DPYD Genotyping Research Articles

Fluoropyrimidine chemotherapy: recommendations for DPYD genotyping and therapeutic drug monitoring of the Swiss Group of Pharmacogenomics and Personalised Therapy.

Fluoropyrimidines (FPs), mainly 5-fluorouracil (5-FU) and its oral prodrug capecitabine (Cap), remain the backbone of the treatment of many different solid tumors. Despite their broad use in clinical routine, 10–40% of patients experience severe, and in rare cases (0.2–0.5%) even lethal, FP-related toxicity in early chemotherapy cycles. Today, there is a plethora of evidence that genetic variants in the gene encoding for the 5-FU catabolising enzyme dihydropyrimidine dehydrogenase (DPD, encoded by DPYD) are predictive of severe FP-related toxicities, and international clinical practice recommendations for DPYD genotype-guided FP dosing and therapeutic drug monitoring (TDM) are available. In spite of this strong evidence and DPYD genotyping becoming standard practice in other countries, it is has not been widely adopted in Switzerland to date. Here, we discuss current guidelines on genotype-guided FP dosing and TDM, and propose recommendations tailored to the situation in Switzerland to facilitate their clinical uptake for the further individualisation of FP chemotherapy. We recommend preemptive testing of four DPYD variants (c.1905+1G>A (rs3918290), c.1679T>G (rs55886062), c.2846A>T (rs67376798) and c.1129-5923C>G (rs75017182, c.1236G>A/HapB3)) in patients with an indication for FP-based chemotherapy, with the costs reimbursed through the compulsory health insurance in Switzerland. Carriers of these variants (6.5% in the Swiss population) have a 40–50% risk of developing severe early-onset toxicity when treated with standard FP doses. In these patients, we therefore recommend the use of a reduced starting dose, based on a dose adjustment scheme provided herein. Furthermore, we recommend the use of infusional 5-FU in patients with a DPYD risk genotype in order to enable TDM-based dose escalation. Only if the use of an infusional 5-FU regimen is not feasible should a slow titration of Cap, starting with the recommended reduced dose and basing further doses on monitoring of toxicity, be considered. Given that several studies have shown that TDM in 5-FU treatment improves not only the therapy’s safety, but potentially also its efficacy, we also include detailed TDM-based dosing guidelines and discuss the pre-analytical aspects of 5-FU TDM.

Association of 5-FU Therapeutic Drug Monitoring to DPD Phenotype Assessment May Reduce 5-FU Under-Exposure.

In order to limit 5-fluorouracil (5-FU) toxicity, some health agencies recommend evaluating dihydropyrimidine dehydrogenase (DPD) deficiency before any 5-FU treatment introduction. In our study, we investigated relationships between 5-FU clearance and markers of DPD activity such as uracilemia (U), dihydrouracilemia (UH2)/U ratio, or genotype of the gene encoding DPD (DPYD). All patients with gastrointestinal cancers who received 5-FU-based regimens form March 2018 to June 2020 were included in our study. They routinely benefited of a pre-therapeutic DPYD genotyping and phenotyping. During 5-FU infusion, blood samples were collected to measure 5-FU steady-state concentration in order to adapt 5-FU doses at the following cycles. A total of 169 patients were included. Median age was 68 (40–88) years and main primary tumor sites were colorectal (40.8%) and pancreas (31.4%), metastatic in 76.3%. 5-FU was given as part of FOLFIRINOX (44.4%), simplified FOLFOX-6 (26.6%), or docetaxel/FOLFOX-4 (10.6%). Regarding DPD activity, median U and UH2/U were, respectively, 10.8 ng/mL and 10.1, and almost 15% harbored a heterozygous mutation. On the range of measured U and UH2/U, no correlation was observed with 5-FU clearance. Moreover, in patients with U < 16 ng/mL, 5-FU exposure was higher than in other patients, and most of them benefited of dose increase following 5-FU therapeutic drug monitoring (TDM). If recent guidelines recommend decreasing 5-FU dose in patients harboring U ≥ 16 ng/mL, our study highlights that those patients are at risk of under-exposure and that 5-FU TDM should be conducted in order to avoid loss of efficacy.

