Lethal Capecitabine Toxicity in Patients With Complete Dihydropyrimidine Dehydrogenase Deficiency Due to Ultra-Rare DPYD Variants.

A DPD deficiency should be considered in case of severe toxicity even in the absence of common risk variants in DPYD.

Unveiling Discrepant and Rare Dihydropyrimidine Dehydrogenase (DPYD) Results Using an In-House Genotyping Test: A Case Series.

Fluoropyrimidine chemotherapy is a primary component of many solid tumor treatment regimens, particularly those for gastrointestinal malignancies. Approximately one-third of patients receiving fluoropyrimidine-based chemotherapies experience serious adverse effects. This risk is substantially higher in patients carrying DPYD genetic variants, which cause reduced fluoropyrimidine metabolism and inactivation (ie, dihydropyridine dehydrogenase [DPD] deficiency). Despite the known relationship between DPD deficiency and severe toxicity risk, including drug-related fatalities, pretreatment DPYD testing is not standard of care in the United States. We developed an in-house DPYD genotyping test that detects 5 clinically actionable variants associated with DPD deficiency, and genotyped 827 patients receiving fluoropyrimidines, of which 49 (6%) were identified as heterozygous carriers. We highlight 3 unique cases: (1) a patient with a false-negative result from a commercial laboratory that only tested for the c.1905 + 1G>A (*2A) variant, (2) a White patient in whom the c.557A>G variant (typically observed in people of African ancestry) was detected, and (3) a patient with the rare c.1679T>G (*13) variant. Lastly, we evaluated which DPYD variants are detected by commercial laboratories offering DPYD genotyping in the United States and found 6 of 13 (46%) did not test for all 5 variants included on our panel. We estimated that 20.4% to 81.6% of DPYD heterozygous carriers identified on our panel would have had a false-negative result if tested by 1 of these 6 laboratories. The sensitivity and negative predictive value of the diagnostic tests from these laboratories ranged from 18.4% to 79.6% and 95.1% to 98.7%, respectively. These cases underscore the importance of comprehensive DPYD genotyping to accurately identify patients with DPD deficiency who may require lower fluoropyrimidine doses to mitigate severe toxicities and hospitalizations. Clinicians should be aware of test limitations and variability in variant detection by commercial laboratories, and seek assistance by pharmacogenetic experts or available resources for test selection and result interpretation.

Germline cis variant determines epigenetic regulation of the anti-cancer drug metabolism gene dihydropyrimidine dehydrogenase (DPYD).

Enhancers are critical for regulating tissue-specific gene expression, and genetic variants within enhancer regions have been suggested to contribute to various cancer-related processes, including therapeutic resistance. However, the precise mechanisms remain elusive. Using a well-defined drug-gene pair, we identified an enhancer region for dihydropyrimidine dehydrogenase (DPD, DPYD gene) expression that is relevant to the metabolism of the anti-cancer drug 5-fluorouracil (5-FU). Using reporter systems, CRISPR genome-edited cell models, and human liver specimens, we demonstrated in vitro and vivo that genotype status for the common germline variant (rs4294451; 27% global minor allele frequency) located within this novel enhancer controls DPYD transcription and alters resistance to 5-FU. The variant genotype increases recruitment of the transcription factor CEBPB to the enhancer and alters the level of direct interactions between the enhancer and DPYD promoter. Our data provide insight into the regulatory mechanisms controlling sensitivity and resistance to 5-FU.

Capecitabine-induced severe adverse events-therapeutic drug monitoring and DPYD-gene analysis are recommended.

