Browsing by Subject "Pyrimidines"
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Item Open Access Aspergillus niger: an unusual cause of invasive pulmonary aspergillosis.(J Med Microbiol, 2010-07) Person, AK; Chudgar, SM; Norton, BL; Tong, BC; Stout, JEInfections due to Aspergillus species cause significant morbidity and mortality. Most are attributed to Aspergillus fumigatus, followed by Aspergillus flavus and Aspergillus terreus. Aspergillus niger is a mould that is rarely reported as a cause of pneumonia. A 72-year-old female with chronic obstructive pulmonary disease and temporal arteritis being treated with steroids long term presented with haemoptysis and pleuritic chest pain. Chest radiography revealed areas of heterogeneous consolidation with cavitation in the right upper lobe of the lung. Induced bacterial sputum cultures, and acid-fast smears and cultures were negative. Fungal sputum cultures grew A. niger. The patient clinically improved on a combination therapy of empiric antibacterials and voriconazole, followed by voriconazole monotherapy. After 4 weeks of voriconazole therapy, however, repeat chest computed tomography scanning showed a significant progression of the infection and near-complete necrosis of the right upper lobe of the lung. Serum voriconazole levels were low-normal (1.0 microg ml(-1), normal range for the assay 0.5-6.0 microg ml(-1)). A. niger was again recovered from bronchoalveolar lavage specimens. A right upper lobectomy was performed, and lung tissue cultures grew A. niger. Furthermore, the lung histopathology showed acute and organizing pneumonia, fungal hyphae and oxalate crystallosis, confirming the diagnosis of invasive A. niger infection. A. niger, unlike A. fumigatus and A. flavus, is less commonly considered a cause of invasive aspergillosis (IA). The finding of calcium oxalate crystals in histopathology specimens is classic for A. niger infection and can be helpful in making a diagnosis even in the absence of conidia. Therapeutic drug monitoring may be useful in optimizing the treatment of IA given the wide variations in the oral bioavailability of voriconazole.Item Open Access Comparative cost-effectiveness analysis of voriconazole and fluconazole for prevention of invasive fungal infection in patients receiving allogeneic hematopoietic cell transplants.(American journal of health-system pharmacy : AJHP : official journal of the American Society of Health-System Pharmacists, 2013-09) Mauskopf, Josephine; Chirila, Costel; Graham, Jon; Gersten, Iris D; Leather, Helen; Maziarz, Richard T; Baden, Lindsey R; Bolaños-Meade, Javier; Brown, Janice MY; Walsh, Thomas J; Horowitz, Mary H; Kurtzberg, Joanne; Marr, Kieren A; Wingard, John RPurpose
The cost-effectiveness of voriconazole versus fluconazole prophylaxis against fungal infections in hematopoietic cell transplant (HCT) recipients is investigated.Methods
A decision-analytic model was developed to estimate the drug costs associated with planned or supplemental prophylaxis and empirical therapy and the costs of treating suspected or documented invasive fungal infections (IFIs) in HCT recipients. Published clinical trial data on 599 patients who received 100-180 days of prophylactic therapy with voriconazole or fluconazole were used to model specified IFI-prevention and mortality outcomes; 6-month, 12-month, and lifetime incremental cost-effectiveness ratios (ICERs) were estimated, with a bootstrap analysis performed to reffect the uncertainty of the clinical trial data.Results
Estimated mean total prophylaxis and IFI-related costs associated with voriconazole versus fluconazole prophylaxis over 12 months were higher in the entire study population and among patients receiving HCT for diagnoses other than acute myeloid leukemia (AML) but were not significantly different for patients with AML. The cost per IFI avoided ($66,919) and the cost per life-year gained ($5,453) were lower among patients with AML who received voriconazole relative to the full study population. ICERs were more favorable for voriconazole over a 6-month time frame and when modeling was conducted using generic price data. Assuming a threshold value of $50,000 for one year of life gained, the calculated probability of voriconazole being cost-effective was 33% for the full study population and 85% for the AML subgroup.Conclusion
