Preharvest Platelet Counts Predict Response To Plerixafor in Pediatric Patients Undergoing Autologous Stem Cell...

Autologous stem cell transplantation (ASCT) following high dose chemotherapy is used for management of various pediatric malignancies, and plerixafor used in conjunction with GCSF is used to mobilize hematopoietic stem cells (HSCs) from bone marrow to peripheral blood for collection. While the efficacy and safety of plerixafor is established in adults, data for its use in children are limited. Factors influencing plerixafor response in pediatric patients have not been extensively investigated. This retrospective study aimed to identify predictors of response to plerixafor in pediatric patients undergoing ASCT. This single-center, retrospective study evaluated 22 pediatric patients who underwent mobilization with granulocyte colony-stimulating factor (GCSF) and plerixafor for ASCT between 2017 and 2024. Patient factors such as age, sex, baseline platelet count, marrow involvement, comorbidities, and malnutrition were recorded. Baseline platelet counts were measured on Day - 1 (the day prior to plerixafor administration). Treatment factors, including exposure to radiotherapy, anthracyclines, and multiple lines of chemotherapy, were also considered. CD34 + cell counts were measured before plerixafor administration and after harvest, and response was assessed by percentage, absolute, and log percent increase in CD34 counts. Regression analysis was done to look at the effect of various factors on response to plerixafor. The study found a significant increase in CD34 counts after plerixafor administration, with a median log percent increase of 3.54 (3.24-3.61). While age and malnutrition showed a significant correlation with log percent CD34 increase (p = 0.012 and p = 0.021, respectively), multivariate regression analysis revealed that only baseline platelet count achieved statistical significance as a predictor of response to plerixafor (p = 0.046). Pre-harvest baseline platelet count is an independent predictor of response to plerixafor in pediatric patients undergoing autologous stem cell transplantation. This finding suggests that baseline platelet counts can help predict the effectiveness of plerixafor-mediated stem cell mobilization in this patient population. Further larger prospective studies are warranted to validate these findings and identify additional factors influencing plerixafor response in pediatric patients.