The clinical relevance of multiple DPYD polymorphisms on patients candidate for fluoropyrimidine based-chemotherapy. An Italian case-control study

MIR27A Gene Polymorphism Modifies the Effect of Common DPYD Gene Variants on Severe Toxicity in Patients with Gastrointestinal Tumors Treated with Fluoropyrimidine-Based Anticancer Therapy

To reduce severe fluoropyrimidine-related toxicity, pharmacogenetic guidelines recommend a dose reduction for carriers of four high-risk variants in the DPYD gene (*2A, *13, c.2846A>T, HapB3). The polymorphism in the MIR27A gene has been shown to enhance the predictive value of these variants. Our study aimed to explore whether rs895819 in the MIR27A gene modifies the effect of five common DPYD variants: c.1129-5923C>G (rs75017182, HapB3), c.2194G>A (rs1801160, *6), c.1601G>A (rs1801158, *4), c.496A>G (rs2297595), and c.85T>C (rs1801265, *9A). The study included 370 Caucasian patients with gastrointestinal tumors who received fluoropyrimidine-containing chemotherapy. Genotyping was performed using high-resolution melting analysis. The DPYD*6 allele was associated with overall severe toxicity and neutropenia with an increased risk particularly pronounced in patients carrying the MIR27A variant. All carriers of DPYD*6 exhibited an association with asthenia regardless of their MIR27A status. The increased risk of neutropenia in patients with c.496G was only evident in those co-carrying the MIR27A variant. DPYD*4 was also significantly linked to neutropenia risk in co-carriers of the MIR27A variant. Thus, we have demonstrated the predictive value of the *6, *4, and c.496G alleles of the DPYD gene, considering the modifying effect of the MIR27A polymorphism.

Rapid detection of the irinotecan-related UGT1A1 & 5-fluorouracil related DPYD polymorphism by asymmetric polymerase chain reaction melting curve analysis

BACKGROUND

Determination of DPYD and UGT1A1 polymorphisms prior to 5-fluorouracil and irinotecan therapy is crucial for avoiding severe adverse drug effects. Hence, there is a pressing need for accurate and reliable genotyping methods for the most common DPYD and UGT1A1 polymorphisms. In this study, we introduce a novel polymerase chain reaction (PCR) melting curve analysis method for discriminating DPYD c.1236G > A, c.1679 T > G, c.2846A > T, IVS14 + 1G > A and UGT1A1*1, *28, *6 (G71R) genotypes.

METHODS

Following protocol optimization, this technique was employed to genotype 28 patients, recruited between March 2023 and October 2023, at the First Affiliated Hospital of Xiamen University. These patients included 20 with UGT1A1 *1/*1, 8 with UGT1A1 *1/*28, 4 with UGT1A1 *28/*28, 22 with UGT1A1*6 G/G, 6 with UGT1A1*6 G/A, 4 with UGT1A1*6 A/A, 27 with DPYD(c.1236) G/G, 3 with DPYD(c.1236) G/A, 2 with DPYD(c.1236) A/A, 27 with DPYD(c.1679) T/T, 2 with DPYD(c.1679) T/G, 3 with DPYD(c.1679) G/G, 28 with DPYD(c.2846A/T) A/A, 2 with DPYD(c.2846A/T) A/T, 2 with DPYD(c.2846A/T) T/T, 28 with DPYD(c.IVS14 + 1) G/G, 2 with DPYD(c.IVS14 + 1) G/G, and 2 with DPYD(c.IVS14 + 1) G/G, as well as 3 plasmid standards. Method accuracy was assessed by comparing results with those from Sanger sequencing or Multiplex quantitative PCR(qPCR). Intra- and inter-run precision of melting temperatures (Tms) were calculated to evaluate reliability, and sensitivity was assessed through limit of detection examination.

RESULTS

The new method accurately identified all genotypes and exhibited higher accuracy than Multiplex qPCR. Intra- and inter-run coefficients of variation for Tms were both ≤1.97 %, with standard deviations ≤0.95 °C. The limit of detection was 0.09 ng/μL of input genomic DNA.

CONCLUSION

Our developed PCR melting curve analysis offers accurate, reliable, rapid, simple, and cost-effective detection of DPYD and UGT1A1 polymorphisms. Its application can be easily extended to clinical laboratories equipped with a fluorescent PCR platform.

Fluoropyrimidine Toxicities and DPYD Genotyping: A Clinical Case

Fluoropyrimidines are metabolized mainly by the enzyme dihydropyrimidine dehydrogenase (DPD). Some variants in the coding gene, DPYD, have already been associated with increased toxicity, and their testing is recommended in patients proposed for treatment with these drugs. In this clinical case, a patient without the four variants recommended for testing showed toxicity from the second cycle of capecitabine onwards, requiring hospitalization in the third cycle. Sequencing of the DPYD gene showed the presence of three heterozygous variants which the laboratory interpreted as deleterious to the expression or function of DPD. In the absence of phenotypic testing, the patient stopped treatment, which is also the usual procedure in the case of compound heterozygosity of the variants usually tested. The literature review shows data for and against the role of each variant found in fluoropyrimidine toxicity, but there may be more concrete data in the study of haplotypes with multiple variants and the need to research alterations in other genes to better understand their relationship with toxicity.

