5-Fluorouracil degradation rate as a predictive biomarker of toxicity in breast cancer patients treated with capecitabine.
Summary (2 min read)
Introduction
- Capecitabine is an oral prodrug of 5-fluorouracil (5-FU), enzymatically activated by timidina phosphorylase in tumour tissue, that was rationally designed to mimic continuous infusion 5-FU.1 Capecitabine is rapidly absorbed from the gastrointestinal (GI) tract and metabolized by carboxylesterase in liver, and it is converted to 50 deoxy-5-fluorocytidine and then to 50 deoxy-5-fluorouridine (50 DFUR) by cytidine deaminase.
- In advanced breast cancer (ABC), the efficacy and safety of capecitabine have been demonstrated both as monotherapy and in combination with other drugs.
- Several trials of adjuvant capecitabine administered in combination with other effective drugs did not show an advantage over regimens without capecitabine.
- Finally, skin reactions are common: rash and hand&foot syndrome are frequent but also severe skin toxicities such as Stevens– Johnson syndrome and toxic epidermal necrolysis are reported.
- The authors previously demonstrated that the evaluation of dihydropyrimidine dehydrogenase (DPYD) polymorphisms and the 5-FU degradation rate (5FUDR) can help to distinguish patients prone to develop severe side effects in colorectal and gastric patients treated with 5-FU in both adjuvant and metastatic setting.
Patients
- Clinical data of 37 patients treated for locally advanced and metastatic breast cancer at their institutions were retrospectively collected.
- Age >18 years old, diagnosis of metastatic breast cancer, previous treatment with capecitabine for metastatic breast cancer, PS 0-1 at baseline, absence of liver or kidney impairment, also known as Inclusion criteria were.
- The authors performed a monthly assessment of treatment toxicity according to the National Cancer Institute-Common Terminology Criteria for Adverse Events version 5 (CTCAE v.5, 2017).
- Patients were instructed to report and were usually asked for common toxicities during follow-up visits.
- The study was conducted in accordance with the Declaration of Helsinki and the protocol approved by the institutional (Sapienza University) ethical committee.
Methods
- Peripheral blood samples from all patients enrolled were collected at the baseline as clinical practice in their Institution to perform genotype analysis and evaluate 5FUDR on peripheral blood cells.
- The individual 5FUDR was assessed by a liquid chromatography–tandem mass spectrometry on peripheral blood mononuclear cells (PBMC).
- The assay is composed of three steps: (1) PBMC isolation from peripheral blood, (2) PBMC incubation with 5-FU in vitro and (3) determination of 5-FU amount to calculate the degradation rate.
- 18 5FUDR is the result of the whole intracellular metabolizing process, regardless the presence or not of a single enzyme alterations.
Statistical analysis
- SPSS statistical software, Version 24 (SPSS Inc. Chicago, Illinois, USA), was used.
- The v2 test and t test for unpaired data were applied to compare the frequencies and mean, respectively.
- Genotype variant association with toxicity events was first analysed using univariate logistic regression and further by a multivariate logistic regression including patient age ( 60 vs. <60 years old), comorbidity ( 2 vs. <2) and type of chemotherapy regimen (CAPE alone vs. CAPE plus navelbine/lapatinib).
Results
- Overall, 37 Caucasian patients with a median age of 58 years old (range 34–79) treated with CAPE-based chemotherapy for stage II–IV breast cancer were included in this study.
- Their baseline and demographic characteristics are shown in Table 1.
- The frequency of toxicity (73.7 vs. 77.3% and 26.7 vs. 22.7% for any grade and G3–4 toxicity, respectively) did not differ between patients who received CAPE alone or in combination with other drugs.
Pharmacogenetic variant analyses
- Homozygous DPYD IVS14þ 1G>A SNP nor heterozygous DPYD was not observed in the cohort.
- No association was found between 5FUDR and either TSER or MTHFR genotypes (Table 3).
Discussion
- Several enzymes are involved in the capecitabine metabolism.
- The dihydropyrimidine dehydrogenase enzyme (DPD) metabolizes about 80% of the administered 5-FU into the inactive metabolite 5,6-dihydro-5fluorouracil.
- 1G>A polymorphism in the DPYD gene, which leads to the production of an inactive protein and severe toxicity in about one-half of carrier patients.
- 33,34 Besides, the authors showed that 5FUDR is associated with progression-free survival in metastatic colorectal patients with an advantage for ultra/poor metabolizers versus normal metabolizers.
- Hence, the authors carried out a retrospective study aimed to evaluate the impact of each of the following gene polymorphisms MTHFR C667T, MTHFR A1298C, DPYD IVS14þ 1G>A, TSER and the 5-fluorouracil degradation rate (5-FUDR) on toxicities in breast cancer patients treated with capecitabine.
MTHFR
- Suggesting a predictive value of 5FU-degradation regardless of cancer origin and stage.
- 1G>A polymorphism in the DPYD gene, but this alteration has a low frequency, and it is not present in some of the patients with severe toxicity.
- In the adjuvant setting, a test able to predict severe toxicities in these particular setting is crucial in order to avoid reduced dose, delayed administration or interruption of therapy and to maintain dose intensity.