Comparison of 4 Screening Methods for Detecting Fluoropyrimidine Toxicity Risk: Identification of the Most Effective, Cost-Efficient Method to Save Lives.

Background:Fluoropyrimidines (FPs) carry around 20% risk of G3-5 toxicity and 0.2-1% risk of death, due to dihydropyrimidine dehydrogenase (DPD) deficiency. Several screening approaches exist for predicting toxicity, however there is ongoing debate over which method is best. This study compares 4 screening approaches.Method:472 patients treated for colorectal, head-and-neck, breast, or pancreatic cancers, who had not been tested pre-treatment for FP toxicity risk, were screened using: DPYD genotyping (G); phenotyping via plasma Uracil (U); phenotyping via plasma-dihydrouracil/uracil ratio (UH2/U); and a Multi-Parametric Method (MPM) using genotype, phenotype, and epigenetic data. Performance was compared, particularly the inability to detect at-risk patients (false negatives).Results:False negative rates for detecting G5 toxicity risk were 51.2%, 19.5%, 9.8% and 2.4%, for G, U, UH2/U and MPM, respectively. False negative rates for detecting G4-5 toxicity risk were 59.8%, 36.1%, 21.3% and 4.7%, respectively. MPM demonstrated significantly (p < 0.001) better prediction performance.Conclusion:MPM is the most effective method for limiting G4-5 toxicity. Its systematic implementation is cost-effective and significantly improves the risk-benefit ratio of FP-treatment. The use of MPM, rather than G or U testing, would avoid nearly 8,000 FP-related deaths per year globally (500 in France), and spare hundreds of thousands from G4 toxicity.

Upfront DPYD genotyping and toxicity associated with fluoropyrimidine-based concurrent chemoradiotherapy for oropharyngeal carcinomas.

6580 Background: The combination of carboplatin and 5-fluorouracil (5-FU) is effective when used concurrently with radiotherapy for locoregionally advanced oropharyngeal carcinomas (Calais et al. 1999). DPYD polymorphisms can be associated with an increased risk of severe toxicity to fluoropyrimidines (Deenen et al. 2016). Upfront screening for the DPYD*2A allele is available in the province of Québec, Canada since March 2017. This study aimed to determine the effect of upfront genotyping on grade ≥3 toxicities. Methods: The studied population included all consecutive cases of oropharyngeal carcinomas treated with 5-FU based chemoradiotherapy one year before and after the implementation of upfront DPYD*2A genotyping. All patients were treated at the Centre Hospitalier de l’Université de Montréal (CHUM) between March 2016 and April 2018. Clinical data were extracted from chart review. Extended screening for 3 supplemental at-risk DPYD variants was also retrospectively performed in August 2019. Results: 181 patients were included in the analysis (87 patients before and 94 patients after DPYD*2A screening implementation). 91% of patients (n = 86) were prospectively genotyped for the DPYD*2A allele. Of those screened, 2% (n = 2/87) demonstrated a heterozygous DPYD*2A mutation. Those two patients received cisplatin-based treatment and thus avoided 5-FU toxicities. Extended genotyping of DPYD*2A-negative patients later allowed for the retrospective identification of 6 additional patients with alternative DPYD variants (two c.2846A &gt; T and four c.1236G &gt; A allele mutations). Conclusions: The DPYD*2A, c.2846A &gt; T and c.1236G &gt; A polymorphisms are associated with an increased risk of G3-4 toxicity to 5-FU, as well as higher hospitalization rates. Upfront DPYD genotyping can identify patients in whom fluoropyrimidine-related toxicity should be avoided. This represents an interesting addition in terms of pharmacovigilance. [Table: see text]

DPD Testing Before Treatment With Fluoropyrimidines in the Amsterdam UMCs: An Evaluation of Current Pharmacogenetic Practice.