AXL receptor as an emerging molecular target in colorectal cancer

AXL receptor tyrosine kinase (AXL) is a receptor tyrosine kinase whose aberrant expression has recently been associated with colorectal cancer (CRC), contributing to tumor growth, epithelial-mesenchymal transition (EMT), increased invasiveness, metastatic spreading, and the development of drug resistance. In this review we summarize preclinical data, the majority of which are limited to recent years, convincingly linking the AXL receptor to CRC. These findings support the value of targeting AXL with molecules in drug discovery, offering novel and advanced therapeutic or diagnostic tools for CRC management.

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.

Can immunotherapy reinforce chemotherapy efficacy? a new perspective on colorectal cancer treatment

As one of the main threats to human life (the fourth most dangerous and prevalent cancer), colorectal cancer affects many people yearly, decreases patients' quality of life, and causes irreparable financial and social damages. In addition, this type of cancer can metastasize and involve the liver in advanced stages. However, current treatments can't completely eradicate this disease. Chemotherapy and subsequent surgery can be mentioned among the current main treatments for this disease. Chemotherapy has many side effects, and regarding the treatment of this type of tumor, chemotherapy can lead to liver damage, such as steatohepatitis, steatosis, and sinus damage. These damages can eventually lead to liver failure and loss of its functions. Therefore, it seems that other treatments can be used in addition to chemotherapy to increase its efficiency and reduce its side effects. Biological therapies and immunotherapy are one of the leading suggestions for combined treatment. Antibodies (immune checkpoint blockers) and cell therapy (DC and CAR-T cells) are among the immune system-based treatments used to treat tumors. Immunotherapy targets various aspects of the tumor that may lead to 1) the recruitment of immune cells, 2) increasing the immunogenicity of tumor cells, and 3) leading to the elimination of inhibitory mechanisms established by the tumor. Therefore, immunotherapy can be used as a complementary treatment along with chemotherapy. This review will discuss different chemotherapy and immunotherapy methods for colorectal cancer. Then we will talk about the studies that have dealt with combined treatment.

Precision fluoropyrimidines dosing in a compound heterozygous variant carrier of the DPYD gene: a case report

BACKGROUND

Fluoropyrimidines (FPs) form still nowadays the backbone of chemotherapic schemes in colorectal cancer (CRC). Inter-patient variability of the toxicity profile of FPs may be partially accounted for by variable expression of dihydropyrimidine dehydrogenase (DPD). DPD rate activity is genetically determined by its extremely polymorphic coding gene DPYD. In spite of pharmacogenetic guideline-directed-dosing of FPs based regimens treating carrier of multiple variants of DPYD gene remains still challenging.

CASE PRESENTATION

We present a case of a 48-year-old Caucasian man, compound heterozygous variant carrier of the DPYD gene (HapB3 and c.2194G>A) who had a diagnosis of adenocarcinoma of the left colon and was safely treated with a pharmacogenetic-guided 25% dose reduction of the standard CAP adjuvant treatment. Compound heterozygosis may have been responsible for an earlier over exposure to CAP resulting into low-grade toxicity with an anticipated median time to toxicity of the c.2194G>A variant to the 4th vs. 6th cycles. Some haplotypes of DPYD variants may have an advantage in terms of survival compared to wild-type patients. Our patient may also have benefitted from compound heterozygosis, as shown by no evidence of disease (NED) at 6-month follow-up.

CONCLUSION

Pharmacogenetic-guided dosing of DPYD intermediate metabolizer compound heterozygous HapB3 and c.2194G>A variant carries should be managed by a multidisciplinary team with a dose reduction ranging from 25 to 50% to maintain effectiveness and close clinical monitoring for early detection of ADRs.