The decision model indicated that voriconazole prophylaxis was cost-effective for patients undergoing allogeneic HCT for AML.Item Open Access Determination of metarrestin (ML-246) in human plasma for a first-in-human clinical pharmacokinetic application by a simple and efficient uHPLC-MS/MS assay.(Journal of chromatography. B, Analytical technologies in the biomedical and life sciences, 2023-05) Richardson, William J; Zimmerman, Sara M; Reno, Annieka; Corvalan Cabanas, Natalia; Arisa, Oluwatobi; Rudloff, Udo; Figg, William D; Peer, Cody JMetarrestin is a first-in-class small molecule inhibitor targeting the perinucleolar compartment, a subnuclear body associated with metastatic capacity. Promising preclinical results led to the clinical translation of the compound into a first-in-human phase I trial (NCT04222413). To characterize metarrestin's pharmacokinetic profile in humans, a uHPLC-MS/MS assay was developed and validated to determine the disposition of the drug in human plasma. Efficient sample preparation was accomplished through one-step protein precipitation paired with elution through a phospholipid filtration plate. Chromatographic separation was achieved with gradient elution through an Acuity UPLC® BEH C18 column (50 × 2.1 mm, 1.7 µm). Tandem mass spectrometry facilitated the detection of metarrestin and tolbutamide, the internal standard. The effective calibration range spanned 1-5000 ng/mL and was both accurate (range -5.9 % to 4.9 % deviation) and precise (≤9.0 %CV). Metarrestin proved stable (≤4.9 % degradation) under various assay-imposed conditions. Matrix effects, extraction efficiency, and process efficiency were assessed. Further, the assay was successfully able to determine the disposition of orally administered metarrestin in patients from the lowest dose cohort (1 mg) for 48 h post-administration. Thus, the validated analytical method detailed in this work is simple, sensitive, and clinically applicable.Item Open Access Engineering a BCR-ABL-activated caspase for the selective elimination of leukemic cells.(Proc Natl Acad Sci U S A, 2013-02-05) Kurokawa, Manabu; Ito, Takahiro; Yang, Chih-Sheng; Zhao, Chen; Macintyre, Andrew N; Rizzieri, David A; Rathmell, Jeffrey C; Deininger, Michael W; Reya, Tannishtha; Kornbluth, SallyIncreased understanding of the precise molecular mechanisms involved in cell survival and cell death signaling pathways offers the promise of harnessing these molecules to eliminate cancer cells without damaging normal cells. Tyrosine kinase oncoproteins promote the genesis of leukemias through both increased cell proliferation and inhibition of apoptotic cell death. Although tyrosine kinase inhibitors, such as the BCR-ABL inhibitor imatinib, have demonstrated remarkable efficacy in the clinic, drug-resistant leukemias emerge in some patients because of either the acquisition of point mutations or amplification of the tyrosine kinase, resulting in a poor long-term prognosis. Here, we exploit the molecular mechanisms of caspase activation and tyrosine kinase/adaptor protein signaling to forge a unique approach for selectively killing leukemic cells through the forcible induction of apoptosis. We have engineered caspase variants that can directly be activated in response to BCR-ABL. Because we harness, rather than inhibit, the activity of leukemogenic kinases to kill transformed cells, this approach selectively eliminates leukemic cells regardless of drug-resistant mutations.Item Open Access Expanded safety analysis of pevonedistat, a first-in-class NEDD8-activating enzyme inhibitor, in patients with acute myeloid leukemia and myelodysplastic syndromes.