Upfront DPYD Genotyping and Toxicity Associated with Fluoropyrimidine-Based Concurrent Chemoradiotherapy for Oropharyngeal Carcinomas: A Work in Progress

Simple SummaryThe combination of carboplatin and 5-fluorouracil (5-FU) is effective when used concurrently with radiotherapy for locoregionally advanced oropharyngeal carcinomas. DPYD polymorphisms can be associated with an increased risk of severe toxicity to fluoropyrimidines. Upfront screening for the DPYD*2A allele has been available in the province of Québec, Canada, since March 2017. This study aimed to determine the effect of upfront genotyping on the incidence of grade ≥3 toxicities. We included 181 patients in the analysis. Extended screening for three supplemental at-risk DPYD variants was also retrospectively performed in August 2019. The DPYD*2A, c.2846A>T and c.1236G>A polymorphisms were associated with an increased risk of grade ≥3 toxicity to 5-FU. Upfront DPYD genotyping can thus identify patients in whom 5-FU-related toxicity should be avoided.AbstractBackground: 5-FU-based chemoradiotherapy (CRT) could be associated with severe treatment-related toxicities in patients harboring at-risk DPYD polymorphisms. Methods: The studied population included consecutive patients with locoregionally advanced oropharyngeal carcinoma treated with carboplatin and 5-FU-based CRT one year before and after the implementation of upfront DPYD*2A genotyping. We aimed to determine the effect of DPYD genotyping on grade ≥3 toxicities. Results: 181 patients were analyzed (87 patients before and 94 patients following DPYD*2A screening). Of the patients, 91% (n = 86) were prospectively genotyped for the DPYD*2A allele. Of those screened, 2% (n = 2/87) demonstrated a heterozygous DPYD*2A mutation. Extended genotyping of DPYD*2A-negative patients later allowed for the retrospective identification of six additional patients with alternative DPYD variants (two c.2846A>T and four c.1236G>A mutations). Grade ≥3 toxicities occurred in 71% of the patients before DPYD*2A screening versus 62% following upfront genotyping (p = 0.18). When retrospectively analyzing additional non-DPYD*2A variants, the relative risks for mucositis (RR 2.36 [1.39–2.13], p = 0.0063), dysphagia (RR 2.89 [1.20–5.11], p = 0.019), and aspiration pneumonia (RR 13 [2.42–61.5)], p = 0.00065) were all significantly increased. Conclusion: The DPYD*2A, c.2846A>T, and c.1236G>A polymorphisms are associated with an increased risk of grade ≥3 toxicity to 5-FU. Upfront DPYD genotyping can identify patients in whom 5-FU-related toxicity should be avoided.     

The Prevalence of DPYD*9A (c.85T>C) Genotype and the Genotype-Phenotype Correlation in Patients with Gastrointestinal Malignancies Treated With Fluoropyrimidines: Updated Analysis

IntroductionThe dihydropyrimidine dehydrogenase gene (DPYD)*9A (c.85T>C) genotype is relatively common. The correlation between DPYD*9A genotype and dihydropyrimidine dehydrogenase (DPD) deficiency phenotype is controversial. In a cohort of 28 patients, DPYD*9A was the most commonly diagnosed variant (13 patients [46%]) and there was a noticeable genotype-phenotype correlation. In this study we genotyped a larger cohort of a mixed racial background to explore the prevalence of DPYD*9A variant and to confirm the genotype-phenotype correlation.Patients and MethodsBetween 2011 and 2018, in addition to genotyping for high-risk DPYD variants (DPYD*2A, DPYD*13 and DPYD*9B), genotyping for DPYD*9A variant was performed on 113 patients with gastrointestinal malignancies treated with fluoropyrimidines. Fluoropyrimidines-associated toxicity was graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (version 5.0). Fisher exact test was used for statistical analysis.ResultsHeterozygous and homozygous DPYD*9A genotypes were identified in 46 (41%) and 11 (10%) patients, respectively. Among patients with DPYD*9A genotypes (n = 57), men and women represented 30 (53%) and 27 (47%) patients, respectively. Caucasian, African American, and other ethnicities represented 29 (50.9%), 26 (45.6%), and 2 (3.5%) patients, respectively. Grade 3/4 toxicities were experienced in 26 patients with DPYD*9A genotype (3 patients had homozygous status) and in 20 patients with wild type DPYD*9A (P = .4405). In patients who received full-dose fluoropyrimidines (n = 85), Grade 3/4 toxicities were experienced in 22 patients with DPYD*9A genotype (2 patients had homozygous status), and in 17 patients with wild type DPYD (P = .8275).ConclusionIn our updated analysis, the prevalence of heterozygous and homozygous DPYD*9A genotypes were 41% and 10%, respectively. The correlation between DPYD*9A genotype and DPD clinical phenotype was not reproduced. The noticeable correlation that we previously reported is likely because of small sample size and selection bias.     

