Recommendation on testing for dihydropyrimidine dehydrogenase deficiency in the ESMO consensus guidelines for the management of patients with metastatic colorectal cancer

Cost-effectiveness of extended DPYD testing before fluoropyrimidine chemotherapy in metastatic breast cancer in the UK

The aim of this study was to evaluate the cost-effectiveness of ToxNav©, a multivariant genetic test, to screen for DPYD followed by personalized chemotherapy dosing for metastatic breast cancer in the UK compared with no testing followed by standard dose, standard of care. In the main analysis, ToxNav was dominant over standard of care, producing 0.19 additional quality-adjusted life years and savings of £78,000 per patient over a lifetime. The mean additional quality-adjusted life years per person from 1000 simulations was 0.23 savings (95% CI: 0.22-0.24) at £99,000 (95% CI: £95-102,000). Varying input parameters independently by range of 20% was unlikely to change the results in the main analysis. The probabilistic sensitivity analysis showed ~97% probability of the ToxNav strategy to be dominant.

Transgelin-2 interacts with CD44 to regulate Notch1 signaling pathway and participates in colorectal cancer proliferation and migration

The abnormal expression of transgelin-2 (TAGLN2) is related to tumor occurrence and progression. However, the underlying molecular mechanism of TAGLN2 in human colorectal cancer (CRC) is still poorly understood. Compared with adjacent tissues, TAGLN2 is overexpressed in CRC tissues. Its expression level is negatively correlated with the overall survival rate of patients with CRC. In addition, knockdown of TAGLN2 inhibited the proliferation and invasion of CRC cells. We also showed that TAGLN2 could interact with CD44 to regulate the Notch-1 signaling pathway. Our findings indicate there is increased TAGLN2 expression in CRC and that it may serve as a promising potential therapeutic target for CRC.

The use of pharmacogenetics to increase the safety of colorectal cancer patients treated with fluoropyrimidines

Fluoropyrimidines (FP) are given in the combination treatment of the advanced disease or as monotherapy in the neo-adjuvant and adjuvant treatment of colorectal cancerand other solid tumors including breast, head and neck and gastric cancer. FP present a narrow therapeutic index with 10 to 26% of patients experiencing acute severe or life-threatening toxicity. With the high number of patients receiving FP-based therapies, and the significant effects of toxicities on their quality of life, the prevention of FP-related adverse events is of major clinical interest. Host genetic variants in the rate limiting enzyme dihydropyrimidine dehydrogenase (DPYD) gene are related to the occurrence of extremely severe, early onset toxicity in FP treated patients. The pre-treatment diagnostic test of 4 DPYD genetic polymorphisms is suggested by the currently available pharmacogenetic guidelines. Several prospective implementation projects are ongoing to support the introduction of up-front genotyping of the patients in clinical practice. Multiple pharmacogenetic studies tried to assess the predictive role of other polymorphisms in genes involved in the FP pharmacokinetics/pharmacodynamic pathways, TYMS and MTHFR, but no additional clinically validated genetic markers of toxicity are available to date. The development of next-generation sequencing platforms opens new possibilities to highlight previously unreported genetic markers. Moreover, the investigation of the genetic variation in the patients immunological system, a pivotal target in cancer treatment, could bring notable advances in the field. This review will describe the most recent literature on the use of pharmacogenetics to increase the safety of a treatment based on FP administration in colorectal cancer patients.