(Blood cancer journal, 2017-02-03) Swords, RT; Watts, J; Erba, HP; Altman, JK; Maris, M; Anwer, F; Hua, Z; Stein, H; Faessel, H; Sedarati, F; Dezube, BJ; Giles, FJ; Medeiros, BC; DeAngelo, DJItem Open Access Synergistic antitumor effects of 9.2.27-PE38KDEL and ABT-737 in primary and metastatic brain tumors.(PloS one, 2019-01-09) Yu, Xin; Dobrikov, Mikhail; Keir, Stephen T; Gromeier, Matthias; Pastan, Ira H; Reisfeld, Ralph; Bigner, Darell D; Chandramohan, VidyalakshmiStandard treatment, unfortunately, yields a poor prognosis for patients with primary or metastatic cancers in the central nervous system, indicating a necessity for novel therapeutic agents. Immunotoxins (ITs) are a class of promising therapeutic candidates produced by fusing antibody fragments with toxin moieties. In this study, we investigated if inherent resistance to IT cytotoxicity can be overcome by rational combination with pro-apoptotic enhancers. Therefore, we combined ITs (9.2.27-PE38KDEL or Mel-14-PE38KDEL) targeting chondroitin sulfate proteoglycan 4 (CSPG4) with a panel of Bcl-2 family inhibitors (ABT-737, ABT-263, ABT-199 [Venetoclax], A-1155463, and S63845) against patient-derived glioblastoma, melanoma, and breast cancer cells/cell lines. In vitro cytotoxicity assays demonstrated that the addition of the ABT compounds, specifically ABT-737, sensitized the different tumors to IT treatment, and improved the IC50 values of 9.2.27-PE38KDEL up to >1,000-fold. Mechanistic studies using 9.2.27-PE38KDEL and ABT-737 revealed that increased levels of intracellular IT, processed (active) exotoxin, and PARP cleavage correlated with the enhanced sensitivity to the combination treatment. Furthermore, we confirmed the synergistic effect of 9.2.27-PE38KDEL and ABT-737 combination therapy in orthotopic GBM xenograft and cerebral melanoma metastasis models in nude mice. Our study defines strategies for overcoming IT resistance and enhancing specific antitumor cytotoxicity in primary and metastatic brain tumors.Item Open Access Treatment with Imatinib in NSCLC is associated with decrease of phosphorylated PDGFR-beta and VEGF expression, decrease in interstitial fluid pressure and improvement of oxygenation.(Br J Cancer, 2006-10-23) Vlahovic, G; Rabbani, ZN; Herndon, JE; Dewhirst, MW; Vujaskovic, ZElevated intratumoral interstitial fluid pressure (IFP) and tumour hypoxia are independent predictive factors for poor survival and poor treatment response in cancer patients. However, the relationship between IFP and tumour hypoxia has not yet been clearly established. Preclinical studies have shown that lowering IFP improves treatment response to cytotoxic therapy. Interstitial fluid pressure can be reduced by inhibition of phosphorylated platelet-derived growth factor receptor-beta (p-PDGFR-beta), a tyrosine kinase receptor frequently overexpressed in cancer stroma, and/or by inhibition of VEGF, a growth factor commonly overexpressed in tumours overexpressing p-PDGFR-beta. We hypothesised that Imatinib, a specific PDGFR-beta inhibitor will, in addition to p-PDGFR-beta inhibition, downregulate VEGF, decrease IFP and improve tumour oxygenation. A549 human lung adenocarcinoma xenografts overexpressing PDGFR-beta were grown in nude mice. Tumour-bearing animals were randomised to control and treatment groups (Imatinib 50 mg kg(-1) via gavage for 4 days). Interstitial fluid pressure was measured in both groups before and after treatment. EF5, a hypoxia marker, was administered 3 h before being killed. Tumours were sectioned and stained for p-PDGFR-beta, VEGF and EF5 binding. Stained sections were viewed with a fluorescence microscope and image analysis was performed. Imatinib treatment resulted in significant reduction of p-PDGFR-beta, VEGF and IFP. Tumour oxygenation was also significantly improved. This study shows that p-PDGFR-beta-overexpressing tumours can be effectively treated with Imatinib to decrease tumour IFP. Importantly, this is the first study demonstrating that Imatinib treatment improves tumour oxygenation and downregulates tumour VEGF expression.