Prospective DPYD genotyping to reduce the risk of fluoropyrimidine-induced severe toxicity: Ready for prime time

5-Fluorouracil (5-FU) and capecitabine (CAP) are among the most frequently prescribed anticancer drugs. They are inactivated in the liver by the enzyme dihydropyrimidine dehydrogenase (DPD). Up to 5% of the population is DPD deficient and these patients have a significantly increased risk of severe and potentially lethal toxicity when treated with regular doses of 5-FU or CAP. DPD is encoded by the gene DPYD and variants in DPYD can lead to a decreased DPD activity. Although prospective DPYD genotyping is a valuable tool to identify patients with DPD deficiency, and thus those at risk for severe and potential life-threatening toxicity, prospective genotyping has not yet been implemented in daily clinical care. Our goal was to present the available evidence in favour of prospective genotyping, including discussion of unjustified worries on cost-effectiveness, and potential underdosing. We conclude that there is convincing evidence to implement prospective DPYD genotyping with an upfront dose adjustment in DPD deficient patients. Immediate benefit in patient care can be expected through decreasing toxicity, while maintaining efficacy.     

Capecitabine‐based treatment of a patient with a novel DPYD genotype and complete dihydropyrimidine dehydrogenase deficiency

Fluoropyrimidines are frequently used anti‐cancer drugs. It is known that patients with reduced activity of dihydropyrimidine dehydrogenase (DPD), the key metabolic enzyme in fluoropyrimidine inactivation, are at increased risk of developing severe fluoropyrimidine‐related toxicity. Upfront screening for DPD deficiency and dose reduction in patients with partial DPD deficiency is recommended and improves patient safety. For patients with complete DPD deficiency, fluoropyrimidine‐treatment has generally been discouraged. During routine pretreatment screening, we identified a 59‐year‐old patient with a sigmoid adenocarcinoma who proved to have a complete DPD deficiency. Genetic analyses showed that this complete absence of DPD activity was likely to be caused by a novel DPYD genotype, consisting of a combination of amplification of exons 17 and 18 of DPYD and heterozygosity for DPYD*2A. Despite absence of DPD activity, the patient was treated with capecitabine‐based chemotherapy, but capecitabine dose was drastically reduced to 150 mg once every 5 days (0.8% of original dose). Pharmacokinetic analyses showed that the area under the concentration‐time curve (AUC) and half‐life of 5‐fluorouracil were respectively tenfold and fourfold higher than control values of patients receiving capecitabine 850 mg/m². When extrapolating from the dosing schedule of once every 5 days to twice daily, the AUC of 5‐fluorouracil was comparable to controls. Treatment was tolerated well for eight cycles by the patient without occurrence of capecitabine‐related toxicity. This case report demonstrates that a more comprehensive genotyping and phenotyping approach, combined with pharmacokinetically‐guided dose administration, enables save fluoropyrimidine‐treatment with adequate drug exposure in completely DPD deficient patients.     

Effectiveness and safety of reduced-dose fluoropyrimidine therapy in patients carrying the DPYD*2A variant: A matched pair analysis

Carriers of the genetic DPYD*2A variant, resulting in dihydropyrimidine dehydrogenase deficiency, are at significantly increased risk of developing severe fluoropyrimidine-associated toxicity. Upfront DPYD*2A genotype-based dose reductions improve patient safety, but uncertainty exists whether this has a negative impact on treatment effectiveness. Therefore, our study investigated effectiveness and safety of DPYD*2A genotype-guided dosing. A cohort of 40 prospectively identified heterozygous DPYD*2A carriers, treated with a ~50% reduced fluoropyrimidine dose, was identified. For effectiveness analysis, a matched pair-analysis was performed in which for each DPYD*2A carrier a matched DPYD*2A wild-type patient was identified. Overall survival and progression-free survival were compared between the matched groups. The frequency of severe (grade ≥ 3) treatment-related toxicity was compared to 1] a cohort of 1606 wild-type patients treated with full dose and 2] a cohort of historical controls derived from literature, i.e. 86 DPYD*2A variant carriers who received a full fluoropyrimidine dose. For 37 out of 40 DPYD*2A carriers, a matched control could be identified. Compared to matched controls, reduced doses did not negatively affect overall survival (median 27 months versus 24 months, p = 0.47) nor progression-free survival (median 14 months versus 10 months, p = 0.54). Risk of severe fluoropyrimidine-related toxicity in DPYD*2A carriers treated with reduced dose was 18%, comparable to wild-type patients (23%, p = 0.57) and significantly lower than the risk of 77% in DPYD*2A carriers treated with full dose (p < 0.001). Our study is the first to show that DPYD*2A genotype-guided dosing appears to have no negative effect on effectiveness of fluoropyrimidine-based chemotherapy, while resulting in significantly improved patient safety.     

