ArticleLiterature Review

Dihydropyrimidine Dehydrogenase Deficiency, a Pharmacogenetic Syndrome Associated with Potentially Life-Threatening Toxicity Following 5-Fluorouracil Administration

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Abstract

Dihydropyrimidine dehydrogenase (DPD) deficiency is a pharmacogenetic syndrome associated with potentially life-threatening toxicity following the administration of standard doses of 5-fluorouracil. This syndrome derives its importance from the fact that approximately 2 million patients receive the drug worldwide each year. Population studies have suggested that 4%-7% of the American population exhibit dose-limiting toxicity that might be associated with a genetic defect in the DPYD gene that encodes for the DPD enzyme. During the past several years it has become increasingly clear that genetics is a major determinant of the variability in drug response, accounting for the probability of drug efficacy and the likelihood of toxic drug reactions. This article briefly discusses the clinical presentation, laboratory diagnosis, pharmacokinetics, inheritance, and the clinical management options of DPD deficiency. The variability of DPD enzyme activity in population studies and the different DPYD alleles together with new phenotypic and genotypic methods of screening for DPD deficiency will also be reviewed.

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... Deficiencies in the DPD enzyme may lead to the toxicities of grade 3 or be even more significant due to the 5-FU toxicity. Since the symptom for the toxicity has appeared after the administration of the drug, intensive care and medical interventions are required [71]. Some clinical manifestations that have occurred due to the toxicity of 5-FU are fever, mucositis, stomatitis, nausea, vomiting and diarrhoea. ...
... The dosage of 5-FU can be reduced or increased in the following sessions according to the enzymatic status of the DPD observed during the first treatment, and depending on the tolerance level of the patient [77]. If the patient is suspected with the toxicity of 5-FU occurred due to the DPD deficiency, then administration of the drug should be stopped immediately followed by the utilisation of haemodialysis and haemoperfusion to rapidly remove any remaining traces of the drug from the body [71,78]. Additionally, tumours have also been noted to express variable levels of DPD activity. ...
... Additionally, to boost the WBC count, colonystimulating growth factor can be administered in the patients with toxicity. Mainly, an aggressive, holistic, and supportive care is the only way to treat it [71]. ...
Article
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Cancer caused by fundamental defects in cell cycle regulation leads to uncontrolled growth of cells. In spite of the treatment with chemotherapeutic agents of varying nature, multiple resistance mechanisms are identified in cancer cells. Similarly, numerous variations, which decrease the metabolism of chemotherapeutics agents and thereby increasing the toxicity of anticancer drugs have been identified. 5-Fluorouracil (5-FU) is an anticancer drug widely used to treat many cancers in the human body. Its broad targeting range is based upon its capacity to act as a uracil analogue, thereby disrupting RNA and DNA synthesis. Dihydropyrimidine dehydrogenase (DPD) is an enzyme majorly involved in the metabolism of pyrimidines in the human body and has the same metabolising effect on 5-FU, a pyrimidine analogue. Multiple mutations in the DPD gene have been linked to 5-FU toxicity and inadequate dosages. DPD inhibitors have also been used to inhibit excessive degradation of 5-FU for meeting appropriate dosage requirements. This article focusses on the role of dihydropyrimidine dehydrogenase in the metabolism of the anticancer drug 5-FU and other associated drugs.
... The drug was presumed to be eliminated from the central compartment where elimination was tested to follow either a linear behaviour or nonlinear Michaelis-Menten kinetics. The fraction of 5FU converted to 5FUH2 was fixed a priori to 0.85, according to the literature [6,34]. ...
... The PD model was developed according to Friberg et al. [24,34] using simultaneous approach. The model was driven by 5FU plasma concentrations from the PK model and comprised a compartment of proliferating leukocytes (rate constant describing the proliferation of cells: k prol ), transit compartments representing leukocytes undergoing maturation (rate constant describing the transfer between transit compartments: k tr ) and a compartment of circulating leukocytes (rate constant describing the rate of exit from the circulating compartment: k circ ). ...
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PurposeTo describe 5-fluorouracil (5FU) pharmacokinetics, myelotoxicity and respective covariates using a simultaneous nonlinear mixed effect modelling approach.Methods Thirty patients with gastrointestinal cancer received 5FU 650 or 1000 mg/m2/day as 5-day continuous venous infusion (14 of whom also received cisplatin 20 mg/m2/day). 5FU and 5-fluoro-5,6-dihydrouracil (5FUH2) plasma concentrations were described by a pharmacokinetic model using NONMEM. Absolute leukocyte counts were described by a semi-mechanistic myelosuppression model. Covariate relationships were evaluated to explain the possible sources of variability in 5FU pharmacokinetics and pharmacodynamics.ResultsTotal clearance of 5FU correlated with body surface area (BSA). Population estimate for total clearance was 249 L/h. Clearances of 5FU and 5FUH2 fractionally changed by 77%/m2 difference from the median BSA. 5FU central and peripheral volumes of distribution were 5.56 L and 28.5 L, respectively. Estimated 5FUH2 clearance and volume of distribution were 121 L/h and 96.7 L, respectively. Baseline leukocyte count of 6.86 × 109/L, as well as mean leukocyte transit time of 281 h accounting for time delay between proliferating and circulating cells, was estimated. The relationship between 5FU plasma concentrations and absolute leukocyte count was found to be linear. A higher degree of myelosuppression was attributed to combination therapy (slope = 2.82 L/mg) with cisplatin as compared to 5FU monotherapy (slope = 1.17 L/mg).ConclusionsBSA should be taken into account for predicting 5FU exposure. Myelosuppression was influenced by 5FU exposure and concomitant administration of cisplatin.
... 5-FU and its next-generation drug, Tegafur, are particularly associated with the treatment of gastrointestinal cancers [2]. Approximately 10-30% of individuals treated with 5-FU experienced a serious life-threatening adverse effect at the standard dose [3]; these complications have been attributed to the catabolic pathway of 5-FU [4]. Over 85% of the administered 5-FU compound is degraded into 5-fluoro-5,6-dihydrouracil in the liver through a catabolic pathway mediated by dihydropyrimidine dehydrogenase (DPD) [5,6]. ...
... associated with the treatment of gastrointestinal cancers [2]. Approximately 10-30% of individuals treated with 5-FU experienced a serious life-threatening adverse effect at the standard dose [3]; these complications have been attributed to the catabolic pathway of 5-FU [4]. Over 85% of the administered 5-FU compound is degraded into 5-fluoro-5,6-dihydrouracil in the liver through a catabolic pathway mediated by dihydropyrimidine dehydrogenase (DPD) [5,6]. ...
Article
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Background: Xiang-Sha-Liu-Jun-Zi-Tang (XSLJZT) is the most common traditional formula given to colorectal and breast cancer patients in Taiwan, according to a statistical study of the National Health Insurance Research Database. 5-Fluorouracil (5-FU) is widely used as the first line of treatment for colorectal cancer. Thus, the aim of study is to investigate the pharmacokinetic interaction of XSLJZT and 5-FU. Methods: To investigate the herb-drug interaction of XSLJZT with 5-FU as well as its metabolite 5-fluoro-5,6-dihydrouracil (5-FDHU) using pharmacokinetics, a high-performance liquid chromatography (HPLC) system coupled with a photodiode array detector was developed to monitor 5-FU and 5-FDHU levels in rat blood. Rats were divided into three cohorts, one of which was administered 5-FU (100 mg/kg, iv-intravenous) alone, while the other two groups were pretreated with low and high doses of XSLJZT (600 mg/kg/day or 2400 mg/kg/day for 5 consecutive days) in combination with 5-FU. Results: The results demonstrated that 5-FU level was not significantly different between the group treated with only 5-FU and the group pretreated with a normal dose of XSLJZT (600 mg/kg/day). However, pharmacokinetic analysis revealed that pretreatment with a high dose of XSLJZT (2400 mg/kg/day) extended the residence time and increased the volume of distribution of 5-FU. No significant distinctions were found in 5-FDHU pharmacokinetic parameters at three doses of XSLJZT. Conclusions: Overall, the pharmacokinetic results confirm the safety of coadministering 5-FU with XSLJZT, and provide practical dosage information for clinical practice.
... Many oncologic therapeutics have wellknown PGx associations, and preemptive genotyping and the use of germline PGx information offers an opportunity to improve oncology care by identifying individuals at risk of adverse drug effects (ADEs). [4][5][6][7][8] However, aside from Implementation of pharmacogenomic testing in oncology care (PhOCus): study protocol of a pragmatic, randomized clinical trial thiopurine methyltransferase (TPMT) testing prior to 6-mercaptopurine administration in pediatric oncology, PGx has not been routinely incorporated into oncologic practice in the vast majority of countries (including the US), and in fact, oncology may lag behind other fields. 9,10 This is somewhat surprising, as oncologists routinely utilize information on germline cancer predisposition and somatic (tumor-based) genomic alterations for patient care planning (notably in the context of Poly ADP ribose polymerase (PARP) inhibitors, in which BRCA germline variants are hypothesized to accompany somatic susceptibility to therapy). ...
... 15 Polymorphisms in the DPYD gene can result in enzyme deficiency leading to an increased risk of severe, sometimes fatal toxicities in up to 10% of patients. 8 Allele frequencies of these variants vary among ethnic groups and confer different levels of predicted enzymatic activity, also called 'activity scores'. Table 1 shows several well-described clinically actionable alleles in DPYD, with their associated enzymatic activity scores and observed frequencies in various populations. ...
Article
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Background Many cancer patients who receive chemotherapy experience adverse drug effects. Pharmacogenomics (PGx) has promise to personalize chemotherapy drug dosing to maximize efficacy and safety. Fluoropyrimidines and irinotecan have well-known germline PGx associations. At our institution, we have delivered PGx clinical decision support (CDS) based on preemptively obtained genotyping results for a large number of non-oncology medications since 2012, but have not previously evaluated the utility of this strategy for patients initiating anti-cancer regimens. We hypothesize that providing oncologists with preemptive germline PGx information along with CDS will enable individualized dosing decisions and result in improved patient outcomes. Methods Patients with oncologic malignancies for whom fluoropyrimidine and/or irinotecan-inclusive therapy is being planned will be enrolled and randomly assigned to PGx and control arms. Patients will be genotyped in a clinical laboratory across panels that include actionable variants in UGT1A1 and DPYD. For PGx arm patients, treating providers will be given access to the patient-specific PGx results with CDS prior to treatment initiation. In the control arm, genotyping will be deferred, and dosing will occur as per usual care. Co-primary endpoints are dose intensity deviation rate (the proportion of patients receiving dose modifications during the first treatment cycle), and grade ⩾3 treatment-related toxicities throughout the treatment course. Additional study endpoints will include cumulative drug dose intensity, progression-free survival, dosing of additional PGx supportive medications, and patient-reported quality of life and understanding of PGx. Discussion Providing a platform of integrated germline PGx information may promote personalized chemotherapy dosing decisions and establish a new model of care to optimize oncology treatment planning.
... Fluoropyrimidines (FU) are the most prescribed anticancer drugs for the treatment of solid cancers, in particular breast, colorectal, head and neck, pancreas and gastric cancers [1,2] . The most common side effects are represented by emesis, bone marrow suppression, diarrhea, mucositis, fatigue and hand-foot syndrome. ...
... The correct management of fluoropyrimidine toxicity consists in the temporary suspension or interruption of treatment [4][5][6][7] . The metabolic pathway of 5-fluorouracil depends on the activity of many intracellular enzymes including dihydropyrimidine dehydrogenase (DPD) [1] . DPD expression varies throughout several tissues and exerts his activity predominantly in liver, peripheral blood mononuclear cells, tumor and inflammatory tissues. ...
Article
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Fluoropyrimidines are widely used in the treatment of solid tumors, mainly gastrointestinal, head and neck and breast cancer. Dihydropyrimidine dehydrogenase (DPD) is the rate-limiting enzyme for catabolism of 5-FU and it is encoded by DPYD gene. To date, many known polymorphisms cause DPD deficiency and subsequent increase of 5-FU toxicity. In addition, reduced inactivation of 5-FU could lead to increased 5-FU intracellular concentration and augmented efficacy of this drugs. Therefore DPD expression, particularly intratumoral, has been investigated as predictive and prognostic marker in 5-FU treated patients. There also seems to be a tendency to support the correlation between DPD expression and response/survival in patients treated with fluoropyrimidine even if definitive conclusions cannot be drawn considering that some studies are conflicting. Therefore, the debate on intratumoral DPD expression as a potential predictor and prognostic marker in patients treated with fluoropyrimidines is still open. Four DPD-polymorphisms are the most relevant for their frequency in population and clinical relevance. Many studies demonstrate that treating a carrier of one of these polymorphisms with a full dose of fluoropyrimidine can expose patient to a severe, even life-threatening, toxicity. Severe toxicity is reduced if this kind of patients received a dose-adjustment after being genotyped. CPIC (Clinical Pharmacogenetics Implementation Consortium) is an International Consortium creating guidelines for facilitating use of pharmacogenetic tests for patient care and helps clinicians ensuring a safer drug delivery to the patient. Using predictive DPD deficiency tests in patients receiving 5FU-based chemotherapy, in particular for colorectal cancer, has proven to be a cost-effective strategy.
