Hematopoietic stem cell mobilization using plerixafor – single center experience at the University medical centre Ljubljana

Abstract

Background: Autologous stem cell transplant is a standard of care for hematologic malignacies. Mobilization and collection of hemopoietic stem cells (HSC) is a prerequisite for its success. Between 5–30 % of healthy donors and up to 60 % of high risk patients for poor mobilization are not able to collect sufficient amount of HSC for the procedure. Bone marrow infiltration, irradiation, age and prior treatment with melphalan, fludarabine, lenalidomide or any high dose chemotherapy are risk factors for poor mobilization. In case of collection failure, a CXCR4 antagonist plerixafor (Mozobil) can be successfuly used with up to 70 % collection rate in this high-risk patient group. Methods: Hipokrat program with its medical database was used to retrospectively analyse data on patients treated with plerixafor at the Department of Hematology, UMC Ljubljana. Basic statistics were applied to the collected data. Results: From 2008 until November 2011 we treated 16 patients with a median age of 57 years (range 21–71). They were diagnosed with multiple myeloma (n = 13/81.3 %), lymphoplasmacytic immunocytoma (6.3 %), mantle cell lymphoma (6.3 %) and Burkitt’s lymphoma (6.3 %). At the time of mobilization three (18.8 %) patients were in complete remission, four (25.0 %) in very good partial remission, six (37.6 %) in partial remisson, two (12.5 %) had stable disease, while in one (6.3 %) the disease status was not assessed. The patients were treated with bortezomib (n = 13/81.3 %), irradiation (n = 7/43.8 %), cyclophosphamide (n = 5/31.8 %), purine analogoues (n = 3/18.8 %), revlimid (n = 3/18.8 %) and thalidomide (n = 1/6.3 %). Ten (62.5 %) patients underwent previous attempt of mobilzation and only one collected > 2x106/kg CD34+ HSC. On the day of plerixafor administration, median CD34+ HSC blood count was 8.7 x106/l (2.0–50.04) and after plerixafor 27.15 x106/l (13.9–307.11). Ten (62.5 %) patients required two administrations of plerixafor. Median collected CD34+ HSC were 2.34 x106/kg (0.98–6,73). Three (18.8 %) patients failed to mobilize. Conclusions: Plerixafor is a new highly successful mobilizing agent in high-risk patients or patients with previously failed mobilization. According to our experience, 13 (81 %) poor mobilizers collected a sufficient amount of HSC on plerixafor to proceed to transplant.