Influence of DPYD*9A,DPYD*6 and GSTP1 ile105val Genetic Polymorphisms on Capecitabine and Oxaliplatin (CAPOX) Associated Toxicities in Colorectal Cancer (CRC) Patients

Aim: CAPOX treatment in CRC patients was reported to cause several dose-limiting toxicities, and are found responsible for treatment interruption or even discontinuation. Therefore there is a critical need for identifying the predictive biomarkers for such toxicities to prevent them. The aim of our present study is to find the influence of DPYD*9A, DPYD*6 and GSTP1 ile105val gene polymorphisms on CAPOX treatment-associated toxicities in south Indian patients with CRC. Patients and Methods: We have recruited 145 newly diagnosed and treatment naive CRC patients in the study. Each Patient received a standard treatment schedule of oxaliplatin 130 mg/m2 infusion over 2 hours on day 1 and oral capecitabine 1000mg/m2 in divided doses twice daily for the next 14 days of a 21-day cycle. 5 ml of the venous blood was collected from each patient and genomic DNA extraction and genotyping. The genotyping analysis of the selected genetic polymorphisms was carried out by real-time PCR using TaqMan SNP genotyping assays obtained from applied biosystems. Results: The major dose-limiting toxicities observed with CAPOX treatment were thrombocytopenia, HFS and PN. DPYD*9A carries were found to be at higher risk for HFS, diarrhoea and thrombocytopenia when compared to patients with wild allele. No significant association was found between DPYD*6, GSTP1 ile105val polymorphisms and CAPOX related toxicities except for thrombocytopenia. Conclusion: A significant association was observed between DPYD*9A polymorphism and CAPOX induced dose-limiting toxicities strengthening its role as a predictive biomarker.     

DPYD*5 gene mutation contributes to the reduced DPYD enzyme activity and chemotherapeutic toxicity of 5-FU

Background Dihydropyrimidine dehydrogenase (DPYD) plays an important role in the metabolism of 5-FU, which can directly influence the pharmacokinetics and toxicity of 5-FU in patients undergoing chemotherapy. However, little is known of the relationship between DPYD gene polymorphism and metabolism and chemotherapeutic toxicity of 5-FU in gastric carcinoma and colon carcinoma. The present genotyping study demonstrated the relationship between DPYD gene polymorphism among 75 gastric carcinoma and colon carcinoma patients and its impact on 5-FU pharmacokinetic and side effect. Methods We used a chemotherapy scheme based on 5-FU for the treatment of 75 patients with gastrointestinal carcinoma and detected the serum drug concentration and DPYD gene polymorphism (DPYD*2, *3, *4 *5 *9 *12). Results We found that there were no DPYD*2, *3, *4, *12 type mutation, in all patients. Of DPYD*9 gene polymorphism loci in 75 patients, 7 were heterozygote and 68 wild type; of DPYD*5 gene polymorphism loci in 75 patients, 11 were mutation and 23 heterozygote and 41 wild type. The elimination rate constant (Ke) value of DPYD*5 mutation group was statistically lower than the wild type (p=0.022). The incidence of middle-severe nausea and vomiting and white blood cell decreases in DPYD*5 gene type ranging from the highest to lowest can be listed as: mutation, heterozygote, wild type (p<0.05). The incidence of middle-severe nausea and vomiting was significantly higher in DPYD*9 heterozygous genotype than in DPYD*9 wild genotype (p<0.05). Conclusions DPYD*5 gene mutation contribute to reduced DPYD enzyme activity and 5-FU dysmetabolism, which is associated with the accumulation of 5-FU and the chemotherapeutic toxicity in gastric carcinoma and colon carcinoma.     