In this report, two cases of patients with severe adverse events after an adjuvant treatment with capecitabine are described in detail. The first patient suffered from a severe ileocolitis, where ultimately intensive care treatment, total colectomy and ileum resection was necessary. The second patient experienced a toxic enteritis, which could be managed conservatively. Post-therapeutic DPYD genotyping was negative in the former and positive in the latter case. Patients can be categorised in normal, moderate and poor DPYD metabolisers to predict the risk of adverse events of capecitabine treatment. Guidelines in various European countries recommend pretherapeutic DPYD genotyping, whereas it is not recommended by the National Comprehensive Cancer Network in the USA. Irrespective of DPYD genotyping, strict therapeutic drug monitoring is highly recommended to reduce the incidence and severity of adverse events.

A novel large intragenic DPYD deletion causing dihydropyrimidine dehydrogenase deficiency: a case report.

BACKGROUND: Dihydropyrimidine dehydrogenase (DPD), is the initial and rate-limiting enzyme in the catabolic pathway of pyrimidines. Deleterious variants in the DPYD gene cause DPD deficiency, a rare autosomal recessive disorder. The clinical spectrum of affected individuals is wide ranging from asymptomatic to severely affected patients presenting with intellectual disability, motor retardation, developmental delay and seizures. DPD is also important as the main enzyme in the catabolism of 5-fluorouracil (5-FU) which is extensively used as a chemotherapeutic agent. Even in the absence of clinical symptoms, individuals with either complete or partial DPD deficiency face a high risk of severe and even fatal fluoropyrimidine-associated toxicity. The identification of causative genetic variants in DPYD is therefore gaining increasing attention due to their potential use as predictive markers of fluoropyrimidine toxicity. METHODS: A male infant patient displaying biochemical features of DPD deficiency was investigated by clinical exome sequencing. Bioinformatics tools were used for data analysis and results were confirmed by MLPA and Sanger sequencing. RESULTS: A novel intragenic deletion of 71.2 kb in the DPYD gene was identified in homozygosity. The deletion, DPYD(NM_000110.4):c.850 + 23455_1128 + 8811del, eliminates exons 9 and 10 and may have resulted from a non-homologous end-joining event, as suggested by in silico analysis. CONCLUSIONS: The study expands the spectrum of DPYD variants associated with DPD deficiency. Furthermore, it raises the concern that patients at risk for fluoropyrimidine toxicity due to DPYD deletions could be missed during pre-treatment genetic testing for the currently recommended single nucleotide polymorphisms.

Complete DPYD genotyping combined with dihydropyrimidine dehydrogenase phenotyping to prevent fluoropyrimidine toxicity: A retrospective study.

INTRODUCTION: In April 2019, French authorities mandated dihydropyrimidine dehydrogenase (DPD) screening, specifically testing uracilemia, to mitigate the risk of toxicity associated with fluoropyrimidine-based chemotherapy. However, this subject is still of debate as there is no consensus on a standardized DPD deficiency screening test. We conducted a real-life retrospective study with the aim of assessing the impact of DPD screening on the occurrence of severe toxicity and exploring the potential benefits of complete genotyping using next-generation sequencing. METHODS: All adult patients consecutively treated with 5-fluorouracil (5-FU) or its oral prodrug at six cancer centers between March 2018 and February 2019 were considered for inclusion. Dihydropyrimidine dehydrogenase deficiency screening included gene encoding DPD (DPYD) genotyping using complete genome sequencing and DPD phenotyping (uracilemia or dihydrouracilemia/uracilemia ratio) or both tests. Associations between each DPD screening method and (i) severe (grade ≥3) early toxicity and (ii) fluoropyrimidine dose reduction in the second chemotherapy cycle were evaluated using multivariable logistic regression analysis. Furthermore, we assessed the concordance between DPD genotype and phenotype using Cohen's kappa. RESULTS: A total of 551 patients were included. Most patients were tested for DPD deficiency (86%) including DPYD genotyping only (6%), DPD phenotyping only (8%), or both (72%). Complete DPD deficiency was not detected in the study population. Severe early toxicity events were observed in 73 patients (13%), with two patients (0.30%) presenting grade 5 toxicity. Despite the numerically higher toxicity rate in untested patients, the occurrence of severe toxicity was not significantly associated with the DPD screening method (p = 0.69). Concordance between the DPD genotype and phenotype was weak (Cohen's kappa of 0.14). CONCLUSION: Due to insufficient numbers, our study was not able to demonstrate any added value of DPYD genotyping using complete genome sequencing to prevent 5-FU toxicity. The optimal strategy for DPD screening before fluoropyrimidine-based chemotherapy requires further clinical evaluation.

