Safety and Efficacy of Plerixafor (Mozobil) Addition to Chemotherapy and Growth Factor Stem Cell Mobilization Regimens in Patients with Low Pre-CD34 Counts Undergoing Stem Cell Collection Prior to Autologous Stem Cell Transplantation

Prior to introduction of Plerixafor, CXCR4 receptor antagonist, up to 30% of patients in need of autologous stem cell transplant were unable to collect adequate numbers of peripheral blood stem cells (PBSCs).  Plerixafor is currently approved for hematopoetic stem cell mobilization and collection in combination with Filgrastim in patients with Non-Hodgkin Lymphoma (NHL) and multiple myeloma (MM) undergoing autologous stem cell transplantation.  Due to high costs associated with use of Plerixafor, the above combination is usually reserved for patients who are at high risk of failure or fail previous stem cell mobilization.  

We have administed Plerixafor to 13 patients that failed to achieve adequate peripheral blood pre CD34 counts after undergoing stem cell mobilization utilizing the combination of chemotherapy and Pegfilgrastim.   We retrospectively reviewed our data to evaluate efficacy and safety of the above combination.

Thirteen patients (25-69 years) with lymphoma (NHL n= 4 HL n= 2) and MM (n=7) underwent treatment with ICE based chemotherapy or Cytoxan 3 gm/m2 followed by Neulasta 12 mg.  Absolute pre CD34 count was performed on peripheral blood upon recovery of neutrophils.  If peripheral blood CD34 count was below 10/microL, Plerixafor 0.24 mg/kg/day with or without Neupogen 10mcg/kg/day was added.  Absolute pre CD34 values prior to Plerixafor ranged from 0 – 6.  Pre CD34 values after Plerixafor ranged from 6 - 303.  Target CD34 yield per kg for NHL/HL patients was 2-5 X 10⁶.  Target CD34 yield per kg for MM patients was 5-10 X 10⁶.  Following this intervention 11 patients were able to successfully complete stem cell mobilization and achieve target yields.  2 MM patients did not meet the collection goal for 2 transplants but did have sufficient yield for one.  Median total CD34 yield per kg was 6.9 X 10⁶.  Mean total CD34 yield for NHL/HL pts was 6.17 X 10⁶ per kg.  Mean total CD34 yield for MM pts was 10.59 X 10⁶ per kg.  Mean total MNC yield was 14.23 X 10⁸ per kg for NHL/HL pts.  Mean total MNC yield was 8.71 X 10⁸ per kg for MM pts. Average time for neutrophil engraftment was 11.46 days.  Average time for platelet engraftment was 19.91 days.  There were no major complications associated with the above combination and no unanticipated side effects.

Combination of Plerixafor and Filgrastim can be safely and successfully administered to patients with inadequate peripheral blood pre-CD34 counts following chemotherapy based mobilization regimens. This will prevent delay in the transplantation process.