IntroductionThe fluoropyrimidines (FP) (5-Fluorouracil, capecitabine, and tegafur) are commonly used anti-cancer drugs, but lead to moderate to severe toxicity in about 10–40% of patients. DPD testing [either the enzyme activity of dihydropyrimidine dehydrogenase (DPD) or the DPYD genotype] identifies patients at higher risk for toxicity who may be treated more safely with a lower drug dose. The Netherland's National guideline for colon carcinoma was updated in 2017 to recommend DPYD genotyping before treatment with FP. Pretreatment DPYD genotyping identifies approximately 50% of the patients that will develop severe FP toxicity. The aim of the study was to assess the uptake of DPD testing in the Amsterdam University Medical Centers over time and to evaluate stakeholder experiences to indicate barriers and facilitators of implementation in routine clinical care.Materials and MethodsWe used a mixed-method approach involving electronic patient records of 753 unique patients and pharmacy information systems analyses and fifteen semi-structured interviews with oncologists, pharmacists, and patients. The constellation perspective was used to identify barriers and facilitators at the level of practice, culture and structure. The proportion of FP users who were DPD tested pretreatment showed an increase from 1% (1/86) in Q2-2017 up to 87% (73/84) in Q4-2018. Unlike a landmark paper published in 2015, the National guideline for colorectal carcinoma followed by meetings to achieve local consensus led to this steep increase in the proportion of patients tested.ResultsFacilitating factors for stakeholders to implement testing included the existence of clear protocols, (anecdotal) evidence of the utility, being aware that peers are adhering to standard practice and clear and simple procedures for ordering and reporting. Main barriers included the lack of clear divisions of responsibilities, the lack of consensus on a test approach, long turn-around times and non-user-friendly IT-infrastructures. More professional education on the utility and limitations of pharmacogenetic testing was desired by most stakeholders.ConclusionWhile the evidence for DPD testing was sufficient, only after the update of a National guideline and local consensus meetings the proportion of FP users that were DPD tested pretreatment rose to 87%. The implementation of personalized medicine requires stakeholders involved to attune practice, culture and structure.

Dutch Pharmacogenetics Working Group (DPWG) guideline for the gene\u2013drug interaction of DPYD and fluoropyrimidines

Despite advances in the field of pharmacogenetics (PGx), clinical acceptance has remained limited. The Dutch Pharmacogenetics Working Group (DPWG) aims to facilitate PGx implementation by developing evidence-based pharmacogenetics guidelines to optimize pharmacotherapy. This guideline describes the starting dose optimization of three anti-cancer drugs (fluoropyrimidines: 5-fluorouracil, capecitabine and tegafur) to decrease the risk of severe, potentially fatal, toxicity (such as diarrhoea, hand-foot syndrome, mucositis or myelosuppression). Dihydropyrimidine dehydrogenase (DPD, encoded by the DPYD gene) enzyme deficiency increases risk of fluoropyrimidine-induced toxicity. The DPYD-gene activity score, determined by four DPYD variants, predicts DPD activity and can be used to optimize an individual’s starting dose. The gene activity score ranges from 0 (no DPD activity) to 2 (normal DPD activity). In case it is not possible to calculate the gene activity score based on DPYD genotype, we recommend to determine the DPD activity and adjust the initial dose based on available data. For patients initiating 5-fluorouracil or capecitabine: subjects with a gene activity score of 0 are recommended to avoid systemic and cutaneous 5-fluorouracil or capecitabine; subjects with a gene activity score of 1 or 1.5 are recommended to initiate therapy with 50% the standard dose of 5-fluorouracil or capecitabine. For subjects initiating tegafur: subjects with a gene activity score of 0, 1 or 1.5 are recommended to avoid tegafur. Subjects with a gene activity score of 2 (reference) should receive a standard dose. Based on the DPWG clinical implication score, DPYD genotyping is considered “essential”, therefore directing DPYD testing prior to initiating fluoropyrimidines.