- Finally, their study has some relevant limitations: it is a retrospective and monocentric study and the population is limited.
- The authors highlight the importance of conducting prospective studies on larger sample size and on a homogeneous population in order to evaluate the 5FUDR impact on both toxicities and outcome.
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Cites background from "5-Fluorouracil degradation rate as ..."
...is warranted.(76) Setting up processes for collection of samples and routine analysis would facilitate further work to expand monitoring beyond the current recommended dosage regimens detailed by IATDMCT....
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...Due to its cytotoxicity [8] and resistance occurrence, 5-FU is one of the most commonly used TS-directed anticancer drugs applied in combination with other chemotherapy compounds for the treatment of various cancers, including breast cancer [9,10]....
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References
99 citations
"5-Fluorouracil degradation rate as ..." refers background in this paper
...Several enzymes are involved in the capecitabine metabolism.(19) The dihydropyrimidine dehydrogenase enzyme (DPD) metabolizes about 80% of the administered 5-FU into the inactive metabolite 5,6-dihydro-5fluorouracil....
[...]
93 citations
"5-Fluorouracil degradation rate as ..." refers background in this paper
...Other enzymes are involved in 5-FU metabolism, and their polymorphisms could result in increased and unexpected toxicities such as MTHFR, one of the most relevant enzyme that regulates intracellular folate levels that affect DNA synthesis and methylation and TYMS.(24,25) The single-nucleotide polymorphisms (SNPs) of MTHFR 677C>T and 1298A>C are clinically relevant and have been associated with the toxicity of 5-FU....
[...]
...Other enzymes are involved in 5-FU metabolism, and their polymorphisms could result in increased and unexpected toxicities such as MTHFR, one of the most relevant enzyme that regulates intracellular folate levels that affect DNA synthesis and methylation and TYMS.24,25 The single-nucleotide polymorphisms (SNPs) of MTHFR 677C>T and 1298A>C are clinically relevant and have been associated with the toxicity of 5-FU.26 Moreover, variations of the TSER in the promoter of TYMS gene have been related to both survival/response outcomes and toxicities in patients affected by colorectal cancer treated with 5-FU-based chemotherapy.27–30 Finally, we previously described a non-genomic assay that seems to be able to predict 5-FU toxicity by the assessment of the 5FUDR in the PBMC.31 This parameter indicates the amount of drug consumed by cells in a time unit and reflexes the result of the entire 5-FU degradation metabolism, not only a single enzyme activity.32 Applying the assay on colorectal patients, we previously described two different classes of patients with a higher risk to develop 5-FU unexpected toxicities: poor metabolizers and ultrarapid metabolizers.33,34 Besides, we showed that 5FUDR is associated with progression-free survival in metastatic colorectal patients with an advantage for ultra/poor metabolizers versus normal metabolizers.35 Up to now, no data were available on the correlation between 5FUDR and DPD/MTHFR/TSER polymorphism and capecitabine-related toxicity specifically in breast cancer patients....
[...]
92 citations
"5-Fluorouracil degradation rate as ..." refers background in this paper
...Other enzymes are involved in 5-FU metabolism, and their polymorphisms could result in increased and unexpected toxicities such as MTHFR, one of the most relevant enzyme that regulates intracellular folate levels that affect DNA synthesis and methylation and TYMS.(24,25) The single-nucleotide polymorphisms (SNPs) of MTHFR 677C>T and 1298A>C are clinically relevant and have been associated with the toxicity of 5-FU....
[...]
...Other enzymes are involved in 5-FU metabolism, and their polymorphisms could result in increased and unexpected toxicities such as MTHFR, one of the most relevant enzyme that regulates intracellular folate levels that affect DNA synthesis and methylation and TYMS.24,25 The single-nucleotide polymorphisms (SNPs) of MTHFR 677C>T and 1298A>C are clinically relevant and have been associated with the toxicity of 5-FU.26 Moreover, variations of the TSER in the promoter of TYMS gene have been related to both survival/response outcomes and toxicities in patients affected by colorectal cancer treated with 5-FU-based chemotherapy.27–30 Finally, we previously described a non-genomic assay that seems to be able to predict 5-FU toxicity by the assessment of the 5FUDR in the PBMC.31 This parameter indicates the amount of drug consumed by cells in a time unit and reflexes the result of the entire 5-FU degradation metabolism, not only a single enzyme activity.32 Applying the assay on colorectal patients, we previously described two different classes of patients with a higher risk to develop 5-FU unexpected toxicities: poor metabolizers and ultrarapid metabolizers.33,34 Besides, we showed that 5FUDR is associated with progression-free survival in metastatic colorectal patients with an advantage for ultra/poor metabolizers versus normal metabolizers.35 Up to now, no data were available on the correlation between 5FUDR and DPD/MTHFR/TSER polymorphism and capecitabine-related toxicity specifically in breast cancer patients....
[...]
85 citations
75 citations
"5-Fluorouracil degradation rate as ..." refers background in this paper
...Oral administration seems to be preferred by patients and allows to avoid complications and costs linked to 5-FU IV infusion.(3)...
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