Dihydropyrimidine Dehydrogenase Activity Research Articles

Clinical Value of Pharmacogenomic Testing in a Patient Receiving FOLFIRINOX for Pancreatic Adenocarcinoma.

Pharmacogenomic testing may have clinical value in the treatment of patients with gastrointestinal malignancies such as colorectal and pancreatic cancer. These types of cancer are often treated with combination chemotherapy regimens. These regimens can lead to severe adverse effects in patients with diminished drug tolerability potentially due to certain genetic variants in the enzymes involved in the metabolism of the chemotherapies. Genetic variants resulting in decreased enzymatic activity of uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) and dihydropyrimidine dehydrogenase (DPD) are known to increase irinotecan and 5-fluorouracil-related toxicity, respectively. We report a case of a patient with pancreatic adenocarcinoma who was found to be not only homozygous for the UGT1A1∗28 allele, but also heterozygous for a DPYD variant through pharmacogenomic testing. Potentially severe adverse effects were prevented in this patient’s case by implementing preemptive dose reductions. On the basis of the significant implications of chemotherapy-related toxicity in this and other similar cases, we report on the clinical value of integrating pharmacogenomic testing into clinical practice to allow for preemptive and/or point-of-care dose reductions in patients potentially at risk for increased toxicity. This is even more important in an era where combinatorial triplet chemotherapies are increasingly being used.

Value of plasma SN-38 levels and DPD activity in irinotecan-based individualized chemotherapy for advanced colorectal cancer with heterozygous type UGT1A1*6 or UGT1A1*28.

PurposeThe relationship between the pharmacokinetics of irinotecan and outcomes of advanced colorectal cancer is unclear, and few studies have examined individualized irinotecan-based chemotherapy depending on plasma 7-ethyl-10-hydroxy camptothecin (SN-38) levels and dihydropyrimidine dehydrogenase (DPD) activity, particularly for the UGT1A1*6 or UGT1A1*28 heterozygous type.MethodsThis study retrospectively explored the relationship among plasma SN-38 level 1.5 hours after critical enzyme for irinotecan (CPT-11) administration (CSN-38 1.5h), plasma SN-38 level 49 hours after CPT-11 administration (CSN-38 49h), DPD activity, and clinical outcomes for the UGT1A1*6 and UGT1A1*28 heterozygous types.ResultsCSN-38 1.5h and CSN-38 49h of the UGT1A1*6 or UGT1A1*28 heterozygous type were close to those of UGT1A1*6 and UGT1A1*28 wild-types; some of those with relatively high CSN-38 1.5h levels obtained better median progression-free survival (mPFS), whereas others with higher CSN-38 49h concentrations showed a relatively high incidence of adverse reactions possibly because of the decreased activity of DPD.ConclusionIncreasing the dosage of CPT-11 according to CSN-38 1.5h may improve the efficacy in patients with lower CSN-38 1.5h levels. For cases with comparably low DPD activity, advisable primary and subsequent dose adjustment of 5-fluorouracil based on plasma 5-fluorouracil levels may be a practical strategy for reducing the occurrence of adverse reactions for personalized treatment of the UGT1A1*6 or UGT1A1*28 heterozygous type.

Evolution of Dihydropyrimidine Dehydrogenase Diagnostic Testing in a Single Center during an 8-Year Period of Time

ObjectiveFluoropyrimidine treatment can be optimized based on dihydropyrimidine dehydrogenase (DPD) activity. DPD dysfunction leads to increased exposure to active metabolites, which can result in severe or even fatal toxicity.MethodsWe provide an overview of 8 years of DPD diagnostic testing (n = 1194).ResultsWithin the study period, our diagnostic test evolved from a single-enzyme measurement using first a radiochemical and then a nonradiochemical assay by ultra HPLC-MS in peripheral blood mononuclear cells with uracil, to a combined enzymatic and genetic test (ie, polymerase chain reaction) followed by Sanger sequence analysis of 4 variants of the DPYD gene (ie, DPYD*2A, DPYD*13, c.2846A>T, and 1129-5923C>G; allele frequencies 0.58%, 0.03%, 0.29%, and 1.35%, respectively). Patients who have 1 of the 4 variants tested (n = 814) have lower enzyme activity than the overall patient group. The majority of patients with the DPYD*2A variant (83%) consistently showed decreased enzyme activity. Only 24 (25.3%) of 95 patients (tested for 4 variants) with low enzyme activity carried a variant. Complete DPYD sequencing in a subgroup with low enzyme activity and without DPYD*2A variant (n = 47) revealed 10 genetic variants, of which 4 have not been described previously. We did not observe a strong link between DPYD genotype and enzyme activity.ConclusionsPrevious studies have shown that DPD status should be determined before treatment with fluoropyrimidine agents to prevent unnecessary side effects with possible fatal consequences. Our study in combination with literature shows that there is a discrepancy between the DPD enzyme activity and the presence of clinically relevant single nucleotide polymorphisms. At this moment, a combination of a genetic and enzyme test is preferable for diagnostic testing. (Curr Ther Res Clin Exp. 2018; 79:XXX–XXX).