The past, present, and future of chemotherapy with a focus on individualization of drug dosing

While there have been rapid advances in developing new and more targeted drugs to treat cancer, much less progress has been made in individualizing dosing. Even though the introduction of immunotherapies such as CAR T-cells and checkpoint inhibitors, as well as personalized therapies that target specific mutations, have transformed clinical treatment of cancers, chemotherapy remains a mainstay in oncology. Chemotherapies are typically dosed on either a body surface area (BSA) or weight basis, which fails to account for pharmacokinetic differences between patients. Drug absorption, distribution, metabolism, and excretion rates can vary between patients, resulting in considerable differences in exposure to the active drugs. These differences result in suboptimal dosing, which can reduce efficacy and increase side-effects. Therapeutic drug monitoring (TDM), genotype guided dosing, and chronomodulation have been developed to address this challenge; however, despite improving clinical outcomes, they are rarely implemented in clinical practice for chemotherapies. Thus, there is a need to develop interventions that allow for individualized drug dosing of chemotherapies, which can help maximize the number of patients that reach the most efficacious level of drug in the blood while mitigating the risks of underdosing or overdosing. In this review, we discuss the history of the development of chemotherapies, their mechanisms of action and how they are dosed. We discuss substantial intraindividual and interindividual variability in chemotherapy pharmacokinetics. We then propose potential engineering solutions that could enable individualized dosing of chemotherapies, such as closed-loop drug delivery systems and bioresponsive biomaterials.

Concomitant Administration of Capecitabine and Folate Supplements: Need to Encourage Medication Reconciliation

Hand-Foot syndrome (HFS) and diarrhoea are dose-limiting Adverse Drug Reactions (ADRs) of capecitabine-based chemotherapy. Four polymorphisms in the dihydropyrimidine dehydrogenase (DPYD) gene, encoding the DPD enzyme responsible for the metabolism of fluoropyrimidines, such as capecitabine, are strongly associated with severe ADRs, and their screening should be performed before starting treatment. Moreover, capecitabine-related toxicity may worsen due to drug-drug and drug-supplement interactions. Here we investigated factors responsible for severe HFS and diarrhoea presented by two patients, non-carriers of the recommended DPYD single nucleotide polymorphisms (SNPs) but carriers of other genetic variants suggested to increase the risk of capecitabine-related ADRs. Through careful therapy recognition, we demonstrated that, unbeknownst to the oncologists, the patients were taking folic acid during the treatment with capecitabine at a dosage higher than 2000 mg/m2, which is the maximum tolerated dose when folate is administered. To resolve the ADRs, the therapy had to be drastically changed. In one case, dose reduction of capecitabine and discontinuation of lipid-lowering agents were carried out. In the other case, discontinuation of capecitabine and folic acid and capecitabine re-administration were performed after a month. Genetic and environmental factors should be considered good predictors of severe capecitabine-related toxicity. Medication reconciliation should be encouraged to avoid the harmful consequences of inappropriate treatments.

Introducing a simple and cost-effective RT-PCR protocol for detection of DPYD*2A polymorphism: the first study in Kurdish population

PURPOSE

Fluoropyrimidines, the major chemotherapeutic agents in various malignancies treatment, are metabolized by dihydropyrimidine dehydrogenase (DPD). DPD deficiency can lead to severe and sometimes fatal toxicity. In the present study, we developed a simple protocol to detect the DPYD*2A variant. Common side effects in patients treated with these drugs were also evaluated in a Kurdish population.

METHOD

We established a reverse-transcriptase polymerase chain reaction (RT-PCR) technique for detection of DPYD*2A. Sanger sequencing was used to confirm the results. 121 Kurdish patients receiving fluoropyrimidine derivatives were enrolled, and clinical information regarding the dosage and toxicity was analyzed.

RESULTS

Our RT-PCR method was able to detect one patient with heterozygous state for DPYD*2A (0.8%). The most observed adverse drug reactions were tingling, nausea, and hair loss. The frequency of patients with the toxicity of grade 3 or worse was 6.6%.

CONCLUSION

This was the first study that detect DPYD*2A polymorphism in the Kurdish population. Our method was successfully able to detect the DPYD*2A variant and, due to its simplicity and cost-effectiveness, it may be considered as an alternative to the current methods, especially in developing countries. Our detected polymorphism rate at 0.8% is comparable with other studies. Despite the low rate of DPYD*2A polymorphism, pharmacogenetics assessment before beginning the treatment process is highly recommended due to its association with a high risk of severe toxicity.

Elevated Risk of Fluoropyrimidine-Associated Toxicity in European Patients with DPYD Genetic Polymorphism: A Systematic Review and Meta-Analysis

Background: Fluoropyrimidine is widely used owing to its clinical efficacy, however, patients with dihydropyrimidine dehydrogenase (DPD) deficiency can experience fluoropyrimidine-associated toxicity. The dihydropyrimidine dehydrogenase (DPYD) gene encodes DPD, and studies suggest that DPYD polymorphisms can result in DPD deficiency. Since there is not a complete consistency of how much the risk of complication is elevated, we aimed to conduct a systematic literature review and a meta-analysis to provide the risk of fluoropyrimidine-associated toxicity in patients with DPYD rs1801160 polymorphism. Methods: We searched for qualifying studies published before October 2021 from PubMed, Web of Science, and EMBASE based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to evaluate the strength of the association between rs1801160 polymorphism and toxicities. A sensitivity analysis using the leave-one-out method was performed on the overall toxicity. Results: The pooled OR for overall toxicity in the patients with A allele was elevated 1.73 times higher than those with the GG genotype (95% CI 1.44-2.07). Sensitivity analysis yielded similar results, showing the robustness of the result. Subjects with variants showed a 2.37-fold increased hematological toxicity (95% CI 1.48-3.81); especially a 1.87-fold increased neutropenia compared to patients with wildtype (95% CI 1.49-2.34). Patients with A allele revealed 1.22 times higher gastrointestinal toxicity compared to those with GG genotype (95% CI 0.93-1.61), and among gastrointestinal toxicity, the risk of diarrhea was elevated 1.43 times higher in those with variants than patients with wildtype (95% CI 1.12-1.83). Conclusions: rs1801160 polymorphism is associated with elevated fluoropyrimidine-associated toxicity. Therefore, rs1801160 can be a potential candidate for DPD deficiency screening prior to fluoropyrimidine-based regimen.

