The purpose of this guideline is to provide information for the interpretation of clinical dihydropyrimidine dehydrogenase (DPYD) genotype tests so that the results can be used to guide dosing of ...fluoropyrimidines (5‐fluorouracil and capecitabine). Detailed guidelines for the use of fluoropyrimidines, their clinical pharmacology, as well as analyses of cost‐effectiveness are beyond the scope of this document. The Clinical Pharmacogenetics Implementation Consortium (CPIC®) guidelines consider the situation of patients for which genotype data are already available (updates available at https://cpicpgx.org/guidelines/guideline‐for‐fluoropyrimidines‐and‐dpyd/).
Abstract 5-Fluorouracil (5-FU) and capecitabine (CAP) are among the most frequently prescribed anticancer drugs. They are inactivated in the liver by the enzyme dihydropyrimidine dehydrogenase (DPD). ...Up to 5% of the population is DPD deficient and these patients have a significantly increased risk of severe and potentially lethal toxicity when treated with regular doses of 5-FU or CAP. DPD is encoded by the gene DPYD and variants in DPYD can lead to a decreased DPD activity. Although prospective DPYD genotyping is a valuable tool to identify patients with DPD deficiency, and thus those at risk for severe and potential life-threatening toxicity, prospective genotyping has not yet been implemented in daily clinical care. Our goal was to present the available evidence in favour of prospective genotyping, including discussion of unjustified worries on cost-effectiveness, and potential underdosing. We conclude that there is convincing evidence to implement prospective DPYD genotyping with an upfront dose adjustment in DPD deficient patients. Immediate benefit in patient care can be expected through decreasing toxicity, while maintaining efficacy.
The character of EGFR signals can influence cell fate but mechanistic insights into intestinal EGFR-Ras signalling are limited. Here we show that two distinct Ras nucleotide exchange factors, RasGRP1 ...and SOS1, lie downstream of EGFR but act in functional opposition. RasGRP1 is expressed in intestinal crypts where it restricts epithelial growth. High RasGRP1 expression in colorectal cancer (CRC) patient samples correlates with a better clinical outcome. Biochemically, we find that RasGRP1 creates a negative feedback loop that limits proliferative EGFR-SOS1-Ras signals in CRC cells. Genetic Rasgrp1 depletion from mice with either an activating mutation in KRas or with aberrant Wnt signalling due to a mutation in Apc resulted in both cases in exacerbated Ras-ERK signalling and cell proliferation. The unexpected opposing cell biological effects of EGFR-RasGRP1 and EGFR-SOS1 signals in the same cell shed light on the intricacy of EGFR-Ras signalling in normal epithelium and carcinoma.
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DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SBMB, UILJ, UKNU, UL, UM, UPUK
Fluoropyrimidines are widely used in the treatment of several types of solid tumors. Although most often well tolerated, severe toxicity is encountered in ~ 20–30% of the patients. Individualized ...dosing for these patients can reduce the incidence of severe fluoropyrimidine‐related toxicity. However, no consensus has been achieved on which dosing strategy is preferred. The most established strategy for individualized dosing of fluoropyrimidines is upfront genotyping of the DPYD gene. Prospective research has shown that DPYD‐guided dose‐individualization significantly reduces the incidence of severe toxicity and can be easily applied in routine daily practice. Furthermore, the measurement of the dihydropyrimidine dehydrogenase (DPD) enzyme activity has shown to accurately detect patients with a DPD deficiency. Yet, because this assay is time‐consuming and expensive, it is not widely implemented in routine clinical care. Other methods include the measurement of pretreatment endogenous serum uracil concentrations, the uracil/dihydrouracil‐ratio, and the 5‐fluorouracil (5‐FU) degradation rate. These methods have shown mixed results. Next to these methods to detect DPD deficiency, pharmacokinetically guided follow‐up of 5‐FU could potentially be used as an addition to dosing strategies to further improve the safety of fluoropyrimidines. Furthermore, baseline characteristics, such as sex, age, body composition, and renal function have shown to have a relationship with the development of severe toxicity. Therefore, these baseline characteristics should be considered as a dose‐individualization strategy. We present an overview of the current dose‐individualization strategies and provide perspectives for a future multiparametric approach.