DPYD genotype-guided dose individualisation of fluoropyrimidine therapy in patients with cancer: a prospective safety analysis.

Fluoropyrimidine treatment can result in severe toxicity in up to 30% of patients and is often the result of reduced activity of the key metabolic enzyme dihydropyrimidine dehydrogenase (DPD), mostly caused by genetic variants in the gene encoding DPD (DPYD). We assessed the effect of prospective screening for the four most relevant DPYD variants (DPYD*2A [rs3918290, c.1905+1G>A, IVS14+1G>A], c.2846A>T [rs67376798, D949V], c.1679T>G [rs55886062, DPYD*13, I560S], and c.1236G>A [rs56038477, E412E, in haplotype B3]) on patient safety and subsequent DPYD genotype-guided dose individualisation in daily clinical care. In this prospective, multicentre, safety analysis in 17 hospitals in the Netherlands, the study population consisted of adult patients (≥18 years) with cancer who were intended to start on a fluoropyrimidine-based anticancer therapy (capecitabine or fluorouracil as single agent or in combination with other chemotherapeutic agents or radiotherapy). Patients with all tumour types for which fluoropyrimidine-based therapy was considered in their best interest were eligible. We did prospective genotyping for DPYD*2A, c.2846A>T, c.1679T>G, and c.1236G>A. Heterozygous DPYD variant allele carriers received an initial dose reduction of 25% (c.2846A>T and c.1236G>A) or 50% (DPYD*2A and c.1679T>G), and DPYD wild-type patients were treated according to the current standard of care. The primary endpoint of the study was the frequency of severe (National Cancer Institute Common Terminology Criteria for Adverse Events version 4.03 grade ≥3) overall fluoropyrimidine-related toxicity across the entire treatment duration. We compared toxicity incidence between DPYD variant allele carriers and DPYD wild-type patients on an intention-to-treat basis, and relative risks (RRs) for severe toxicity were compared between the current study and a historical cohort of DPYD variant allele carriers treated with full dose fluoropyrimidine-based therapy (derived from a previously published meta-analysis). This trial is registered with ClinicalTrials.gov, number NCT02324452, and is complete. Between April 30, 2015, and Dec 21, 2017, we enrolled 1181 patients. 78 patients were considered non-evaluable, because they were retrospectively identified as not meeting inclusion criteria, did not start fluoropyrimidine-based treatment, or were homozygous or compound heterozygous DPYD variant allele carriers. Of 1103 evaluable patients, 85 (8%) were heterozygous DPYD variant allele carriers, and 1018 (92%) were DPYD wild-type patients. Overall, fluoropyrimidine-related severe toxicity was higher in DPYD variant carriers (33 [39%] of 85 patients) than in wild-type patients (231 [23%] of 1018 patients; p=0·0013). The RR for severe fluoropyrimidine-related toxicity was 1·31 (95% CI 0·63-2·73) for genotype-guided dosing compared with 2·87 (2·14-3·86) in the historical cohort for DPYD*2A carriers, no toxicity compared with 4·30 (2·10-8·80) in c.1679T>G carriers, 2·00 (1·19-3·34) compared with 3·11 (2·25-4·28) for c.2846A>T carriers, and 1·69 (1·18-2·42) compared with 1·72 (1·22-2·42) for c.1236G>A carriers. Prospective DPYD genotyping was feasible in routine clinical practice, and DPYD genotype-based dose reductions improved patient safety of fluoropyrimidine treatment. For DPYD*2A and c.1679T>G carriers, a 50% initial dose reduction was adequate. For c.1236G>A and c.2846A>T carriers, a larger dose reduction of 50% (instead of 25%) requires investigation. Since fluoropyrimidines are among the most commonly used anticancer agents, these findings suggest that implementation of DPYD genotype-guided individualised dosing should be a new standard of care. Dutch Cancer Society.