569P - FUSAFE individual patient data meta-analysis (MA) to assess the performance of dihydropyrimidine dehydrogenase (DPD) gene polymorphisms for predicting grade 4-5 fluoropyrimidine (FP) toxicity

BackgroundDespite decades of research, performance of DPYD genotyping to predict FP toxicity (tox) is poorly documented. GPCO-UNICANCER and RNPGx groups initiated the FUSAFE MA on individual patient data (IPD) to assess the prognostic value of consensual deleterious DPYD variants on grade (G) 4-5 FP tox. MethodsEligibility criteria included unbiased recruitment of Caucasian patients (pts) without FP dose adjustment based on DPD status. Main endpoint was 12 weeks hematological or digestive G4-5 tox. Age, sex, body mass index (BMI), advanced stage (M- vs M+), FP drug (5FU vs capecitabine), FP administration (bolus±continuous vs continuous alone or p.o.) and associated anticancer drugs (AAD) were collected. Multivariable logistic models were applied. Performance was assessed by AUC and diagnostic indices maximizing Youden index. ResultsFrom the 18 identified eligible studies (10230 pts), 14 were included (9030 pts), with complete IPD collected for 6403 pts (84% colorectal, 16% M+, 66% 5FU, 80% AAD). G4-5 tox prevalence was 8% (518 events). DPYD variants *2A, D949V, *13 and HapB3 were carried by 0.9%, 1.2%, 0.2% and 3.9% of pts, respectively. The clinical model (M1) retained age, sex, BMI, FP-administration, AAD. Adding variants *2A/D949V/*13 (at least one mutated allele) significantly (p<.0001) improved the model (M2). Further adding HapB3 did not improve the model (p=.24, M3). M3-adjusted OR (95%CI) was 10.0 (6.9-14.7) for the 3 variants *2A/D949V/*13 and 2.1 (1.4-3.0) for HapB3. Similar results were observed on colorectal pts only, or when excluding bolus administration alone.Table569PTableModelAUC (area under the curve)SensitivitySpecificityPositive predictive valueNegative predictive valueM10.72569.7%65.4%15.1%96.1%M20.75075.5%62.8%15.2%96.7%M30.75276.4%61.9%15.0%96.8% ConclusionsThis is the largest MA on DPYD genotyping and toxicity. It shows the relevance of clinical variables and of the 3 consensual DPYD variants. Despite its association with tox, HapB3 does not improve the discriminant ability to identify pts at risk of G4-5 toxicity. Legal entity responsible for the studyCentre Antoine Lacassagne, Nice, France (Dr Marie-Christine Etienne-Grimaldi, coordinator). FundingFrench Cancer Institute (INCa) funding (PHRC-K 14-193 FUSAFE) and French Ligue Nationale Contre le Cancer. DisclosureV. Boige: Honoraria (self), Advisory / Consultancy, Research grant / Funding (self), Travel / Accommodation / Expenses: Merck Serono; Honoraria (self): Amgen; Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Bayer; Honoraria (self), Travel / Accommodation / Expenses: Roche Genentech; Honoraria (self): MSD; Honoraria (self), Advisory / Consultancy: Ipsen; Advisory / Consultancy: Prestizia; Advisory / Consultancy: Eisai; Travel / Accommodation / Expenses: Sanofi. J. Taieb: Advisory / Consultancy: Amgen; Advisory / Consultancy: Lily; Advisory / Consultancy: Sanofi; Advisory / Consultancy: Roche; Advisory / Consultancy: Merck; Advisory / Consultancy: MSD; Advisory / Consultancy: Celgene; Advisory / Consultancy: Servier; Advisory / Consultancy: Sirtex; Advisory / Consultancy: Pierre Fabre. D. Meulendijks: Full / Part-time employment: AstraZeneca UK. C. Palles: Advisory / Consultancy: Oxford Cancer Biomarkers. U. Zanger: Licensing / Royalties: Robert Bosch GmbH. M. Boisdron-Celle: Speaker Bureau / Expert testimony, Leadership role, Shareholder / Stockholder / Stock options, Licensing / Royalties, Officer / Board of Directors: ODPM. A. Marinaki: Full / Part-time employment: Viapath. E. Gross: Licensing / Royalties: Klinikum Rechts der Isar der Technischen Universitat Munchen. All other authors have declared no conflicts of interest.

