Evaluation of a Data-Derived Algorithm for Preemptive Use of Plerixafor for Stem Cell Harvest in Patients Eligible for Autologous Stem Cell Transplant (ASCT)

Evaluation of a data-derived algorithm for preemptive Use of plerixafor for stem cell harvest in patients eligible for autologous stem cell transplant (ASCT)

Stem cell mobilization and collection is a prerequisite for ASCT.  In 25-35% of patients, initial mobilization attempts fail to harvest sufficient peripheral blood stem cells (PBSC).  The standard practice was the addition of plerixafor to the second mobilization attempt.  A data-derived algorithm was developed to guide the use of plerixafor as a preemptive strategy, at first harvest, with the objective of preventing ASCT delays, risk of disease progression, and reducing patient stress.

Patients and Methods:  25 patients were harvested for ASCT in the first year of implementation. The data-derived algorithm identified patients likely to fail mobilization based on a CD34+ cut-off for one or two ASCTs.  Eight patients received preemptive plerixafor and were compared to 6 patients who received plerixafor as second line therapy in the previous year.

Results: 

The average number of doses of filgrastim for the second-line group was 16.5 vs 10.3 for the preemptive group, a decrease of 38%.  The doses of plerixafor and days of apheresis were 2.33 vs 1.38 and 2.3 vs 1.6 for the second-line vs the preemptive group (a 41% and 30% decrease for preemptive).  83% of second-line patients proceeded to ASCT (1 progressed) vs 100% of preemptive patients at an average number of days from first harvest of 109 vs 47.7 days, respectively.  Engraftment was identical.

Figures 1 and 2 concur that the minimum PBSC count required to harvest enough for one or two ASCTs is 10x10⁶/L and 2x10⁶/L, respectively. 

Conclusion:  The algorithm has optimized the use of plerixafor.  The number of doses of plerixafor and filgrastim, the days of apheresis and the number of days to ASCT were all reduced.  A successful first harvest attempt avoids transplant delays, reduces the risk of interim disease progression, avoids scheduling difficulties and reduces the stress to the patient.

Authors: Pat Danyluk, BScPharm and Kathy Gesy, BSP MSc.  Saskatoon Cancer Center, 20 Campus Drive, Saskatoon, SK, S7N 4N4.