Food-effect study on uracil and dihydrouracil plasma levels as marker for dihydropyrimidine dehydrogenase activity in human volunteers.

AimsThis study aimed to determine the effect of food intake on uracil and dihydrouracil plasma levels. These levels are a promising marker for dihydropyrimidine dehydrogenase activity and for individualizing fluoropyrimidine anticancer therapy.MethodsA randomized, cross‐over study in 16 healthy volunteers was performed, in which subjects were examined in fasted and fed state on two separate days. In fed condition, a high‐fat, high‐caloric breakfast was consumed between 8:00 h and 8:30 h. Whole blood for determination of uracil, dihydrouracil and uridine plasma levels was drawn on both test days at predefined time points between 8:00 h and 13:00 h.ResultsUracil levels were statistically significantly different between fasting and fed state. At 13:00 h, the mean uracil level in fasting state was 12.6 ± 3.7 ng ml−1 and after a test meal 9.4 ± 2.6 ng ml−1 (P < 0.001). Dihydrouracil levels were influenced by food intake as well (mean dihydrouracil level at 13:00 h in fasting state 147.0 ± 36.4 ng ml−1 and in fed state 85.7 ± 22.1 ng ml−1, P < 0.001). Uridine plasma levels showed curves with similar patterns as for uracil.ConclusionsIt was shown that both uracil and dihydrouracil levels were higher in fasting state than in fed state. This is hypothesized to be an direct effect of uridine plasma levels, which were previously shown to be elevated in fasting state and reduced after intake of food. These findings show that, when assessing plasma uracil and dihydrouracil levels for adaptive fluoropyrimidine dosing in clinical practice, sampling should be done between 8:00 h and 9:00 h after overnight fasting to avoid bias caused by circadian rhythm and food effects.

Preliminary Evidence for Enhanced Thymine Absorption: A Putative New Phenotype Associated With Fluoropyrimidine Toxicity in Cancer Patients.

Chemotherapy for colorectal, head and neck, and breast cancer continues to rely heavily on 5-fluorouracil and its oral prodrug capecitabine. Associations of serious fluoropyrimidine adverse effects have focused on inherited deficiency of the catabolic enzyme, dihydropyrimidine dehydrogenase. However, abnormal dihydropyrimidine dehydrogenase activity accounts for only about one-third of observed toxicity cases. Thus, the cause of most fluorouracil toxicity cases remains unexplained. For this small cohort study, thymine (THY) 250 mg was administered orally to 6 patients who had experienced severe toxicity during treatment with 5FU or capecitabine. Plasma and urine were analyzed for THY and its catabolites dihydrothymine (DHT) and β-ureidoisobutyrate. Of the 6 patients, 2 had decreased THY elimination and raised urinary THY recovery consistent with inherited partial dihydropyrimidine dehydrogenase deficiency, confirmed by DPYD sequencing. Unexpectedly, 3 patients displayed grossly raised plasma THY concentrations but normal elimination profiles (compared with a normal range for healthy volunteers previously published by the authors). DPYD and DPYS sequencing of these 3 patients did not reveal any significant loss-of-activity allelic variants. The authors labeled the phenotype in these 3 patients as "enhanced thymine absorption". Only 1 of the 6 cases of toxicity had a normal postdose plasma profile for THY and its catabolites. Postdose urine collections from all 6 patients had THY/DHT urinary ratios above 4.0, clearly separated from the ratios in healthy subjects that were all below 3.0. This small cohort provided evidence for a hypothesis that fluorouracil toxicity cases may include a previously undescribed pyrimidine absorption variant, "enhanced thymine absorption," and elevated THY/DHT ratios in urine may predict fluorouracil toxicity. A prospective study is currently being conducted.

Abstract 3892: Upfront DPD screening with adaptive dosing to secure 5-FU administration in head and neck cancer patients