Precision treatment in colorectal cancer: Now and the future

Until recently, a one‐drug‐fits‐all model was applied to every patient diagnosed with the same condition. But not every condition is the same, and this has led to many cases of ineffective treatment. Pharmacogenetics is increasingly used to stratify patients for precision medicine treatments, for instance, the UGT1A1*28 polymorphism as a dosage indicator for the use of irinotecan as well as epidermal growth factor receptor (EGFR) immunohistochemistry and KRAS Proto‐Oncogene (KRAS) exon 2 mutation tests for determining the likelihood of treatment response to cetuximab or panitumumab treatment in metastatic colorectal cancer (CRC). The other molecular subtypes, such as KRAS exon 3/4, B‐Raf Proto‐Oncogene, NRAF, PIK3CA, and PETN, were also reported as potential new pharmacogenetic targets for the current and the newly discovered anticancer drugs. In addition to next‐generation sequencing (NGS), primary tumor cells for in vivo and in vitro drug screening, imaging biomarker 3′‐Deoxy‐3′‐18F‐fluorothymidine positron emission tomography, and circulating tumor DNA (ctDNA) detection methods are being developed and may represent the future direction of precision medicine. This review will discuss the current environment of precision medicine, including clinically approved targeted therapies, the latest potential therapeutic agents, and the ongoing pharmacogenetic trials for CRC patients.

DPYD*6 plays an important role in fluoropyrimidine toxicity in addition to DPYD*2A and c.2846A>T: a comprehensive analysis in 1254 patients

Dihydropyrimidine dehydrogenase (DPYD) is a highly polymorphic gene and classic deficient variants (i.e., c.1236G>A/HapB3, c.1679T>G, c.1905+1G>A and c.2846A>T) are characterized by impaired enzyme activity and risk of severe adverse drug reactions (ADRs) in patients treated with fluoropyrimidines. The identification of poor metabolizers by pre-emptive DPYD screening may reduce the rate of ADRs but many patients with wild-type genotype for classic variants may still display ADRs. Therefore, the search for additional DPYD polymorphisms associated with ADRs may improve the safety of treatment with fluoropyrimidines. This study included 1254 patients treated with fluoropyrimidine-containing regimens and divided into cohort 1, which included 982 subjects suffering from gastrointestinal G≥2 and/or hematological G≥3 ADRs, and cohort 2 (control group), which comprised 272 subjects not requiring dose reduction, delay or discontinuation of treatment. Both groups were screened for DPYD variants c.496A>G, c.1236G>A/HapB3, c.1601G>A (DPYD*4), c.1627A>G (DPYD*5), c.1679T>G (DPYD*13), c.1896T>C, c.1905 + 1G>A (DPYD*2A), c.2194G>A (DPYD*6), and c.2846A>T to assess their association with toxicity. Genetic analysis in the two cohorts were done by Real-Time PCR of DNA extracted from 3 ml of whole blood. DPYD c.496A>G, c.1601G>A, c.1627A>G, c.1896T>C, and c.2194G>A variants were found in both cohort 1 and 2, while c.1905+1G>A and c.2846A>T were present only in cohort 1. DPYD c.1679T>G and c.1236G>A/HapB3 were not found. Univariate analysis allowed the selection of c.1905+1G>A, c.2194G>A and c.2846A>T alleles as significantly associated with gastrointestinal and hematological ADRs (p < 0.05), while the c.496A>G variant showed a positive trend of association with neutropenia (p = 0.06). In conclusion, c.2194G>A is associated with clinically-relevant ADRs in addition to the already known c.1905+1G>A and c.2846A>T variants and should be evaluated pre-emptively to reduce the risk of fluoropyrimidine-associated ADRs.

The Genotype for DPYD Risk Variants in Patients With Colorectal Cancer and the Related Toxicity Management Costs in Clinical Practice

