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Busulfan is an alkylating agent used as part of conditioning chemotherapy regimens prior to allogeneic hematopoietic cell transplant (allo-HCT). Pharmacokinetic (PK)-guided test-dose strategies have been shown to improve the number of patients achieving busulfan exposure goals and improve clinical outcomes. However, current practices require extensive PK sampling. In this study, PK data were retrospectively collected from busulfan drug monitoring records from adult allo-HCT recipients who received once-daily intravenous busulfan at the University of North Carolina Medical Center (UNCMC). A population pharmacokinetic (popPK) model was developed to identify sources of interindividual variability and evaluate alternative PK sampling strategies. A 2-compartment model, with covariate effects of actual body weight and sex, best described the data. The typical value of clearance for an 83 kg male was estimated to be 11.21 L/h. Fifty-nine percent of allo-HCT recipients were estimated to have met the UNCMC institutional myeloablative conditioning (MAC) exposure goal based on model post hoc estimates of clearance using all PK samples obtained following MAC dosing. Fifty-seven percent of patients were estimated to have met this goal based on post hoc estimates using a single PK sample. Our results indicate once-daily, intravenous busulfan PK in adult allo-HCT recipients receiving MAC dosing can be reasonably described by a popPK model, and the use of a sparse PK sampling strategy may be feasible for determining target exposure attainment following MAC dosing. Use of a popPK model and sparse PK sampling strategy to carry out busulfan test-dose procedures could reduce health care costs and inconvenience to patients., (© 2023, The American College of Clinical Pharmacology.)

Addition of plerixafor (P) to granulocyte colony stimulating factor (G-CSF) during peripheral blood mobilization of hematopoietic stem cells (HSC) increases the number of patients meeting collection goals prior to autologous stem cell transplant (aSCT). However, use of P is not universal among transplant centers due to cost. This study aims to compare clinical and financial impacts of using an algorithm-based P mobilization strategy versus use in all patients. This was a single center, retrospective analysis of adult patients with myeloma or amyloidosis receiving aSCT who received apheresis of their HSC between 3/1/2017 and 3/1/2019. Patients prior to 3/1/2018 were classified as receiving P "per algorithm" and those after this date were classified as "up-front" P. For the per-algorithm group, P was given for a pre-apheresis CD34+ cell count of <20 cells/μL on mobilization day 5 and patients returned on day 6 for apheresis. Of the 129 patients included, 55 received P per-algorithm and 74 received up-front P. There was a reduction in median number of apheresis days (1.5 vs 1 day, p < 0.001) and an increase in median number of CD34+ cells collected (6.6 vs 8.5 × 10 6 cells/kg, p < 0.001) with up-front P. Up-front P increased drug cost but reduced apheresis costs, which resulted in a net savings of $121 per patient in total mobilization costs. These findings suggest that use of up-front P for mobilization significantly reduces apheresis days and increases HSC collection yield without increasing overall cost per patient., (Copyright © 2021 Elsevier Ltd. All rights reserved.)