Abstract Upfront screening for dihydropyrimidine dehydrogenase (DPD) deficiency in patients scheduled for 5-FU-based protocols should reduce the risk of treatment-related toxicities by preventive adaptive dosing. Our group has developed a simple, rapid and cheap functional testing that helps categorizing patients on their DPD status and detecting poor metabolizer (PM) patients, using UH2/U ratio measurement in plasma as a surrogate for DPD activity. 5-FU dosing can be next tailored using a geometric scale, according to the level of DPD deficiency. We report here the performances of this adaptive dosing strategy implemented in routine clinical practice in head and neck cancer patients. A total of 218 evaluable adult patients were scheduled for a 5-FU-regimen (mostly TPF protocol), with prospective search for DPD deficiency and, if required, tailored dosing. Overall, 20 patients (9%) were identified as PM and received subsequently an average 20-50% reduced dose of 5-FU as compared with extensive metabolizer (EM) patients (2102 ± 254 mg VS. 2577 ±353mg, p&amp;lt;0.001 t-test). Gender (Female) was associated with higher risk for being PM (p=0.01, Pearson's Chi-square test), whereas age was not. Early severe toxicities were seen only in 5% of patients, a figure markedly lower than the one usually reported with 5-FU-based regimen in head-and-neck cancer patients. Similarly, all severe toxicities (i.e; including now the delayed or cumulative ones) were observed in 12.8% of patients only. No statistical difference was evidenced in overall toxicities between PM patients with adapted dosing (10%) and EM patients with standard dosing (13%, p=0.7014, Chi-square test), suggesting that being DPD-deficient is not anymore a risk for severe or life-threatening toxicities with 5-FU, provided that corrective action is undertaken. As for early toxicities, incidence of global toxicities was lower than the 30-40% usually described with 5-FU in this setting. Finally, despite an average -20% reduction in 5-FU dosing between PM and EM patients, clinical efficacy was not statistically different between the two groups (CR+PR: 56% VS. 40%, SD: 11% VS. 5%, PD: 22% VS. 43%, p = 0.2774, chi-square test), thus demonstrating how cutting 5-FU dose in PM patients does not hinder treatment efficacy. In conclusion, this study shows that 5-FU-related toxicities can be avoided at low cost by the upfront detection of DPD deficient patients with simple adaptive dosing strategies. Of note, reducing 5-FU dosing in PM patients did not affect negatively treatment efficacy, while limiting the incidence of treatment-related toxicities, thus improving the efficacy/toxicity balance of this drug. Citation Format: Joseph Ciccolini, Manon Launay, Charlotte Dupuis, Florence Duffaud, Bruno Lacarelle, Sébastien Salas. Upfront DPD screening with adaptive dosing to secure 5-FU administration in head and neck cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3892.

DPD functional tests in plasma, fresh saliva and dried saliva samples as predictors of 5-fluorouracil exposure and occurrence of drug-related severe toxicity

Objectiveto evaluate plasma and salivary uracil (U) to dihydrouracil (UH2) ratios as tools for predicting 5-fluorouracil systemic exposure and drug-related severe toxicity, and clinically validate the use of dried saliva spots (DSS) as an alternative sampling strategy for dihydropyrimidine dehydrogenase (DPD) deficiency assessment. MethodsPre-chemotherapy plasma, fresh saliva and DSS samples were obtained from gastrointestinal patients (N = 40) for measurement of endogenous U and UH2 concentrations by LC-MS/MS. A second plasma sample collected during 5FU infusion was used for 5FU area under the curve (AUC) determination by HPLC-DAD. Data on toxicity was reported according to CTCAE. Results15% of the patients developed severe 5FU-related toxicity, with neutropenia accounting for 67% of the cases. U, UH2 and [UH2,]/[U] were highly correlated between fresh and dried saliva samples (rs = 0.960; rs = 0.828; rs = 0.910, respectively). 5FU AUC ranged from 11.3 to 37.31 mg h L−1, with 46.2% of under-dosed and 10.3% over-dosed patients. The [UH2]/[U] ratios in plasma, fresh saliva and dried saliva samples were moderately correlated with 5FU AUC and adverse events grade, indicating a partial contribution of the variables to drug exposure (r = −0.412, rs = −0.373, rs = 0.377) and toxicity (r = −0.363, rs = −0.523, rs = 0.542). Metabolic ratios were lower in patients with severe toxicity (P < .01 salivary ratios, and P < .5 plasma ratios), and 5FU AUC were in average 47% higher in this group than in moderate toxicity. The diagnostic performance of [UH2]/[U] ratios in fresh saliva and DSS for the identification of patients with severe toxicity were comparable. ConclusionsThe [UH2]/[U] metabolic ratios in plasma, fresh saliva and DSS were significantly associated with 5FU systemic exposure and toxicity degree. This study also demonstrated the applicability of DSS as alternative sampling for evaluating DPD activity.

UPFRONT DPD DEFICIENCY DETECTION TO SECURE 5-FU ADMINISTRATION: PART 2- APPLICATION TO HEAD-AND-NECK CANCER PATIENTS.