Lack of information on the clinical utility of preemptive DPYD screening before fluoropyrimidine treatment is a major barrier preventing its use in clinical practice. This study aimed to define the association between DPYD variants and fluoropyrimidine-related toxicity management costs. A cost analysis was conducted on the toxicities experienced by 550 patients with colorectal cancer treated with fluoropyrimidine-based chemotherapy. Genotyping for DPYD*2A, DPYD*13, DPYDc. 2846A>T, DPYD-HapB3, and UGT1A1*28 was done retrospectively and did not affect patients' treatments. Carriers of at least one DPYD variant experienced higher toxicity management costs (€2,972; 95% confidence interval (CI), €2,456-€3,505) than noncarriers (€825; 95% CI, €785-€864) (P < 0.0001) and had a higher risk for toxicity requiring hospitalization (odds ratio, 4.14; 95% CI, 1.87-9.14). In patients receiving fluoropyrimidine/irinotecan, the incremental cost between DPYD variant and UGT1A1*28/*28 carriers and noncarriers was €2,975. This study suggests that the toxicity management costs during fluoropyrimidine-based therapy are associated with DPYD and UGT1A1*28 variants and supports the utility of genotyping.

Host genetic profiling to increase drug safety in colorectal cancer from discovery to implementation

Adverse events affect the pharmacological treatment of approximately 90% of colorectal cancer (CRC) patients at any stage of the disease. Chemotherapy including fluoropyrimidines, irinotecan, and oxaliplatin is the cornerstone of the pharmacological treatment of CRC. The introduction of novel targeted agents, as anti-EGFR (i.e. cetuximab, panitumumab) and antiangiogenic (i.e. bevacizumab, ziv-aflibercept, regorafenib, and ramucirumab) molecules, into the oncologist's toolbox has led to significant improvements in the life expectancy of advanced CRC patients, but with a substantial increase in toxicity burden. In this respect, pharmacogenomics has largely been applied to the personalization of CRC chemotherapy, focusing mainly on the study of inhered polymorphisms in genes encoding phase I and II enzymes, ATP-binding cassette (ABC)/solute carrier (SLC) membrane transporters, proteins involved in DNA repair, folate pathway and immune response. These research efforts have led to the identification of some validated genetic markers of chemotherapy toxicity, for fluoropyrimidines and irinotecan. No validated genetic determinants of oxaliplatin-specific toxicity, as peripheral neuropathy, has thus far been established. The contribution of host genetic markers in predicting the toxicity associated with novel targeted agents' administration is still controversial due to the heterogeneity of published data. Pharmacogenomics guidelines have been published by some international scientific consortia such as the Clinical Pharmacogenomics Implementation Consortium (CPIC) and the Dutch Pharmacogenetics Working Group (DPWG) strongly suggesting a pre-treatment dose adjustment of irinotecan based on UGT1A1*28 genotype and of fluoropyrimidines based on some DPYD genetic variants, to increase treatment safety. However, these recommendations are still poorly applied at the patient's bedside. Several ongoing projects in the U.S. and Europe are currently evaluating how pharmacogenomics can be implemented successfully in daily clinical practice. The majority of drug-related adverse events are still unexplained, and a great deal of ongoing research is aimed at improving knowledge of the role of pharmacogenomics in increasing treatment safety. In this review, the issue of pre-treatment identification of CRC patients at risk of toxicity via the analysis of patients' genetic profiles is addressed. Available pharmacogenomics guidelines with ongoing efforts to implement them in clinical practice and new exploratory markers for clinical validation are described.

SNPs in predicting clinical efficacy and toxicity of chemotherapy: walking through the quicksand

In the "precision medicine" era, chemotherapy still remains the backbone for the treatment of many cancers, but no affordable predictors of response to the chemodrugs are available in clinical practice. Single nucleotide polymorphisms (SNPs) are gene sequence variations occurring in more than 1% of the full population, and account for approximately 80% of inter-individual genomic heterogeneity. A number of studies have investigated the predictive role of SNPs of genes enrolled in both pharmacodynamics and pharmacokinetics of chemotherapeutics, but the clinical implementation of related results has been modest so far. Among the examined germline polymorphic variants, several SNPs of dihydropyrimidine dehydrogenase (DPYD) and uridine diphosphate glucuronosyltransferases (UGT) have shown a robust role as predictors of toxicity following fluoropyrimidine- and/or irinotecan-based treatments respectively, and a few guidelines are mandatory in their detection before therapy initiation. Contrasting results, however, have been reported on the capability of variants of other genes as MTHFR, TYMS, ERCC1, XRCC1, GSTP1, CYP3A4/3A5 and ABCB1, in predicting either therapy efficacy or toxicity in patients undergoing treatment with pyrimidine antimetabolites, platinum derivatives, irinotecan and taxanes. While formal recommendations for routine testing of these SNPs cannot be drawn at this moment, therapeutic decisions may indeed benefit of germline genomic information, when available. Here, we summarize the clinical impact of germline genomic variants on the efficacy and toxicity of major chemodrugs, with the aim to facilitate the therapeutic expectance of clinicians in the odiern quicksand field of complex molecular biology concepts and controversial trial data interpretation.

