The impact of recent vincristine on human hematopoietic progenitor cell collection in pediatric patients with central nervous system tumors

Background Central nervous system ( CNS ) malignancies represent 20% of all childhood cancers. To improve outcomes in infants and children with high‐risk disease, treatment can include adjuvant chemotherapy and early autologous peripheral blood human progenitor cell collection ( AHPCC ), followed by high‐dose chemotherapy and stem cell rescue. In many protocols, postoperative chemotherapy includes the administration of weekly vincristine ( VCR ) between induction chemotherapy cycles, regardless of scheduled AHPCC . We observed anecdotal AHPCC failures in children receiving midcycle VCR ( MC ‐ VCR ). Study Design and Methods The study was an 8‐year retrospective chart review of all children with a CNS malignancy and who underwent AHPCC . Information included patient demographic and clinical data, mobilization regimen, VCR administration, product yields, infusion toxicity, and patient charges. Data were analyzed relative to MC ‐ VCR administration. Graphics and statistical analysis (t‐test, chi‐square, linear regression) were performed with commercial software. Results Twenty‐four patients and 47 AHPCCs were available for analysis. Nine patients (37%) received MC ‐ VCR within 7 days of scheduled AHPCC . MC ‐ VCR was associated with delayed marrow recovery (17.9 days vs. 14.9 days, p = 0.0012), decreased median peripheral CD 34 counts (75 × 10 6 CD 34/ L vs. 352 × 10 6 CD 34/ L , p = 0.03), decreased median CD 34 yields (2.4 × 10 6 CD 34/ L vs. 17.8 × 10 6 CD 34/kg, p = 0.08), more AHPCCs per mobilization (2.9 vs. 1.1, p = 0.01), and an increased rate of remobilization (33% vs. 6%). Mean patient charges were 2.5× higher in patients receiving MC ‐ VCR than controls (p = 0.01). Conclusion MC ‐ VCR should be withheld before scheduled AHPCC to optimize CD 34 collection.