Browsing by Subject "Vincristine"

Now showing 1 - 5 of 5
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    CYP3A5 genotype and its impact on vincristine pharmacokinetics and development of neuropathy in Kenyan children with cancer
    (Wiley, 2018-03) Skiles, Jodi L.; Chiang, ChienWei; Li, Claire H.; Martin, Steve; Smith, Ellen L.; Olbara, Gilbert; Jones, David R.; Vik, Terry A.; Mostert, Saskia; Abbink, Floor; Kaspers, Gertjan J.; Li, Lang; Njuguna, Festus; Sajdyk, Tammy J.; Renbarger, Jamie L.; Pediatrics, School of Medicine
    BACKGROUND: Vincristine (VCR) is a critical part of treatment in pediatric malignancies and is associated with dose-dependent peripheral neuropathy (vincristine-induced peripheral neuropathy [VIPN]). Our previous findings show VCR metabolism is regulated by the CYP3A5 gene. Individuals who are low CYP3A5 expressers metabolize VCR slower and experience more severe VIPN as compared to high expressers. Preliminary observations suggest that Caucasians experience more severe VIPN as compared to nonCaucasians. PROCEDURE: Kenyan children with cancer who were undergoing treatment including VCR were recruited for a prospective cohort study. Patients received IV VCR 2 mg/m2 /dose with a maximum dose of 2.5 mg as part of standard treatment protocols. VCR pharmacokinetics (PK) sampling was collected via dried blood spot cards and genotyping was conducted for common functional variants in CYP3A5, multi-drug resistance 1 (MDR1), and microtubule-associated protein tau (MAPT). VIPN was assessed using five neuropathy tools. RESULTS: The majority of subjects (91%) were CYP3A5 high-expresser genotype. CYP3A5 low-expresser genotype subjects had a significantly higher dose and body surface area normalized area under the curve than CYP3A5 high-expresser genotype subjects (0.28 ± 0.15 hr·m2 /l vs. 0.15 ± 0.011 hr·m2 /l, P = 0.027). Regardless of which assessment tool was utilized, minimal neuropathy was detected in this cohort. There was no difference in the presence or severity of neuropathy assessed between CYP3A5 high- and low-expresser genotype groups. CONCLUSION: Genetic factors are associated with VCR PK. Due to the minimal neuropathy observed in this cohort, there was no demonstrable association between genetic factors or VCR PK with development of VIPN. Further studies are needed to determine the role of genetic factors in optimizing dosing of VCR for maximal benefit.
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    Evaluation of four chemotherapy regimens for treatment of advanced AIDS-associated Kaposi sarcoma in Kenya: a cost-effectiveness analysis
    (Elsevier, 2022) Freeman, Esther E.; McCann, Nicole C.; Semeere, Aggrey; Reddy, Krishna P.; Laker-Oketta, Miriam; Byakwaga, Helen; Pei, Pamela P.; Hajny Fernandez, Maya E.; Kiprono, Samson; Busakhala, Naftali; Martin, Jeffery N.; Maurer, Toby; Bassett, Ingrid V.; Freedberg, Kenneth A.; Hyle, Emily P.; Dermatology, School of Medicine
    Background: The most effective treatment for advanced AIDS-associated Kaposi sarcoma is paclitaxel or pegylated liposomal doxorubicin (PLD); neither is routinely used in sub-Saharan Africa due to limited availability and high cost. We examined the clinical impact, costs, and cost-effectiveness of paclitaxel or PLD in Kenya, compared with etoposide or bleomycin-vincristine. Methods: In this study, we use the Cost-Effectiveness of Preventing AIDS Complications (CEPAC)-International Model to project clinical outcomes and costs among people living with HIV and advanced Kaposi sarcoma on antiretroviral therapy. We compared four different treatment strategies: etoposide, bleomycin-vincristine, paclitaxel, or PLD. We derived cohort characteristics and costs from the Kenyan Academic Model for Providing Access to Healthcare network, and adverse events, efficacy, and mortality from clinical trials. We projected model outcomes over a lifetime and included life expectancy, per-person lifetime costs, and incremental cost-effectiveness ratios (ICERs). We conducted budget impact analysis for 5-year total costs and did deterministic and probabilistic sensitivity analyses to evaluate the effect of uncertainty in input parameters. Findings: We found that paclitaxel would be more effective than bleomycin-vincristine and would increase life expectancy by 4·2 years per person. PLD would further increase life expectancy by 0·6 years per person. Paclitaxel would be the most cost-effective strategy (ICER US$380 per year-of-life-saved compared with bleomycin-vincristine) and would remain cost-effective across a range of scenarios. PLD would be cost-effective compared with paclitaxel if its price were reduced to $100 per cycle (base case $180 per cycle). Implementing paclitaxel instead of bleomycin-vincristine would save approximately 6400 life-years and would increase the overall 5-year Kenyan health-care costs by $3·7 million; increased costs would be primarily related to ongoing HIV care given improved survival. Interpretation: Paclitaxel would substantially increase life expectancy and be cost-effective compared with bleomycin-vincristine for advanced AIDS-associated Kaposi sarcoma in Kenya and should be the standard of care. PLD would further improve survival and be cost-effective with a 44% price reduction.