Upfront screening for dihydropyrimidine dehydrogenase (DPD) deficiency in patients scheduled for 5-FU should help reduce the risk of toxicities by preventive adaptive dosing. Our group has developed a simple functional testing categorizing patients upon their DPD status, i.e. extensive metabolizer (EM) or poor metabolizer (PM) patients, using UH2/U ratio measurement in plasma as a surrogate for DPD activity. 5-FU dosing can then be tailored according to DPD deficiency status. We present here an observational study of this strategy implemented in routine clinical practice when treating head-and-neck cancer patients. A total of 218 evaluable adult patients were treated with a 5-FU-regimen, with DPD-based adaptive dosing. Among them, 20 (9%) were identified as PM and received subsequently a 20-50% reduced dosing of 5-FU as compared with EM patients (2102 ±254 mg VS. 2577 ±353mg, p<0.001 ttest). Gender (Female) was associated with higher risk for being PM (p=0.01, Pearson's Chi squared test). Overall, early severe toxicities were seen only in 5% of patients, all being EM with standard dosing. Similarly, overall severe toxicities were observed in 12.8% of patients only, both figures being markedly lower than usually reported with standard 5-FU. Despite the average -20% reduction in 5-FU dosing between PM and EM patients, clinical efficacy was not statistically different between the two groups (p = 0.2774, chi-square test). This study shows that 5-FU-related toxicities can be greatly reduced in routine clinical practice by the upfront detection of DPD deficient patients with simple adaptive dosing strategy.

Human liver degradation of 5-fluorouracil: endogenous uracil may result in phenoconversion of dihydropyrimidine dehydrogenase activity

Human liver degradation of 5-fluorouracil: endogenous uracil may result in phenoconversion of dihydropyrimidine dehydrogenase activity

Dihydropyrimidine Dehydrogenase Deficiency: Homozygosity for an Extremely Rare Variant in DPYD due to Uniparental Isodisomy of Chromosome 1.

Dihydropyrimidine dehydrogenase (DPD) deficiency is a rare autosomal recessive disorder of the pyrimidine degradation pathway and can lead to intellectual disability, motor retardation, and seizures. Genetic variations in DPYD have also emerged as predictive risk factors for severe toxicity in cancer patients treated with fluoropyrimidines. We recently observed a child born to non-consanguineous parents, who demonstrated seizures, cognitive impairment, language delay, and MRI abnormalities and was found to have marked thymine-uraciluria. No residual DPD activity could be detected in peripheral blood mononuclear cells. Molecular analysis showed that the child was homozygous for the very rare c.257C>T (p.Pro86Leu) variant in DPYD. Functional analysis of the recombinantly expressed DPD mutant showed that the DPD mutant carrying the p.Pro86Leu did not possess any residual DPD activity. Carrier testing in parents revealed that the father was heterozygous for the variant but unexpectedly the mother did not carry the variant. Microsatellite repeat testing with markers covering chromosome 1 showed that the DPD deficiency in the child is due to paternal uniparental isodisomy. Our report thus extends the genetic spectrum underlying DPYD deficiency.

Dihydropyrimidine dehydrogenase pharmacogenetics for predicting fluoropyrimidine-related toxicity in the randomised, phase III adjuvant TOSCA trial in high-risk colon cancer patients

Background:Dihydropyrimidine dehydrogenase (DPD) catabolises ∼85% of the administered dose of fluoropyrimidines. Functional DPYD gene variants cause reduced/abrogated DPD activity. DPYD variants analysis may help for defining individual patients’ risk of fluoropyrimidine-related severe toxicity.Methods:The TOSCA Italian randomised trial enrolled colon cancer patients for 3 or 6 months of either FOLFOX-4 or XELOX adjuvant chemotherapy. In an ancillary pharmacogenetic study, 10 DPYD variants (*2A rs3918290 G>A, *13 rs55886062 T>G, rs67376798 A>T, *4 rs1801158 G>A, *5 rs1801159 A>G, *6 rs1801160 G>A, *9A rs1801265 T>C, rs2297595 A>G, rs17376848 T>C, and rs75017182 C>G), were retrospectively tested for associations with ⩾grade 3 fluoropyrimidine-related adverse events (FAEs). An association analysis and a time-to-toxicity (TTT) analysis were planned. To adjust for multiple testing, the Benjamini and Hochberg’s False Discovery Rate (FDR) procedure was used.Results:FAEs occurred in 194 out of 508 assessable patients (38.2%). In the association analysis, FAEs occurred more frequently in *6 rs1801160 A allele carriers (FDR=0.0083). At multivariate TTT analysis, significant associations were found for *6 rs1801160 A allele carriers (FDR<0.0001), *2A rs3918290 A allele carriers (FDR<0.0001), and rs2297595 GG genotype carriers (FDR=0.0014). Neutropenia was the most common FAEs (28.5%). *6 rs1801160 (FDR<0.0001), and *2A rs3918290 (FDR=0.0004) variant alleles were significantly associated with time to neutropenia.Conclusions:This study adds evidence on the role of DPYD pharmacogenetics for safety of patients undergoing fluoropyrimidine-based chemotherapy.