... The fluoropyrimidine analog 5-fluorouracil (5-FU) was introduced as an anti-cancer agent in the late 1950s and remains one of the most widely prescribed chemotherapeutics, with an estimated 2 million people worldwide receiving 5-FU or one of its prodrug forms (e.g., capecitabine) each year [1]. 5-FU is used to treat many types of cancers, most predominantly colorectal cancer, where it is used as a component of first-line adjuvant therapy and for advanced disease [2]. ...
... While carriers of this variant are more likely to experience severe 5-FU toxicity, the rarity precludes conclusive clinical analyses [19], and the variant is the only one of these four that is not currently assigned a "strong" level of evidence for 5-FU toxicity association by the Clinical Pharmacogenetics Implementation Consortium (CPIC) [20]. 1 Does not directly encode for an amino acid change but causes alternative splicing and the in-frame deletion of exon 14. 2 Does not directly encode for an amino acid change; causes non-obligate alternative splicing that introduces a frameshift and premature stop codon. 3 The rs56038477 variant is in strong LD with the causal variant (rs75017182), can be assessed using exome-level data, and is often used as a proxy for rs75017182. ...
Article
Severe adverse events (toxicity) related to the use of the commonly used chemotherapeutic drug 5-fluorouracil (5-FU) affect one in three patients and are the primary reason cited for premature discontinuation of therapy. Deficiency of the 5-FU catabolic enzyme dihydropyrimidine dehydrogenase (DPD, encoded by DPYD) has been recognized for the past 3 decades as a pharmacogenetic syndrome associated with high risk of 5-FU toxicity. An appreciable fraction of patients with DPD deficiency that receive 5-FU-based chemotherapy die as a result of toxicity. In this manuscript, we review recent progress in identifying actionable markers of DPD deficiency and the current status of integrating those markers into the clinical decision-making process. The limitations of currently available tests, as well as the regulatory status of pre-therapeutic DPYD testing, are also discussed.
... Several DPYD variants (rs3918290, rs72547602, rs55886062, 67376798) are associated with risk for 5-FU toxicity, such as capecitabine or tegafur (Ezzeldin et al. 2004;Maring et al. 2005;Baskin et al. 2013). ...
Article
Full-text available
Dihydropyrimidine dehydrogenase (DPD) acts as the first-step enzyme catabolizing pyrimidines in vivo. DPYD gene mutations interfere with the breakdown of uracil and thymine. Genetic variations of DPYD can cause an enzyme deficiency state, which results in severe toxicity or other adverse side effects such as DNA damage or RNA damage caused by imbalance of the nucleotide pool. Our case-control study investigates the possible association between seven DPYD gene polymophisms (rs1801267, rs72547602, rs1801160, rs3918290, rs1801159, rs1801158, rs1801265) and risk of colorectal cancer (CRC). The association analysis for DPD was performed on 273 CRC patients and 187 healthy controls. There is significant allele association of SNP rs1801160 with colorectal cancer (p = 0.003, OR = 3.264, 95% CI = 1.425-7.475) in present analysis. Haplotype analysis of four DPYD polymorphisms showed significant difference in the distribution "IISt" haplotype between cases and controls. In comparison to the most common haplotype (VISt), the "IISt" haplotype was associated with increased risk for CRC (p = 0.038, OR = 2.733, 95% CI = 1.019-7.326). The present study suggests that the SNP rs1801160 and the "IISt" haplotype in the DPYD gene may also have a role in colorectal cancer risk.
... Because 5-FU is commonly used, and severe toxicity effects are associated with DPD deficiency, several methods have been developed to detect DPD deficiency. These include genotyping, radio-immunoassays, and measuring serum uracil concentrations, but these tests are expensive and time-consuming [9]. Given the rarity of life- Fig. 1 a Forearms post 1-week of nightly 0.5% 5-FU topical cream; b oral mucositis post 1-week with nightly 0.5% 5-FU cream threatening adverse events caused by topical 5-FU, developing a test to detect DPD deficiency would be more suitable for systemic therapy. ...
Article
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A 67-year-old man developed a suspected adverse drug reaction during treatment with topical 5-fluorouracil (5-FU) for multiple actinic keratosis of the face, neck, and forearms. The man received topical 5-FU at a dosage of 0.5% for the actinic keratoses. After 1 week, he developed extreme lethargy, fatigue, fever, and mouth erosions. Several days later, and after discontinuation of 5-FU, painful mucositis and systemic side effects occurred, meeting criteria for hospitalization because of dehydration and a 6.8 kg weight loss. Hematology/oncology was consulted, and a possible systemic 5-FU reaction, similar to reactions to intravenous chemotherapy seen with a dihydropyrimidine dehydrogenase deficiency was suggested. The patient was not taking any concurrent medications, and he refused dihydropyrimidine dehydrogenase deficiency testing.
... 10 During the past decade, the detrimental effects of specific DPYD mutations on fluoropyrimidine metabolism have been well recognized. 3,10,11 Many publications have called for upfront DPYD genotyping before starting fluoropyrimidinebased treatments. 10,12,13 This is still under some debate, and arguments against implementation include the lack of evidence from randomized controlled trials 12 and suboptimal sensitivity and specificity to predict toxicity. ...
... Grade 3-4 diarrhea occurs in 11.4% of patients treated with capecitabine monotherapy [1]. In contrast, in patients with a DPD deficiency the diarrhea starts often within the first week and is life threatening [2]. ...
Article
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Capecitabine is an oral fluoropyrimidine used as adjuvant and palliative chemotherapy in patients with colorectal cancer. Diarrhea is a well-known side effect of capecitabine and 5-fluorouracil agents. We present a case with terminal ileitis as a rare adverse event of capecitabine treatment. Capecitabine-induced terminal ileitis is likely to be underreported. It should be considered more often as a cause of severe and atypical complaints of diarrhea during treatment with capecitabine or other 5-fluorouracil agents.
... While Caucasian frequencies range from 3-5% for partial deficiency and 0.2% for complete deficiency, it is estimated to be extremely rare in Asians [32,33]. In the case of asymptomatic DPD deficiency, there is a considerable risk of FP accumulation during treatment, including 5-FU, which could lead to severe toxicity in patients [34][35][36]. Therefore, it is imperative to diagnose DPD deficiency before chemotherapy administration, even in cases with no prior clinical evidence of this condition. ...
Article
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Fluoropyrimidine drugs (FPs), including 5-fluorouracil, tegafur, capecitabine, and doxifluridine, are among the most widely used anticancer agents in the treatment of solid tumors. However, severe toxicity occurs in approximately 30% of patients following FP administration, emphasizing the importance of predicting the risk of acute toxicity before treatment. Three metabolic enzymes, dihydropyrimidine dehydrogenase (DPD), dihydropyrimidinase (DHP), and β-ureidopropionase (β-UP), degrade FPs; hence, deficiencies in these enzymes, arising from genetic polymorphisms, are involved in severe FP-related toxicity, although the effect of these polymorphisms on in vivo enzymatic activity has not been clarified. Furthermore, the clinical usefulness of current methods for predicting in vivo activity, such as pyrimidine concentrations in blood or urine, is unknown. In vitro tests have been established as advantageous for predicting the in vivo activity of enzyme variants. This is due to several studies that evaluated FP activities after enzyme metabolism using transient expression systems in Escherichia coli or mammalian cells; however, there are no comparative reports of these results. Thus, in this review, we summarized the results of in vitro analyses involving DPD, DHP, and β-UP in an attempt to encourage further comparative studies using these drug types and to aid in the elucidation of their underlying mechanisms.
... Treatment with these drugs is generally well tolerated, except in a small percentage of patients who develop severe, potentially life-threatening toxicity. The clinical presentation of this toxicity is similar to a 5-FU overdose and includes myelosuppression, mucositis, stomatitis, diarrhea, skin changes, and neurological abnormalities [1]. Treatment of severe toxicity includes interruption or even discontinuation of an effective anticancer therapy and often requires hospitalization [2]. ...
Article
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Background Dihydropyrimidine dehydrogenase deficiency secondary to polymorphisms in the DPYD gene can lead to significant toxicity associated with the administration of fluoropyrimidine chemotherapy. Case presentation We report a case of a 59-year-old Lebanese woman with metastatic pancreatic cancer who received FOLFIRINOX therapy and developed severe 5-fluorouracil toxicity after a single cycle. The entire DPYD gene was sequenced, and the patient was found to be heterozygous for three different polymorphisms that have reportedly been associated with dihydropyrimidine dehydrogenase deficiency. Conclusion Because data regarding the prevalence and clinical significance of several heterozygous polymorphisms in a single DPYD gene are very limited, we suggest that full gene sequencing should be carried out, at least in populations in which the allele frequencies are unknown.
... One branch of research chooses to focus on DPD activity in the malignant cells as a predictor of fluoropyrimidine efficacy [37,38,46]. The complimentary studies aim to interrogate global DPD activity, as a more relevant variable in the systemic clearance of 5-FU and therefore fluoropyrimidine-related AEs [47]. ...
Article
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5-Fluorouracil remains a foundational component of chemotherapy for solid tumour malignancies. While considered a generally safe and effective chemotherapeutic, 5-fluorouracil has demonstrated severe adverse event rates of up to 30%. Understanding the pharmacokinetics of 5-fluorouracil can improve the precision medicine approaches to this therapy. A single enzyme, dihydropyrimidine dehydrogenase (DPD), mediates 80% of 5-fluorouracil elimination, through hepatic metabolism. Importantly, it has been known for over 30-years that adverse events during 5-fluorouracil therapy are linked to high systemic exposure, and to those patients who exhibit DPD deficiency. To date, pre-treatment screening for DPD deficiency in patients with planned 5-fluorouracil-based therapy is not a standard of care. Here we provide a focused review of 5-fluorouracil metabolism, and the efforts to improve predictive dosing through screening for DPD deficiency. We also outline the history of key discoveries relating to DPD deficiency and include relevant information on the potential benefit of therapeutic drug monitoring of 5-fluorouracil. Finally, we present a brief case report that highlights a limitation of pharmacogenetics, where we carried out therapeutic drug monitoring of 5-fluorouracil in an orthotopic liver transplant recipient. This case supports the development of robust multimodality precision medicine services, capable of accommodating complex clinical dilemmas.
... The use of 5-Fluorouracil (5-FU) as an anticancer agent became routine practice soon after its primary synthesis in 1957, and remains essential in many chemotherapeutic regimens today (Longley, Harkin, and Johnston 2003). The fluoropyrimidines, especially 5-FU, capecitabine, tegafur and cytarabine, are currently the third most commonly used anticancer drug in the treatment of solid cancers, including colorectal and breast cancers, and over two million patients are estimated to be treated with fluoropyrimidines each year ( Ezzeldin and Diasio 2004). Response rates of 5-FU as a single drug are 10-15%, but increase drastically (>50% response) when given in combination therapies with leucovorin together with oxaliplatin or irinotecan (i.e. ...
Preprint
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5-Fluorouracil (5-FU) is a chemotherapeutic drug component that is commonly used for the treatment of solid cancers. It is proposed that 5-FU possesses anticancer properties via the interference with nucleotide synthesis and incorporation into DNA. As both mechanisms may have a mutational impact on both surviving tumor and healthy cells, we treated intestinal organoids with 5-FU followed by whole genome sequencing analysis and uncovered a highly characteristic mutational pattern that is dominated by T>G substitutions in a CTT context. Analysis of tumor whole genome sequencing data confirmed that this signature can also be identified in vivo in colorectal and breast cancer patients that have undergone treatment with 5-FU. We also found that more 5-FU mutations are induced in TP53 null backgrounds which may be of clinical relevance. Taken together, our results demonstrate that 5-FU is mutagenic and may drive tumor evolution and increase the risk of secondary malignancies. Furthermore, the identified signature shows a strong resemblance to COSMIC signature 17, the hallmark signature of treatment-naive esophageal and gastric tumors, which indicates that distinct endogenous and exogenous triggers can converge onto highly similar mutational signatures.
... [14][15][16] Dihydropyrimidine dehydrogenase (DPD) deficiency, which is associated with DPYD gene mutations, has been reported to increase 5-FU-related adverse events by incompetent 5-FU degradation. [17] Different formulations, dosing, and route of administration of fluorouracil have been reported to result in diverse toxicities. [18][19][20] Whether our patient with hypersensitivity to 5-FU had cross-hypersensitivity to other formulations such as capecitabine, tegafur, and TS-1 is unknown. ...