Abnormal Dihydropyrimidine Dehydrogenase Activity as an Indicator of Potential 5-Fluorouracil Linked Cardiotoxicity in Colorectal Cancer Patients: Are Toxic Events Inevitable?

Colorectal cancer (CRC) treatment can be limited to surgical resection for low stages of the disease while subsequent chemotherapy is the preferred treatment for the higher-stage disease. This chemotherapy relies heavily on fluoropyrimidine: 5-fluorouracil (5-FU) and capecitabine, a role played for decades. Fluoropyrimidine-linked treatment can present important and even lethal toxic events at the cardiac level like acute coronary syndrome, arrhythmias, and death.

The production of these toxic events depends on the capacity of a subject to metabolize the fluoropyrimidines adequately, and this depends on the activity of the enzyme dihydropyrimidine dehydrogenase (DPD). Any change that affects the quantity or quality of this enzyme will compromise its capacity to metabolize the fluoropyrimidines. The resultant abnormal enzyme activity exposes the patient to continuously high levels of the chemotherapeutic agent or its catabolites. Consequently, the patient becomes more susceptible to pyrimidine-linked toxic adverse events.

Genetic testing of patients for potential decreased DPD activity before subjecting them to fluoropyrimidine-based chemotherapy will help identify subjects at greater risk of increased cardiotoxicities, the possibility of prompt intervention, should these appear, and a multidisciplinary strategy aimed at managing these cases. Potential cases of cardiotoxicity in CRC patients, candidates to fluoropyrimidine toxicities, can be anticipated by pretreatment screening of DPD activity. Pretreatment screening will reduce many hospitalizations with a consequent decrease in costs both to the patients and the healthcare system.

This review article will examine the 5-FU linked cardiotoxicity, known correlated risk factors, clinical manifestations, management strategy, and the role of genetic testing in identifying high-risk patients.

DPYD Genotyping in Patients Who Have Planned Cancer Treatment With Fluoropyrimidines: A Health Technology Assessment

BACKGROUND

Fluoropyrimidine drugs (such as 5-fluorouracil and capecitabine) are used to treat different types of cancer. However, these drugs may cause severe toxicity in about 10% to 40% of patients. A deficiency in the dihydropyrimidine dehydrogenase (DPD) enzyme, encoded by the DPYD gene, increases the risk of severe toxicity. DPYD genotyping aims to identify variants that lead to DPD deficiency and may help to identify people who are at higher risk of developing severe toxicity, allowing their treatment to be modified before it begins. Recommendations for fluoropyrimidine treatment modification are available for four DPYD variants, which are the focus of this review: DPYD∗2A, DPYD∗13, c.2846A>T, and c.1236G>A. We conducted a health technology assessment of DPYD genotyping for patients who have planned cancer treatment with fluoropyrimidines, which included an evaluation of clinical validity, clinical utility, the effectiveness of treatment with a reduced fluoropyrimidine dose, cost-effectiveness, the budget impact of publicly funding DPYD genotyping, and patient preferences and values.

METHODS

We performed a systematic literature search of the clinical evidence. We assessed the risk of bias of each included systematic review and primary study using the Risk of Bias in Systematic Reviews (ROBIS) tool and the Newcastle-Ottawa Scale, respectively, and we assessed the quality of the body of evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria. We performed a systematic economic literature review and conducted cost-effectiveness and cost-utility analyses with a half-year time horizon from a public payer perspective. We also analyzed the budget impact of publicly funding pre-treatment DPYD genotyping in patients with planned fluoropyrimidine treatment in Ontario. To contextualize the potential value of DPYD testing, we spoke with people who had planned cancer treatment with fluoropyrimidines.

