San Francisco, CA—The upfront use of plerixafor plus granulocyte colony-stimulating factor (G-CSF) for stem-cell mobilization is more cost-effective than the more widely used cyclophosphamide plus G-CSF regimen, according to a cost analysis from Memorial Sloan Kettering Cancer Center investigators that was presented at ASH 2014.
“Phase 3 trials demonstrated higher stem-cell collection efficiency with plerixafor plus G-CSF, and plerixafor can rescue patients failing mobilization with G-CSF with or without cyclophosphamide. But despite the proven efficacy of plerixafor plus G-CSF, its upfront use has been limited, mostly due to concerns of the high cost of the drug,” said Salma Afifi, PharmD, of the Department of Pharmacy, Memorial Sloan Kettering Cancer Center, New York.
“As a measure to contain cost, ‘on-demand’ plerixafor has been used in patients anticipated to be poor mobilizers with G-CSF with or without cyclophosphamide,” Dr Afifi said.
The assumption is that using plerixafor plus G-CSF upfront will promote cost-effectiveness by limiting the use of plerixafor; however, a comprehensive comparison has not been done. This retrospective study is the first to compare the mobilization and cost-effectiveness of cyclophosphamide plus G-CSF versus plerixafor plus G-CSF as upfront mobilization regimens.
Dr Afifi and colleagues identified 223 patients with multiple myeloma undergoing upfront mobilization, with 111 patients receiving cyclophosphamide plus G-CSF and 112 patients receiving plerixafor plus G-CSF. Patients collecting <5 × 106 CD34+ cells/kg were considered mobilization failures and had a second attempt using an alternate approach.
Mobilization costs included upfront mobilization, salvage mobilization, and complications directly related to the mobilization procedures. All costs were calculated using the institution’s ratio of cost to charges, and were normalized and adjusted based on institutional charges and costs for 2012.
Differences in Outcomes Favor Plerixafor
Plerixafor was associated with reduced use of G-CSF, fewer toxicities and related hospitalizations, and a lower rate of mobilization failure and its need for salvage mobilization associated with plerixafor plus G-CSF.
The mean apheresis sessions were 2.3 with plerixafor and 2.6 with cyclophosphamide (P = .06). The median CD34+ cells/kg were 11.4 × 106 and 10.9 × 106, respectively (P = .29).
A successful total yield was achieved by 105 (94%) patients receiving plerixafor plus G-CSF versus 92 (83%) patients receiving cyclophosphamide plus G-CSF (P = .01).
Approximately 85% of each group went to transplant. Platelet engraftment and neutrophil engraftment were achieved by 100% of patients in each group.
Overall, 13 (12%) patients were rehospitalized as a result of complications after receiving cyclophosphamide plus G-CSF, with an average hospital stay of 6.5 days. No patients in the plerixafor plus G-CSF arm were hospitalized. Of the patients in the cyclophosphamide plus G-CSF group, 19 (17%) failed first mobilization compared with 7 (6.2%) patients receiving plerixafor plus G-CSF upfront.
Plerixafor plus G-CSF More Cost-Effective
“Plerixafor plus G-CSF was more cost-effective than cyclophosphamide plus G-CSF,” Dr Afifi concluded.
The average charges were $74,884 in the cyclophosphamide plus G-CSF cohort versus $59,127 in the plerixafor plus G-CSF cohort (P = .004). The average cost of stem-cell collection per patient was 22% higher in the cyclophosphamide group than in the plerixafor group (P = .017), Dr Afifi reported.
“When the costs associated with salvage pheresis was discounted for the 19 patients in the cyclophosphamide plus G-CSF upfront group who failed first stem-cell mobilization, assuming that these patients could have been salvaged by plerixafor on demand, the cost per patient in the cyclophosphamide plus G-CSF group remains 1.26 times greater [P = .019] than that of the plerixafor plus G-CSF group,” Dr Afifi and her colleagues noted.
“Overall, this single institution study provides additional rationale for the standard use of plerixafor plus G-CSF as an upfront mobilization regimen in multiple myeloma patients,” Dr Afifi concluded.