Pretreatment DPYD Genotyping Reduces the Risk of Capecitabine-associated Severe Toxicities: a Prospective Validation Study

Pretreatment DPYD Genotyping Reduces the Risk of Capecitabine-associated Severe Toxicities: a Prospective Validation Study

Estimating the Effectiveness of DPYD Genotyping in Italian Individuals Suffering from Cancer Based on the Cost of Chemotherapy-Induced Toxicity

Fluoropyrimidines (FLs) have been widely used for more than 60 years against a range of solid tumors and still remains the cornerstone for the treatment of colorectal, gastric, and breast cancer. Here, we performed an economic analysis to estimate the cost of DPYD-guided toxicity management and the clinical benefit expressed as quality adjusted life years (QALYs) in a large group of 571 individuals of Italian origin suffering from cancer and treated with a fluoropyrimidines-based chemotherapy. Individuals suffering from cancer with a histologically confirmed diagnosis of cancer, who received a fluoropyrimidines-based treatment, were retrospectively genotyped in the DPYD gene. Effectiveness was measured as survival of individuals from chemotherapy, while study data on safety and efficacy as well as on resource utilization associated with each adverse drug reaction were used to measure costs to treat these adverse drug reactions. A generalized linear regression model was used to estimate cost differences for both study groups. DPYD extensive metabolizers (528 individuals) had greater effectiveness and lesser cost, representing a cost-saving option over DPYD intermediate and poor metabolizers (43 individuals) with mean QALYs of 4.18 (95%CI: 3.16-5.55) versus 3.02 (95%CI: 1.94-4.25), respectively. Our economic analysis showed that there are some indications for differences in survival between the two groups (p > 0.05), while the cost of DPYD extensive metabolizers was significantly lower (p < 0.01) compared with those belonging to the group of intermediate/poor metabolizers. These findings suggest that DPYD-guided fluoropyrimidines treatment represent a cost-saving choice for individuals suffering from cancer in the Italian healthcare setting.

Prospective cohort study of the impact of hospital-wide dihydropyrimidine dehydrogenase (DPYD) genotype testing for fluoropyrimidine-based chemotherapy on adverse events and hospital costs.

3028 Background: Fluoropyrimidines remain integral components of modern chemotherapy for solid tumors, and their toxicities can be reduced by pretreatment DPYD genotyping. Our main objective was to demonstrate the feasibility of implementing a hospital-wide pretreatment DPYD testing service based on the CPIC 2013 guideline on fluoropyrimidines and DPYD. Methods: We enrolled participants prior to planned fluoropyrimidine treatment as well as those who had experienced adverse events (AEs) after initiation of therapy, from December 1, 2013 to November 30, 2018. The patients tested pretreatment were analyzed as a prospective cohort to assess AEs within 90 days of fluoropyrimidine initiation and associated hospital cost. The primary outcome was the rate of severe global fluoropyrimidine-related toxicity in the pretreatment cohort (grade≥3, CTCAE v.4.0.3). Results: Of 1362 patients genotyped for DPYD within the study period 1041 were enrolled pretreatment and included in the primary analysis. The median age was 65 years (19-90), 57% male, 51% 5-FU, and 49% capecitabine. Dose reductions were recommended for 21 DPYD variant carriers who were detected pretreatment. There was no significant difference in the primary outcome between DPYD variant (29%) and wild type (18%) patients (Fisher’s exact test p = 0.25). Costs associated with ER visits and hospitalizations at our tertiary care centre were $1,268 (89-8,562) (Median (IQR)) and $2,961 (341-13,567) for DPYD variant (n = 4) and wild-type (n = 99) patients respectively. Post-AE genotyping (n = 70) found five DPYD variant patients; all experienced grade≥3 toxicity, costs were $15,825 (10,962-25,310), and one poor metabolizer died due to complications. Targeted next generation exome sequencing of DPYD wild-type patients who experienced severe AEs identified five potentially deleterious genetic variants in ABC efflux transporters. Conclusions: Pretreatment DPYD genotype guided dosing of fluorouracil and capecitabine is feasible and benefits patients, health care providers, and hospitals. Our data supports adoption of pretreatment DPYD genotyping as a standard of care.