RESULTS

We included 29 observational studies in the clinical evidence review, 25 of which compared the risk of severe toxicity in carriers of a DPYD variant treated with a standard fluoropyrimidine dose with the risk in wild-type patients (i.e., non-carriers of the variants under assessment). Heterozygous carriers of a DPYD variant treated with a standard fluoropyrimidine dose may have a higher risk of severe toxicity, dose reduction, treatment discontinuation, and hospitalization compared to wild-type patients (GRADE: Low). Six studies evaluated the risk of severe toxicity in DPYD carriers treated with a genotype-guided reduced fluoropyrimidine dose versus the risk in wild-type patients; one study also included a second comparator group of DPYD carriers treated with a standard dose. The evidence was uncertain, because the results of most of these studies were imprecise (GRADE: Very low). The length of hospital stay was shorter in DPYD carriers treated with a reduced dose than in DPYD carriers treated with a standard dose, but the evidence was uncertain (GRADE: Very low). One study assessed the effectiveness of a genotype-guided reduced fluoropyrimidine dose in DPYD∗2A carriers versus wild-type patients, but the results were imprecise (GRADE: Very low).We found two cost-minimization analyses that compared the costs of the DPYD genotyping strategy with usual care (no testing) in the economic literature review. Both studies found that DPYD genotyping was cost-saving compared to usual care. Our primary economic evaluation, a cost-utility analysis, found that DPYD genotyping might be slightly more effective (incremental quality-adjusted life years of 0.0011) and less costly than usual care (a savings of $144.88 per patient), with some uncertainty. The probability of DPYD genotyping being cost-effective compared to usual care was 91% and 96% at the commonly used willingness-to-pay values of $50,000 and $100,000 per quality-adjusted life-year gained, respectively. Assuming a slow uptake, we estimated that publicly funding pre-treatment DPYD genotyping in Ontario would lead to a savings of $714,963 over the next 5 years.The participants we spoke to had been diagnosed with cancer and treated with fluoropyrimidines. They reported on the negative side effects of their treatment, which affected their day-to-day activities, employment, and mental health. Participants viewed DPYD testing as a beneficial addition to their treatment journey; they noted the importance of having all available information possible so they could make informed decisions to avoid adverse reactions. Barriers to DPYD testing include lack of awareness of the test and the fact that the test is being offered in only one hospital in Ontario.

CONCLUSIONS

Studies found that carriers of a DPYD variant who were treated with a standard fluoropyrimidine dose may have a higher risk of severe toxicity than wild-type patients treated with a standard dose. DPYD genotyping led to fluoropyrimidine treatment modifications. It is uncertain whether genotype-guided dose reduction in heterozygous DPYD carriers resulted in a risk of severe toxicity comparable to that of wild-type patients. It is also uncertain if the reduced dose resulted in a lower risk of severe toxicity compared to DPYD carriers treated with a standard dose. It is also uncertain whether the treatment effectiveness of a reduced dose in carriers was comparable to the effectiveness of a standard dose in wild-type patients.For patients with planned cancer treatment with fluoropyrimidines, DPYD genotyping is likely cost-effective compared to usual care. We estimate that publicly funding DPYD genotyping in Ontario may be cost-saving, with an estimated total of $714,963 over the next 5 years, provided that the implementation, service delivery, and program coordination costs do not exceed this amount.For people treated with fluoropyrimidines, cancer and treatment side effects had a substantial negative effect on their quality of life and mental health. Most saw the value of DPYD testing as a way of reducing the risk of serious adverse events. Barriers to receipt of DPYD genotyping included lack of awareness and limited access to DPYD testing.

Genetic polymorphisms on the effectiveness or safety of breast cancer treatment: Clinical relevance and future perspectives

Breast cancer (BC) is the most frequent neoplasm and one of the main causes of death in women. The pharmacological treatment of BC consists of hormonal therapy, chemotherapeutic agents and targeted therapy. The response to BC therapy is highly variable in clinical practice. This variability can be explained by the presence of genetic polymorphisms in genes involved in the pharmacokinetics, pharmacodynamics or immune response of patients. The abundant evidence of associations between low-activity alleles CYP2D6*3, *4, *5, *6, *10 and *41 and poor results with tamoxifen therapy, and between DPYD gene polymorphisms rs3918290, rs55886062, rs67376798 and rs75017182 and increased risk of toxicity to fluoropyrimidine therapy, justify the existence of clinical pharmacogenetic guidelines. The NQO1 rs1800566 polymorphism is related to poorer results in BC therapy with chemotherapy agents. The polymorphism rs1695 of the GSTP1 gene has been associated with the effectiveness and toxicity of fluorouracil, cyclophosphamide and epirubicin therapy. Finally, the HLA-DQA1*02:01 allele is significantly associated with the occurrence of liver toxicity events in patients receiving lapatinib. There is moderate evidence to support the aforementioned associations and, therefore, a high probability of these being considered as future predictive genetic biomarkers of response. However, further studies are required to reinforce or clarify their clinical relevance.

