Single Dose of Pegfilgrastim (Neulasta™) Is Effective in Mobilizing CD34+ Stem Cells in Patients Undergoing Autologous Stem Cell Transplant.

Introduction: Numerous methods of stem cell mobilization for autologous donors are utilized. These strategies include the use of chemotherapy with growth factor support or growth factors alone. All strategies involve multiple injections, lab draws, and patient discomfort and inconvenience. The addition of the PEG molecule to the N-terminus of filgrastim (G-CSF) increases its serum half-life, thereby requiring less frequent dosing. Pegfilgrastim has been found to be safe and effective for patients with chemotherapy-induced neutropenia. Pegfilgrastim in healthy donors mobilizes stem cells in a dose-dependent fashion. A previous study has shown that 12mg of pegfilgrastim given after chemomobilization with cyclophosphamide mobilized sufficient stem cells for auto-grafting. In this study, we evaluated whether a single 12mg injection of pegfilgrastim could mobilize a sufficient number of CD34+ stem cells in autologous donors who did not receive chemomobilization.

Methods: Six patients intending to undergo high-dose chemotherapy with stem cell transplant were enrolled onto the study. Four of the subjects had multiple myeloma and had received prior treatment. Two of these patients had previously undergone HDC/ASCT. One patient had mantle cell lymphoma and another had AL amyloidosis. All participants received a 12mg injection of pegfilgrastim. Four days after pegfilgrastim administration, a CD34 level was checked. If this level was greater than 10 cells per uL, stem cell apheresis was initiatiated.

Results: Results are presented in the table below. Five of the six participants achieved a day four CD34+ level greater that 10 cells per uL and underwent successful stem cell apheresis. The one participant that failed to mobilize had been heavily pre-treated to include a prior autologous stem cell transplant. This patient underwent a repeat stem cell transplant with cells stored from a previous collection. All of the patients with multiple myeloma or amyloidosis proceeded onto high dose chemotherapy with melphalan and autologous stem cell rescue. The patient with mantle cell lymphoma received high-dose chemotherapy with cyclophosphamide, busulfan and vincristine followed autologous stem cell rescue. The most commonly reported side effect from the pegfilgrastim was bone pain. No serious side effects were noted.

Conclusions: A single, 12mg injection of pegfilgrastim is capable of mobilizing sufficient numbers of stem cells in autologous donors. This regimen is convenient to both the patient and institution. Hematologic reconstitution is similar to other stem cell mobilization regimens. Alternative mobilization strategies should be considered in patients who have been heavily pretreated.