Summary Background The best-known cause of intolerance to fluoropyrimidines is dihydropyrimidine dehydrogenase (DPD) deficiency, which can result from deleterious polymorphisms in the gene encoding ...DPD ( DPYD ), including DPYD *2A and c.2846A>T. Three other variants— DPYD c.1679T>G, c.1236G>A/HapB3, and c.1601G>A—have been associated with DPD deficiency, but no definitive evidence for the clinical validity of these variants is available. The primary objective of this systematic review and meta-analysis was to assess the clinical validity of c.1679T>G, c.1236G>A/HapB3, and c.1601G>A as predictors of severe fluoropyrimidine-associated toxicity. Methods We did a systematic review of the literature published before Dec 17, 2014, to identify cohort studies investigating associations between DPYD c.1679T>G, c.1236G>A/HapB3, and c.1601G>A and severe (grade ≥3) fluoropyrimidine-associated toxicity in patients treated with fluoropyrimidines (fluorouracil, capecitabine, or tegafur-uracil as single agents, in combination with other anticancer drugs, or with radiotherapy). Individual patient data were retrieved and analysed in a multivariable analysis to obtain an adjusted relative risk (RR). Effect estimates were pooled by use of a random-effects meta-analysis. The threshold for significance was set at a p value of less than 0·0167 (Bonferroni correction). Findings 7365 patients from eight studies were included in the meta-analysis. DPYD c.1679T>G was significantly associated with fluoropyrimidine-associated toxicity (adjusted RR 4·40, 95% CI 2·08–9·30, p<0·0001), as was c.1236G>A/HapB3 (1·59, 1·29–1·97, p<0·0001). The association between c.1601G>A and fluoropyrimidine-associated toxicity was not significant (adjusted RR 1·52, 95% CI 0·86–2·70, p=0·15). Analysis of individual types of toxicity showed consistent associations of c.1679T>G and c.1236G>A/HapB3 with gastrointestinal toxicity (adjusted RR 5·72, 95% CI 1·40–23·33, p=0·015; and 2·04, 1·49–2·78, p<0·0001, respectively) and haematological toxicity (adjusted RR 9·76, 95% CI 3·03–31·48, p=0·00014; and 2·07, 1·17–3·68, p=0·013, respectively), but not with hand-foot syndrome. DPYD *2A and c.2846A>T were also significantly associated with severe fluoropyrimidine-associated toxicity (adjusted RR 2·85, 95% CI 1·75–4·62, p<0·0001; and 3·02, 2·22–4·10, p<0·0001, respectively). Interpretation DPYD variants c.1679T>G and c.1236G>A/HapB3 are clinically relevant predictors of fluoropyrimidine-associated toxicity. Upfront screening for these variants, in addition to the established variants DPYD *2A and c.2846A>T, is recommended to improve the safety of patients with cancer treated with fluoropyrimidines. Funding None.
We investigated the predictive value of dihydropyrimidine dehydrogenase (DPD) phenotype, measured as pretreatment serum uracil and dihydrouracil concentrations, for severe as well as fatal ...fluoropyrimidine-associated toxicity in 550 patients treated previously with fluoropyrimidines during a prospective multicenter study.
Pretreatment serum concentrations of uracil and dihydrouracil were measured using a validated LC-MS/MS method. The primary endpoint of this analysis was global (any) severe fluoropyrimidine-associated toxicity, that is, grade ⩾3 toxicity according to the NCI CTC-AE v3.0, occurring during the first cycle of treatment. The predictive value of uracil and the uracil/dihydrouracil ratio for early severe fluoropyrimidine-associated toxicity were compared. Pharmacogenetic variants in DPYD (c.2846A>T, c.1679T>G, c.1129-5923C>G, and c.1601G>A) and TYMS (TYMS 5'-UTR VNTR and TYMS 3'-UTR 6-bp ins/del) were measured and tested for associations with severe fluoropyrimidine-associated toxicity to compare predictive value with DPD phenotype. The Benjamini-Hochberg false discovery rate method was used to control for type I errors at level q<0.050 (corresponding to P<0.010).
Uracil was superior to the dihydrouracil/uracil ratio as a predictor of severe toxicity. High pretreatment uracil concentrations (>16 ng ml
) were strongly associated with global severe toxicity (OR 5.3, P=0.009), severe gastrointestinal toxicity (OR 33.7, P<0.0001), toxicity-related hospitalisation (OR 16.9, P<0.0001), as well as fatal treatment-related toxicity (OR 44.8, P=0.001). None of the DPYD variants alone, or TYMS variants alone, were associated with severe toxicity.
High pretreatment uracil concentration was strongly predictive of severe, including fatal, fluoropyrimidine-associated toxicity, and is a highly promising phenotypic marker to identify patients at risk of severe fluoropyrimidine-associated toxicity.
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•A rapid UPLC–MS/MS assay to quantify uracil and dihydrouracil in human plasma.•Sample pre-treatment only consists of protein precipitation.•Validation experiments showed good assay ...accuracy, precision and sensitivity.•The role of matrix effects was effectively minimized using the internal standards uracil-15N2 and dihydrouracil-13C4-15N2.
Quantification of the endogenous dihydropyrimidine dehydrogenase (DPD) substrate uracil (U) and the reaction product dihydrouracil (UH2) in plasma might be suitable for identification of patients at risk of fluoropyrimidine-induced toxicity as a result of DPD deficiency. In this paper, we describe the development and validation of a rapid and sensitive ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) assay for quantification of U and UH2 in human plasma.
Analytes were extracted by protein precipitation, chromatographically separated on an Acquity UPLC® HSS T3 column with gradient elution and analyzed with a tandem mass spectrometer equipped with an electrospray ionization source. U was quantified in the negative ion mode and UH2 in the positive ion mode. Stable isotopes for U and UH2 were used as internal standards.