Abstract 3823: High intrinsic DPD activity matters too

Abstract Introduction: Fluoropyrimidines (FP) are of major use in treating cancer. Dihydropyrimidine dehydrogenase (DPD) is the main enzyme responsible for FP catabolism. Low DPD activity screening has proven its predictive clinical value in identifying patients at risk for toxicity. However, high DPD activity may translate to decreased FP activation and efficacy. Patients and methods: One hundred and forty-three patients (monocentric retrospective study) underwent a pretreatment assessment of DPD activity in lymphocytes between 01/01/2004 and 20/04/2016. Included patients were male or female, &amp;gt;18 years, FP-treatment-based. Cut-off for DPD activity was assessed using smoothing spline curves. Results: Median patient follow-up was 30 months [CI95%: 27.3-36.2], mean age 63+/-3 years, females accounted for 53%, 90% of patients had a good performance status (0 or 1). Fifty-eight percent of FP indications (65% 5-FU and 35% capecitabine) were adjuvant or neoadjuvant and 42% were prescribed for local or metastatic recurrences. Tolerance was poor for 43% of patients and 49% needed dose reduction. Objective response (complete and partial) was observed in 50% of patients, stable disease in 38% and progression in 12%. No significant correlation was observed between DPD activity and response to treatment. Mean DPD activity (pmol min−1 mg−1 protein) was 0.21+/-0.1 (quartile: [0.001-0.14-0.20-0.28-0.48]). DPD activity analyzed as a continuous variable was significantly linked to overall survival (OS) (p=0.042) but not with progression-free survival (PFS). The higher the DPD activity, the lower the OS. DPD activity analyzed as a binary variable (cut-off at 0.30) was significantly linked to overall survival (p=0.012) but also with PFS (p=0.016). A Cox regression model for OS and PFS adjusted for age, sex, type of cancer, type of administered FP, and associated surgical or radiotherapy treatment was performed. After adjustment, DPD activity remained significantly linked to OS (p=0.03) and PFS (p=0.021). Conclusions: DPD activity screening could lead to a two-pronged approach: FP dose reduction in the event of low DPD and dose increase for high DPD. Such a strategy needs to be prospectively validated under personalized DPD-based treatment. Note: This abstract was not presented at the meeting. Citation Format: Emmanuel Chamorey, Eric Francois, Marie-Christine Etienne-Grimaldi, Julien Viotti, Frederic Peyrade, Alexandre Bozec, Jean-Marc Ferrero, Renaud Schiappa, Gerard Milano. High intrinsic DPD activity matters too [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3823. doi:10.1158/1538-7445.AM2017-3823

Development, validation and application of a novel liquid chromatography tandem mass spectrometry assay measuring uracil, 5,6-dihydrouracil, 5-fluorouracil, 5,6-dihydro-5-fluorouracil, α-fluoro-β-ureidopropionic acid and α-fluoro-β-alanine in human plasma

