Peripheral Blood Stem Cell (PBSC) Harvest Is More Expensive Following Bortezomib-Based Therapy in Multiple Myeloma (MM), Related to Increase Number of Days of Collect.

High-dose therapy is the front line treatment of reference in young patients with Multiple Myeloma (MM). Although induction therapy remains a matter of controversy, bortezomib-based therapy is considered more and more as a standard of care. Prior to autologous stem cell transplantation (ASCT), patients undergo PBSC collect, usually starting after cycle 2 to 4 of the induction treatment. Currently, patients receive one transplant at front line, but most of the patients will benefit throughout the MM disease history of a second or a third ASCT procedure. We have noticed that the number of days of collection vary from patient-to-patient following bortezomib-based induction therapy. This increase in collection procedures might increase the cost of PBSC harvest with more patients discomfort and staff unavailability. We have therefore further studied the quality, yields and days of collection in myeloma patients following bortezomib-based therapy as compared to other regimens-based treatment courses.

We retrospectively studied 70 patients with myeloma that underwent PBSC harvestsafter mobilization with GCSF following debulking with bortezomib-based therapy (58 days of procedures – 26 patients) versus other agents-based therapy [65 days of procedure – 44 patients; VAD vincristine, adriamycin, dexamethasone).

-Yields. CD34 Mobilization is lower following bortezomib-based therapy as compared to other regimen-based therapy. Similarly, more days of collection are also needed to collect the requested yield of PBSC.

-Engrafment. No significant differences regarding engraftment was noticed among the 2 groups studied. The days to neutrophil and platelet counts recovery, the number of days with fever and the number of red cell and platelet transfusions were not significantly different between the 2 groups, mobilization following bortezomib-based therapy versus other regimen-based therapy, respectively.

In our series, bortezomib-based induction regimen does not increase the number of PBSC harvest failure and the quality of engraftment was identical to other regimen-based induction treatment. However, CD34 mobilization was lower following bortezomib-based therapy, which explains lower daily harvest counts and therefore an increase number of days of collection in bortezomib-based treated patients. Therefore, PBSC harvest procedure following bortezomib-based therapy significantly increases the cost of PBSC collection. These results need to be confirmed in larger studies. New agents in use for mobilization might be considered for future PBSC collection in bortezomib-based treated patients.

Leleu: Janssen Cilag: Research Funding.