Background

5-fluorouracil

The agent 5-FU is a widely used antineoplastic chemotherapy drug that targets thymidylate synthase (TYMS) enzyme, which is involved in DNA production. 5-FU has been used for many years to treat solid tumors (e.g., colon and rectal cancer, head and neck cancer). In general, the incidence of grade 3 or 4 toxicity (mainly neutropenia, diarrhea, mucositis, and hand-foot syndrome) increases with higher systemic exposure to 5-FU. Several studies also have reported statistically significant positive associations between 5-FU exposure and tumor response. In current practice, however, 5-FU dose is reduced when symptoms of severe toxicity appear but is seldom increased to promote efficacy.

Based on known 5-FU pharmacology, it is possible to determine a sampling scheme for the area under the curve (AUC) determination and to optimize an AUC target and dose-adjustment algorithm for a particular 5-FU chemotherapy regimen and patient population. For each AUC value or range, the algorithm defines the dose adjustment during the next chemotherapy cycle most likely to achieve the target AUC without overshooting and causing severe toxicity.

In clinical research studies, 5-FU blood plasma levels most recently have been determined by high-performance liquid chromatography or liquid chromatography coupled with tandem mass spectrometry. Both methods require expertise to develop an in-house assay and may be less amenable to routine clinical laboratory settings.

Measuring Exposure to 5-FU

Laboratory Testing

Patient exposure to 5-FU is most accurately described by estimating the AUC, the total drug exposure over a defined period of time. 5-FU exposure is influenced by the method of administration, circadian variation, liver function, and the presence of inherited dihydropyrimidine reductase (DPYD)-inactivating genetic variants that can greatly reduce or abolish 5-FU catabolism. As a result, both inter- and intrapatient variability in 5-FU plasma concentration during administration is high.

Determination of 5-FU AUC requires complex technology and expertise that may not be readily available in a clinical laboratory setting. In the U. S., a commercial immunoassay (My5-FU) can quantify plasma 5-FU concentration from a blood sample drawn during continuous infusion at steady state (18-44 hours after the start of infusion) and provide a dose-adjustment algorithm to maintain plasma 5-FU AUC between 20 and 30 mg/h/L during the next cycle.^1,

Genetic Testing

5-FU is a pyrimidine antagonist, similar in structure to the normal pyrimidine building blocks of RNA (uracil) and DNA (thymine). More than 80% of administered 5-FU is inactivated and eliminated via the catabolic pathway; the remainder is metabolized via the anabolic pathway.

Catabolism of 5-FU is controlled by the activity of DPYD. Because DPYD is a saturable enzyme, the pharmacokinetics of 5-FU are strongly influenced by the dose and schedule of administration.^2, For example, 5-FU clearance is faster with continuous infusion than with bolus administration, resulting in very different systemic exposure to 5-FU during the course of therapy. Genetic variants in DPYD, located on chromosome 1, can lead to reduced 5-FU catabolism and increased toxicity. Many variants have been identified (e.g., IVS14+1G>A [also known as DPYD*2A], 2846A>T [D949V]). DPYD deficiency is an autosomal codominantly inherited trait.^3,

The anabolic pathway metabolizes 5-FU to an active form that inhibits DNA and RNA synthesis by competitive inhibition of TYMS or by incorporation of cytotoxic metabolites into nascent DNA.^4, Genetic variants in TYMS can cause tandem repeats in the TYMS enhancer region (TSER). One variant leads to three tandem repeats (TSER*3) and has been associated with 5-FU resistance due to increased tumor TYMS expression compared with the TSER*2 variant (two tandem repeats) and wild-type forms.

Regulatory Status

Clinical laboratories may develop and validate tests in-house and market them as a laboratory service; laboratory-developed tests must meet the general regulatory standards of the Clinical Laboratory Improvement Amendments. My5-FU™ (Saladax Biomedical) and genetic testing for variants in DPYD and TYMS for predicting the risk of 5-FU toxicity and chemotherapeutic response (ARUP Laboratories) are available under the auspices of the Clinical Laboratory Improvement Amendments. Laboratories that offer laboratory-developed tests must be licensed by the Clinical Laboratory Improvement Amendments for high-complexity testing. To date, the U.S. Food and Drug Administration has chosen not to require any regulatory review of this test.

Related Policies

• None

The Human Genome Variation Society nomenclature is used to report information on variants found in DNA and serves as an international standard in DNA diagnostics. It is being implemented for genetic testing medical policy updates starting in 2017 (see Table PG1). The Society’s nomenclature is recommended by the Human Variome Project, the HUman Genome Organization, and by the Human Genome Variation Society itself.