Screening patients for fluoropyrimidine-related toxicity risk.

3529 Background: Severe, sometimes fatal, toxicity can occur during the 1st or 2nd course of chemotherapy using fluoropyrimidines (FPs), and poses a serious public health problem. FPs carry a 3-5% risk of grade ≥ 3 early toxicities and 0.2% risk of death linked to Dihydropyrimidine Dehydrogenase (DPD) deficiency. Methods: Of 29,000 patients screened since July 2000, 472 were referred to us due to severe toxicity during 1st round 5-FU, or because pre-screening was done too late. Toxicity evaluation was performed according to the NCI scale of adverse reactions to cancer drugs (0=none, 5=death). Patients were previously 5-FU naïve, had different cancers, and received various protocols, eg. 5FU or Capecitabine; bolus±continuous or per os. The reliability of the following 4 pre-treatment screening tests to predict grade≥ 4 toxicity was assessed: 1) DPYD genotype mutation (*2A,*2B,*7, 13, HapB3) 2) Plasma uracil (U) level, 3) Plasma dihydrouracil/uracil ratio (UH2/U) 4) a multiparametric approach with genotyping, UH2/U ratio and key patient factors (age, sex, etc.). McNemar’s test with Bonferroni correction was used for statistical analysis. Results: Of the 472 referred patients, 169 had grade 4 or 5 toxicity, of which 41 died from toxicity. 98 had one or plus DPYD mutation: 42(42.9%)*2A; 43(43.9%)*2B; 3(3%)*7; 4(4%)*13; 8(8.16%) HapB3; 1 was homozygous *2A. Data below compare the 4 screening methods for predicting grade 4-5 toxicity. Conclusions: The multiparametric approach is statistically (p&lt;0.0001) the most efficient in terms of preventing grade 4 and 5 toxicity (death) due to 5-FU treatment. Around 290,000 patients are treated with 5-FU per year in the USA. Assuming a 0.2% mortality rate due to toxicity, around 580 lives could be saved per year using the multiparametric pre-treatment test. [Table: see text]

Confirmation practice in pharmacogenetic testing; how good is good enough?

Pharmacogenetic testing is increasingly implemented in routine diagnostics. However, quality control measures, in particular confirmation practices e.g. the use of two independent genotyping techniques, are subject of debate and there are no clear guidelines. The aim of the current paper is to discuss the current practice in confirmation testing in the field of pharmacogenetics and draw attention to this situation. DPYD genotyping is used as a case example to highlight the importance of assigning the correct genotype. Current confirmation practices in laboratories are explored through a survey. Substantial heterogeneity was observed with 54% of the laboratories applying different forms of confirmation practice. Finally, we evaluated over 10 years of genotyping results from two large genotyping facilities, which both use a second, independent genotyping technique. Discrepancies between tests were identified in 9 patients (0.01%), possibly due to allele dropout. We feel that a second, independent technique is useful for genetic tests with a high clinical impact, such as DPYD testing. Guidelines can help to align confirmatory laboratory practices for pharmacogenetics, which may need to be specified per gene and test.

A cost analysis of upfront DPYD genotype–guided dose individualisation in fluoropyrimidine-based anticancer therapy