Article
An in vitro T-cell activation assay measuring granulysin and granzyme B has been used to identify the drug hypersensitivity of common causative drugs, but not of chemotherapeutic drugs. Both granulysin and granzyme B are cytotoxic molecules involved in skin eruptions during drug hypersensitivity. Herein, we report the first clinical application of an in vitro T-cell activation assay to identify the causative agent in docetaxel, cisplatin, and 5-fluorouracil (5-FU)-related hypersensitivity in a patient with head-and-neck cancer. A significant increase in granulysin and granzyme B was observed for 5-FU rather than for docetaxel or cisplatin. Despite several limitations, we were still able to pinpoint 5-FU as the culprit drug in a chemotherapy combination without further drug rechallenge in our patient. In conclusion, an in vitro T-cell activation assay measuring granulysin and granzyme B can be a safe and alternative tool to determine the causative agent of hypersensitivity reactions in cancer patients who need combination chemotherapy.
... Fluoropyrimidine toxicity in partial DPD-deficient individuals may manifest as severe mucositis, neutropenia, thrombocytopenia, hemorrhage, hand-foot syndrome, diarrhea, dyspnea, and alopecia. 4,5 The prevalence of DPD deficiency seems to be dependent on race and sex. African American women showed the highest prevalence of DPD deficiency compared with African American men, white women, and white men (12.3%, 4.0%, 3.5%, and 1.9%, respectively). ...
Article
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Dihydropyrimidine dehydrogenase (DPD) deficient patients might only become aware of their genotype after exposure to dihydropyrimidines, if testing is performed. Case reports to pharmacovigilance databases might only contain phenotypical manifestations of DPD, without information on the genotype. This poses a difficulty to estimating the cases due to DPD. Auto machine learning models were developed to train patterns of phenotypical manifestations of toxicity, which were then used as a surrogate to estimate the number of cases of DPD related toxicity. Results indicate that between 8,878 (7.0%) to 16,549 (13.1%) patients have a profile similar to DPD deficient status. Feature importance matches the known end‐organ damage of DPD related toxicity, however accuracies in the range of 90% suggest presence of overfitting, and thus results need to be interpreted carefully. This study shows the potential for use of machine learning in the regulatory context but additional studies are required.
... The cytosolic enzyme DPD in the catabolism of 5-FU is widely expressed in the body (Lu et al., 1993;Van Kuilenburg et al., 1997;Mcleod et al., 1998). The increased AUC ratio of 5-FU/5-FDHU is associated with adverse events (Di Paolo et al., 2001), and the modulation of the catabolic pathway of 5-FU has an impact on the side effects and adverse reactions (Ezzeldin and Diasio, 2004). ...
Article
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Background The effects of radiotherapy (RT) on the pharmacokinetics (PK) of 5-FU and 5-fluoro-5,6-dihydro-uracil (5-FDHU) were investigated by animal experiments.Methods Whole-pelvis RT with 0.5 and 2 Gy was delivered to Sprague–Dawley rats. 5-FU at 100 mg/kg was intravenously infused 24 h after radiation. The pharmacokinetics of 5-FU and 5-FDHU in the plasma and bile system were calculated.ResultsThe areas under the concentration versus time curve (AUC) of 5-FU in the plasma were reduced by local irradiation by 23.7% at 0.5 Gy (P < 0.001) and 35.3% at 2 Gy (P < 0.001). The AUCs of 5-FDHU were also reduced by 21.4% at 0.5 Gy (P < 0.001) and 51.5% at 2 Gy (P < 0.001). Irradiation significantly increased the clearance values (CLs) of 5-FU by 30.6% at 0.5 Gy and 50.1% at 2 Gy, respectively. The CLs of 5-FDHU were increased by 27.2% at 0.5 Gy and 106% at 2 Gy. The AUCs of 5-FU in the bile were increased by 36.7% at 0.5 Gy (P < 0.001) and 68.6% at 2 Gy (P = 0.005). The AUCs of 5-FDHU in the bile were increased by 40.3% at 0.5 Gy (P < 0.001) and 248.1% at 2 Gy (P < 0.001). The CLs of 5-FU in the bile were increased by 31.8% at 0.5 Gy and 11.2% at 2 Gy. However, the CLs of 5-FDHU in the bile were decreased by 29.1% at 0.5 Gy and 71.0% at 2 Gy.Conclusion Both conventional and low-dose irradiation can affect the pharmacokinetics of 5-FU and its metabolite, 5-FDHU. RT plus 5-FU could cause more adverse events than 5-FU alone by increasing the AUC ratio of 5-FU/5-FDHU. Irradiation decreases the AUC of 5-FU in the plasma, which may cause poor clinical outcomes.
... DPYD catabolizing 5-fluorouracil (5-FU), which is commonly used for the treatment of solid carcinomas [66][67][68] , and is also the component of FAC regime. A decrease in enzyme activity may lead to an increase in the half-life of 5-FU and an increased risk of dose-dependent toxicity [67][68][69][70] . The SNP rs291593 CC DPYD was described in the study of Kim et al., which focused on allele distribution in 150 Korean subjects 68 . ...
Article
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The study describes a relationship between the 3′UTR variants, clinicopathological parameters and response to chemotherapy. We analyzed 33 germline polymorphisms in 3′UTRs of ADME genes in 305 breast cancer women treated with FAC regime. Clinical endpoints of this study were: overall survival (OS), progression-free survival (PFS), recurrence-free survival (RFS) and overall response defined as treatment failure-free survival (TFFS). The shortened OS was connected with the presence of NR1/2 rs3732359 AA, SLC22A16 rs7756222 CC, as well as SLC22A16 rs9487402 allele G and clinical factors belonging to TNM classification: tumor size >1 cm, nodal involvement and presence of metastases. PFS was related to two polymorphisms PGR rs1824125 GG, PGR rs12224560 CC and SLC22A16 rs7756222 CC as well as preexisting metastases. The RFS was shortened due to the DPYD rs291593 CC, AKR1C3 rs3209896 AG and negative expression of PGR. The presence of ALDH5A1 rs1054899 allele A, lack of pre-chemotherapy surgery and negative status of PGR correlated with worse treatment response. The germline variants commonly present in the population are important factors determining the response to treatment. We observed the effect of the accumulation of genetic and clinical factors on poor survival prognosis and overall treatment response.
... TNF receptor associated factor 6 Introduction 5-fluorouracil (5-FU) is a commonly administered chemotherapy drug used for the treatment of breast, colorectal and upper gastrointestinal (GI) tract solid tumours [1,2]. Although highly effective, with response rates for 5-FUbased regimens between 40 and 50% in patients with advanced colorectal cancer [3,4], 5-FU causes severe damage to mucosal membranes of the GI tract [5][6][7]. ...
Article
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Purpose Severe gastrointestinal (GI) toxicity is a common adverse effect following 5-fluorouracil (5-FU)-based chemotherapy treatment. The presence of severe GI toxicity leads to treatment revisions, sub-optimal therapy outcomes, and decreases to patients’ quality of life. There are no adequate predictors for 5-FU-induced severe GI toxicity risk. The Toll-like receptor/interleukin-1 (TIR) domain innate immune signalling pathway is known to be a mediating pathway in the development of GI toxicity. Hence, genetic variability in this signalling pathway may alter the pathophysiology of GI toxicity and, therefore, be predictive of risk. However, little research has investigated the effects of TIR domain innate immune signalling pathway single nucleotide polymorphism (SNPs) on the risk and development of severe GI toxicity. Methods This critical review surveyed the literature and reported on the in vitro, ex vivo and in vivo effects, as well as the genetic association, of selected TIR domain innate immune signalling pathway SNPs on disease susceptibility and gene functioning. Results Of the TIR domain innate immune signalling pathway SNPs reviewed, evidence suggests interleukin-1 beta (IL1B) and tumour necrosis factor alpha (TNF) SNPs have the greatest potential as predictors for severe GI toxicity risk. These results warrant further research into the effect of IL1B and TNF SNPs on the risk and development of severe GI toxicity. Conclusions SNPs of the TIR domain innate immune signalling pathway have profound effects on disease susceptibility and gene functioning, making them candidate predictors for severe GI toxicity risk. The identification of a predictor for 5-FU-induced severe GI toxicity will allow the personalization of supportive care measures.
... They retrospectively found that these patients were suffering from profound DPD deficiency [12]. Several authors recommend screening for DPD deficiency before 5-FU treatment, however, it is not practical to obtain levels of DPD for all patients because of its low incidence [13]. Furthermore, the enzyme assay is complicated and not readily available [14]. ...
... Colorectal cancer (CRC) is the third most common cancer in men and the second most common cancer in women and the fourth leading cause of cancer-related deaths worldwide [1]. 5-Fluorouracil (5-FU) is the most commonly used chemotherapeutic agent for the treatment of CRC either as a monotherapy or in combination with other chemotherapeutic drugs and it is central to all chemotherapeutic combinations for CRC treatment [2][3][4][5][6][7][8][9][10][11]. Although clinical trials provided evidence of efficacy and safety of 5-fluorouracil at usual doses in populations, some patients showed a wide variation in the response and even adverse effects [11][12][13]. ...
Article
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Background Significant inter-individual variation in the sensitivity to 5-fluorouracil (5-FU) represents a major therapeutic hindrance either by impairing drug response or inducing adverse drug reactions (ADRs). This study aimed at exploring the cause behind this inter-individual alterations in consequences of 5-fluorouracil-based chemotherapy by investigating the effects of DPYD*2A and MTHFR C677T polymorphisms on toxicity and response of 5-FU in Bangladeshi colorectal cancer patients. Methods Colorectal cancer patients (n = 161) receiving 5-FU-based chemotherapy were prospectively enrolled. DPYD and MTHFR polymorphisms were assessed in peripheral leukocytes. Multivariate analyses were applied to evaluate which variables could predict chemotherapy-induced toxicity and efficacy. ResultsMultivariate analyses showed that DPYD*2A polymorphism was a predictive factor (P = 0.023) for grade 3 and grade 4 5-fluorouracil-related toxicities. Although MTHFR C677T polymorphism might act as forecasters for grade 3 or grade 4 neutropenia, diarrhea, and mucositis, this polymorphism was found to increase significantly (P = 0.006) the response of 5-FU. ConclusionDPYD*2A and MTHFR C677T polymorphisms could explain 5-FU toxicity or clinical outcome in Bangladeshi colorectal patients.
... The effects of SNPs on DPD protein sequence and function have been validated in many cases. For example, the *2A (rs3918290) locus alters a splice recognition sequence leading to a 165 base pair deletion and expression of an inactive DPD protein (60). DPYD*13 (rs55886062) and rs67376798 result in amino acid changes decreasing DPD activity. ...
Article
Objective: Our objective is to document progress in developing personalized therapy with fluoropyrimidine drugs (FPs) to improve outcomes for cancer patients and to identify areas requiring further investigation. Background: FPs including 5-fluorouracil (5-FU), are among the most widely used drugs for treating colorectal cancer (CRC) and other gastrointestinal (GI) malignancies. While FPs confer a survival benefit for CRC patients, serious systemic toxicities, including neutropenia, occur in ~30% of patients with lethality in 0.5-1% of patients. While serious systemic toxicities may occur in any patient, patients with polymorphisms in DPYD, which encodes the rate-limiting enzyme for pyrimidine degradation are at very high risk. Other genetic factors affecting risk for 5-FU toxicity, including miR-27a, are under investigation. Methods: Literature used to inform the text of this article was selected from PubMed.gov from the National Library of Medicine while regulatory documents were identified via Google search. Conclusions: Clinical studies to date have validated four DPYD polymorphisms (DPYD*2A, DPYD*13, c.2846A>T, HapB3) associated with serious toxicities in patients treated with 5-FU. Genetic screening for these is being implemented in the Netherlands and the UK and has been shown to be a cost-effective way to improve outcomes. Factors other than DPYD polymorphisms (e.g., miR-27a, TYMS, ENOSF1, p53) also affect 5-FU toxicity. Functional testing for deficient pyrimidine catabolism {defined as [U] >16 ng/mL or [UH2]:[U] <10} is being implemented in France and has demonstrated utility in identifying patients with elevated risk for 5-FU toxicity. Therapeutic drug monitoring (TDM) from plasma levels of 5-FU during first cycle treatment also is being used to improve outcomes and pharmacokinetic-based dosing is being used to increase the percent of patients within optimal area under the curve (AUC) (18-28 mg*h/L) values. Patients maintained in the optimal AUC range experienced significantly reduced systemic toxicities. As understanding the genetic basis for increased risk of 5-FU toxicity becomes more refined, the development of functional-based methods to optimize treatment is likely to become more widespread.
... In addition, microdeletion and chromosomal instability in the 1p21 region of DPYD may cause DPD deficiency (Brečević et al., 2015), which is an autosomal recessive genetic disorder with clinical symptoms that vary widely and include seizures, mental developmental disorders, microcephaly, autism, and asymptomatic individuals ( van Kuilenburg, 2004;van Kuilenburg et al., 2009). It is important to be able to predict the risk of developing toxicity because a DPD deficiency may only be detected after 5-FU chemotherapy leads to severe toxicity in asymptomatic patients (Ezzeldin and Diasio, 2004). ...