MIR27A rs895819 TC genotype increases risk of fluoropyrimidine-induced severe toxicity independently of DPYD variations.

Aim: MicroRNA 27a (miR-27a) regulates post-transcriptionally DPD activity. We have analyzed the association of MIR27A rs895819T>C variation, that modulates miR-27a expression, with fluropyrimidine-induced toxicity. Materials & methods: MIR27A rs895819T>C genotyping was conducted by TaqMan® allelic discrimination assay in 313 FP-treated cancer patients. Results: In overdominance (TC vs TT + CC), TC genotype was associated with grade 3-4 toxicity (p = 0.002), any grade toxicity (p = 0.052), and delayed drug administration or therapy discontinuation (p = 0.038). Odds of grade 3-4 toxicity were increased by both DPYD deficiency (OR: 8.923; p = 0.006) and MIR27A rs895819 TC genotype (OR: 3.865; p = 0.002). Conclusion: MIR27A rs895819 TC genotype is an independent risk factor for fluoropyrimidine-associated toxicity in the Greek population. Thus, MIR27A rs895819TC patients can be closely monitored for fluoropyrimidine-induced severe toxicity.

What is this summary about? To date, for cancer patients treated with fluoropyrimidines (capecitabine and 5-fluorouracil), analyzing DPYD gene can be used to guide the optimal dose of treatment in order to reduce the incidence of severe, even life threatening toxicity and thus, increase drug safety. However, the frequency of clinically significant DPYD variants is rare, below 5%, and there is therefore an urgent medical need to identify additional genes that can help in predicting response to fluoropyrimidines. Apart from changes in DPYD gene, noncoding RNAs modulate DPD enzymatic activity. MiR-27a is such a modulator. MIR27A rs895819 polymorphism affects miR-27a expression and is a potential candidate of fluoropyrimidine response. In this study, we have analyzed the association of MIR27A rs895819T>C polymorphism with fluoropyrimidine-induced toxicity in cancer patients. What were the results? MIR27A rs895819 TC genotype is associated with fluoropyrimidine-induced grade 3­4 toxicity, any grade toxicity and delayed drug administration or therapy discontinuation. Carrying MIR27A rs895819 TC genotype leads to over of threefold increased risk for grade 3­4 toxicity and can improve sensitivity of DPYD genotyping alone. What do the results mean? MIR27A rs895819 TC carriers should be closely monitored for fluoropyrimidine-induced severe toxicity. Fluoropyrimidine pharmacogenomics can help in improving drug safety and patient response.

Personalized Chronomodulated 5-Fluorouracil Treatment: A Physiologically-Based Pharmacokinetic Precision Dosing Approach for Optimizing Cancer Therapy.