Cost-effectiveness of DPYD Genotyping Prior to Fluoropyrimidine-based Adjuvant Chemotherapy for Colon Cancer

BackgroundAdjuvant fluoropyrimidine-based chemotherapy substantially reduces recurrence and mortality after resection of stage 3 colon cancer. While standard doses of 5-fluorouracil and capecitabine are safe for most patients, the risk of severe toxicity is increased for the approximately 6% of patients with dihydropyimidine dehydrogenase (DPD) deficiency caused by pathogenic DPYD gene variants. Pre-treatment screening for pathogenic DPYD gene variants reduces severe toxicity but has not been widely adopted in the United States.MethodsWe conducted a cost-effectiveness analysis of DPYD genotyping prior to fluoropyrimidine-based adjuvant chemotherapy for stage 3 colon cancer, covering the c.1129-5923C>G (HapB3), c.1679T>G (*13), c.1905+1G>A (*2A), and c.2846A>T gene variants. We used a Markov model with a 5-year horizon, taking a United States healthcare perspective. Simulated patients with pathogenic DPYD gene variants received reduced-dose fluoropyrimidine chemotherapy. The primary outcome was the incremental cost-effectiveness ratio (ICER) for DPYD genotyping.ResultsCompared with no screening for DPD deficiency, DPYD genotyping increased per-patient costs by $78 and improved survival by 0.0038 quality-adjusted life years (QALYs), leading to an ICER of $20,506/QALY. In 1-way sensitivity analyses, The ICER exceeded $50,000 per QALY when the cost of the DPYD genotyping assay was greater than $286. In probabilistic sensitivity analysis using a willingness-to-pay threshold of $50,000/QALY DPYD genotyping was preferred to no screening in 96.2% of iterations.ConclusionAmong patients receiving adjuvant chemotherapy for stage 3 colon cancer, screening for DPD deficiency with DPYD genotyping is a cost-effective strategy for preventing infrequent but severe and sometimes fatal toxicities of fluoropyrimidine chemotherapy.     

DPYD*2A mutation: the most common mutation associated with DPD deficiency

Background Dihydropyrimidine dehydrogenase (DPD) enzyme is responsible for the elimination of approximately 80% of administered dose of 5-FU. DPD deficiency has been associated with severe 5-FU toxicity. Syndrome of DPD deficiency manifests as diarrhea, stomatitis, mucositis, and neurotoxicity and in some cases death. This is a true pharmacogenetic syndrome, with symptoms being unrecognizable until exposure to the drug. Patients and methods A 75-year-old patient with metastatic pancreatic adenocarcinoma developed grade 4 thrombocytopenia, grade 3 coagulopathy, and grade 3 neurologic toxicity with a fatal outcome following administration of 5-FU. Due to pancytopenia, DPD activity could not be determined in peripheral blood mononuclear cells (PBMC) using a previously described radioassay. Therefore, screening and genotypic analysis of homozygous and heterozygous, known and unknown sequence variants, in the DPYD gene were performed using DHPLC as previously described. All DPYD sequence variants identified by DHPLC were confirmed by DNA sequencing using a dideoxynucleotide chain termination method and capillary electrophoresis on an ABI 310 Automated DNA Sequencer. Results Genotyping analysis of the DPYD gene revealed the presence of the heterozygous mutation, IVS14 + 1 G > A, DPYD*2A. Conclusion Genotypic analysis using DHPLC can be employed to screen DPD deficiency in a patient with severe neutropenia. The mutation IVS14 + 1 G > A, DPYD*2A, is the most common mutation associated with DPD deficiency. A G > A base change at the splice recognition sequence of intron 14, leads to exon skipping and results in a 165-bp deletion in the DPD mRNA. We have previously demonstrated that a homozygote DPYD*2A genotype results in complete deficiency while the heterozygous DPYD*2A genotype results in partial deficiency of DPD. This work was supported in part by NIH grant CA 62164.     

DPYD genotype-guided dose individualization to improve patient safety of fluoropyrimidine therapy: call for a drug label update