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    Obesity as a Potential Risk Factor for Vincristine Induced Peripheral Neuropathy
    (Wolters Kluwer, 2020-10) Sajdyk, Tammy J.; Boyle, Frances A.; Foran, Kaitlin S.; Tong, Yan; Pandya, Pankita; Smith, Ellen M.L.; Ho, Richard H.; Wells, Elizabeth; Renbarger, Jamie L.; Pediatrics, School of Medicine
    Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer. Vincristine is a core chemotherapeutic agent for patients with ALL; unfortunately, approximately 78% will develop vincristine-induced peripheral neuropathy (VIPN). VIPN can result in vincristine dose reductions that decrease therapeutic efficacy: making it important to understand which children are at highest risk for VIPN. We hypothesized that pediatric ALL patients who were obese at diagnosis would develop worse VIPN than healthy weight children with ALL within the first year. Our results confirmed that obese pediatric patients have significantly (p=0.03) worse VIPN than patients of healthy weight.
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    Simultaneous Quantification of Vincristine and Its Major M1 Metabolite from Dried Blood Spot Samples of Kenyan Pediatric Cancer Patients by UPLC-MS/MS
    (Elsevier, 2021-09) Agu, Lorita; Skiles, Jodi L.; Masters, Andrea R.; Renbarger, Jamie L.; Chow, Diana S-L; Pediatrics, School of Medicine
    Vincristine (VCR) is an integral part of chemotherapy regimens in the US and in developing countries. There is a paucity of information about its disposition and optimal therapeutic dosing. VCR is preferentially metabolized to its major M1 metabolite by the polymorphic CYP3A5 enzyme, which may be clinically significant as CYP3A5 expression varies across populations. Thus, it is important to monitor both VCR and M1 and characterize their dispositions. A previously developed HPLC-MS/MS method for VCR quantification was not sensitive enough to quantify the M1 metabolite beyond 1 hr. post VCR dose (not published). Establishing a highly sensitive assay is a pre-requisite to simultaneously quantify and monitor VCR and M1, which will enable characterization of drug exposure and dispositions of both analytes in a pediatric cancer population. The addition of formic acid during the extraction process enhanced M1 extraction from DBS samples. A sensitive, accurate, and precise UPLC-MS/MS assay method for the simultaneous quantification of VCR and M1 from human dried blood spots (DBS) was developed and validated. Chromatographic separation was performed on Inertsil ODS-3 C18 column (5 μm, 3.0 x 150 mm). A gradient elution of mobile phase A (methanol-0.2% formic acid in water, 20:80 v/v) and mobile phase B (methanol-0.2% formic acid in water, 80:20 v/v) was used with a flow rate of 0.4 mL/min and a total run time of 5 min. The analytes were ionized by electrospray ionization in the positive ion mode. The linearity range for both analytes in DBS were 0.6-100 ng/ml for VCR and 0.4-100 ng/ml for M1. The intra- and inter-day accuracies for VCR and M1 were 93.10-117.17% and 95.88-111.21%, respectively. While their intra- and inter-day precisions were 1.05 to 10.11% and 5.78 to 8.91%, respectively. The extraction recovery of VCR from DBS paper was 35.3 – 39.4% and 10.4 – 13.4% for M1, with no carryover observed for both analytes. This is the first analytical method to report the simultaneous quantification of VCR and M1 from human DBS. For the first time, concentrations of M1 from DBS patient samples were obtained beyond 1 -h post VCR dose. The developed method was successfully employed to monitor both compounds and perform pharmacokinetic analysis in a population of Kenyan pediatric cancer patients.
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    Vincristine Metabolism and the Role of CYP3A5
    (2007-11-16T20:07:34Z) Dennison, Jennifer Bolin; Hall, Stephen D. (Stephen David), 1957-; Kamendulis, Lisa M.; Queener, Sherry F.; Erickson, Leonard C.; Wrighton, Steven A.
    Vincristine is metabolized by the cytochrome P450 3A subfamily of enzymes possibly including CYP3A5, a genetically polymorphic enzyme. The contribution of CYP3A5 to the metabolism of vincristine was quantified by various in vitro models: cDNA-expressed enzymes, human liver microsomes, and human hepatocytes. With these models, the major CYP metabolite of vincristine, M1, was identified and extensively characterized. The rates of M1 formation in the cDNA-expressed enzyme models were at least 7-fold higher with CYP3A5 than CYP3A4; approximately 90% of the hepatic metabolism was predicted to be CYP3A5-mediated. For human liver microsomes with high CYP3A5 expression, the CYP3A5 contribution was substantial, approximately 80%. Human hepatocytes with at least one CYP3A5*1 allele also metabolized vincristine, albeit at a slower rate (10-fold) than human liver microsomes. The CYP3A5 low-expressing hepatocytes did not metabolize vincristine. We conclude that for high CYP3A5 expressers, the majority of the CYP metabolism is mediated by CYP3A5. By in vitro/in vivo scaling with microsomes, the hepatic clearances of high CYP3A5 expressers are predicted to have a 5-fold higher hepatic clearance than low expressers. However, the role of metabolism in the systemic clearance of vincristine is unknown. To study the disposition of vincristine in vivo, a sensitive and selective LC/MS/MS assay was validated for the quantification of vincristine and M1 quantification in human plasma. Vincristine and M1 were identified and quantified in select pediatric plasma and urine samples. For future large-scale clinical studies, the vincristine and M1 concentrations in plasma will be quantified to understand the role of CYP3A5 genotype in vincristine pharmacokinetics. For patients that are CYP3A5 high expressers, the systemic clearance of vincristine may be higher than that of low CYP3A5 expressers. Thus, CYP3A5 genotype may be an important determinant of inter-individual variability in clinical outcomes.