| 1. |
- Glimelius, Bengt, et al.
(författare)
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Prediction of irinotecan and 5-fluorouracil toxicity and response in patients with advanced colorectal cancer
- 2011
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Ingår i: The Pharmacogenomics Journal. - : Springer Science and Business Media LLC. - 1470-269X .- 1473-1150. ; 11:1, s. 61-71
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Tidskriftsartikel (refereegranskat)abstract
- Irinotecan and 5-fluorouracil (5-FU) are used to treat metastatic colorectal cancer. Irinotecan's active metabolite is inactivated by UDP-glucuronosyltransferase 1A1 (UGT1A1), which is deficient in Gilbert's syndrome. Irinotecan and metabolites are transported by P-glycoprotein, encoded by ABCB1. 5-FU targets folate metabolism through inhibition of thymidylate synthase (TYMS). Methylenetetrahydrofolate reductase (MTHFR) generates active folate necessary for haematopoiesis. We retrospectively genotyped 140 Swedish and Norwegian irinotecan and 5-FU-treated colorectal cancer patients from the Nordic VI clinical trial for selected variants of UGT1A1, ABCB1, TYMS and MTHFR. We found an increased risk of clinically relevant early toxicity in patients carrying the ABCB1 3435 T/T genotype, Odds ratio (OR)=3.79 (95% confidence interval (CI)=1.09-13.2), and in patients carrying the UGT1A1(*)28/(*)28 genotype, OR=4.43 (95% CI=1.30-15.2). Patients with UGT1A1(*)28/(*)28 had an especially high risk of neutropenia, OR=6.87 (95% CI=1.70-27.7). Patients who had reacted with toxicity during the first two cycles were in total treated with fewer cycles (P<0.001), and less often responded to treatment (P<0.001). Genetic variation in ABCB1 was associated with both early toxicity and lower response to treatment. Carriers of the ABCB1 1236T-2677T-3435T haplotype responded to treatment less frequently (43 vs 67%, P=0.027), and survived shorter time, OR=1.56 (95% CI=1.01-2.45).
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| 2. |
- Howard, Rebecca, et al.
(författare)
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Genotyping for CYP2C9 and VKORC1 alleles by a novel point of care assay with HyBeacon® probes
- 2011
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Ingår i: Clinica Chimica Acta. - : Elsevier BV. - 0009-8981 .- 1873-3492. ; 412:23-24, s. 2063-2069
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Coumarin anticoagulants such as warfarin are used to treat and prevent thromboembolic events in patients. The required dosage is difficult to predict and the risk of over or under anticoagulation are dependent on several environmental and clinical factors, such as concurrent medication, diet, age and genotype for polymorphisms in two genes CYP2C9 and VKORC1.METHODS: A novel fluorescent PCR genotyping assay using HyBeacon® probes, was developed to enable clinical staff to genotype the CYP2C9*2 and CYP2C9*3 alleles and the VKORC1 G-1639A polymorphism directly from unextracted blood samples. A prototype PCR instrument, Genie 1, suitable for point of care use was developed to carry out the assays. The panel of tests was validated by analysing blood samples from 156 individuals and comparing genotypes with data obtained using DNA samples from the same individuals. The accuracy of genotypes obtained with the Genie 1 was compared against results from well validated real time PCR and PCR-restriction fragment length polymorphism analysis.RESULTS: Identical results were obtained for the newly developed HyBeacon® method and the validation method in all cases except for one where no result was obtained for the VKORC1 polymorphism on the Genie instrument. The samples used for validation represented all six possible *2 and *3 allele-related CYP2C9 genotypes and all three VKORC1 G-1639A genotypes.CONCLUSIONS: We observed excellent accuracy for the newly developed method which can determine genotype in less than 2 h.
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| 3. |
- Pirmohamed, Munir, et al.
(författare)
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A Randomized Trial of Genotype-Guided Dosing of Warfarin
- 2013
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Ingår i: New England Journal of Medicine. - 0028-4793 .- 1533-4406. ; 369:24, s. 2294-2303
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Tidskriftsartikel (refereegranskat)abstract
- Background: The level of anticoagulation in response to a fixed-dose regimen of warfarin is difficult to predict during the initiation of therapy. We prospectively compared the effect of genotype-guided dosing with that of standard dosing on anticoagulation control in patients starting warfarin therapy.Methods: We conducted a multicenter, randomized, controlled trial involving patients with atrial fibrillation or venous thromboembolism. Genotyping for CYP2C9*2, CYP2C9*3, and VKORC1 (-1639GA) was performed with the use of a point-of-care test. For patients assigned to the genotype-guided group, warfarin doses were prescribed according to pharmacogenetic-based algorithms for the first 5 days. Patients in the control (standard dosing) group received a 3-day loading-dose regimen. After the initiation period, the treatment of all patients was managed according to routine clinical practice. The primary outcome measure was the percentage of time in the therapeutic range of 2.0 to 3.0 for the international normalized ratio (INR) during the first 12 weeks after warfarin initiation.Results: A total of 455 patients were recruited, with 227 randomly assigned to the genotype-guided group and 228 assigned to the control group. The mean percentage of time in the therapeutic range was 67.4% in the genotype-guided group as compared with 60.3% in the control group (adjusted difference, 7.0 percentage points; 95% confidence interval, 3.3 to 10.6; P<0.001). There were significantly fewer incidences of excessive anticoagulation (INR 4.0) in the genotype-guided group. The median time to reach a therapeutic INR was 21 days in the genotype-guided group as compared with 29 days in the control group (P<0.001).Conclusions: Pharmacogenetic-based dosing was associated with a higher percentage of time in the therapeutic INR range than was standard dosing during the initiation of warfarin therapy.
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