What the Cardiologist Needs to Consider in the Management of Oncologic Patients with STEMI-Like Syndrome: A Case Report and Literature Review

In pre-hospital care, an accurate and quick diagnosis of ST-segment elevation myocardial infarction (STEMI) is imperative to promptly kick-off the STEMI network with a direct transfer to the cardiac catheterization laboratory (cath lab) in order to reduce myocardial infarction size and mortality. Aa atherosclerotic plaque rupture is the main mechanism responsible for STEMI. However, in a small percentage of patients, emergency coronarography does not reveal any significant coronary stenosis. The fluoropyrimidine agents such as 5-Fluorouracil (5-FU) and capecitabine, widely used to treat gastrointestinal, breast, head and neck cancers, either as a single agent or in combination with other chemotherapies, can cause potentially lethal cardiac side effects. Here, we present the case of a patient with 5-FU cardiotoxicity resulting in an acute coronary syndrome (ACS) with recurrent episodes of chest pain and ST-segment elevation.. Our case report highlights the importance of widening the knowledge among cardiologists of the side effects of chemotherapeutic drugs, especially considering the rising number of cancer patients around the world and that fluoropyrimidines are the main treatment for many types of cancer, both in adjuvant and advanced settings.

Comprehensive pharmacogenetic analysis of DPYD, UGT, CDA, and ABCB1 polymorphisms in pancreatic cancer patients receiving mFOLFIRINOX or gemcitabine plus nab-paclitaxel

Modified FOLFIRINOX (mFOLFIRINOX) and gemcitabine + nab-paclitaxel (GemNab) regimens represent a standard treatment in advanced pancreatic cancer (aPC). DPYD and UGT1A1 variants are relevant predictors of fluoropyrimidine and irinotecan-associated adverse events (AEs). Furthermore, data about the associations between polymorphisms in ABCB and CDA genes and GemNab-related toxicities are still controversial. The present study analyzes the association between DPYD, UGT, ABCB1, CDA variants, and AEs in aPC patients (pts) treated with mFOLFIRINOX or GemNab. Blood samples collected from 104 aPC pts treated with mFOLFIRINOX and 63 with GemNab were tested for DPYD c.1679T>G, IVS14+1G>A, c.2194G>A, c.2846A>T, UGT1A1*28, CDA c.79A>C, and ABCB1 c.1236C>T, c.2677G>T/A, c.3435C>T by real-time PCR and automatic sequencing. In mFOLFIRINOX cohort, DPYD IVS14+1GA genotype was associated with G4 hematological AEs, while the UGT1A1*28 significantly correlated with the risk of thrombocytopenia (p = 0.006). In the GemNab cohort, a significant association between CDA c.79CC and high-grade nausea was observed (p = 0.002). Moreover, the presence of at least a mutant allele in ABCB1 increased the risk of overall hematological AEs (p = 0.01), both further strengthened by the presence of CDA c.79CC (p = 0.0002). DPYD IVS14+1A allele is confirmed to be associated with fluoropyrimidine life-threatening toxicities, and UGT1A1*28 is related with a higher risk of hematologic AEs following irinotecan treatment. CDA c.79C and ABCB1 c.1236T, c.2677T/A, and c.3435T mutant alleles are predictive biomarkers of GemNab-related AEs. All these variants should be considered in aPC pts candidate to mFOLFIRINOX or GemNab treatments.

Development of a Pharmacogenetic Lab-on-Chip Assay Based on the In-Check Technology to Screen for Genetic Variations Associated to Adverse Drug Reactions to Common Chemotherapeutic Agents

BACKGROUND

Antineoplastic agents represent the most common class of drugs causing Adverse Drug Reactions (ADRs). Mutant alleles of genes coding for drug-metabolizing enzymes are the best studied individual risk factors for these ADRs. Although the correlation between genetic polymorphisms and ADRs is well-known, pharmacogenetic tests are limited to centralized laboratories with expensive or dedicated instrumentation used by specialized personnel. Nowadays, DNA chips have overcome the major limitations in terms of sensibility, specificity or small molecular detection, allowing the simultaneous detection of several genetic polymorphisms with time and costs-effective advantages. In this work, we describe the design of a novel silicon-based lab-on-chip assay able to perform low-density and high-resolution multi-assay analysis (amplification and hybridization reactions) on the In-Check platform.

METHODS

The novel lab-on-chip was used to screen 17 allelic variants of three genes associated with adverse reactions to common chemotherapeutic agents: DPYD (Dihydropyrimidine dehydrogenase), MTHFR (5,10-Methylenetetrahydrofolate reductase) and TPMT (Thiopurine S-methyltransferase).

RESULTS

Inter- and intra assay variability were performed to assess the specificity and sensibility of the chip. Linear regression was used to assess the optimal hybridization temperature set at 52 °C (R2 ≈ 0.97). Limit of detection was 50 nM.

CONCLUSIONS

The high performance in terms of sensibility and specificity of this lab-on-chip supports its further translation to clinical diagnostics, where it may effectively promote precision medicine.