Article
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Dihydropyrimidine dehydrogenase (DPD), encoded by the DPYD gene, is the rate-limiting enzyme in 5-fluorouracil (5-FU) degradation. In Caucasians, four DPYD risk variants are recognized to be responsible for interindividual variations in the development of 5-FU toxicity. However, these risk variants have not been identified in Asian populations. Recently, 41 DPYD allelic variants, including 15 novel single nucleotide variants, were identified in 3,554 Japanese individuals by analyzing their whole-genome sequences; however, the effects of these variants on DPD enzymatic activity remain unknown. In the present study, an in vitro analysis was performed on 41 DPD allelic variants and three DPD risk variants to elucidate the changes in enzymatic activity. Wild-type and 44 DPD-variant proteins were heterologously expressed in 293FT cells. DPD expression levels and dimerization of DPD were determined by immunoblotting after SDS-PAGE and blue native PAGE, respectively. The enzymatic activity of DPD was evaluated by quantification of dihydro-5-FU, a metabolite of 5-FU, using high-performance liquid chromatography-tandem mass spectrometry. Moreover, we used 3D simulation modeling to analyze the effect of amino acid substitutions on the conformation of DPD. Among the 41 DPD variants, seven exhibited drastically decreased intrinsic clearance (CL int ) compared to the wild-type protein. Moreover, R353C and G926V exhibited no enzymatic activity, and the band patterns observed in the immunoblots after blue native PAGE indicated that DPD dimerization is required for its enzymatic activity. Our data suggest that these variants may contribute to the significant inter-individual variability observed in the pharmacokinetics and pharmacodynamics of 5-FU. In our study, nine DPD variants exhibited drastically decreased or no enzymatic activity due to dimerization inhibition or conformational changes in each domain. Especially, the rare DPYD variants, although at very low frequencies, may serve as important pharmacogenomic markers associated with the severe 5-FU toxicity in Japanese population.
... In Asian populations, the rs59086055 and rs186169810 haplotypes have additionally been linked to poor 5-FU catabolism [17]. Fluoropyrimidine toxicity has been associated with reduced DPD activity and DPYD*2A polymorphism, based on numerous reports [18][19][20][21][22][23][24], including two recent meta analyses [16,25]. ...
Article
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Background: 5-FU-based chemoradiotherapy (CRT) could be associated with severe treatment-related toxicities in patients harboring at-risk DPYD polymorphisms. Methods: The studied population included consecutive patients with locoregionally advanced oropharyngeal carcinoma treated with carboplatin and 5-FU-based CRT one year before and after the implementation of upfront DPYD*2A genotyping. We aimed to determine the effect of DPYD genotyping on grade ≥3 toxicities. Results: 181 patients were analyzed (87 patients before and 94 patients following DPYD*2A screening). Of the patients, 91% (n = 86) were prospectively genotyped for the DPYD*2A allele. Of those screened, 2% (n = 2/87) demonstrated a heterozygous DPYD*2A mutation. Extended genotyping of DPYD*2A-negative patients later allowed for the retrospective identification of six additional patients with alternative DPYD variants (two c.2846A>T and four c.1236G>A mutations). Grade ≥3 toxicities occurred in 71% of the patients before DPYD*2A screening versus 62% following upfront genotyping (p = 0.18). When retrospectively analyzing additional non-DPYD*2A variants, the relative risks for mucositis (RR 2.36 [1.39–2.13], p = 0.0063), dysphagia (RR 2.89 [1.20–5.11], p = 0.019), and aspiration pneumonia (RR 13 [2.42–61.5)], p = 0.00065) were all significantly increased. Conclusion: The DPYD*2A, c.2846A>T, and c.1236G>A polymorphisms are associated with an increased risk of grade ≥3 toxicity to 5-FU. Upfront DPYD genotyping can identify patients in whom 5-FU-related toxicity should be avoided.
... In patients with certain enzyme deficiencies that act on the fluoropyrimidine metabolism, however, the use of these chemotherapeutic agents can lead to life-threatening complications, including severe nausea, vomiting and diarrhoea with volume depletion, extensive skin and mucositis changes, pancytopenia with risk of bleeding and infection, cardiotoxicity and neurological abnormalities such as cerebellar ataxia, cognitive dysfunction and altered level of consciousness [5][6][7][8][9][10][11][12][13]. In these cases, toxicity can occur early during the first treatment cycle, reinforcing the importance of detecting these enzyme deficiencies before the start of therapy, so that personalised dose adjustments of fluoropyrimidine, or even alternative drugs, can be prescribed [14]. ...
Article
Identifying polymorphisms in the dihydropyrimidine dehydrogenase (DPYD) genes is gaining importance as predictors of fluoropyrimidine-associated toxicity. The recommendation of dose adjustment for chemotherapy guided by the presence of polymorphisms of the DPYD gene can potentially improve treatment safety for a large number of patients, saving lives, avoiding complications and reducing health care costs. This article discusses how personalisation of fluoropyrimidine treatment based on the identification of DPYD variants can mitigate toxicities and be cost effective.
... Fluoropyrimidines, including 5-fluorouracil and its prodrugs capecitabine and tegafur, are important chemotherapeutics for the treatment of various solid tumors. They are among the most prescribed anticancer drugs worldwide with more than two million patients estimated to use fluoropyrimidines each year (Ezzeldin and Diasio 2004). However, up to 40% of patients experience fluoropyrimidine-induced toxicity that is severe enough to require discontinuation of therapy, and in 0.5-1% of patients these ADRs are fatal (Hoff et al. 2001;Van Cutsem et al. 2001). ...
Article
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Both safety and efficacy of medical treatment can vary depending on the ethnogeographic background of the patient. One of the reasons underlying this variability is differences in pharmacogenetic polymorphisms in genes involved in drug disposition, as well as in drug targets. Knowledge and appreciation of these differences is thus essential to optimize population-stratified care. Here, we provide an extensive updated analysis of population pharmacogenomics in ten pharmacokinetic genes ( CYP2D6 , CYP2C19 , DPYD , TPMT , NUDT15 and SLC22A1 ), drug targets ( CFTR ) and genes involved in drug hypersensitivity ( HLA-A , HLA-B ) or drug-induced acute hemolytic anemia ( G6PD ). Combined, polymorphisms in the analyzed genes affect the pharmacology, efficacy or safety of 141 different drugs and therapeutic regimens. The data reveal pronounced differences in the genetic landscape, complexity and variant frequencies between ethnogeographic groups. Reduced function alleles of CYP2D6 , SLC22A1 and CFTR were most prevalent in individuals of European descent, whereas DPYD and TPMT deficiencies were most common in Sub-Saharan Africa. Oceanian populations showed the highest frequencies of CYP2C19 loss-of-function alleles while their inferred CYP2D6 activity was among the highest worldwide. Frequencies of HLA-B*15:02 and HLA-B*58:01 were highest across Asia, which has important implications for the risk of severe cutaneous adverse reactions upon treatment with carbamazepine and allopurinol. G6PD deficiencies were most frequent in Africa, the Middle East and Southeast Asia with pronounced differences in variant composition. These variability data provide an important resource to inform cost-effectiveness modeling and guide population-specific genotyping strategies with the goal of optimizing the implementation of precision public health.
... The DPYD gene encodes dihydropyrimidine dehydrogenase (DPD), the rate-limiting enzyme in fluoropyrimidine metabolism, and deficiency of DPD enzymatic function leads to toxic accumulation of fluoropyrimidine metabolites [6,8]. Germline variants in DPYD are the predominant cause of DPD deficiency, and pathogenic DPYD variants have been linked to a 5-8 times increased odds of grade 3 or higher toxicity [9,10]. ...
Article
Background: Pathogenic variants of the DPYD gene are strongly associated with grade ≥3 toxicity during fluoropyrimidine chemotherapy. We conducted a systematic review and meta-analysis to estimate the risk of treatment-related death associated with DPYD gene variants. Methods: We searched for reports published prior to September 17, 2020 that described patients receiving standard-dose fluoropyrimidine chemotherapy (5-fluorouracil or capecitabine) who had baseline testing for ≥1 of 4 pathogenic DPYD variants (c.1129-5923C>G [HapB3], c.1679T>G [*13], c.1905+1G>A [*2A], and c.2846A>T) and were assessed for toxicity. Two reviewers assessed studies for inclusion and extracted study-level data. The primary outcome was the relative risk of treatment-related mortality for DPYD variant carriers, vs. non-carriers; we performed data synthesis using a Mantel-Haenszel fixed effects model. Results: Of the 2923 references screened, 35 studies involving 13,929 patients were included. DPYD variants (heterozygous or homozygous) were identified in 566 patients (4.1%). There were 14 treatment-related deaths in 13,363 patients without identified DPYD variants (treatment-related mortality = 0.1%, 95% CI 0.1-0.2) and 13 treatment-related deaths in 566 patients with any of the four DPYD variants (treatment-related mortality = 2.3%, 95% CI 1.3-3.9%). Carriers of pathogenic DPYD gene variants had a 25.6 times increased risk of treatment-related death (95% CI 12.1-53.9, p < 0.001). After excluding carriers of the more common but less deleterious c.1129-5923C>G variant, carriers of c.1679T>G, c.1905+1G>A and/or c.2846A>T had treatment-related mortality of 3.7%. Conclusions: Patients with pathogenic DPYD gene variants who receive standard-dose fluoropyrimidine chemotherapy have greatly increased risk for treatment-related death. Implications for practice: The syndrome of dihydropyrimidine deaminase (DPD) deficiency is an uncommon but well-described cause of severe toxicity related to fluoropyrimidine chemotherapy agents (5-fluorouracil and capecitabine). Patients with latent DPD deficiency can be identified pre-emptively with genotyping of the DPYD gene, or with measurement of the plasma uracil concentration. In this systematic review and meta-analysis, the authors study the rare outcome of treatment-related death after fluoropyrimidine chemotherapy. DPYD gene variants associated with DPD deficiency were linked to a 25.6 times increased risk of fluoropyimidine-related mortality. These findings support the clinical utility of DPYD genotyping as a screening test for DPD deficiency.
... For instance, patients with enzyme deficiencies may experience excessive toxicity that leads to stopping fluoropyrimidine-and irinotecan-based therapies, hence patients having toxicity are unlikely to derive benefit from treatment. 8,9 Thus, the proper assessment of the benefit/risk of a treatment requires knowledge of the association between benefits and harms. ...
Article
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Objective : The assessment of benefits and harms from experimental treatments often ignores the association between outcomes. Generalized pairwise comparisons (GPC) can be used to assess the Net Benefit of treatment in a randomized trial accounting for that association. Study Design and Settings : We use GPC to analyze a fictitious trial of treatment versus control, with a binary efficacy outcome (response) and a binary toxicity outcome, as well as data from two actual randomized trials in oncology. In all cases, we compute the Net Benefit for scenarios with different orders of priority between response and toxicity, and a range of odds ratios (ORs) for the association between outcomes. Results : The GPC Net Benefit was quite different from the benefit/harm computed using marginal treatment effects on response and toxicity. In the fictitious trial using response as first priority, treatment had an unfavorable Net Benefit if OR<1, but favorable if OR>1. With OR=1, the Net Benefit was 0. Results changed drastically using toxicity as first priority. Conclusion : Even in a simple situation, marginal treatment effects can be misleading. In contrast, GPC assesses the Net Benefit as a function of the treatment effects on each outcome, the association between outcomes, and individual patient priorities.
... In some cases, there is a positive association between response and toxicity; for instance, epidermal growth factor receptor inhibitors induce severe skin rash that is associated with response [77]. In other cases, the association is negative; for instance, patients with enzyme deficiencies may experience excessive toxicity that leads to stopping fluoropyrimidine-and irinotecan-based therapy, thus being unlikely to derive benefit from treatment [78,79]. Finally, a third problem with the current framework is that individual priorities with regard to different outcomes from treatment cannot be reliably taken into account just by looking at "average" results for different endpoints in isolation and without due consideration to a hierarchy of individual priorities for a given person. ...
Article
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The design of the best possible clinical trials of adjuvant interventions in colorectal cancer will entail the use of both time-tested and novel methods that allow efficient, reliable and patient-relevant therapeutic development. The ultimate goal of this endeavor is to safely and expeditiously bring to clinical practice novel interventions that impact patient lives. In this paper, we discuss statistical aspects and provide suggestions to optimize trial design, data collection, study implementation, and the use of predictive biomarkers and endpoints in phase 3 trials of systemic adjuvant therapy. We also discuss the issues of collaboration and patient centricity, expecting that several novel agents with activity in the (neo)adjuvant therapy of colon and rectal cancers will become available in the near future.