The fluoropyrimidine anticancer drugs, especially 5-fluorouracil (5-FU) and capecitabine, are frequently prescribed for several types of cancer, including breast, colorectal, head and neck and gastric cancer. In the current drug labels of 5-FU and capecitabine in the European Union and the United States, no adaptive dosing strategies are incorporated for polymorphic metabolism of 5-FU. Although treatment with fluoropyrimidines is generally well tolerated, a major clinical limitation is that a proportion of the treated population experiences severe, sometimes life-threatening, fluoropyrimidine-related toxicity. This toxicity is strongly affected by interindividual variability in activity of dihydropyrimidine dehydrogenase (DPD), the main metabolic enzyme for inactivation of fluoropyrimidines, with an estimated 3%–8% of the population being partially DPD deficient. A reduced functional or abrogated DPD enzyme is often caused by genetic polymorphisms in DPYD, the gene encoding for DPD, and heterozygous carriers of such DPYD polymorphisms have a partial DPD deficiency. When these partially DPD deficient patients are treated with a full dose of fluoropyrimidines, they are generally exposed to toxic levels of 5-FU and its metabolites, and the risk of developing severe treatment-related toxicity is therefore significantly increased.Currently, functional and clinical validity is well established for four DPYD variants (DPYD*2A, c.2846A>T, c.1679T>G and c.1236G>A), as those variants have retrospectively and in a large population study prospectively been shown to be associated with increased risk of fluoropyrimidine-associated toxicity. Patient safety of fluoropyrimidine treatment can be significantly improved by pre-emptive screening for DPYD genotype variants and dose reductions in heterozygous DPYD variant allele carriers, thereby normalizing 5-FU exposure. Based on the critical appraisal of currently available data, adjusting the labels of capecitabine and 5-FU by including recommendations on pre-emptive screening for DPYD variants and DPYD genotype-guided dose adjustments should be the new standard of care.     

Clinical validity of a DPYD‐based pharmacogenetic test to predict severe toxicity to fluoropyrimidines

Pre‐therapeutic DPYD pharmacogenetic test to prevent fluoropyrimidines (FL)‐related toxicities is not yet common practice in medical oncology. We aimed at investigating the clinical validity of DPYD genetic analysis in a large series of oncological patients. Six hundred three cancer patients, treated with FL, have been retrospectively tested for eight DPYD polymorphisms (DPYD‐rs3918290, DPYD‐rs55886062, DPYD‐rs67376798, DPYD‐rs2297595, DPYD‐rs1801160, DPYD‐rs1801158, DPYD‐rs1801159, DPYD‐rs17376848) for association with Grade ≥3 toxicity, developed within the first three cycles of therapy. DPYD‐rs3918290 and DPYD‐rs67376798 were associated to Grade ≥3 toxicity after bootstrap validation and Bonferroni correction (p = 0.003, p = 0.048). DPYD‐rs55886062 was not significant likely due to its low allelic frequency, nonetheless one out of two heterozygous patients (compound heterozygous with DPYD‐rs3918290) died from toxicity after one cycle. Test specificity for the analysis of DPYD‐rs3918290, DPYD‐rs55886062 and DPYD‐rs67376798 was assessed to 99%. Among the seven patients carrying one variant DPYD‐rs3918290, DPYD‐rs55886062 or DPYD‐rs67376798 allele, not developing Grade ≥3 toxicity, 57% needed a FL dose or schedule modification for moderate chronic toxicity. No other DPYD polymorphism was associated with Grade ≥3 toxicity. Our data demonstrate the clinical validity and specificity of the DPYD‐rs3918290, DPYD‐rs55886062, DPYD‐rs67376798 genotyping test to prevent FL‐related Grade ≥3 toxicity and to preserve treatment compliance, and support its introduction in the clinical practice.     

Treating patients with dihydropyrimidine dehydrogenase (DPD) deficiency with fluoropyrimidine chemotherapy since the onset of routine prospective testing—The experience of a large oncology center in the United Kingdom

BackgroundFluoropyrimidine chemotherapy is used across many tumor types and settings. The incidence of severe adverse events (SAEs) is around 20%. Mortality is 0.5%-1%. Dihydropyrimidine dehydrogenase (DPD) plays a key role in fluoropyrimidine inactivation. Key DPYD mutations are linked to a high risk of SAEs. Pretreatment DPD screening was mandated by EMA guidelines in April 2020 and widely adopted thereafter. Uncertainty remains regarding optimal dosing practice.MethodsWe retrospectively examined records of all 23 patients with DPYD mutation who started chemotherapy between April and November 2020. Our center tests for the mutations considered clinically actionable by Clinical Pharmacogenetics Implementation Consortium and uses the Gene Activity Score (GAS) to guide dose reduction.ResultsMost patients started on a 50% dose. One started on 100% and experienced mild diarrhea after cycle 2; DPD was tested belatedly, subsequent cycles were reduced to 50% and he remained well. Three patients receiving chemo-radiotherapy started on 76% dose; 50% was felt to be subtherapeutic. One of them had no toxicities; another had grade 2 nausea and a hospital attendance with non-neutropenic fever; the third was admitted for 6 weeks with pancolitis. Seven patients did not have toxicities above grade 1 and no hospital attendances. Five patients had further dose reductions. None had dose escalation.ConclusionAs our experience shows, patients with DPD deficiency are heterogeneous. Worryingly, SAEs occur despite dose reduction according to GAS. Others had minimal toxicity and may be under-dosed by GAS. There are clearly many factors at play other than the 4 DPYD variants. The DPD result must be available and inform first cycle dosing. Dose should be cautiously titrated up if tolerated; this was not done at our center due to clinician caution. Further research is needed to guide this. Patients should be reviewed frequently, counselled regarding their DPD status, and empowered to seek advice promptly when they feel unwell.     