Pharmacogenomic Assessment of Patients with Colorectal Cancer and Potential Treatments

Evolving intensiveness of colorectal cancer (CRC) treatment, including chemotherapeutics and targeted agents associations, in adjuvant and metastatic CRC (MCRC) settings, increased overall survival (OS) with individual variability of toxicity. Pharmacogenomic guidelines recommended pre-treatment identification of at-risk patients suggesting dose adjustment of fluoropyrimidines based on dihydropyrimidine dehydrogenase (DPYD), and irinotecan on UDP glucuronosyl-transferase 1 family polypeptide A1 (UGT1A1) genetic variants, but they are poorly applied in clinical practice. This review highlighted clinically validated pharmacogenetic markers, to underline the need of their implementation in the multidisciplinary molecular board for individual CRC patients in clinical practice. Five clinically relevant DPYD variants with different prevalence impair enzymatic effectiveness and significantly increase toxicity: c.1236 G>A (c.1129–5923 C>G, HapB3), 4.1–4.8%; c.1679 T>G (DPYD*13), c.1905+1G>A (DPYD*2A), c.2846 A>T, c.2194 A>T (DPYD*6) 1% each. c.1679T>G and c.1905+1G>A are most deleterious on DPD effectiveness, moderately reduced in c.1236/HapB3 and c.2846A>T. Cumulatively, these variants explain approximately half of the estimated 10–15% fluoropyrimidine-related gastrointestinal and hematological toxicities due to DPD. Prevalent UGT1A1 gene [TA]₇TAA promoter allelic variant UGT1A1*28, characterized by an extra TA repeat, is associated with low transcriptional and reduced enzymatic effectiveness, decreased SN38 active irinotecan metabolite glucuronidation, vs wild-type UGT1A1*1 [A(TA)6TAA]. Homozygote UGT1A1*28 alleles patients are exposed to higher hematological and gastrointestinal toxicities, even more than heterozygote, at >150 mg/m² dose. Dose reduction is recommended for homozygote variant. Wild-type UGT1A1*28 alleles patients could tolerate increased doses, potentially affecting favorable outcomes. Implementation of up-front evaluation of the five validated DPYD variants and UGT1A1*28 in the multidisciplinary molecular tumor board, also including CRC genetic characterization, addresses potential treatments with fluoropyrimidines and irinotecan associations at proper doses and schedules, particularly for early CRC, MCRC patients fit for intensive regimens or unfit for conventional regimens, requiring treatment modulations, and also for patients who experience severe, unexpected toxicities. Integration of individual evaluation of toxicity syndromes (TS), specifically limiting TS (LTS), an innovative indicator of toxicity burden in individual patients, may be useful to better evaluate relationships between pharmacogenomic analyses with safety profiles and clinical outcomes.

Pharmacogenomics meets precision cardio-oncology: is there synergistic potential?

An individual's inherited genetic makeup and acquired genomic variants may account for a significant portion of observable variability in therapy efficacy and toxicity. Pharmacogenomics (PGx) is the concept that treatments can be modified to account for these differences to increase chances of therapeutic efficacy while minimizing risk of adverse effects. This is particularly applicable to oncology in which treatment may be multimodal. Each tumor type has a unique genomic signature that lends to inclusion of targeted therapy but may be associated with cumulative toxicity, such as cardiotoxicity, and can impact quality of life. A greater understanding of therapeutic agents impacted by PGx and subsequent implementation has the potential to improve outcomes and reduce risk of drug-induced adverse effects.

A Genotyping/Phenotyping Approach with Careful Clinical Monitoring to Manage the Fluoropyrimidines-Based Therapy: Clinical Cases and Systematic Review of the Literature

Fluoropyrimidines (FP) are mainly metabolised by dihydropyrimidine dehydrogenase (DPD), encoded by the DPYD gene. FP pharmacogenetics, including four DPYD polymorphisms (DPYD-PGx), is recommended to tailor the FP-based chemotherapy. These polymorphisms increase the risk of severe toxicity; thus, the DPYD-PGx should be performed prior to starting FP. Other factors influence FP safety, therefore phenotyping methods, such as the measurement of 5-fluorouracil (5-FU) clearance and DPD activity, could complement the DPYD-PGx. We describe a case series of patients in whom we performed DPYD-PGx (by real-time PCR), 5-FU clearance and a dihydrouracil/uracil ratio (as the phenotyping analysis) and a continuous clinical monitoring. Patients who had already experienced severe toxicity were then identified as carriers of DPYD variants. The plasmatic dihydrouracil/uracil ratio (by high-performance liquid chromatography (HPLC)) ranged between 1.77 and 7.38. 5-FU clearance (by ultra-HPLC with tandem mass spectrometry) was measured in 3/11 patients. In one of them, it reduced after the 5-FU dosage was halved; in the other case, it remained high despite a drastic dosage reduction. Moreover, we performed a systematic review on genotyping/phenotyping combinations used as predictive factors of FP safety. Measuring the plasmatic 5-FU clearance and/or dihydrouracil/uracil (UH2/U) ratio could improve the predictive potential of DPYD-PGx. The upfront DPYD-PGx combined with clinical monitoring and feasible phenotyping method is essential to optimising FP-based chemotherapy.

