcomes to matched historical controls mobilized with chemotherapy/G-CSF at two centers that participated in the study. Control pts were matched for age, sex, disease stage, and number of prior therapies. Control pts received cyclophosphamide 3-5 gm/m² followed by daily G-CSF. Study pts received G-CSF 10 mcg/kg daily for 5 days and plerixafor 0.24 mg/kg was given on the evening of day 4, twelve hours before a 3 blood volume apheresis on day 5, and the same plerixafor and G-CSF dosing was given for each subsequent day of apheresis. Apheresis was scheduled for 5 days after starting G-CSF in the study pts and 10 days after starting G-CSF in the control pts, but the actual start of apheresis was based on the peripheral blood (PB) CD34+ cell counts of 10/ul or greater. Mobilization costs were considered to be the costs of medical procedures, resource utilization and medications. Median national CMS national reimbursement rates were used to evaluate the costs of mobilization procedures, hospitalization, provider visits, apheresis, CD34+ cell processing and cryopreservation. Average sale price was used for medications related to mobilization including G-CSF, plerixafor, cyclophosphamide, mesna, antiemetics and antimicrobials.

A total of 34 patients from EAP and 34 matched controls were studied (Rocky Mountain BMT:25 study pts and 25 controls, Texas Transplant Institute:9 study pts and 9 controls). Study pts had a median age of 58 years, 18 (53%) were male, and had myeloma (n=20, 59%), or NHL (n=14, 41%). Control pts had a median age of 58 years, 18 (53%) were male and had myeloma (n=20, 59%), NHL (n=13, 38%), or Hodgkins disease (n=1, 3%). Comparison of the G-CSF dose, the number of doses of G-CSF, number of apheresis, total CD34+ cells collected, and cost is given in the table. All pts proceeded to auto HSCT with no difference in median time to ANC or platelet engraftment. The median costs of mobilization were similar between the groups. Two pts in the control group were hospitalized for neutropenic fever during the mobilization period after receiving cyclophosphamide. Apheresis started on the scheduled day in 27 (79%) of study pts and in 18 (53%) of control pts (p=0.021). Unplanned starts of apheresis resulted in 17 (50%) of control pts undergoing weekend apheresis. CMS national reimbursement data does not differentiate the costs of weekend or weekday apheresis or flow cytometry, and thus no cost difference for weekend procedures is reflected in the cost data. Study pts received a median of 1 dose of plerixafor (median 16.9 mg), and the average sale price for plerixafor in this analysis was set at $6,250 per 24 mg/vial. Adding this cost to the study pts resulted in a non-significant difference in total cost of mobilization for the two groups.

In conclusion, plerixafor/G-CSF compared to cyclophosphamide/G-CSF for upfront mobilization of CD34+ cells for auto HSCT results in similar number of cells collected, cost of mobilization, and clinical outcomes. However, plerixafor/G-CSF mobilization resulted in more predictable days of collection, no weekend apheresis procedures, and no unscheduled hospital admissions. Higher acquisition cost of plerixafor was offset by less G-CSF use and less resource utilization compared to cyclophosphamide based mobilization.

Shaughnessy:Genzyme: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Silva:Genzyme: Consultancy. Steinberg:Genzyme: Consultancy. Selvey:Genzyme: Consultancy. Maris:Genzyme: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. McSweeney:Genzyme: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.