The discovery of circadian clock genes greatly amplified the study of diurnal variations impacting cancer therapy, transforming it into a rapidly growing field of research. Especially, use of chronomodulated treatment with 5-fluorouracil (5-FU) has gained significance. Studies indicate high interindividual variability (IIV) in diurnal variations in dihydropyrimidine dehydrogenase (DPD) activity - a key enzyme for 5-FU metabolism. However, the influence of individual DPD chronotypes on chronomodulated therapy remains unclear and warrants further investigation. To optimize precision dosing of chronomodulated 5-FU, this study aims to: (i) build physiologically-based pharmacokinetic (PBPK) models for 5-FU, uracil, and their metabolites, (ii) assess the impact of diurnal variation on DPD activity, (iii) estimate individual DPD chronotypes, and (iv) personalize chronomodulated 5-FU infusion rates based on a patient's DPD chronotype. Whole-body PBPK models were developed with PK-Sim(R) and MoBi(R). Sinusoidal functions were used to incorporate variations in enzyme activity and chronomodulated infusion rates as well as to estimate individual DPD chronotypes from DPYD mRNA expression or DPD enzymatic activity. Four whole-body PBPK models for 5-FU, uracil, and their metabolites were established utilizing data from 41 5-FU and 10 publicly available uracil studies. IIV in DPD chronotypes was assessed and personalized chronomodulated administrations were developed to achieve (i) comparable 5-FU peak plasma concentrations, (ii) comparable 5-FU exposure, and (iii) constant 5-FU plasma levels via "noise cancellation" chronomodulated infusion. The developed PBPK models capture the extent of diurnal variations in DPD activity and can help investigate individualized chronomodulated 5-FU therapy through testing alternative personalized dosing strategies.

Dihydropyrimidine dehydrogenase gene variants for predicting grade 4-5 fluoropyrimidine-induced toxicity: FUSAFE individual patient data meta-analysis.

BACKGROUND: Dihydropyrimidine dehydrogenase (DPD) deficiency is the main known cause of life-threatening fluoropyrimidine (FP)-induced toxicities. We conducted a meta-analysis on individual patient data to assess the contribution of deleterious DPYD variants *2A/D949V/*13/HapB3 (recommended by EMA) and clinical factors, for predicting G4-5 toxicity. METHODS: Study eligibility criteria included recruitment of Caucasian patients without DPD-based FP-dose adjustment. Main endpoint was 12-week haematological or digestive G4-5 toxicity. The value of DPYD variants *2A/p.D949V/*13 merged, HapB3, and MIR27A rs895819 was evaluated using multivariable logistic models (AUC). RESULTS: Among 25 eligible studies, complete clinical variables and primary endpoint were available in 15 studies (8733 patients). Twelve-week G4-5 toxicity prevalence was 7.3% (641 events). The clinical model included age, sex, body mass index, schedule of FP-administration, concomitant anticancer drugs. Adding *2A/p.D949V/*13 variants (at least one allele, prevalence 2.2%, OR 9.5 [95%CI 6.7-13.5]) significantly improved the model (p < 0.0001). The addition of HapB3 (prevalence 4.0%, 98.6% heterozygous), in spite of significant association with toxicity (OR 1.8 [95%CI 1.2-2.7]), did not improve the model. MIR27A rs895819 was not associated with toxicity, irrespective of DPYD variants. CONCLUSIONS: FUSAFE meta-analysis highlights the major relevance of DPYD *2A/p.D949V/*13 combined with clinical variables to identify patients at risk of very severe FP-related toxicity.

Integrating rare genetic variants into DPYD pharmacogenetic testing may help preventing fluoropyrimidine-induced toxicity.

Variability in genes involved in drug pharmacokinetics or drug response can be responsible for suboptimal treatment efficacy or predispose to adverse drug reactions. In addition to common genetic variations, large-scale sequencing studies have uncovered multiple rare genetic variants predicted to cause functional alterations in genes encoding proteins implicated in drug metabolism, transport and response. To understand the functional importance of rare genetic variants in DPYD, a pharmacogene whose alterations can cause severe toxicity in patients exposed to fluoropyrimidine-based regimens, massively parallel sequencing of the exonic regions and flanking splice junctions of the DPYD gene was performed in a series of nearly 3000 patients categorized according to pre-emptive DPD enzyme activity using the dihydrouracil/uracil ([UH2]/[U]) plasma ratio as a surrogate marker of DPD activity. Our results underscore the importance of integrating next-generation sequencing-based pharmacogenomic interpretation into clinical decision making to minimize fluoropyrimidine-based chemotherapy toxicity without altering treatment efficacy.