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

Background

Upfront screening for dihydropyrimidine dehydrogenase (DPD) deficiency in patients scheduled for 5-FU should help reduce the risk of toxicities by preventive adaptive dosing. Our group has developed a simple functional testing categorizing patients upon their DPD status, i.e. extensive metabolizer (EM) or poor metabolizer (PM) patients, using UH2/U ratio measurement in plasma as a surrogate for DPD activity. 5-FU dosing can then be tailored according to DPD deficiency status.

Objectives

We present here an observational study of this strategy implemented in routine clinical practice when treating head-and-neck cancer patients.

Results

A total of 218 evaluable adult patients were treated with a 5-FU-regimen, with DPD-based adaptive dosing. Among them, 20 (9%) were identified as PM and received subsequently a 20-50% reduced dosing of 5-FU as compared with EM patients (2102 ±254 mg VS. 2577 ±353mg, p<0.001 ttest). Gender (Female) was associated with higher risk for being PM (p=0.01, Pearson's Chi squared test). Overall, early severe toxicities were seen only in 5% of patients, all being EM with standard dosing. Similarly, overall severe toxicities were observed in 12.8% of patients only, both figures being markedly lower than usually reported with standard 5-FU. Despite the average -20% reduction in 5-FU dosing between PM and EM patients, clinical efficacy was not statistically different between the two groups (p = 0.2774, chi-square test).

Conclusion

This study shows that 5-FU-related toxicities can be greatly reduced in routine clinical practice by the upfront detection of DPD deficient patients with simple adaptive dosing strategy.

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

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

Fluoropyrimidine-Associated Toxicity in Two Gastrointestinal Cancer Patients: Potential Role of Common DPYD Polymorphisms

While the majority of patients can be treated safely with fluoropyrimidine, some experience severe fluoropyrimidine-associated toxicity. The frequency and severity of these adverse events vary from patient to patient and are partially explained by genetic polymorphism into the dihydropyrimidine dehydrogenase (DPYD) gene. Carriers of the rare allelic variants DPYD*2A, DPYD*13, and DPYD D949V are more likely to experience severe adverse reactions during fluoropyrimidine-based therapy. However, these 3 genetic variants explain only a small percentage of the overall drug toxicity, and more frequent ones such as homozygous or compound heterozygous DPYD V732I can play a key role.

Lethal hepatotoxicity following 5-fluorouracil/cisplatin chemotherapy: a relevant case report

Some articles have reported severe toxicities induced by cisplatin/5-fluorouracil regimens, nevertheless, severe and lethal liver toxicity has not been previously reported. In this article, we report the case of a 72-year-old woman, who developed fulminant hepatitis, hypoglycemia and hypotension with atrial fibrillation not responding to treatment. After ruling out all other possible causes of hepatitis, the toxicity was more likely attributed to 5-fluorouracil. Genotyping was performed and the patient was found to be a homozygote carrier of the T variant of the MTHFR gene. The patient died two days later. Several factors, including genetic factors, could explain this severe toxicity. The present case discusses the importance of personalized medicine in oncology based on pharmacogenetic analysis of polymorphisms.