The plasma 5,6-dihydrouracil/uracil (UH2/U) ratio is a possible phenotypic marker of dihydropyrimidine dehydrogenase (DPD) activity, hence an index of 5-fluorouracil (5-FU) response and toxicity. Studies have re-affirmed the value of 5-FU and 5,6-dihydro-5-fluorouracil (FUH2) for therapeutic drug monitoring (TDM). However, FUH2 has limited stability in plasma, necessitating expedited plasma separation and freezing, where routine compliance may not be easy. The metabolites α-fluoro-β-ureidopropionic acid (FUPA) and α-fluoro-β-alanine (FβAL) are stable in plasma and are probable candidates for TDM. This paper describes development, validation and application of an LC–MS/MS assay quantifying U, UH2, 5-FU, FUH2, FUPA and FβAL in human plasma.Extraction was by salt-assisted liquid–liquid extraction (LLE) in two-stages with pH adjustment. The supernatants were mixed, dried and reconstituted. Analytes were resolved on the Luna PFP (2) (150×2.00mm, 3μ) column by gradient elution and analyzed by tandem mass spectrometry via electrospray ionisation in positive polarity.The analytical response was linear (r2≥0.99) in the concentration (ng/mL) ranges: 50–10 000 for FβAL and FUH2, 50–5 000 for FUPA, 50–100 000 for 5–FU, 5–200 for U and 10–400 for UH2. Within- and between-run accuracy and precision were ≤ 10.2% and ≤ 9.8% respectively across the QC range and inclusive of LLOQ. The internal standard (IS) normalised matrix effects were within 93–112% with CV of ≤ 9.7% and normalised recoveries were within 91–107% with CV of ≤ 9.8%. This robust assay was successfully applied to samples from rectal and colorectal cancer patients (n=10) on 5-FU. Deviations ≤ 2.0% from the mean values were observed when incurred samples were reanalysed.

A multicenter phase II study of personalized FOLFIRI-cetuximab for safe dose intensification

We conducted a multicenter proof of concept phase II trial in patients with advanced colorectal cancer receiving FOLFIRI-cetuximab regimens to explore individual drug tailoring using pharmacogenetics and pharmacokinetics (PK) monitoring. Patients were stratified by their pharmacogenetic/phenotypic status: the irinotecan dose was adjusted according to the number of TA tandem repeats in the UGT1A1 promoter, while the 5-fluorouracil (5-FU) dose was initially adjusted according to dihydropyrimidine dehydrogenase (DPD) activity at initial screening (5-FUODPM Tox) followed by PK-guided dose optimization (5-FUODPM Protocol). An advanced cetuximab PK/pharmacodynamics (PD) study was performed but dosage remained unchanged. Eighty-five patients receiving second-line chemotherapy were enrolled. Mean irinotecan doses at 3 months were 247 ± 50, 210 ± 53 and 140 ± 21 mg/m2 for those with 6/6 (33), 6/7 (26), and 7/7 (7) TATA repeats in the UGT1A1 promoter region, respectively. The 5-FU dose was initially reduced in four patients with DPD deficiency, but mean 5-FU dose at 3 months was 2,412 ± 364 mg/m2 (1,615–3,170 mg/m2). Grade 4 toxicities were not encountered and grade 4 neutropenia occurred in 6.8%, 5.9%, and 0% of patients with 6/6, 6/7, and 7/7 UGT1A1 genotypes. The objective response rate was 25.8% among the 85 patients, 57.3% in patients with tumors wild type (WT) for KRAS, and 25% in those whose tumor harbored a mutant-KRAS. Secondary resection of hepatic metastases was performed in 31.7% of patients. Median progression-free survival (PFS) for all 85 patients was 181 days and 200, 132, and 121 days for patients with 6/6, 6/7, and 7/7 UGT1A1 genotypes, respectively; these differences were not statistically different. In parallel, a strong relationship was shown between cetuximab AUC and regimen efficacy. We conclude that personalized drug tailoring when administering in FOLFIRI + cetuximab allows for safe and efficient individual dose intensification.

S-1 for treatment of advanced hepatocellular carcinoma: a systematic review of the literature.

Hepatocellular carcinoma (HCC) is the most common liver neoplasm worldwide. Based on its potent inhibition of dihydropyrimidine dehydrogenase (DPD), S-1 is expected to be more active than other fluoropyrimidines against HCC with DPD activity. This systematic review was aimed to assess the efficacy and safety of S-1 for treatment of advanced HCC.PubMed, the Cochrane Library, EMBA-SE, and ClinicalTrials.gov were searched using the terms “Hepatocellular Carcinoma” or “HCC” or “Hepatoma” or “Liver cancer” and ‘‘S-1’’. Outcomes of main interest included overall survival (OS) and toxicities.We identified four studies of S-1 treatment alone from 1059 references, including a total of 272 patients. There were two original articles and two conference abstracts. The percentage of male patients ranged from 88 to 91.3% and median age ranged from 59 to 70 years. Median OS ranged from 8.6 to 16.5 months. The incidences of toxicity of more than 50% were thrombocytopaenia and fatigue. According to the original description, toxicities were acceptable.The current evidence from the available clinical studies suggests that S-1 may be an effective and tolerable treatment for advanced HCC. Further clinical studies are warranted to further investigate this treatment option.