Near Miss or Standard of Care? DPYD Screening for Cancer Patients Receiving Fluorouracil

5-fluorouracil (5-FU) and its pro-drug capecitabine are widely used anticancer agents. Most 5-FU catabolism is dependent on dihydropyrimidine dehydrogenase (DPD) encoded by the DPYD gene, and DPYD variants that reduce DPD function increase 5-FU toxicity. Most DPD deficient patients are heterozygous and can be treated with reduced 5-FU dosing. We describe a patient with a genotype associated with near complete absence of DPD function, and severe and likely fatal toxicity with 5-FU treatment. The patient was treated effectively with alternative systemic therapy. Routine pretreatment DPYD genotyping is recommended by the European Medicines Agency, and guidelines for use of 5-FU in DPD deficient patients are available. However, outside the province of Quebec, routine pretreatment screening for DPD deficiency remains unavailable in Canada. It is likely our patient would have died from 5-FU toxicity under the current standard of care, but instead provides an example of the potential benefit of DPYD screening on patient outcomes.     

Benefit–Risk Summary of Nivolumab for the Treatment of Patients with Unresectable Advanced,Recurrent, or Metastatic Esophageal Squamous Cell Carcinoma After Prior Fluoropyrimidine- and Platinum-Based Chemotherapy

On June 10, 2020, the U.S. Food and Drug Administration (FDA) approved nivolumab (OPDIVO; Bristol Myers Squibb, New York, NY) for the treatment of patients with unresectable advanced, recurrent, or metastatic esophageal squamous cell carcinoma (ESCC) after prior fluoropyrimidine‐ and platinum‐based chemotherapy. Approval was based on the results of a single, randomized, active‐control study (ATTRACTION‐3) that randomized patients to receive nivolumab or investigator''s choice of taxane chemotherapy (docetaxel or paclitaxel). The study demonstrated a significant improvement in overall survival (OS; hazard ratio = 0.77; 95% confidence interval: 0.62–0.96; p = .0189) with an estimated median OS of 10.9 months in the nivolumab arm compared with 8.4 months in the chemotherapy arm. Overall, fewer patients in the nivolumab arm experienced treatment‐emergent adverse events (TEAEs) of any grade, grade 3–4 TEAEs, and serious adverse events compared with the control arm. The safety profile of nivolumab in patients with ESCC was generally similar to the known safety profile of nivolumab in other cancer types with the following exception: esophageal fistula was identified as a new, clinically significant risk in patients with ESCC treated with nivolumab. Additionally, the incidence of pneumonitis was higher in the ESCC population than in patients with other cancer types who are treated with nivolumab. This article summarizes the FDA review of the data supporting the approval of nivolumab for the treatment of ESCC.Implications for PracticeThe approval of nivolumab for the treatment of adult patients with unresectable advanced, recurrent, or metastatic esophageal squamous cell carcinoma (ESCC) after prior fluoropyrimidine‐ and platinum‐based chemotherapy was based on an overall survival (OS) benefit from a randomized, open‐label, active‐controlled study called ATTRACTION‐3. Prior to this study, no drug or combination regimen had demonstrated an OS benefit in a randomized study for patients with ESCC after prior fluoropyrimidine‐ and platinum‐based chemotherapy.     

Lack of large intragenic rearrangements in dihydropyrimidine dehydrogenase (DPYD) gene in fluoropyrimidine-treated patients with high-grade toxicity

Purpose  Deficiency of dihydropyrimidine dehydrogenase (DPD) has been associated with severe fluoropyrimidines (FP) toxicity. Mutations in DPD-coding gene (DPYD) were shown to increase the risk of severe toxicity in FP-treated cancer patients. However, the majority of DPYD alterations characterized in these patients has been considered as polymorphisms and known deleterious mutations are rare and present in only limited subgroup of patients with high toxicity. Recently, the common fragile site FRA1E was mapped within DPYD locus but intragenic rearrangements in DPYD gene were not studied so far. Methods  We performed the analysis of intragenic rearrangements of DPYD using multiplex ligation-dependent probe amplification in 68 patients with high-grade gastrointestinal and/or hematological toxicity developed at the beginning of FP treatment. Results  We did not detect any deletion/duplication of one or more DPYD exons in analyzed patients. Conclusions  We assume that rearrangements in DPYD gene play insignificant role in the development of serious FP-related toxicity. I. Ticha, P. Kleiblova contributed equally to this work.     