The American College of Medical Genetics and Genomics and the Association for Molecular Pathology standards and guidelines for interpretation of sequence variants represent expert opinion from both organizations, in addition to the College of American Pathologists. These recommendations primarily apply to genetic tests used in clinical laboratories, including genotyping, single genes, panels, exomes, and genomes. Table PG2 shows the recommended standard terminology-“pathogenic,” “likely pathogenic,” “uncertain significance,” “likely benign,” and “benign”-to describe variants identified that cause Mendelian disorders.

Table PG1. Nomenclature to Report on Variants Found in DNA

Previous	Updated	Definition
Mutation	Disease-associated variant	Disease-associated change in the DNA sequence
	Variant	Change in the DNA sequence
	Familial variant	Disease-associated variant identified in a proband for use in subsequent targeted genetic testing in first-degree relatives

Table PG2. ACMG-AMP Standards and Guidelines for Variant Classification

Variant Classification	Definition
Pathogenic	Disease-causing change in the DNA sequence
Likely pathogenic	Likely disease-causing change in the DNA sequence
Variant of uncertain significance	Change in DNA sequence with uncertain effects on disease
Likely benign	Likely benign change in the DNA sequence
Benign	Benign change in the DNA sequence

ACMG: American College of Medical Genetics and Genomics; AMP: Association for Molecular Pathology.

Genetic Counseling

Experts recommend formal genetic counseling for patients who are at risk for inherited disorders and who wish to undergo genetic testing. Interpreting the results of genetic tests and understanding risk factors can be difficult for some patients; genetic counseling helps individuals understand the impact of genetic testing, including the possible effects the test results could have on the individual or their family members. It should be noted that genetic counseling may alter the utilization of genetic testing substantially and may reduce inappropriate testing; further, genetic counseling should be performed by an individual with experience and expertise in genetic medicine and genetic testing methods.

Medicare Coverage:
There is no National Coverage Determination (NCD) or Local Coverage Determination (LCD) for jurisdiction JL for this service. Therefore, Medicare Advantage Products will follow the Horizon BCBSNJ Medical Policy.


[RATIONALE: This policy was created in 2012 and has been updated regularly with searches of the MEDLINE database. The most recent literature update was performed through May 29, 2019.

The primary goal of pharmacogenomics testing and personalized medicine is to achieve better clinical outcomes compared with the standard of care. Drug response varies greatly between individuals, and genetic factors are known to play a role. However, in most cases, the genetic variation only explains a modest portion of the variance in the individual response because clinical outcomes are also affected by a wide variety of factors including alternate pathways of metabolism and patient- and disease-related factors that may affect absorption, distribution, and elimination of the drug. Therefore, assessment of clinical utility cannot be made by a chain of evidence from clinical validity data alone. In such cases, evidence evaluation requires studies that directly demonstrate that the pharmacogenomic test alters clinical outcomes; it is not sufficient to demonstrate that the test predicts a disorder or a phenotype.

Evidence reviews assess whether a medical test is clinically useful. A useful test provides information to make a clinical management decision that improves the net health outcome. That is, the balance of benefits and harms is better when the test is used to manage the condition than when another test or no test is used to manage the condition.

The first step in assessing a medical test is to formulate the clinical context and purpose of the test. The test must be technically reliable, clinically valid, and clinically useful for that purpose. Evidence reviews assess the evidence on whether a test is clinically valid and clinically useful. Technical reliability is outside the scope of these reviews, and credible information on technical reliability is available from other sources.

Laboratory Testing to determine 5-fluorouracil Area Under the Curve for Dose Adjustment

Clinical Context and Proposed Clinical Utility

The proposed clinical utility of laboratory testing is to use test results to guide 5-FU dosing so that the therapeutic impact is maximized and the toxicity is decreased.

The question addressed in this policy is: Can lab tests be used to guide 5-FU dosing to maximize therapeutic impact and minimize toxicity?

The following PICOTS were used to select literature to inform this policy.

Patients

The relevant population of interest are patients with cancer who have an indication for 5-FU treatment.

Interventions

The test being considered is laboratory assays to determine 5-FU AUC.

Comparators

The following practice is currently being used to make decisions about dosing of 5-FU. This involves standard dosing by body weight, specifically body surface area (BSA)-based dosing.