CapeOX投与により重篤な副作用をきたしたDPD活性低下症の1例

CapeOX投与により重篤な副作用をきたしたDPD活性低下症の1例

The Impact of the Expression Level of Intratumoral Dihydropyrimidine Dehydrogenase on Chemotherapy Sensitivity and Survival of Patients in Gastric Cancer: A Meta-Analysis.

The potential impact that the intratumoral expression level of dihydropyrimidine dehydrogenase (DPD) has on chemotherapy sensitivity and long-term survival for gastric cancer (GC) patients remains controversial; therefore, this study seeks to clarify this issue. Our meta-analysis was performed using Review Manager (RevMan) 5.3 software. In vitro drug sensitivity tests, correlation coefficients between sensitivity to 5-fluorouracil (5-FU), and expression levels of intratumoral DPD were used as effective indexes to analyse. Overall survival (OS) and progression-free survival (PFS) were used as endpoints for patient outcome, and hazard ratios (HRs) and 95% confidence intervals (CIs) were noted as measures of effect. There were 15 eligible studies including 1805 patients for the final analysis. The analysis revealed a statistically significant difference between the expression level of intratumoral DPD activity, DPD mRNA levels, and sensitivity to 5-FU in GC patients, with high expression levels of intratumoral DPD resulting in low sensitivity to 5-FU. However, no matter what therapeutic regimens were used, there was no significant difference for patient outcomes between high and low DPD expression groups, either in OS or in PFS. In conclusion, high levels of intratumoral DPD expression have a negative impact on sensitivity to 5-FU in GC patients, but no prognostic value for long-term survival was uncovered.

Low Incidence of the DPD IVS14+1G>A Polymorphism in Jordanian Breast and Colorectal Cancer patients

Background:Dihydropyrimidine dehydrogenase (DPD) is a crucial enzyme in the catabolism of 5-fluorouracil (5-FU), a drug that is frequently used in cancer therapy. Patients with deficient DPD activity are at risk of developing severe 5-FU–associated toxicity. One possible cause of deficiency is genetic polymorphisms in the DPD gene, such as IVS14+1G>A.Aim:The present study was conducted to screen for the IVS14+1G>A polymorphism in cancer patients receiving 5-FU and a control group.Methods:A total of 40 cancer patients (30 colorectal cancer (CRC) and 10 breast cancer patients) were enrolled in this study. One hundred healthy controls were also tested using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). DNA sequence analysis was carried out to confirm the presence of the IVSI14+1G>A polymorphism.Results:Only one CRC patient showed heterozygous IVS14+1G>A polymorphism in the DPD gene.Conclusion:The results of this study demonstrated a very low frequency of the IVS14+1G>A polymorphism among Jordanian patients with colorectal and breast cancer.

Severe fluoropyrimidine toxicity due to novel and rare DPYD missense mutations, deletion and genomic amplification affecting DPD activity and mRNA splicing

Dihydropyrimidine dehydrogenase (DPD) is the initial and rate-limiting enzyme in the catabolism of 5-fluorouracil (5FU). Genetic variations in DPD have emerged as predictive risk factors for severe fluoropyrimidine toxicity. Here, we report novel and rare genetic variants underlying DPD deficiency in 9 cancer patients presenting with severe fluoropyrimidine-associated toxicity. All patients possessed a strongly reduced DPD activity, ranging from 9 to 53% of controls. Analysis of the DPD gene (DPYD) showed the presence of 21 variable sites including 4 novel and 4 very rare aberrations: 3 missense mutations, 2 splice-site mutations, 1 intronic mutation, a deletion of 21 nucleotides and a genomic amplification of exons 9–12. Two novel/rare variants (c.2843T>C, c.321+1G>A) were present in multiple, unrelated patients. Functional analysis of recombinantly-expressed DPD mutants carrying the p.I948T and p.G284V mutation showed residual DPD activities of 30% and 0.5%, respectively. Analysis of a DPD homology model indicated that the p.I948T and p.G284V mutations may affect electron transfer and the binding of FAD, respectively. cDNA analysis showed that the c.321+1G>A mutation in DPYD leads to skipping of exon 4 immediately upstream of the mutated splice-donor site in the process of DPD pre-mRNA splicing. A lethal toxicity in two DPD patients suggests that fluoropyrimidines combined with other therapies such as radiotherapy might be particularly toxic for DPD deficient patients. Our study advocates a more comprehensive genotyping approach combined with phenotyping strategies for upfront screening for DPD deficiency to ensure the safe administration of fluoropyrimidines.