Total chromatographic run time was 5min. Validated concentration ranges for U and UH2 were from 1 to 100ng/mL and 10 to 1000ng/mL, respectively. Inter-assay bias and inter-assay precision for U were within ±2.8% and ≤12.4%. For UH2, inter-assay bias and inter-assay precision were within ±2.9% and ≤7.2%. Adequate stability of U and UH2 in dry extract, final extract, stock solution and plasma was demonstrated. Stability of U and UH2 in whole blood was only satisfactory when stored up to 4hours at 2–8°C, but not at ambient temperatures.
An accurate, precise and sensitive UPLC-MS/MS assay for quantification of U and UH2 in plasma was developed. This assay is now applied to support clinical studies with fluoropyrimidine drugs.
Carriers of the genetic DPYD*2A variant, resulting in dihydropyrimidine dehydrogenase deficiency, are at significantly increased risk of developing severe fluoropyrimidine‐associated toxicity. ...Upfront DPYD*2A genotype‐based dose reductions improve patient safety, but uncertainty exists whether this has a negative impact on treatment effectiveness. Therefore, our study investigated effectiveness and safety of DPYD*2A genotype‐guided dosing. A cohort of 40 prospectively identified heterozygous DPYD*2A carriers, treated with a ~50% reduced fluoropyrimidine dose, was identified. For effectiveness analysis, a matched pair‐analysis was performed in which for each DPYD*2A carrier a matched DPYD*2A wild‐type patient was identified. Overall survival and progression‐free survival were compared between the matched groups. The frequency of severe (grade ≥ 3) treatment‐related toxicity was compared to 1 a cohort of 1606 wild‐type patients treated with full dose and 2 a cohort of historical controls derived from literature, i.e. 86 DPYD*2A variant carriers who received a full fluoropyrimidine dose. For 37 out of 40 DPYD*2A carriers, a matched control could be identified. Compared to matched controls, reduced doses did not negatively affect overall survival (median 27 months versus 24 months, p = 0.47) nor progression‐free survival (median 14 months versus 10 months, p = 0.54). Risk of severe fluoropyrimidine‐related toxicity in DPYD*2A carriers treated with reduced dose was 18%, comparable to wild‐type patients (23%, p = 0.57) and significantly lower than the risk of 77% in DPYD*2A carriers treated with full dose (p < 0.001). Our study is the first to show that DPYD*2A genotype‐guided dosing appears to have no negative effect on effectiveness of fluoropyrimidine‐based chemotherapy, while resulting in significantly improved patient safety.
What's new?
Genetic variants in the dihydropyrimidine dehydrogenase gene (DPYD) enhance toxicity associated with fluoropyrimidine‐based chemotherapies and a 50% reduction in drug dosing in affected carriers. Here the authors addressed the fear of “underdosing” by retrospectively matching cancer patients with mutant or wild‐type DPYD status. No significant difference was seen in overall survival, progression‐free survival or disease control between the two groups affirming current clinical guidelines.
In clinical practice, 25–30% of the patients treated with fluoropyrimidines experience severe fluoropyrimidine‐related toxicity. Extensively clinically validated DPYD genotyping tests are available ...to identify patients at risk of severe toxicity due to decreased activity of dihydropyrimidine dehydrogenase (DPD), the rate limiting enzyme in fluoropyrimidine metabolism. In April 2020, the European Medicines Agency recommended that, as an alternative for DPYD genotype‐based testing for DPD deficiency, also phenotype testing based on pretreatment plasma uracil levels is a suitable method to identify patients with DPD deficiency. Although the evidence for genotype‐directed dosing of fluoropyrimidines is substantial, the level of evidence supporting plasma uracil levels to predict DPD activity in clinical practice is limited. Notwithstanding this, uracil‐based phenotyping is now used in clinical practice in various countries in Europe. We aimed to determine the value of pretreatment uracil levels in predicting DPD deficiency and severe treatment‐related toxicity. To this end, we determined pretreatment uracil levels in 955 patients with cancer, and assessed the correlation with DPD activity in peripheral blood mononuclear cells (PBMCs) and fluoropyrimidine‐related severe toxicity. We identified substantial issues concerning the use of pretreatment uracil in clinical practice, including large between‐center study differences in measured pretreatment uracil levels, most likely as a result of pre‐analytical factors. Importantly, we were not able to correlate pretreatment uracil levels with DPD activity nor were uracil levels predictive of severe treatment‐related toxicity. We urge that robust clinical validation should first be performed before pretreatment plasma uracil levels are used in clinical practice as part of a dosing strategy for fluoropyrimidines.
Highlights • Combining antibodies, targeting distinct pathways, may induce synergistic effects. • Most antibodies have limited overlapping toxicity and no pharmacokinetic interactions. • Several ...studies showed additive effects of combining antibodies, but a few did not. • It is unknown why some combinations appear to result in an antagonistic effect.
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