Outcomes

The outcomes of interest are reductions in treatment-related morbidity related to 5-FU toxicity. Types of severe toxicity include neutropenia, diarrhea, mucositis, and hand-foot syndrome.

Timing

Specific survival outcomes may vary by type of cancer but generally, 1- to 2-year survival is a short-term outcome and 5- and 10-year survival is a long-term outcome. Treatment-related morbidity can be acute toxicity (≤14 days) or late toxicity (>14 days).

Setting

Patients would be tested in the oncology setting.

Simplifying Test Terms

There are three core characteristics for assessing a medical test. Whether imaging, laboratory, or other, all medical tests must be:

• Technically reliable
• Clinically valid
• Clinically useful.

Diagnostic tests detect the presence or absence of a condition. Surveillance and treatment monitoring are essentially diagnostic tests over a time frame. Surveillance to see whether a condition develops or progresses is a type of detection. Treatment monitoring is also a type of detection because the purpose is to see if treatment is associated with the disappearance, regression, or progression of the condition.

Prognostic tests predict the risk of developing a condition in the future. Tests to predict response to therapy are also prognostic. Response to therapy is a type of condition and can be either a beneficial response or adverse response. The term predictive test is often used to refer to a response to therapy. To simplify terms, we use prognostic to refer both to predicting a future condition or predicting response to therapy.

Technically Reliable

Assessment of technical reliability focuses on specific tests and operators and requires a review of unpublished and often proprietary information. Review of specific tests, operators, and unpublished data are outside the scope of this policy, and alternative sources exist. This policy focuses on the clinical validity and clinical utility.

Clinically Valid

A test must detect the presence or absence of a condition, the risk of developing a condition in the future, or treatment response (beneficial or adverse).

Kline et al (2014) assessed My5-FU in a retrospective study of patients with stage II and III (n=35) or stage IV or recurrent (n=49) colorectal cancer (CRC) who received 5-FU regimens at a single-center in the U. S.^5, Thirty-eight patients chose pharmacokinetic monitoring with OnDose and 46 patients were dosed by BSA. Median progression-free survival did not differ by dosing strategy in stage IV or recurrent patients (14 months with AUC monitoring vs 10 months BSA dosing; p=0.16) but did differ in stage II and III patients (p=0.04). Thirty-seven percent of stage IV or recurrent patients in both dosing strategy groups experienced grade 3 toxicity. Among stage II and III patients, 32% of AUC-monitored patients and 69% of BSA-dosed patients experienced grade 3 toxicity (p=0.04). The onset of adverse events also was delayed in the AUC-monitored group (6-7 months) compared with the BSA-dose group (two months; p=0.01).

My5-FU was clinically validated for patients with CRC in an observational analysis reported by Saam et al (2011).^6, Sequential patients (n=357) were treated with constant infusion 5-FU using current adjuvant or metastatic treatment protocols with or without bevacizumab. Samples were drawn at least two hours after the start of and before the end of each infusion and sent for analysis. Sixty-two (17%) patients were studied longitudinally across 4 sequential sample submissions (i.e., 4, 5-FU treatment infusions), of which 3 (5%) were within the target AUC after the first infusion. By the fourth infusion, this percentage rose to 37%, and outliers were reduced. Use of bevacizumab did not affect results. Response and toxicity were not reported.

Section Summary: Clinically Valid

Several analyses of patients with CRC have evaluated the clinical validity of the My5-FU assay. In one study, the rate of severe toxicity was significantly lower in patients with stage II and III cancer who chose pharmacokinetic monitoring vs BSA monitoring but progression-free survival did not differ between groups in patients with stage IV or recurrent cancer. In another study, among patients studied longitudinally and monitored with My5-FU, 3% were within the target AUC after the first infusion, and this reached 37% by the fourth infusion.

Clinically Useful

A test is clinically useful if the use of the results informs management decisions that improve the net health outcome of care. The net health outcome can be improved if patients receive correct therapy, or more effective therapy, or avoid unnecessary therapy, or avoid unnecessary testing.

Direct Evidence

Direct evidence of clinical utility is provided by studies that have compared health outcomes for patients managed with and without the test. Because these are intervention studies, the preferred evidence would be from randomized controlled trials (RCTs).

The results of single-arm trials of AUC-targeted 5-FU dose adjustment in advanced CRC patients have suggested consistently improved tumor response.^7,8,9, Similar, although less compelling, results were seen in single-arm trials of AUC-targeted 5-FU dosing in head and neck cancer.^10,11, The best contemporary evidence supporting AUC-targeted dosing consists of two RCTs, one enrolling patients with CRC and the other enrolling patients with head and neck cancer. No trials of any design were identified for 5-FU dose adjustment in other malignancies.