Article
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Background and Aim: In 10-30% of colorectal cancer (CRC) patients, toxic reactions occur after fluoropyrimidine-based chemotherapy. A dihydropyridine dehydrogenase (DPYD) gene variant, c.1905 + 1G>A, leads to intolerance to fluoropyrimidines. Due to the low frequency of this variant in many populations, the prevalence of fluoropyrimidine-induced hematologic side effects in CRC patients with the c.1905 + 1G>A variant is unclear. In this study, we investigated the prevalence of the DPYD c.1905 + 1 variants in a Turkish CRC cohort and the potential effects of these variants on fluoropyrimidine-induced hematologic side effects. Materials and Methods: The DPYD c.1905 + 1 variant was genotyped using polymerase chain reaction-restriction fragment length polymorphism analysis and confirmed by Sanger sequencing in peripheral blood samples of 100 CRC patients who received fluoropyrimidine-based chemotherapy and 60 healthy volunteers. The association of c.1905 + 1 variants with susceptibility to hematologic side effects was evaluated. Results: The DPYD c.1905 + 1G>A variant was more common in the CRC group than in the healthy control group (p = 0.001). The presence of the c.1905 + 1G>A variant was associated with thrombocytopenia (p = 0.039) and anemia (p = 0.035). CRC patients with fluoropyrimidine-induced anemia had shorter disease-free survival than CRC patients without fluoropyrimidine-induced anemia (p = 0.0009). Conclusions: Before administering fluoropyrimidine-based chemotherapy, genetic screening for the DPYD c.1905 + 1G>A variant should be performed with the aim of preventing anemia and anemia-induced complications in CRC patients.
Chapter
Gastrointestinal symptoms encountered by cancer patients include those not only induced by the primary malignancy but also by its treatment. These symptoms range from being nonspecific and annoying to life-threatening and a harbinger for imminent death. Symptoms from the primary tumor may be resolved with surgery, but subsequent adhesions may produce intermittent discomfort. Opiates may relieve somatic pain but induce severe pain and distress from constipation and bowel obstruction. When symptoms impact one’s quality of life, major efforts and support may be required to prevent a decreased quantity of life. The clinical judgment and experience of the practitioner impact not only which intervention is chosen but also the timing of the specific therapeutic modality. For patients with gastrointestinal symptoms, the management of iatrogenic diarrhea, constipation, and obstructive symptoms is central to the patient’s well-being. As the toxicities from conventional cytotoxic chemotherapeutic agents are predictable and manageable, prescribing “targeted agents” presents new challenges and opportunities in cancer care. The era of “molecular medicines” is here, and going forward with dose escalations and combinations is the immediate future in treating cancer. Success will depend upon not only identifying adverse effects from these anticancer agents but also in the development of supportive care pathways that controls or improves symptom burden.
Article
Background Use of fluoropyrimidine-based therapy in patients with metastatic colorectal cancer is associated with significant toxicities. This study aimed to assess the safety and efficacy of raltitrexed use in patients with metastatic colorectal cancer who developed significant toxicities after fluoropyrimidine-based treatment. Patients and Methods We identified patients with metastatic colorectal cancer who were treated with raltitrexed-based systemic therapy after developing serious adverse events with fluoropyrimidine-based treatment in a large Canadian province from 2004 to 2018. Demographic, tumor, and treatment characteristics were retrieved from the electronic medical records. Progression-free and overall survival were assessed from the start of raltitrexed-based therapy. Results A total of 86 patients were identified for the study. The median age was 66.5 years, and 58.1% of patients were men. The primary cancer site was right, left, and transverse colon in 38.4%, 27.9%, and 9.3%, respectively. The remaining 24.4% had rectal cancer. Among all patients, 43.0% had received more than 2 prior systemic therapies, and 37.6% had developed previous cardiotoxicity to fluoropyrimidine-based treatment. The median progression-free and overall survival were 8.5 and 10.2 months, respectively. On multivariable Cox regression model, patients with left-sided colon cancer (hazard ratio [HR], 0.33; 95% confidence interval [CI], 0.12-0.97; P = .044) and the Eastern Cooperative Oncology Group performance status of 0/1 (HR, 0.10; 95% CI, 0.01-0.82; P = .032) had a longer progression-free survival, whereas left-sidedness of colon cancer was the only factor that predicted overall survival (HR, 0.30; 95% CI, 0.10-0.88; P = .029). Raltitrexed was well-tolerated with common adverse events that included anemia in 41.7% of patients and chemotherapy-induced nausea and vomiting in 27.4%. Most toxicities were grade 1/2, but 16.7% of patients experienced grade 3. There were no cardiac events and treatment-related deaths. Conclusions Raltitrexed in patients with colorectal cancer who were previously treated with fluoropyrimidine-based systemic therapy is effective and well-tolerated.
Article
In the management of colorectal and appendiceal peritoneal metastases, intraperitoneal 5-fluorouracil (5-FU) has been used in 3 different ways. It has been used as part of an early postoperative intraperitoneal chemotherapy (EPIC) regimen along with EPIC mitomycin C. This EPIC mitomycin C plus EPIC 5-FU has been shown to be equivalent or inferior to HIPEC. Because it is more work intensive than HIPEC and not superior, its use should be abandoned if HIPEC is available. A second way to use intraperitoneal 5-FU is along with HIPEC. Several studies suggest a survival advantage for the combination of HIPEC with EPIC 5-FU. However, patient ineligibility for EPIC 5-FU in high-risk CRS is more likely the cause for the alleged survival advantage attributed to the combination. A third use of intraperitoneal 5-FU is long-term through a peritoneal access device. This plan for 5-FU use has shown favorable results in three randomized controlled studies. Normothermic intraperitoneal chemotherapy (NIPEC) with 5-FU should be considered as a regional chemotherapy component of a randomized trial for prevention or treatment of peritoneal metastases from colorectal or appendiceal cancer. Intravenous oxaliplatin combined with NIPEC 5-FU has been suggested as a bidirectional adjuvant regimen.
Article
WPMP-2 is an acid polysaccharide isolated from Polygonum multiflorum, which demonstrated excellent immunomodulatory activity. In order to reduce immunosuppression of 5-fluorouracil (5-Fu), WPMP-2 was utilized as a macromolecular carrier to conjugate the 5-Fu derivatives 5-fluorouracil-1-acetic acid (5-FUAC) through ester bond. The conjugate showed controlled drug release behaviour in vitro at 37 °C in phosphate buffer (pH 7.4), and only 5-FUAC was detected in the media. The cytotoxicity test in vitro showed that the conjugate exhibited different cytotoxicity to HepG-2 and HT-29 cells. In addition, immunization study in vivo illustrated that the conjugate displayed immunoprotective effect by mitigating inhibition and damage effects of 5-Fu on secretion of cytokines, proliferation of splenocytes, and phagocytosis of peritoneal macrophages. It was indicated that the conjugation of 5-Fu and WPMP-2 could be a potential double effective drug delivery system.
Article
Dihydropyrimidine dehydrogenase (DPD, EC 1.3.1.2), encoded by the DPYD gene, is the rate-limiting enzyme in the degradation pathway of endogenous pyrimidine and fluoropyrimidine drugs such as 5-fluorouracil (5-FU). DPD catalyzes the reduction of uracil, thymine, and 5-FU. In Caucasians, DPYD mutations, including DPYD*2A, DPYD*13, c.2846A>T, and 1129-5923C>G/hapB3, are known to contribute to interindividual variations in the toxicity of 5-FU. However, none of these DPYD polymorphisms have been identified in the Asian population. Recently, 21 DPYD allelic variants, including some novel-single nucleotide variants (SNVs), were identified in 1,070 healthy Japanese individuals by analyzing their whole-genome sequences (WGS), but the functional alterations caused by these variants remain unknown. In this study, in vitro analysis was performed on 22 DPD allelic variants by transiently expressing wild-type DPD and 21 DPD variants in 293FT cells and characterizing their enzymatic activities, using 5-FU as a substrate. DPD expression levels and dimeric forms were determined using immunoblotting and blue native-PAGE, respectively. Additionally, the values of three kinetic parameters, the Michaelis constant (Km), maximum velocity (Vmax), and intrinsic clearance (CLint = Vmax/Km), were determined for the reduction of 5-FU. We found that 10 variants exhibited significantly decreased intrinsic clearance in comparison to wild-type DPD. Moreover, the band patterns observed in the immunoblots of blue native gels indicated that DPD dimerization is required for enzymatic activity in DPD. Thus, the detection of rare DPYD variants might facilitate severe adverse effect prediction of 5-FU-based chemotherapy in the Japanese population.
Article
Uridine triacetate has been shown to be an effective antidote against mortality and toxicity caused by either overdoses or exaggerated susceptibility to the widely used anticancer agents 5-fluorouracil (5-FU) and capecitabine. However, a direct assessment of efficacy based on when emergency treatment was initiated was not clinically feasible. In this study we used mouse models of 5-FU overdose and of dihydropyrimidine dehydrogenase (DPD) deficiency to compare the efficacy of uridine triacetate in reducing toxicity and mortality when treatment was initiated at time points from 4 to 144 h after administration of 5-FU. We found that uridine triacetate was effective both in the 5-FU overdose and DPD deficiency models. Starting treatment within 24 h was most effective at reducing toxicity and mortality in both models, while treatment starting >96 to 120 h after 5-FU was far less effective. Uridine triacetate also reduced mortality in the DPD deficiency model when mice were treated with the 5-FU prodrug capecitabine. The results of this study are supportive of clinical observations and practice, indicating that efficacy declined progressively with later and later treatment initiation. Prompt treatment with uridine triacetate, within 24 h, conferred the greatest protection against 5-FU overexposure.
Article
Fluoropyrimidine has been commonly used not only in unresectable cases of metastatic colorectal cancer, but also in adjuvant therapy. Dihydropyrimidine dehydrogenase (DPD) is an enzyme encoded by the DPYD gene, which is responsible for the rate-limiting step in pyrimidine catabolism and breaks down more than 80% of standard doses of 5-fluorouracil (5-FU) and capecitabine, an oral prodrug of 5-FU. The lack of enzymatic activity increases the half-life of the drug, resulting in excess drug accumulation and toxicity which may lead to life-threatening side effects. There have been several published case reports about DPD deficiency in patients with colorectal cancer in Western countries. However, case reports of DPD deficiency in Japanese patients with colorectal cancer are rare because measuring DPD activity is not covered by public medical insurance in Japan, and it is not examined in our daily clinical practice currently. Therefore, we think that it is important to accumulate such case reports for further understanding. This report describes the case of a Japanese patient with colon cancer who experienced severe side effects while taking capecitabine, due to DPD deficiency. A 68-year-old man with ascending colon cancer underwent curative laparoscopic right hemicolectomy. Because final pathologic staging was Stage IIIa, standard adjuvant chemotherapy with capecitabine (3600 mg/body/day, days 1–14, every 3 weeks) was started on postoperative day 50. After 2 weeks, he started to experience Grade 3 diarrhea and was admitted to the hospital on postoperative day 66. On day 70, the patient had Grade 4 febrile neutropenia. Antibiotics and granulocyte-colony-stimulating factor were administered until his blood tests recovered to the normal degree. After 1 week of diarrhea, antidiarrheal agents were administered, and the patient gradually recovered. During the occurrence of diarrhea, specimen cultures were negative for infection. He was discharged on day 21 of the hospital stay. DPD deficiency was suspected, and 2 weeks later the DPD activity of the peripheral blood mononucleocytes was examined. The result was 10.3 U/mg protein which was remarkedly low (reference range 22.6–183.6 U/mg protein), and DPD deficiency was diagnosed. We always must consider the possibility of DPD deficiency in patients who experience severe side effects while taking capecitabine.
Article
Background: Serious and potentially life-threatening toxicities can occur following 5-fluorouracil/capecitabine exposure. Patients carrying Dihydropyrimidine Dehydrogenase (DPYD) variant alleles associated with decreased enzymatic function are at a greater risk of early/severe 5-fluorouracil/capecitabine toxicity. The objective of this systematic review/meta-analysis was to evaluate treatment outcomes between Pharmacogenetics Guided Dosing (PGD) versus non-PGD and within PGD (DPYD variant allele carriers versus wild type). Methods: A systematic review/meta-analysis of original publications indexed in Ovid Medline, Ovid Embase, and the Cochrane CENTRAL (Wiley) library from inception to 7-Dec-2020. Eligible studies evaluated at least one pre-defined treatment outcome measures (toxicity/hospitalisations/survival/overall response/quality of life). Results: Of 1090 identified publications, 17 met predefined eligibility criteria. The meta-analysis observed reduced incidence of grade 3/4 overall toxicity (Risk Ratio [RR] 0.32 [95% Cl 0.27-0.39], p < 0.00001) and grade 3/4 diarrhoea (RR 0.38 [95% Cl 0.24-0.61], p < 0.0001) among PGD versus non-PGD cohorts. Within PGD cohorts, there was no statistical differences for overall response rates (complete/partial) (RR 1.31 [95% Cl 0.93-1.85], p = 0.12). Similar results were found with stable disease (RR 1.27 [95% Cl 0.66-2.44], p = 0.47). Conclusion: PGD improves patient outcomes in terms of grade 3/4 toxicity, in particular overall toxicity and diarrhoea, without impacting on treatment response. Registration number: The study is registered with PROSPERO, registration number CRD42020223768.