BackgroundFluoropyrimidine therapy including capecitabine or 5-fluorouracil can result in severe treatment-related toxicity in up to 30% of patients. Toxicity is often related to reduced activity of dihydropyrimidine dehydrogenase, the main metabolic fluoropyrimidine enzyme, primarily caused by genetic DPYD polymorphisms. In a large prospective study, it was concluded that upfront DPYD-guided dose individualisation is able to improve safety of fluoropyrimidine-based therapy. In our current analysis, we evaluated whether this strategy is cost saving. MethodsA cost-minimisation analysis from a health-care payer perspective was performed as part of the prospective clinical trial (NCT02324452) in which patients prior to start of fluoropyrimidine-based therapy were screened for the DPYD variants DPYD*2A, c.2846A>T, c.1679T>G and c.1236G>A and received an initial dose reduction of 25% (c.2846A>T, c.1236G>A) or 50% (DPYD*2A, c.1679T>G). Data on treatment, toxicity, hospitalisation and other toxicity-related interventions were collected. The model compared prospective screening for these DPYD variants with no DPYD screening. One-way and probabilistic sensitivity analyses were also performed. ResultsExpected total costs of the screening strategy were €2599 per patient compared with €2650 for non-screening, resulting in a net cost saving of €51 per patient. Results of the probabilistic sensitivity and one-way sensitivity analysis demonstrated that the screening strategy was very likely to be cost saving or worst case cost-neutral. ConclusionsUpfront DPYD-guided dose individualisation, improving patient safety, is cost saving or cost-neutral but is not expected to yield additional costs. These results endorse implementing DPYD screening before start of fluoropyrimidine treatment as standard of care.

Diagnostic and Therapeutic Strategies for Fluoropyrimidine Treatment of Patients Carrying Multiple DPYD Variants.

DPYD genotyping prior to fluoropyrimidine treatment is increasingly implemented in clinical care. Without phasing information (i.e., allelic location of variants), current genotype-based dosing guidelines cannot be applied to patients carrying multiple DPYD variants. The primary aim of this study is to examine diagnostic and therapeutic strategies for fluoropyrimidine treatment of patients carrying multiple DPYD variants. A case series of patients carrying multiple DPYD variants is presented. Different genotyping techniques were used to determine phasing information. Phenotyping was performed by dihydropyrimidine dehydrogenase (DPD) enzyme activity measurements. Publicly available databases were queried to explore the frequency and phasing of variants of patients carrying multiple DPYD variants. Four out of seven patients carrying multiple DPYD variants received a full dose of fluoropyrimidines and experienced severe toxicity. Phasing information could be retrieved for four patients. In three patients, variants were located on two different alleles, i.e., in trans. Recommended dose reductions based on the phased genotype differed from the phenotype-derived dose reductions in three out of four cases. Data from publicly available databases show that the frequency of patients carrying multiple DPYD variants is low (< 0.2%), but higher than the frequency of the commonly tested DPYD*13 variant (0.1%). Patients carrying multiple DPYD variants are at high risk of developing severe toxicity. Additional analyses are required to determine the correct dose of fluoropyrimidine treatment. In patients carrying multiple DPYD variants, we recommend that a DPD phenotyping assay be carried out to determine a safe starting dose.

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).

Standard fluoropyrimidine dosages in chemoradiation therapy result in an increased risk of severe toxicity in DPYD variant allele carriers

BackgroundProspective DPYD genotyping prevents severe fluoropyrimidine (FP)-induced toxicity by decreasing dosages in DPYD variant allele carriers. FP dosages in chemoradiation therapy (CRT) are lower than those in other FP-containing regimens. Pharmacogenetic guidelines do not distinguish between regimens, leaving physicians in doubt to apply dose reductions. Our aim was to investigate severe toxicity in DPYD variant allele carriers receiving CRT. MethodsMedical records of 828 patients who received FP-based CRT were reviewed from three centres. Severe (grade ≥III) toxicity in DPYD variant allele carriers receiving upfront FP dose reductions according to pharmacogenetic dosing guidelines and DPYD variant allele carriers not receiving FP dose reductions was compared with DPYD wild-type patients receiving standard dose of FPs in CRT. ResultsDPYD variant allele carriers treated with standard dosages (N = 34) showed an increased risk of severe gastrointestinal (adjusted OR = 2.58, confidence interval [CI] = 1.02–6.53, P = 0.045) or severe haematological (adjusted OR = 4.19, CI = 1.32–13.25, P = 0.015) toxicity compared with wild-type patients (N = 771). DPYD variant allele carriers who received dose reductions (N = 22) showed a comparable frequency of severe gastrointestinal toxicity compared with wild-type patients, but more (not statistically significant) severe haematological toxicity. Hospitalisations for all DPYD variant allele carriers were comparable, independent of dose adjustments; however, the mean duration of hospitalisation was significantly shorter in the dose reduction group (P = 0.010). ConclusionsStandard FP dosages in CRT resulted in an increased risk of severe toxicity in DPYD variant allele carriers. We advise to apply FP dose reductions according to current guidelines in DPYD variant allele carriers starting CRT.