Dihydropyrimidine dehydrogenase pharmacogenetics in the Taiwanese population

Background/purpose 5-Fluorouracil (5-FU) remains the most frequently used chemotherapy agent in various human cancers. Over 80% of the 5-FU administered is metabolized by dihydropyrimidine dehydrogenase (DPD) in the liver. However, mutations in the DPD gene have been found to be associated with low DPD activity causing severe complications. The aim of this study was to determine the frequency of 11 known mutations in Taiwanese subjects and the relationship between mutation and DPD level.Methods Samples from a total of 300 subjects were investigated in this study. The PCR-RFLP method was used to identify 11 mutations of the DPYD gene, including 62G>A, 74A>G, 85T>C (DPYD*9A), 812delT, 1003G>T, 1156G>T, 1627A>G (DPYD*5), 1714C>G, 1897delC (DPYD*3), 2194G>A (DPYD*6), and IVS14+1G>A (DPYD*2A). DPD protein levels were determined using a DPD ELISA kit.Results Four mutations, including 74A>G, 85T>C (DPYD*9A), 1627A>G (DPYD*5), and 2194G>A (DPYD*6), were found in our 300 samples. The following mutations were not detected: 62G>A, 812delT, 1003G>T, 1156G>T, 1714C>G, 1897delC (DPYD*3), and IVS14+1G>A (DPYD*2A). The phenotype analysis by DPD protein level indicated that the 1627A>G (DPYD*5) mutation was not associated with the DPD protein level and might be a polymorphism in the DPD gene. The DPD level was also not correlated with gender.Conclusion No significant correlations between these 11 mutations and DPD protein level were found indicating that examination of these mutations is insufficient to provide a high-value prediction of the 5-FU pharmacogenetic syndrome in Taiwanese. Genotype and phenotype analysis indicated the 1627A>G (DPYD*5) mutation to be a polymorphism.     

二氢嘧啶脱氢酶编码基因DPYD＊ 5及＊ 9A突变频率的研究

目的氟尿嘧啶（5-Fu）是各种肿瘤治疗中应用最为广泛的抗肿瘤药物之一。体内80%以上的5-Fu在肝脏内经由二氢嘧啶脱氢酶（DPD）分解代谢。DPYD基因是DPD酶的编码基因,本研究旨在考察DPYD基因的＊5及＊9A位点在中国汉族乳腺癌患者中的突变频率。方法本研究收集100例乳腺癌患者的外周静脉血,应用基因测序的方法对93例乳腺癌患者DNA标本进行了DPYD＊5及＊9A位点的测序。结果对于DPYD＊5的1627A〉G突变位点,有37例发生突变,其中7例为纯合子突变,30例为杂合子突变;对于DPYD＊9A的85T〉C突变位点,有19例发生突变,其中1例为纯合子突变,18例为杂合子突变。有9例患者呈现DPYD＊5/＊9A联合突变。结论在中国汉族乳腺癌患者中（93例）,DPYD＊5的突变频率为39.8%,DPYD＊9A的突变频率是20.4%,DPYD＊5/＊9A联合突变的发生频率为9.7%。     

Changes in expression levels of ERCC1, DPYD,and VEGFA mRNA after first-line chemotherapy of metastatic colorectal cancer: results of a multicenter study

Our previous study showed that administering oxaliplatin as first-line chemotherapy increased ERCC1 and DPD levels in liver colorectal cancers (CRCs) metastases. Second, whether the anti-VEGF monoclonal antibody bevacizumab alters tumoral VEGFA levels is unknown. We conducted this multicenter observational study to validate our previous findings on ERCC1 and DPD, and clarify the response of VEGFA expression to bavacizumab administration. 346 CRC patients with liver metastases were enrolled at 22 Japanese institutes. Resected liver metastases were available for 175 patients previously treated with oxaliplatin-based chemotherapy (chemotherapy group) and 171 receiving no previous chemotherapy (non-chemotherapy group). ERCC1, DPYD, and VEGFA mRNA levels were measured by real-time RT-PCR. ERCC1 mRNA expression was significantly higher in the chemotherapy group than in the non-chemotherapy group (P = 0.033), and were significantly correlated (Spearman''s correlation coefficient = 0.42; P < 0.0001). VEGFA expression level was higher in patients receiving bevacizumab (n = 51) than in those who did not (n = 251) (P = 0.007). This study confirmed that first-line oxaliplatin-based chemotherapy increases ERCC1 and DPYD expression levels, potentially enhancing chemosensitivity to subsequent therapy. We also found that bevacizumab induces VEGFA expression in tumor cells, suggesting a biologic rationale for extending bevacizumab treatment beyond first progression.     