Article
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Aims Most clinical trials exclude elderly people, leading to a limited understanding of the benefit-to-risk ratio in this population. Despite existing data regarding the oncological management of elderly receiving fluorouracil (5-FU)-based regimen, our objective was to investigate 5-FU exposure/toxicity relationship in patients ≥75 years and compare the effectiveness of 5-FU therapeutic drug monitoring between elderly and younger patients. Methods Hundred fifty-four patients (31 of whom are older than 75 years) with gastrointestinal cancers, who were to receive 5-FU–based regimens, were included in our study. At cycle 1 (C1), the 5-FU dose was calculated using patient's body surface area, then a blood sample was drawn to measure 5-FU concentration and 5-FU dose was adjusted at the subsequent cycles based on C1 concentration. Assessments of toxicity were performed at the beginning of every cycle. Results Seventy-one percent of elderly patients required dose adjustments after C1, compared with 50% for younger patients. Percentages of patients within 5-FU area under the curve range at cycle 2 were 64% and 68%, respectively, for elderly and younger patients. The proportion of elderly patients experiencing severe toxicities fell from 15% at C1 to only 5% at cycle 3. Conclusion Pharmacokinetic-guided 5-FU–dosing algorithm, leading to an improved tolerability while remaining within therapeutic concentration range, is even more valuable for patients older than 75 years than in younger patients.
Article
Aim: To investigate the association of DPYD, MTHFR and TYMS polymorphisms on 5-fluorouracil (5-FU) related toxicities and patient survival. Materials & methods: A total of 103 colorectal cancer patients prescribed 5-FU were included in the study. Genotyping was conducted for several DPYD, MTHFR and TYMS polymorphisms using a microarray analyzer. Results: DPYD 496A>G polymorphism was found to be significantly associated with 5-FU related grade 0–2, but not severe toxicities (p = 0.02). Furthermore, patients with DPYD 85TC and CC genotypes had longer progression and overall survival times compared to TT genotypes in our study group (log rank = 6.60, p = 0.01 and log rank = 4.40, p = 0.04, respectively). Conclusion: According to our results, DPYD 496AG and GG genotypes might be protective against severe adverse events compared to the AA genotype. Another DPYD polymorphism, 85T>C, may be useful in colorectal cancer prognosis. Further studies for both polymorphisms should be conducted in larger populations to achieve accurate results.
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Joseph Savio Jayaraj*1,2, Rajesh Naidu Janapala1,2 and Sanjay Goel1-3 Author Affiliations Received: October 09, 2019 | Published: October 18, 2019 Corresponding author: Joseph Savio Jayaraj, Department of Oncology, Medical Center, Bronx, USA DOI: 10.26717/BJSTR.2019.22.003706
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Pancreatic cancer is the fourth leading cause of cancer-related death in Japan. Pancreatic cancer is categorized as resectable, borderline resectable, or unresectable based on the degree of adjacent vascular invasion and the presence of distant metastases. Neoadjuvant chemotherapy with gemcitabine and S-1 (NAC-GS) has recently become a standard option for resectable pancreatic cancer in Japanese patients. According to previous reports, GS is considered to be relatively safe and feasible treatment for Japanese patients, including the elderly. However, NAC-GS is occasionally associated with severe adverse events which may ultimately render the patient unfit for surgery. A 60-year-old man with resectable pancreatic cancer suffered from severe necrotic enteritis during NAC-GS, which required surgical resection. Considering the time course and histological findings of the resected bowel, S-1 was believed to be the causative agent. The low urinary dihydrouracil to uracil ratio also suggested possible dihydropyrimidine dehydrogenase deficiency, which may have hindered the metabolism of S-1 and contributed to the development of necrotic enteritis. Life-threatening enteritis occurs in approximately 0.3% of all patients who receive S-1. As initial symptoms are non-specific, patients should be instructed to lower the hurdle for contacting the hospital during NAC-GS.
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5-Fluorouracil (5-FU) is a chemotherapeutic drug commonly used for the treatment of solid cancers. It is proposed that 5-FU interferes with nucleotide synthesis and incorporates into DNA, which may have a mutational impact on both surviving tumor and healthy cells. Here, we treat intestinal organoids with 5-FU and find a highly characteristic mutational pattern that is dominated by T>G substitutions in a CTT context. Tumor whole genome sequencing data confirms that this signature is also identified in vivo in colorectal and breast cancer patients who have received 5-FU treatment. Taken together, our results demonstrate that 5-FU is mutagenic and may drive tumor evolution and increase the risk of secondary malignancies. Furthermore, the identified signature shows a strong resemblance to COSMIC signature 17, the hallmark signature of treatment-naive esophageal and gastric tumors, which indicates that distinct endogenous and exogenous triggers can converge onto highly similar mutational signatures.
Chapter
5-Fluorouracil (5-FU) and its oral prodrug capecitabine are mainstays of oncologic therapy. They are fluoropyrimidine derivatives and function as antimetabolites. Fluoropyrimidines may be administered as monotherapy or in combination with other chemotherapeutic agents. They are predominantly used for the treatment of gastrointestinal, breast, and head and neck cancers. The therapeutic and toxicologic effects of 5-FU and capecitabine are attributed to their deleterious incorporation into RNA and DNA, and to their inhibition of thymidylate synthetase. Studies differ, but it is estimated that somewhere between 10% and 40% of patients on 5-FU and capecitabine develop some form of severe or life-threatening toxicity. Life-threatening toxicity may result from myelosuppression, diarrhea, mucositis, neurotoxicity, and cardiotoxicity. Hand-and-foot syndrome is also a characteristic adverse effect of 5-FU and capecitabine. Toxicity may result from intentional overdose, iatrogenic overdose, or therapeutic administration. A significant proportion severe toxicity occurs in the setting of therapeutic administration rather than acute overdose and is generally attributed to genetic polymorphisms. Treatment of toxicity is largely supportive. The antidote for fluoropyrimidine toxicity is uridine triacetate, but its indications are limited, and ideally the treating oncologist or a toxicologist should be consulted prior to its administration.
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Mesoporous Silica Nanoparticles (MSN) as a platform for controlled drug delivery system (DDS) was studied. Highly interest has developed among researchers due to the physicochemical characteristic of MSN which has proven to be promising in drug delivery application. In this study, MSN was modified with polymer poly (2-vinylpyrrolidone) (PVP) by co-condensation method and it was characterized by X- Ray Diffraction (XRD), Transmission Electron Microscope (TEM) and Fourier Transform Infrared (FTIR). The result revealed that modification of MSN with PVP has improved drug loading and release of anticancer drug model 5-fluorouracil (5-FU) without major changes of MSN characteristic. As monitored by UV–Vis Spectrophotometer (UV–Vis) analysis, MSN-PVP enhanced the adsorption of 5-FU from 83% to 88%. Meanwhile, for release of 5-FU from MSN-PVP has increased from 66% for MSN to 81% by using MSN-PVP. Release profile pattern indicate the important of modification of MSN with polymer. Finally, through released profile of MSN-PVP, it has shown that the release of 5-FU was in gradually release condition as desired in DDS.
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5-Fluorouracil, first introduced as a rationally synthesized anticancer agent 30 years ago, continues to be widely used in the management of several common malignancies including cancer of the colon, breast and skin. This drug, an analogue of the naturally occurring pyrimidine uracil, is metabolised via the same metabolic pathways as uracil. Although several potential sites of antitumour activity have been identified, the precise mechanism of action and the extent to which each of these sites contributes to tumour or host cell toxicity remains unclear. Several assay methods are available to quantify 5-fluorouracil in serum, plasma and other biological fluids. Unfortunately, there is no evidence that plasma drug concentrations can predict antitumour effect or host cell toxicity. The recent development of clinically useful pharmacodynamic assays provides an attractive alternative to plasma drug concentrations, since these assays allow the detection of active metabolites of 5-fluorouracil in biopsied tumour or normal tissue. 5-Fluorouracil is poorly absorbed after oral administration, with erratic bioavailability. The parenteral preparation is the major dosage form, used intravenously (bolus or continuous infusion). Recently, studies have demonstrated the pharmacokinetic rationale and clinical feasibility of hepatic arterial infusion and intraperitoneal administration of 5-fluorouracil. In addition, 5-fluorouracil continues to be used in topical preparations for the treatment of malignant skin cancers. Following parenteral administration of 5-fluorouracil, there is rapid distribution of the drug and rapid elimination with an apparent terminal half-life of approximately 8 to 20 minutes. The rapid elimination is primarily due to swift catabolism of the liver. As with all drugs, caution should be used in administering 5-fluorouracil in various pathophysiological states. In general, however, there are no set recommendations for dose adjustment in the presence of renal or hepatic dysfunction. Drug interactions continue to be described with other antineoplastic drugs, as well as with other classes of agents.
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Although dihydropyrimidine dehydrogenase has been purified to varying degrees from several species, very little is known about the human enzyme. The importance of this enzyme has recently been shown with cancer chemotherapy, particularly in patients with genetic deficiency of this enzyme. In the present study, this enzyme was purified 7800-fold to homogeneity from human liver by introducing several novel methods including chromatofocusing, HPLC gel filtration, reversed-phase HPLC for the enzyme assay. Purified human enzyme has a molecular mass of 210 +/- 5 kDa and appears to be composed of two subunits. The apparent pI is pH 4.6 (+/- 0.2). The human enzyme contains approximately four flavin nucleotide molecules (two each of FAD and FMN) and 33 iron atoms per molecule of enzyme. Kinetic studies with uracil, thymine, 5-fluorouracil, and NADPH were carried out. Amino acid composition and the N-terminal amino acid sequence of this enzyme were reported. A rabbit polyclonal antibody was raised and shown to be specific for the human liver enzyme. In conclusion, in the present manuscript, we report not only a novel procedure for purification of dihydropyrimidine dehydrogenase from human liver but also new data on its properties compared to other species, which will provide a basis for further biochemical and molecular studies of this enzyme.
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Severe neurotoxicity due to 5-fluorouracil (FUra) has previously been described in a patient with familial pyrimidinemia. We now report the biochemical basis for both the pyrimidinemia and neurotoxicity in a patient we have recently studied. After administration of a "test" dose of FUra (25 mg/m2, 600 microCi[6-3H]FUra by intravenous bolus) to a patient who had previously developed neurotoxicity after FUra, a markedly prolonged elimination half-life (159 min) was observed with no evidence of FUra catabolites in plasma or cerebrospinal fluid and with 89.7% of the administered dose being excreted into the urine as unchanged FUra. Using a sensitive assay for dihydropyrimidine dehydrogenase in peripheral blood mononuclear cells, we demonstrated complete deficiency of enzyme activity in the patient and partial deficiency of enzyme activity in her father and children consistent with an autosomal recessive pattern of inheritance. Patients who are deficient in this enzyme are likely to develop severe toxicity after FUra administration.
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Kinetics of 5-fluorouracil (FUra) and FUra metabolites in plasma and urine were investigated in 10 cancer patients following i.v. bolus administration of 500 mg/m2 FUra with 600 microCi of [6-3H]FUra. Biliary excretion was examined in two patients with external biliary catheters. Quantitation of unchanged drug and metabolites was assessed by a highly specific high-performance liquid chromatographic method. FUra plasma levels declined rapidly with an apparent elimination half-life of 12.9 +/- 7.3 min. Dihydrofluorouracil was detected within 5 min in most patients, demonstrating rapid catabolism and reached maximum peak levels of 23.7 +/- 9.9 microM at approximately 60 min. The apparent elimination half-life of dihydrofluorouracil (61.9 +/- 39.0 min) was consistently greater than that of the unchanged drug. The apparent elimination half-lives of the subsequent metabolites alpha-fluoro-beta-ureidopropionic acid and alpha-fluoro-beta-alanine were prolonged with values of 238.9 +/- 175.4 min and 1976 +/- 358 min, respectively. Approximately 60-90% of the administered dose was excreted in urine within 24 h, primarily as alpha-fluoro-beta-alanine. Biliary excretion accounted for 2-3% of total administered radioactivity. The major fraction of this radioactivity eluted on high-performance liquid chromatography as a previously unrecognized FUra metabolite. Analysis of its structure is currently ongoing in our laboratory. In conclusion, this study provides the first comprehensive analysis of the formation and excretion of FUra metabolites in plasma, urine, and bile following i.v. bolus administration of FUra in humans.
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The pig and human dihydropyrimidine dehydrogenase (DPD) cDNAs were cloned and sequenced. The pig enzyme, expressed in Escherichia coli, catalyzed the reduction of uracil, thymine, and 5-fluorouracil with kinetics approximating those published for the enzyme purified from mammalian liver. DPD could be expressed in significant quantities only when uracil was added to the bacterial growth medium. The pig and human enzymes contained 1025 amino acids and calculated M(r) = 111,416 and 111,398, respectively. Conserved domains corresponding to a possible NADPH binding site and FAD binding site were found in the NH2-terminal half of the proteins and two motifs of putative [4Fe-4S] binding sites were found near to the carboxyl terminus of the enzyme. The latter corresponds to the labile COOH-terminal fragment previously shown to contain the iron sulfur centers. A sequence encompassing a peptide corresponding to the uracil binding site was found between the NADPH/FAD-containing NH2-terminal portion of the protein and the iron-sulfur binding sites near to the COOH terminus. Thus, the DPD appears to be derived from at least three distinct domains. The DPYD gene was localized to the centromeric region of human chromosome 1 between 1p22 and q21.