New DPYD variants causing DPD deficiency in patients treated with fluoropyrimidine

PURPOSE

Several clinical guidelines recommend genetic screening of DPYD, including coverage of the variants c.1905 + 1G>A(DPYD*2A), c.1679T>G(DPYD*13), c.2846A>T, and c.1129-5923C>G, before initiating treatment with fluoropyrimidines. However, this screening is often inadequate at predicting the occurrence of severe fluoropyrimidine-induced toxicity in patients.

METHODS

Using a complementary approach combining whole DPYD exome sequencing and in silico and structural analysis, as well as phenotyping of DPD by measuring uracilemia (U), dihydrouracilemia (UH₂), and the UH₂/U ratio in plasma, we were able to characterize and interpret DPYD variants in 28 patients with severe fluoropyrimidine-induced toxicity after negative screening.

RESULTS

Twenty-five out of 28 patients (90%) had at least 1 variant in the DPYD coding sequence, and 42% of the variants (6/14) were classified as potentially deleterious by at least 2 of the following algorithms: SIFT, Poly-Phen-2, and DPYD varifier. We identified two very rare deleterious mutations, namely, c.2087G>A (p.R696H) and c.2324T>G (p.L775W). We were able to demonstrate partial DPD deficiency, as measured by the UH₂/U ratio in a patient carrying the variant p.L775W for the first time.

CONCLUSION

Whole exon sequencing of DPYD in patients with suspicion of partial DPD deficiency can help to identify rare or new variants that lead to enzyme inactivation. Combining different techniques can yield abundant information without increasing workload and cost burden, thus making it a useful approach for implementation in patient care.

The Role of Dihydropyrimidine Dehydrogenase and Thymidylate Synthase Polymorphisms in Fluoropyrimidine-Based Cancer Chemotherapy in an Iranian Population

BACKGROUND

The fluoropyrimidine drug 5-Fluorouracil (5-FU) and the prodrug capecitabine have been extensively used for treatment of many types of cancer including colorectal, gastric, head and neck. Approximately, 10 to 25% of patients suffer from severe fluoropyrimidine-induced toxicity. This may lead to dose reduction and treatment discontinuation. Pharmacogenetics research could be useful for the identification of predictive markers in chemotherapy treatment. The aim of the study was to investigate the role of five genetic polymorphisms within two genes (DPYD, TYMS) in toxicity and efficacy of fluoropyrimidine-based chemotherapy.

METHODS

Total genomic DNA was extracted from 83 cancer patients treated with fluoropyrimidine-based chemotherapy. In this study, three polymorphisms were genotyped in dihydropyrimidine dehydrogenase gene c.1905+1 G>A (DPYD*2A; rs3918290), c.1679 T>G (I560S; DPYD*13; rs55886062), and c.2846A>T (D949V; rs67376798) and two polymorphisms, besides the Variable Number of Tandem Repeat (VNTR) polymorphism and 6-bp insertion/deletion polymorphism in thymidylate synthase gene. The analysis of polymorphisms for rs3918290, rs55886062, rs67376798 and 6-bp insertion/deletion in TYMS was done by Polymerase Chain Reaction-restriction Fragment Length Polymorphism (PCRRFLP) TYMS VNTR analysis. 5-FU-related toxicities such as anemia, febrile neutropenia, neurotoxicity, vomiting, nausea, and mucositis were evaluated according to NCI-CTC criteria version 4.0. T-test and chi-square were used and p-values less than 0.05 were considered statistically significant.

RESULTS

DPYD gene polymorphisms were not observed in this study. The frequency of the TYMS +6 bp allele was 40.35% and the -6 bp allele was 59.65% in this study. The frequency of VNTR 2R allele was 48.75% and 3R allele was 51.15%. Toxicity grade II diarrhea, mucositis, nausea, vomiting, and neurotoxicity was 2.2, 24.1, 15.7, 6, and 51.8%, respectively. Thymidylate synthase ins/del polymorphisms were associated with increased grade III neurotoxicity (p=0.02). Furthermore, anemia grade III was significantly associated with 2R/2R genotype (0.009).

CONCLUSION

Thymidylate synthase gene polymorphisms may play a key role in fluoropyrimidne -based chemotherapy. Although rare DPYD polymorphisms were not observed in our study, according to large population studies, DPYD gene polymorphisms could be used as a predictive biomarker for patient treatments.