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.

561P - Standard fluoropyrimidine dosages in chemoradiation therapy result in an increased risk of severe toxicity in DPYD variant allele carriers

Abstract Background Prospective DPYD genotyping prevents severe fluoropyrimidine (FP)-induced toxicity by decreasing dosages in DPYD variant allele carriers. FP dosages in chemoradiation therapy (CRT) are lower than those in other FP-containing regimens. Pharmacogenetic guidelines do not distinguish between regimens, leaving physicians in doubt to apply dose reductions. Our aim was to investigate severe toxicity in DPYD variant allele carriers receiving CRT. Methods Medical records of 828 patients who received FP-based CRT were reviewed from three centres. Severe (grade ≥III) toxicity in DPYD variant allele carriers receiving upfront FP dose reductions according to pharmacogenetic dosing guidelines and DPYD variant allele carriers not receiving FP dose reductions was compared with DPYD wild-type patients receiving standard dose of FPs in CRT. Results DPYD variant allele carriers treated with standard dosages (N = 34) showed an increased risk of severe gastrointestinal (adjusted OR = 2.58, confidence interval [CI] = 1.02–6.53, P = 0.045) or severe haematological (adjusted OR = 4.19, CI = 1.32–13.25, P = 0.015) toxicity compared with wild-type patients (N = 771). DPYD variant allele carriers who received dose reductions (N = 22) showed a comparable frequency of severe gastrointestinal toxicity compared with wild-type patients, but more (not statistically significant) severe haematological toxicity. Hospitalisations for all DPYD variant allele carriers were comparable, independent of dose adjustments; however, the mean duration of hospitalisation was significantly shorter in the dose reduction group (P = 0.010). Conclusions Standard FP dosages in CRT resulted in an increased risk of severe toxicity in DPYD variant allele carriers. We advise to apply FP dose reductions according to current guidelines in DPYD variant allele carriers starting CRT.

DPYD and UGT1A1 genotyping to predict adverse events during first-line FOLFIRI or FOLFOXIRI plus bevacizumab in metastatic colorectal cancer.

Our study addresses the issue of the clinical reliability of three candidate DPYD and one UGT single nucleotide polymorphisms in predicting 5-fluorouracil- and irinotecan-related adverse events. To this purpose, we took advantage of a large cohort of metastatic colorectal cancer patients treated with first-line 5-fluorouracil- and irinotecan-based chemotherapy regimens (i.e., FOLFIRI or FOLFOXIRI) plus bevacizumab in the randomized clinical trial TRIBE by GONO (clinicaltrials.gov: NCT00719797), in which adverse events were carefully and prospectively collected at each treatment cycle. Here we show that patients bearing DPYD c.1905+1G/A and c.2846A/T genotypes, together with UGT1A1*28 variant carriers, have an increased risk of experiencing clinically relevant toxicities, including hematological AEs and stomatitis. No carrier of the DPYD c.1679T>G minor allele was identified. Present results support the preemptive screening of mentioned DPYD and UGT1A1 variants to identify patients at risk of clinically relevant 5-fluoruracil- and irinotecan-related AEs, in order to improve treatments’ safety through a “genotype-guided” approach.

Analysis of DPYD and UGT1A1 genotype in patients with advanced pancreatic cancer treated with modified FOLFIRINOX

Analysis of DPYD and UGT1A1 genotype in patients with advanced pancreatic cancer treated with modified FOLFIRINOX