Safety, efficacy and feasibility of GCSF and plerixafor based CD34 mobilization for backup autologous stem cell collection in patients undergoing alternate donor hematopoietic stem cell transplant for sickle cell disease: Take away lessons for gene therapy.

A retrospective analysis was performed on 70 patients with SCD aged <30 years, who underwent alternate donor HSCT, in whom autologous stem cell was collected as backup. Patients received 3-4 days of 10 mcg/kg GCSF with plerixafor 0.24 mg/kg 6-8 h prior to PBSC harvest and a desired target CD34 + count of > 3 million/ Kg recipient body weight was collected. Median age of cohort was 10 years (1-27 years). Median CD34 dose per collection was 7.7 × 106/ kg recipient body weight (range, 1.7-33.7 × 106/ kg recipient body weight). Sixteen patients had veno-occlusive crisis (VOC); 11, mild, managed with analgesics, while 5 had severe VOC, requiring red cell exchange (RCE). There was a strong positive correlation between the pre-collection CD 34 cells per microliter and the final stem cell dose (r = 0.788, p = 0.01). For 69 patients, we could successfully achieve the desirable stem cell yield. Our retrospective analysis clearly documents safety, efficacy and feasibility of GCSF and plerixafor based CD34 mobilization (as autologous backup) documenting higher pre-collection CD34 cell dose, lesser time to desired CD34 collection, lesser TBV processed, lesser ACD exposure and one cycle of apheresis for the majority of patients with an acceptable increase of VOCs.