153
A Plerixafor-Based Strategy Allows Adequate Hematopoietic Stem Cell Collection in Poor Mobilizers: Results from the Canadian Special Access Program
The collection of a minimum number of hematopoietic stem cells (HSC), generally defined as 2 x 106 CD34+ cells/kg, is a prerequisite for proceeding to HSCT. Primary mobilization failure occurs in 5 – 40% of patients.1-5 When used to unselected patients undergoing a first mobilization attempt, plerixafor plus GCSF allows more CD34+ cells to be mobilization with fewer aphereses than GCSF alone.6, 7 There are no publications describing the patterns of plerixafor use at Canadian transplant centres, nor is there data to guide determinations of cost-effectiveness of mobilization using plerixafor from the Canadian perspective.
Methods
The objectives of this study were to: 1) Summarize the published studies of plerixafor-based mobilization during compassionate access programs, and 2) Describe the Canadian experience with plerixafor during its availability though Health Canada’s Special Access Program (SAP). A literature search was performed and studies were grouped into three strategies: upfront, preemptive and salvage. In Canada, plerixafor was available through the SAP, and funded by Genzyme/Sanofi from September 2008 to December 2010.
Results
Thirteen articles were identified. In all but one study, plerixafor was used as part of a preemptive and/or salvage strategy. The proportion lf patients in whom a minimum of 2 x 106 CD34+ cells/kg was collected ranged from 37 – 100%. At the time of publication, 17 – 87% of patients had proceeded to transplantation.
Thirteen Canadian centres provided data on a total of 132 patients, the majority of whom had multiple myeloma or lymphoma, and had undergone a median of 1 prior mobilization attempt (range 0 – 3). Plerixafor was used preemptively in 23 (17%) patients and as salvage in 109 (83%) patients. In 96 (73%) patients, there was successful collection. Of the 23 patients in whom plerixafor was used preemptively, 19 (83%) had successful collections. Of the 109 patients in whom the drug was used as part of a salvage strategy, 77 (71%) had successful collections. Of the entire cohort, 99 (75%) of patients went on to receive an autologous transplant.
Discussion
Our study summarizes the published experience with plerixafor-based mobilization during compassionate drug access programs and describes the Canadian experience when plerixafor was freely available through Health Canada’s SAP. Canadian practice was similar to published international experience.
Plerixafor use decreased significantly when it was no longer freely available. This may be a reflection of limited resources, a lack of belief in the preemptive use of plerixafor or knowledge of the most cost-effective way to use it. The pharmacoeconomics of mobilization likely vary from centre to centre and are affected by multiple factors such as the patient population, infrastructure, available resources, and who is paying for plerixafor.