Clinical importance of risk variants in the dihydropyrimidine dehydrogenase gene for the prediction of early‐onset fluoropyrimidine toxicity

We investigated the clinical relevance of dihydropyrimidine dehydrogenase gene (DPYD) variants to predict severe early‐onset fluoropyrimidine (FP) toxicity, in particular of a recently discovered haplotype hapB3 and a linked deep intronic splice site mutation c.1129–5923C>G. Selected regions of DPYD were sequenced in prospectively collected germline DNA of 500 patients receiving FP‐based chemotherapy. Associations of DPYD variants and haplotypes with hematologic, gastrointestinal, infectious, and dermatologic toxicity in therapy cycles 1–2 and resulting FP‐dose interventions (dose reduction, therapy delay or cessation) were analyzed accounting for clinical and demographic covariates. Fifteen additional cases with toxicity‐related therapy delay or cessation were retrospectively examined for risk variants. The association of c.1129–5923C>G/hapB3 (4.6% carrier frequency) with severe toxicity was replicated in an independent prospective cohort. Overall, c.1129–5923G/hapB3 carriers showed a relative risk of 3.74 (RR, 95% CI = 2.30–6.09, p = 2 × 10^?5) for severe toxicity (grades 3–5). Of 31 risk variant carriers (c.1129–5923C>G/hapB3, c.1679T>G, c.1905+1G>A or c.2846A>T), 11 (all with c.1129–5923C>G/hapB3) experienced severe toxicity (15% of 72 cases, RR = 2.73, 95% CI = 1.61–4.63, p = 5 × 10^?6), and 16 carriers (55%) required FP‐dose interventions. Seven of the 15 (47%) retrospective cases carried a risk variant. The c.1129–5923C>G/hapB3 variant is a major contributor to severe early‐onset FP toxicity in Caucasian patients. This variant may substantially improve the identification of patients at risk of FP toxicity compared to established DPYD risk variants (c.1905+1G>A, c.1679T>G and c.2846A>T). Pre‐therapeutic DPYD testing may prevent 20–30% of life‐threatening or lethal episodes of FP toxicity in Caucasian patients.     

Clinical implications of dihydropyrimidine dehydrogenase (DPD) activity in 5-FU-based chemotherapy: mutations in the <Emphasis Type="Italic">DPD</Emphasis> gene,and DPD inhibitory fluoropyrimidines

Dihydropyrimidine dehydrogenase (DPD) is the rate-limiting enzyme in the degradation of pyrimidine bases. DPD is also responsible for the degradation of 5-fluorouracil (5-FU), which is the most frequently prescribed anticancer drug for the treatment of malignancies of the gastrointestinal tract. DPD could influence the antitumor effect and the adverse effects of 5-FU. High intratumoral DPD activity markedly decreases the cytotoxic effect of 5-FU. More than 80% of administered 5-FU is detoxified and excreted as F--alanine in urine. In 5-FU-based chemotherapy, escape from the degradation catalyzed by DPD is important. Recently, the dihydropyrimidine dehydrogenase gene (DPYD) was isolated, and its physical map and exon-intron organization were determined. To date, many DPYD variant alleles associated with a lack of DPD activity have been identified. In 5-FU-based cancer chemotherapy, severe toxicities were observed at higher rates in patients who were heterozygous for a mutant DPYD allele, compared with toxicities in patients who were homozygous for the wild DPYD allele. Furthermore, the adverse effects of 5-FU are often lethal for patients homozygous for the mutant DPYD allele. The apparently high prevalence of the DPYD mutation associated with lack of DPD activity in the normal population warrants genetic screening for the presence of these mutations in cancer patients before the administration of 5-FU. DPD inhibitory fluoropyrimidines (DIFs), including uracil plus tegafur (UFT) and tegafur plus 5-chloro-2,4-dihydroxypyridine plus potassium oxonate, in a molar ratio of 1:0.4:1 (TS-1), have recently been used in clinical settings. DIFs should provide chemotherapy that improves both quality of life and duration of survival.