On Demand Plerixafor As a Rescue Strategy in Healthy Donors to Achieve Adequate Stem Cells - a Pilot Study from South India

Aims & Objectives: The aim of the study is to check the safety and feasibility of using Plerixafor in healthy donors who have failed to mobilise > 2 x 10 6/kg of CD34 cells on day 1 of aphresis. The indication at present remains off label.

Patients/Materials & Methods: Seventeen healthy donors, all more than 18 years of age were enrolled in this study after a proper written informed consent who failed to mobilise adequately on day 1 collection. The dose of Plerixafor used was 0.24mg/kg body weight of donor, 10-11 hours before the aphresis procedure. The GCSF was given from day -5 and the last dose was given 4 hours before the second day aphresis. CD34 was done in pre-aphresis peripheral blood and in product bag and compared with day 1 data.

Results: The median donor bw was 54 kg (IQR, 42 kg to 69 kg) and the median recipient bw was 58 kg (IQR, 44 kg to 76 kg).The median CD34⁺ count in peripheral blood was 11.2/µl on day 4 after G-CSF alone and 24.7.0/µl on day 5 after G-CSF plus Plerixafor. The use of Plerixafor increased the number of circulating CD34 cells in peripheral blood by 2.2 fold.There were no major side effects except for the manageable bone pains which can be attributed to GCSF also. There were no differences in the engraftment statistics and rates of GVHD in comparison to historical cases. Though this is not a randomised control study to compare with second day high dose GCSF cases, the amount of increase in stem cells were statistically significant comparing with historical controls(p< 0.05). After a median followup of six months, no adverse effects were noted in donors.

Discussion & Conclusion: Plerixafor is well tolerated in healthy donors and can be used safely in situations of poor mobilisers or when there is a significant difference in weight of donor to receipient. Its a small pilot study. We need a proper randomised control study and a longer follow up to look infor the side effects on healthy donor.