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Dihydropyrimidine dehydrogenase (DPD) is the initial and rate-limiting enzyme in the catabolism of 5-fluorouracil (FUra), one of the most widely used anticancer drugs. Previous studies from our laboratory demonstrated the clinical importance of DPD in cancer patients (G. D. Heggie, J-P. Sommadossi, D. S. Cross, W. J. Huster, and R. B. Diasio. Cancer Res., 47: 2203-2206, 1987; B. E. Harris, R. Song, S-j. Soong, and R. B. Diasio. Cancer Res., 50: 197-201, 1990), particularly in those with DPD deficiency who experience severe FUra toxicity (including death) following FUra treatment [R. B. Diasio, T. L. Beavers, and J. T. Carpenter. J. Clin. Invest., 81: 47-51, 1988; B. E. Harris, J. T. Carpenter, and R. B. Diasio. Cancer (Phila.), 68: 499-501, 1991]. We now suggest that measurement of DPD activity may be useful in routine screening of cancer patients prior to FUra treatment. In this paper, we describe the following serial studies: (a) we developed a sensitive, accurate, and precise DPD assay and a storage method to stabilize DPD activity, permitting large scale DPD screening in cancer patients; (b) we demonstrated a normal distribution (Gaussian distribution) of human DPD activity from peripheral blood mononuclear cells (PBM-DPD) in a population study. Baselines for PBM-DPD with fresh and frozen samples were 0.425 +/- 0.124 (SD) and 0.189 +/- 0.064 nmol/min/mg protein, respectively. The 95% and 99% distribution ranges for both fresh and frozen samples were also determined, providing criteria for detection of DPD-deficient patients; (c) we identified nine new patients with profound or partial DPD deficiency; (d) we determined a baseline for human liver DPD activity, which was shown to be 0.360 +/- 0.182 nmol/min/mg protein (frozen samples); (e) we did a preliminary evaluation of liver DPD from deficient patients. Low liver DPD activity in two deficient patients correlated with low PBM-DPD activity. Using a polyclonal antibody raised against human liver DPD in our laboratory (Z. Lu, R. Zhang, and R. B. Diasio. J. Biol. Chem., 267: 17102-17109, 1992), Western blot analysis demonstrated decreased DPD protein in the liver cytosol from DPD-deficient patients compared to normal subjects. These results may be useful in improving the effectiveness and/or lessening the toxicity of FUra chemotherapy.
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Dihydropyrimidine dehydrogenase (DPD) deficiency constitutes an inborn error in pyrimidine metabolism associated with thymine-uraciluria in pediatric patients and an increased risk of toxicity in cancer patients receiving 5-fluorouracil (5-FU) treatment. The molecular basis for DPD deficiency in a British family having a cancer patient that exhibited grade IV toxicity 10 d after 5-FU treatment was analyzed. A 165-bp deletion spanning a complete exon of the DPYD gene was found in some members of the pedigree having low DPD catalytic activity. Direct sequencing of lymphocyte DNA from these subjects revealed the presence of a G to A point mutation at the 5'-splicing site consensus sequence (GT to AT) that leads to skipping of the entire exon preceding the mutation during pre-RNA transcription and processing. A PCR-based diagnostic method was developed to determine that the mutation is found in Caucasian and Asian populations. This mutation was also detected in a Dutch patient with thymine-uraciluria and completely lacking DPD activity. A genotyping test for the G to A splicing point mutation could be useful in predicting cancer patients prone to toxicity upon administration of potentially toxic 5-FU and for genetic screening of heterozygous carriers and homozygous deficient subjects.
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Dihydropyrimidine dehydrogenase (DPD), the initial and rate-limiting enzyme in pyrimidine catabolism, has recently been purified to homogeneity from several species. In the present study the molecular cloning of DPD with isolation of a cDNA coding for bovine liver DPD is reported using polymerase chain reaction (PCR) methodology. Known amino acid sequence from purified bovine DPD was used to initially design mixed oligonucleotide primers for amplification of a cDNA fragment (65 base pairs). Specific primers were subsequently designed and utilized in the amplification of the full-length cDNA (4422 base pairs). Sequence analysis demonstrated a 74 nucleotide 5'-nontranslated region, an open reading frame of 3075 bases, and a 1273 nucleotide 3'-nontranslated region. Comparison of the nucleotide and deduced amino acid sequences of Bovine DPD to Pig and Human liver DPD reveals 93% and 92% identity respectively.
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To describe the pharmacogenetic syndrome of dihydropyrimidine dehydrogenase (DPD) deficiency, which predisposes patients with cancer to potentially lethal adverse reactions following 5-fluorouracil (5-FU)-based chemotherapy. Published articles, abstracts, and conference proceedings. Genetic deficiencies in DPD, the rate-limiting enzyme responsible for 5-FU catabolism, may occur in 3% or more of patients with cancer putting them at increased risk for unusually severe adverse reactions (e.g., diarrhea, stomatitis, mucositis, myelosuppression, neurotoxicity) to standard doses of 5-FU. Diagnosis of DPD deficiency must be confirmed by specialized laboratory tests. The principle treatment for DPD-deficient patients with severe acute 5-FU reactions is supportive care; however, the administration of thymidine potentially may reverse severe 5-FU-induced neurologic symptoms such as encephalopathy and coma. Early recognition of this serious pharmacogenetic syndrome may allow for the modification of future chemotherapy, thus avoiding further life-threatening toxicities. Nurses must understand the pharmacology, mechanism of action, clinical presentation, potentially lethal risks, and traumatic psychosocial stresses experienced by DPD-deficient patients with cancer receiving 5-FU therapy in order to develop timely interventions and alternative plans of care.
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Deficiency of the pyrimidine catabolic enzyme, dihydropyrimidine dehydrogenase (DPD), has been shown to be responsible for a pharmacogenetic syndrome in which administration of 5-fluorouracil is associated with severe and potentially life-threatening toxicity. Following the recent availability of the cDNA for DPD, there were initial reports of several molecular defects (point mutations, deletions due to exon skipping) that were suggested as a potential molecular basis for DPD deficiency, even before the complete physical structure of the DPD gene was known. To understand the mechanism responsible for DPD deficiency, we have determined the genomic structure and organization of the human DPD gene. The gene is approximately 150 kb in length, and it consists of 23 exons, ranging in size from 69 to 1404 bp. The sequences of intronic regions flanking the exon boundaries have been determined. The physical map of the DPD gene should permit development of rapid assays to detect point mutations or small deletions in the DPD gene associated with 5-fluorouracil toxicity.
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Individuals with a deficiency in the enzyme dihydropyrimidine dehydrogenase (DPD) may experience severe life-threatening toxicity when treated with 5-fluorouracil (5-FU). As routine measurement of enzyme activity is not practical in many clinical centres, we have investigated the use of DNA mutation analysis to identify cancer patients with low enzyme levels. We have identified two new mutations at codons 534 and 543 in the DPD cDNA of a patient with low enzyme activity and screened the DNA from 75 colorectal cancer patients for these mutations and the previously reported splice site mutation (Vreken et al, 1996; Wei et al, 1996). In all cases, DPD enzyme activity was also measured. The splice site mutation was detected in a patient (1 out of 72) with low enzyme activity whereas mutations at codons 534 (2 out of 75) and 543 (11 out of 23) were not associated with low enzyme activity. These studies highlight the need to combine DPD genotype and phenotype analysis to identify mutations that result in reduced enzyme activity. Images Figure 1 Figure 2 Figure 3
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Dihydropyrimidine dehydrogenase (DPD) is the initial, rate-limiting enzyme in the catabolism of 5-fluorouracil (5-FU), one of the most widely used chemotherapeutic agents in the treatment of breast cancer. The objective of this study was to determine the population characteristics of DPD activity in patients with breast cancer as well as the frequency of DPD deficiency in this population. DPD activity in peripheral blood mononuclear cells (PBM-DPD) was determined in 360 patients with breast cancer, with the mean PBM-DPD (0.26 +/- 0.01 nmol/min/mg protein) being significantly lower than that observed in female controls (0.44 +/- 0.02 nmol/min/mg protein; P < 0.01). ANOVA analysis examining the significance of differences in DPD activity among various groups indicated that only disease difference (breast cancer versus normal subjects) was significant after adjustments for race and age. In the present study, 21 (5.8%) patients were considered to be DPD deficient, indicating that this pharmacogenetic syndrome may be more common than anticipated (no DPD-deficient individual was found in the controls). Significantly lower DPD activity in patients with breast cancer may predispose to 5-FU-associated toxicity. These results provide further rationale for individualizing the 5-FU dose, thus reducing the risk of toxicity and/or improving therapeutic efficacy in patients with breast cancer.
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Patients with decreased dihydropyrimidine dehydrogenase (DPD) activity are at increased risk for experiencing serious adverse reactions following 5-fluorouracil (5-FU)-based chemotherapy. Symptoms include severe and potentially life-threatening gastrointestinal toxicity, myelosuppression, and neurological toxicity. In the present study, we describe a 50-year-old Caucasian man who developed severe encephalopathy during his second cycle of 5-FU chemotherapy. The patient remained in a comatose state for 4 days but then showed dramatic improvement in his neurological status following continuous i.v. infusion of thymidine at 8 g/m2/day. Laboratory studies revealed the patient to be severely DPD deficient, as demonstrated by DPD enzyme activity from peripheral blood mononuclear cells being below the lower limit of the 95th percentile of a control population and by Western immunoblot analysis showing undetectable levels of DPD protein. Additional studies revealed a significant defect in pyrimidine catabolism with a 3.3- and 365-fold increase in the levels of uracil in plasma and urine, respectively, compared to normal subjects. Family studies suggest that the inheritance pattern of this syndrome is complex and most consistent with an autosomal recessive trait. This study demonstrates that cancer patients with DPD deficiency are at increased risk for developing severe neurological toxicity secondary to 5-FU chemotherapy, and that infusional thymidine should be considered as a potential rescue agent against this particular host toxicity.
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In humans, 80-90% of an administered dose of 5-fluorouracil (5-FU) is degraded by dihydropyrimidine dehydrogenase (DPD; EC 1.3.1.2), the initial rate-limiting enzyme in pyrimidine catabolism. Cancer patients with decreased DPD activity are at increased risk for severe toxicity including diarrhea, stomatitis, mucositis, myelosuppression, neurotoxicity, and, in some cases, death. We now report the first known cancer patient who developed life-threatening complications after treatment with topical 5-FU and was shown subsequently to have profound DPD deficiency. RT-PCR and genomic PCR methodologies were used to identify a G to A mutation in the GT 5' splicing recognition sequence of intron 14, resulting in a 165-bp deletion (corresponding to exon 14) in this patient's DPD mRNA. Immunoprecipitation and Western blot analysis were then used to demonstrate that the aberrant DPD mRNA is translated into a nonfunctional DPD protein that is ubiquitinated. We conclude that the presence of this metabolic defect combined with topical 5-FU (a drug demonstrating a narrow therapeutic index) results in the unusual presentation of life-threatening toxicity after treatment with a topical drug. These data further suggest that degradation by the ubiquitin-proteosome-mediated system plays a role in the elimination of the DPD protein.
Chapter
Dihydropyrimidine dehydrogenase (DPD) deficiency (McKusick 274270) is a, clinically heterogeneous, autosomal recessive disease. DPD (EC 1.3.1.2) catalyzes the first and rate-limiting step in the catabolism of uracil, thymine and the analogue 5-fluorouracil. Patients with a nearly complete enzyme defect show convulsive disorders in about 50% of cases whereas patients experiencing acute 5-fluorouracil toxicity usually show DPD enzymatic activities in the heterozygous range.1–9
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netics and pharmacologic effects of medica-tions is determined by their importance for the activation or inactivation of drug sub-strates. The effects can be profound toxicity for medications that have a narrow therapeu-tic index and are inactivated by a polymor-phic enzyme (for example, mercaptopurine, azathioprine, thioguanine, and fluorouracil) (6) or reduced efficacy of medications that require activation by an enzyme exhibiting genetic polymorphism (such as codeine) (7). However, the overall pharmacologic ef-fects of medications are typically not mono-genic traits; rather, they are determined by the interplay of several genes encoding proteins involved in multiple pathways of drug metab-olism, disposition, and effects. The potential polygenic nature of drug response is illustrat-
Article
5-Fluorouracil (5FU) is most commonly used in chemotherapy for human malignancy. Over 80% of administered 5FU is metabolically degraded by dihydropyrimidine dehydrogenase (DPD), a primary and rate-limiting enzyme in the 5FU metabolic pathway. A DPD-deficient phenotype among cancer patients, which has posed a serious problem in 5FU-based chemotherapy, was reported to be in part ascribed to germline mutations in dihydropyrimidine dehydrogenase (DPYD) gene. Therefore, we for the first tune examined the frequencies and types of germline mutations in the DPYD gene among a total of 107 Japanese cancer patients and healthy volunteers. Of 214 alleles examined among them, 181 alleles were of the same type, which was assigned as wild type; 21 alleles revealed a nucleotide substitution resulting in silent mutation; and the remaining 12 alleles showed five types of nucleotide deletion or substitutions resulting in one frameshift and four missense mutations. Three of them, A74G, 812delT and L572V, were novel mutations. None of the study subjects showed homozygous frameshift or missense mutated alleles. We also studied the association between toxic response to 5FU and heterozygous frame shift or missense mutation of the DPYD gene among eight cancer patients who had received 5FU-based chemotherapy. These patients did not show any adverse effects higher than grade 3, suggesting that heterozygotes are not associated with increased toxicity to 5FU. Our results indicate that a very small percentage, about 0.2%, of the Japanese population seems to carry homozygous mutations in DPYD gene, mutations which possibly indicate genetically increased toxicity of 5FU-based chemotherapy.