Common dihydropyrimidinase ( DPYS ) genetic variations do not predict fluoropyrimidine-related chemotherapy toxicity in a Canadian cohort.

Known genetic variations in dihydropyrimidine dehydrogenase (gene name DPYD ) do not fully predict patients at risk for severe fluoropyrimidine-associated chemotherapy toxicity. Dihydropyrimidinase (gene name DPYS ), the second catabolic enzyme in fluoropyrimidine metabolism, has been noted as a potential determinant of variation in fluoropyrimidine metabolism and response. In this study, we genotyped for DPYS c.-1T>C (rs2959023), c.265-58T>C (rs2669429) and c.541C>T (rs36027551) in a Canadian cohort of 248 patients who were wild type for Clinical Pharmacogenetics Implementation Consortium recommended DPYD variants and had received a standard dose of fluoropyrimidine chemotherapy. None of our patients were found to carry the DPYS c.541C>T variant, while the minor allele frequencies were 63% and 54% for c.-1T>C and c.265-58T>C, respectively. There was no association between DPYS c.-1T>C wild type and heterozygote [odds ratio (OR) (95% confidence interval, CI) = 1.10 (0.51-2.40)] or homozygote variant carriers [OR (95% CI) = 1.22 (0.55-2.70)], or between DPYS c.265-58T>C wild-type patients and heterozygote [OR (95% CI) = 0.93 (0.48-1.80)] or homozygote variant carriers [OR (95% CI) = 0.76 (0.37-1.55)] in terms of fluoropyrimidine-associated toxicity. Therefore, in our cohort of mostly Caucasian Canadians, genetic variations in DPYS do not appear to be a significant contributor to severe fluoropyrimidine-associated toxicity.

Pharmacogenetics testing (DPYD and UGT1A1) for fluoropyrimidine and irinotecan in routine clinical care: Perspectives of medical oncologists and oncology pharmacists.

BACKGROUND: Despite robust evidence and international guidelines, to support routine pharmacogenetic (PGx) testing, integration in practice has been limited. This study explored clinicians' views and experiences of pre-treatment DPYD and UGT1A1 gene testing and barriers to and enablers of routine clinical implementation. METHODS: A study-specific 17-question survey was emailed (01 February-12 April 2022) to clinicians from the Medical Oncology Group of Australia (MOGA), the Clinical Oncology Society of Australia (COSA) and International Society of Oncology Pharmacy Practitioners (ISOPP). Data were analysed and reported using descriptive statistics. RESULTS: Responses were collected from 156 clinicians (78% medical oncologists, 22% pharmacists). Median response rate of 8% (ranged from 6% to 24%) across all organisations. Only 21% routinely test for DPYD and 1% for UGT1A1. For patients undergoing curative/palliative intent treatments, clinicians reported intent to implement genotype-guided dosing by reducing FP dose for DPYD intermediate metabolisers (79%/94%), avoiding FP for DPYD poor metabolisers (68%/90%), and reducing irinotecan dose for UGT1A1 poor metabolisers (84%, palliative setting only). Barriers to implementation included: lack of financial reimbursements (82%) and perceived lengthy test turnaround time (76%). Most Clinicians identified a dedicated program coordinator, i.e., PGx pharmacist (74%) and availability of resources for education/training (74%) as enablers to implementation. CONCLUSION: PGx testing is not routinely practised despite robust evidence for its impact on clinical decision making in curative and palliative settings. Research data, education and implementation studies may overcome clinicians' hesitancy to follow guidelines, especially for curative intent treatments, and may overcome other identified barriers to routine clinical implementation.

Risk of Toxicity From Topical 5-Fluorouracil Treatment in Patients Carrying DPYD Variant Alleles.

