Experience of Plerixafor Use for Autologous Stem Cell Mobilization in Qatar: A Single Center Experience

Introduction

Plerixafor, a hematopoietic stem cell mobilizer, combined with granulocyte-colony stimulating factor (G-CSF) has demonstrated a significantly higher yield of CD34+ cells following apheresis compared to G-CSF alone. This combination reduces the time and effort required for the management of poor stem cell mobilizers and reduces apheresis costs while maintaining comparable post-transplant engraftment outcomes. In 2016, plerixafor was first utilized at the National Center for Cancer Care and Research (NCCCR) for patients who are poor mobilizers to avoid possible mobilization failure. At our center, a higher target of 4-5×10⁶ CD34+ cells/kg per transplant with a minimum of 2×10⁶ CD34+ cells/kg, was deemed necessary to ensure optimal cell doses for planned transplants and to facilitate faster bone marrow recovery. The primary objective of this retrospective analysis is to evaluate the efficacy and safety of incorporating plerixafor into the mobilization regimen for patients undergoing autologous stem cell collection at NCCCR.

Methods

A retrospective review was conducted using electronic medical records of all adults hematology patients who received plerixafor between 1 May 2016 and 31 December 2023. The collected data included patients' demographics, mobilization regimens, indications for plerixafor administration, number of collected CD34+ stem cells, mobilization failure and plerixafor-related side effects.

Results

During the data collection period, 53 patients received plerixafor as part of their mobilization regimen. The patient cohort was predominantly male (n=37; 69.8%) with median age of 51 years (range 22-66 years). The patients were treated for multiple myeloma (MM) (n=32; 60.4%), non-Hodgkin lymphoma (NHL) (n=19; 35.8%), and Hodgkin lymphoma (HL) (n=2; 3.8%). Most MM patients had received lenalidomide-based induction therapy prior to stem cell harvest. Common treatment protocols included Daratumumab, Bortezomib, Lenalidomide, and Dexamethasone (D-VRD), Bortezomib, Cyclophosphamide, and Dexamethasone (VCD) and VRD. The standard mobilization protocol for MM patients at NCCCR was Cyclophosphamide and G-CSF (n=29; 90.6%). Lymphoma patients were mobilized using various chemotherapy protocols including Dexamethasone, high-dose Cytarabine and Cisplatin with or without Rituximab (DHAP+/-R) (n=11; 52.4%), Ifosfamide, Carboplatin and Etoposide (ICE+/-R) (n=3; 14.3%), Methotrexate, Cytarabine, Thiotepa and Rituximab (MATRix) (n=2; 9.5%), and Cyclophosphamide and Etoposide (n=2; 9.5%), followed by G-CSF at a dose of 10 mcg/kg/day.

Plerixafor was used preemptively in 81.1% of patients while the planned approach was required in 18.9%. Two doses of plerixafor were required in 49% of the patients and only 3.8% required three doses for successful collection. The average number of apheresis sessions was two (rage 1-3) in 52.8% of patients. The median number of the obtained CD34+ cells was 5.5 ×10⁶/kg. Majority of patients completed their apheresis sessions within the expected harvest days.

Five patients (9.4%) failed to harvest 2×10⁶/kg CD34+ cells despite planned plerixafor dosing. These patients had risk factors such as previous mobilization failure, bone marrow hypocellularity, advanced disease, and advanced age. Adverse drug reactions to plerixafor were documented in 11 patients (20.8%), with diarrhea being the most reported side effect.

Conclusion

This analysis represents the first report from Qatar on the effective addition of plerixafor as an adjunct mobilizing agent, allowing for safe and satisfactory harvest of CD34+ stem cells in patients at risk of poor mobilization, and as a rescue strategy for those who failed a previous mobilization attempt.

No relevant conflicts of interest to declare.