Article
Dihydropyrimidine dehydrogenase (DPD) deficiency is an autosomal recessive disease characterised by thymine-uraciluria in homozygous deficient patients and has been associated with a variable clinical phenotype. In order to understand the genetic and phenotypic basis for DPD deficiency, we have reviewed 17 families presenting 22 patients with complete deficiency of DPD. In this group of patients, 7 different mutations have been identified, including 2 deletions [295–298delTCAT, 1897delC], 1 splice-site mutation [IVS14+1G>A)] and 4 missense mutations (85T>C, 703C>T, 2658G>A, 2983G>T). Analysis of the prevalence of the various mutations among DPD patients has shown that the G→A point mutation in the invariant splice donor site is by far the most common (52%), whereas the other six mutations are less frequently observed. A large phenotypic variability has been observed, with convulsive disorders, motor retardation and mental retardation being the most abundant manifestations. A clear correlation between the genotype and phenotype has not been established. An altered β-alanine, uracil and thymine homeostasis might underlie the various clinical abnormalities encountered in patients with DPD deficiency.
Article
Dihydropyrimidine dehydrogenase (DPD) catabolizes endogenous pyrimidines and pyrimidine-based antimetabolite drugs. A deficiency in human DPD is associated with congenital thymine-uraciluria in pediatric patients and severe 5-fluorouracil toxicity in cancer patients. The dihydropyrimidine dehydrogenase gene (DPYD) was isolated, and its physical map and exon–intron organization were determined by analysis of P1, PAC, BAC, and YAC clones. TheDPYDgene was found to contain 23 exons ranging in size from 69 bp (exon 15) to 961 bp (exon 23). A physical map derived from a YAC clone indicated thatDPYDis at least 950 kb in length with 3 kb of coding sequence and an average intron size of about 43 kb.The previously reported 5′ donor splice site mutation present in pediatric thymine-uraciluria and cancer patients can now be assigned to exon 14. All 23 exons were sequenced from a series of human DNA samples, and three point mutations were identified in three racial groups as G1601A (exon 13, Ser534Asn), A1627G (exon 13, Ile543Val), and G2194A (exon 18, Val732Ile). These studies, which have established that theDPYDgene is unusually large, lay a framework for uncovering new mutations that are responsible for thymine-uraciluria and toxicity to fluoropyrimidine drugs.
Article
Dihydropyrimidine dehydrogenase (DPD) is the initial key enzyme in the catabolism of 5-fluorouracil (5-FU). We measured DPD activity in lymphocytes from 57 consecutive head and neck cancer patients while simultaneously monitoring 5-FU pharmacokinetics during 5-day, continuous infusion (1000 mg/m2/day) 5-FU therapy (82 cycles in total). The mean value for DPD activity was 0.186 +/- 0.068 (SD) nmol/min/mg of protein (range, 0.058 to 0.357). The mean value for 5-FU clearance was 2522.6 +/- 684.2 ml/min/m2 (range, 1052 to 4029). A significant linear correlation was observed between DPD activity and 5-FU clearance (r = 0.716, P less than 0.0001). DPD activity was poorly correlated to plasma uracil concentrations (r = -0.260, P = 0.0215). Likewise, plasma uracil concentrations were poorly correlated to 5-FU clearance (r = -0.214, P = 0.0595). In patients evaluated for more than one cycle (n = 18), there was large intrapatient variability in both DPD activity and 5-FU clearance. No significant difference was noted between cycles for DPD activity or 5-FU clearance (Kruskal-Wallis test). Monitoring DPD activity in lymphocytes may be useful in identifying patients at risk for altered 5-FU disposition.
Article
Currently, fluorouracil (5-FU) is one of the major drugs used in cancer chemotherapy. Several investigators, including ourselves, have demonstrated a link between abnormalities in 5-FU clearance (Cl) and the risk of developing more or less 5-FU-related toxicities. Age and sex are among the host factors that have been implicated in the pharmacokinetic variability of drugs. Presently, no data are available on the possible influence of sex and age on 5-FU Cl. Three hundred eighty patients (mean age, 61.7 years; range, 25 to 91; 301 men and 79 women) with squamous cell carcinoma (sre) of the head and neck were treated in our institution between 1987 and 1991. 5-FU Cl was determined for a total of 1,092 chemotherapy cycles. Each cycle consisted of cisplatin and 5-day continuous intravenous infusion 5-FU (daily doses ranging between 365 and 1,224 mg/m2). 5-FU Cl values (L/h/m2) showed a wide dispersion for both men (median, 179; range, 29 to 739) and women (median, 155; range, 56 to 466). 5-FU Cl values were lower significantly for women compared with men (P = .0005). When adjusted for age and dose, the influence of sex on log Cl remained significant (P = .013). There was no evidence that age modified 5-FU Cl when adjusted for sex and dose. Interestingly, for both men and women, the oldest patients (greater than 70 years) maintained their ability to clear 5-FU with daily doses that ranged from 500 to 1,000 mg/m2. These data indicate that the capacities to clear 5-FU are lower in women compared with men and are not influenced by age. It would be of interest to know whether this sex-related difference in 5-FU Cl may be clinically relevant by considering both toxicity and tumor response to 5-FU treatment.
Article
This study describes the inheritance of a defect in pyrimidine catabolism and its association with drug-induced toxicity in a patient receiving 5-fluorouracil (FUra) as adjuvant chemotherapy for breast carcinoma. The study population included the affected patient (proband), nine of her blood relatives, and seven healthy volunteers. The activity of dihydropyrimidine dehydrogenase (DPD), the initial enzyme of pyrimidine (and FUra) catabolism, in peripheral blood mononuclear cells was measured in each subject by a specific radiometric assay using FUra as the substrate. The proband had no detectable DPD activity. When enzyme levels in the proband and relatives were compared with that in controls, an autosomal recessive pattern of inheritance was demonstrated. This is the third patient with severe FUra toxicity secondary to an alteration in pyrimidine catabolism and the second from our clinic population suggesting that the frequency of this genetic defect may be greater than previously thought. Monitoring DPD activity may be important in the management of patients experiencing severe toxicity secondary to FUra chemotherapy.
Article
The pyrimidine antimetabolite drugs consist of base and nucleoside analogues of the naturally occurring pyrimidines uracil, thymine and cytosine. As is typical of antimetabolites, these drugs have a strong structural similarity to endogenous nucleic acid precursors. The structural differences are usually substitutions at one of the carbons in the pyrimidine ring itself or substitutions at on of the hydrogens attached to the ring of the pyrimidine or sugar (ribose or deoxyribose). Despite the differences noted above, these analogues, can still be taken up into cells and then metabolized via anabolic or catabolic pathways used by endogenous pyrimidines. Cytotoxicity results when the antimetabolite either is incorporated in place of the naturally occurring pyrimidine metabolite into a key molecule (such as RNA or DNA) or competes with the naturally occurring pyrimidine metabolite for a critical enzyme. There are four pyrimidine antimetabolites that are currently used extensively in clinical oncology. These include the fluoropyrimidines fluorouracil and fluorodeoxyuridine, and the cytosine analogues, cytosine arabinoside and azacytidine.
Article
This report describes the severe adverse effects produced in a female patient after treatment with a limited dosage of fluorouracil given on a weekly schedule. Subsequent studies identified a disorder of pyrimidine metabolism, manifested by pyrimidinemia or pyrimidinuria in the propositus and her brother. A genetic defect of pyrimidine-base degradation has been proposed as the cause of the severe fluorouracil toxicity manifested in this patient. Such a defect may not be clinically apparent unless the affected patient is treated with a pyrimidine-base analogue.
Article
Dihydropyrimidine dehydrogenase (EC 1.3.1.2, DPD) is the initial rate-limiting enzyme in pyrimidine catabolism, which catalyzes the following reaction.
Article
Dihydropyrimidine dehydrogenase (DPD, EC 1.3.1.2) is the initial and rate-limiting enzyme in the three-step pathway of uracil and thymine catabolism leading to the formation of β-alanine and β-aminobutyric acid, respectively. Several studies have demonstrated the importance of DPD in cancer patients, particularly in those lacking or having only low levels of activity. Patients exhibiting severe toxicity when administered 5-fluorouracil were shown to have low DPD activity. Studies of affected families demonstrated that the deficiency was inherited in an autosomal recessive pattern. DPD deficiency is one of several inherited disorders of pyrimidine metabolism, clinically termed thymine-uracil-uria. 14 refs., 1 fig.
Article
A condition called thymine uracilurea has been described that is due to a lack of dihydropyrimidine dehydrogenase (DPD) activity. Cancer patients experiencing acute 5-fluorouracil toxicity also have lower-than-normal DPD activities. However, to date, the molecular basis of this disorder has not been addressed. In this study, the phenotype and genotype of a family that presents a patient showing no DPD activity was determined. Fibroblast mRNAs from the patient and four family members were subjected to reverse transcriptase polymerase chain reaction (RT-PCR) using primers generated from the human DPD cDNA sequence. DPD mRNA from the patient was found to lack a segment of 165 nucleotides that results from exon skipping. DPD mRNA from the parents and a sibling were found to be heterozygous for the deleted and the normal mRNA, while a brother had two normal transcripts. DPD activities and levels of DPD protein correlated with genotype; the deficient patient had no detectable DPD protein. PCR analysis of the genomic DNA from this family revealed that the defective mRNA is not due to a deletion of a portion of the gene that contains the exon, thus implying that the mutation is the result of an as yet nonidentified point mutation that causes faulty splicing.
Article
We conducted a prospective study on a large set of cancer patients in an attempt to evaluate the incidence of complete or partial dihydropyrimidine dehydrogenase (DPD) deficiency as found in peripheral mononuclear cells (PMNC). One hundred eighty-five unselected consecutive cancer patients were included. The population consisted of 152 men (mean age, 62.1 years; range, 35 to 90) and 33 women (mean age, 59.2 years; range, 36 to 77). Sixty-eight were head and neck patients treated by a 5-day continuous infusion of fluorouracil (FU; starting dose, 1 g/m2/d, with dose adaptation based on pharmacokinetics) for which DPD activity was measured 2 to 3 days before FU administration (94 cycles analyzed). PMNC-DPD activity was measured by a radio-enzymatic assay using carbon-14-FU. DPD activity in the entire population showed a unimodal distribution, which globally fits a gaussian distribution. Mean and median DPD activity values were 0.222 and 0.211 nmol/min/mg protein, respectively (range, 0.065 to 0.559). No total DPD deficiency was found. Multifactor analysis of variance showed that liver function (biologic evaluation) and age did not influence DPD activity, but that DPD activity was, on average, 15% lower in women (0.194 nmol/min/mg protein) than in men (0.228 nmol/min/mg protein) (P = .03). No difference was demonstrated between premenopausal and postmenopausal women. In patients treated with FU, the risk of developing side effects was not linked to pretreatment DPD activity. FU-related toxicity was linked to FU systemic exposure. The correlation between pretreatment DPD activity and FU systemic clearance (CI) was weak (n = 90, linear regression r = .31, P = .002). Pretreatment DPD activity in patients who required a dose reduction was not significantly different from DPD activity in patients who did not require dose modification. From the present study, it appears that total DPD deficiency is a rare event. Although pretreatment DPD activity cannot be a useful indicator for improving FU dose adaptation strategy, the identification of severe DPD deficiency (< 0.100 nmol/min/mg protein) could lead to starting the treatment with a markedly reduced FU dose or even to using an alternative chemotherapy regimen.
Article
Dihydropyrimidine dehydrogenase (DPD, EC 1.3.1.2) is the initial and rate-limiting enzyme in the catabolic pathway of pyrimidines and has an important role in cancer chemotherapy with fluoropyrimidine drugs. Recently, we purified and characterized this enzyme from human liver and raised a rabbit polyclonal antibody against the purified human enzyme (Lu et al., J Biol Chem 267: 17102-17109, 1992). In the present study, using this purification procedure, DPD was purified to homogeneity from three other mammalian species, i.e. pig, rat, and cow. Comparison of the biochemical properties of these purified enzymes was conducted. Molecular masses of DPD from human, pig, rat, and cow liver were: 210, 204, 210, and 216 kDa, respectively. DPD from all four species appeared to be composed of two subunits. The apparent pI values were 4.6, 4.8, 4.85, and 5.25, respectively. Kinetic studies with uracil, thymine, 5-fluorouracil, and NA