Patients carrying DPYD variant alleles have increased risk of severe toxicity from systemic fluoropyrimidine chemotherapy. There is a paucity of data regarding risk of toxicity from topical 5-fluorouracil (5-FU) treatment in these patients, leading to inconsistent guideline recommendations for pretreatment testing and topical 5-FU dosing. The objective of this retrospective cohort study was to investigate whether DPYD variant allele carriers have increased risk of toxicity from topical 5-FU. Treatment and toxicity data were retrospectively abstracted from the electronic medical records. Genotypes for the five DPYD variants that are associated with increased toxicity from systemic fluoropyrimidine chemotherapy (DPYD*2A, DPYD*13, DPYD p.D949V, DPYD HapB3, and DPYD p.Y186C) were collected from a genetic data repository. Incidence of grade 3+ (primary end point) and 1+ (secondary end point) toxicity was compared between DPYD variant carriers vs. wild-type patients using Fisher's exact tests. The analysis included 201 patients, 7% (14/201) of whom carried a single DPYD variant allele. No patients carried two variant alleles or experienced grade 3+ toxicity. DPYD variant allele carriers did not have a significantly higher risk of grade 1+ toxicity (21.4% vs. 10.2%, odds ratio = 2.40, 95% confidence interval: 0.10-2.53, P = 0.19). Given the low toxicity risk in patients carrying a single DPYD variant allele, there is limited potential clinical benefit of DPYD genetic testing prior to topical 5-FU. However, the risk of severe toxicity in patients with complete DPD deficiency remains unknown and topical 5-FU treatment should be avoided in these patients.

DPYD genotyping and 5-fluoropyrimidine toxicity: An overview of systematic reviews protocol. / [Artículo traducido] Genotipado del gen DPYD y toxicidad de las 5-fluoropirimidinas: protocolo de un resumen de revisiones sistemáticas.

INTRODUCTION: The increased risk of severe and life-threatening toxicity in patients with dihydropyridine dehydrogenase deficiency, under treatment with fluoropyrimidines, has been widely studied. An up-to-date overview of systematic reviews summarizing existing literature can add value by highlighting most relevant information and supports decision-making regarding treatment in dihydropyridine dehydrogenase deficient patients. The main objective of this overview is to identify published systematic reviews on the association between germline variations in the DPYD gene and fluoropyrimidine toxicity. METHODS AND ANALYSIS: This protocol was developed following the Preferred Reported Items for Systematic Review and Meta-analysis Protocols (PRISMA-P) checklist, and the overview of systematic reviews will be reported in accordance with the PRISMA statement. PubMed, Embase, Scopus and the Cochrane Library will be searched from inception to 2023. Systematic reviews irrespective of study designs that analyze the association between germline variations in the DPYD and fluoropyrimidine toxicity will be considered. Methodological quality will be assessed using AMSTAR2 checklist (Measurement Tool to Assess Systematic Reviews 2). Two independent investigators will perform the study selection, quality assessment and data collection. Discrepancies will be solved by a third investigator.

Developing DPYD Genotyping Method for Personalized Fluoropyrimidines Therapy.

BACKGROUND: Fluoropyrimidine drugs are widely used in chemotherapy to treat solid tumors. However, severe toxicity has been reported in 10% to 40% of patients. The DPYD gene encodes the rate-limiting enzyme dihydropyrimidine dehydrogenase responsible for fluoropyrimidine catabolism. The DPYD variants resulting in decreased or no enzyme activity are associated with increased risk of fluoropyrimidine toxicity. This study aims to develop a pharmacogenetic test for screening DPYD variants to guide fluoropyrimidine therapy. METHODS: A multiplex allele-specific polymerase chain reaction (AS-PCR) assay, followed by capillary electrophoresis, was developed to detect 5 common DPYD variants (c.557A > G, c.1129-5923C > G, c.1679T > G, c.1905 + 1G > A, and c.2846A > T). Deidentified population samples were used for screening positive controls and optimizing assay conditions. Proficiency testing samples with known genotypes were analyzed for test validation. All variants detected were confirmed by Sanger sequencing. RESULTS: From the deidentified population samples, 5 samples were heterozygous for c.557A > G, 2 samples were heterozygous for c.1129-5923C > G (HapB3), and 1 sample was heterozygous for c.2846A > T. The 20 proficiency samples matched with their assigned genotypes, including 13 wild-type samples, 3 samples heterozygous for c.1679T > G, 2 samples heterozygous for c.1905 + 1G > A, and 2 samples heterozygous for c.2846A > T. One of the 3 patient samples was heterozygous for c.1129-5923C > G (HapB3). All the variants detected by the multiplex AS-PCR assay were concordant with Sanger sequencing results. CONCLUSIONS: A robust multiplex AS-PCR assay was developed to rapidly detect 5 variants in the DPYD gene. It can be used for screening DPYD variants to identify patients with increased risk of toxicity when prescribed fluoropyrimidine therapy.

A Nomogram to Predict Severe Toxicity in DPYD Wild-Type Patients Treated With Capecitabine-Based Anticancer Regimens.

DPYD-guided dosing has improved the safety of fluoropyrimidine-based chemotherapy in recent years. However, severe toxicity remains in ~ 23% of patients not carrying DPYD variant alleles treated with capecitabine. Therefore, we developed a predictive model based on patient-related and treatment-related factors aimed at estimating the risk of developing severe capecitabine-related toxicity. The nomogram was developed using data from two large clinical trials (NCT00838370 and NCT02324452). Patients with cancer carrying a DPYD variant allele (DPYD*2A, c.1236G>A, c.2846A>T, and c.1679T>G) were excluded. Univariable and multivariable logistic regression using predetermined predictors based on previous findings, including age, sex, body surface area, type of treatment regimen, and creatinine levels were used to develop the nomogram. The developed model was internally validated using bootstrap resampling and cross-validation. This model was not externally or clinically validated. A total of 2,147 DPYD wild-type patients with cancer treated with capecitabine-based chemotherapy regimens were included of which complete data of 1,745 patients were available and used for the development of the nomogram. Univariable and multivariable logistic regression showed that age, sex, and type of treatment regimen were strong predictors of severe capecitabine-related toxicity in DPYD wild-type patients. Internal validation demonstrated a concordance index of 0.68 which indicates a good discriminative ability for prediction of severe capecitabine-related toxicity. The developed nomogram includes readily available parameters and may be a helpful tool for clinicians to assess the risk of developing severe capecitabine-related toxicity in patients without known risk DPYD variant alleles treated with capecitabine-based anticancer regimens.

DPYD genotyping and 5-fluoropyrimidine toxicity: An overview of systematic reviews protocol.

INTRODUCTION: The increased risk of severe and life-threatening toxicity in patients with dihydropyridine dehydrogenase (DPD) deficiency, under treatment with fluoropyrimidines, has been widely studied. An up-to-date overview of systematic reviews summarizing existing literature can add value by highlighting most relevant information and supports decision-making regarding treatment in DPD deficient patients. The main objective of this overview of systematic reviews is to identify published systematic reviews on the association between germline variations in the DPYD gene and fluoropyrimidine toxicity. METHODS AND ANALYSIS: This protocol was developed following the Preferred Reported Items for Systematic Review and Meta-analysis Protocols (PRISMA-P) checklist, and the overview of systematic reviews will be reported in accordance with the PRISMA statement. PubMed, Embase, Scopus, and the Cochrane Library will be searched from inception to 2023. Systematic reviews irrespective of study designs that analyze the association between germline variations in the DPYD and fluoropyrimidine toxicity will be considered. Methodological quality will be assessed using AMSTAR2 checklist (Measurement Tool to Assess Systematic Reviews 2). Two independent investigators will perform the study selection, quality assessment, and data collection. Discrepancies will be solved by a third investigator. REGISTRATION DETAILS: Registration number in PROSPERO: CRD42023401226.