Gamelin et al (1998) developed a chart for weekly dose adjustment based on the results of an earlier, similar single-arm study (1996)^12, in which dose was increased by prespecified increments and intervals up to a maximum dose or the first signs of toxicity. In an RCT enrolling patients with metastatic CRC, Gamelin et al (2008) reported significantly improved tumor response (33.6% vs 18.3%, respectively; p<0.001) and a trend toward improved survival (40.5% vs 29.6%, respectively; p=0.08) in the experimental arm using AUC-targeted dosing (by high-performance liquid chromatography) for single-agent 5-FU compared with fixed dosing.^13, However, trialists also reported 18% grade 3 to 4 diarrhea in the fixed-dose control arm, higher than reported in comparable arms of 2 other large chemotherapy trials (5%-7%).^14,15, In the latter 2 trials, the delivery over a longer time period for both 5-FU (22 hours vs 8 hours) and leucovorin (2 hours vs bolus), which is characteristic of currently recommended 5-FU treatment regimens, likely minimized toxicity.

The administration schedule used in the Gamelin et al (2008) trial^13, is rarely currently used in clinical practice and is absent from current guidelines.^6, Additional optimization studies would be needed to apply 5-FU exposure monitoring and AUC-targeted dose adjustment to a more standard single-agent 5-FU treatment regimen, with validation in a comparative trial vs a fixed-dose regimen.

Fety et al (1998), in an RCT of patients with locally advanced head and neck cancer, used a different method of dose adjustment and reported overall 5-FU exposures in head and neck cancer patients that were significantly reduced in the dose-adjustment arm compared with the fixed-dose arm.^16, This reduced toxicity but did not improve clinical response. The dose-adjustment method in this trial might have been too complex because the 12 patients with protocol violations in this treatment arm (of 61 enrolled) all were related to 5-FU dose adjustment miscalculations. Because patients with protocol violations were removed from the analysis, results did not reflect “real-world” results of the dose-adjustment method. Also, the induction therapy regimen used two drugs, not the current standard of three, therefore, the generalizability of results to current clinical practice is limited.

Yang et al (2016) published a meta-analysis of data from the 2 RCTs described above (i.e., Gamelin et al [2008]^13, and Fetyet al [1998]), as well as from 3 observational studies.^17, In a pooled analysis, the overall response rate was significantly higher with pharmacokinetic AUC-monitored 5-FU therapy than with standard BSA-based monitoring (odds ratio, 2.04; 95% confidence interval [CI], 1.41 to 2.95). In terms of toxicity, the incidence of diarrhea (three studies), neutropenia (three studies), and hand-foot syndrome (two studies) did not differ significantly between the pharmacokinetic and BSA monitoring strategies. The rate of mucositis was significantly lower in the BSA-monitored group (3 studies; odds ratio, 0.16; 95% CI, 0.04 to 0.63). Most data were from observational studies, which are subject to selection and observational biases.

Section Summary: Clinically Useful

No RCTs or nonrandomized comparative studies were identified comparing health outcomes in cancer patients who did and did not have 5-FU dose adjustment using the My5-FU assay and who were treated with chemotherapy regimens used in current clinical practice. A systematic review of the available literature found a significantly higher response rate with BSA-based monitoring and no significant difference in toxicity. Most data were from observational studies; RCTs were conducted in the 1980s when different chemotherapy protocols were used.

Testing for DPYD or TYMS Variants Affecting 5-FU Dose Adjustment

Clinical Context and Proposed Clinical Utility

The proposed clinical utility of genetic testing is to use test results to guide 5-FU dosing so that the therapeutic impact is maximized and the toxicity is decreased.

The question addressed in this policy is: Can genetic tests guide 5-FU dosing to maximize therapeutic impact and minimize toxicity?

The following PICOTS were used to select literature to inform this policy.

Patients

The relevant population of interest are patients with cancer who have an indication for 5-FU treatment.

Interventions

The test being considered is genetic testing for variants (e.g., in DPYD and TYMS) affecting 5-FU metabolism.

Comparators

The following practice is currently being used to make decisions about dosing of 5-FU. This involves standard dosing by body weight, specifically BSA-based dosing.

Outcomes

The outcomes of interest are reductions in treatment-related morbidity related to 5-FU toxicity. Types of severe toxicity include neutropenia, diarrhea, mucositis, and hand-foot syndrome.

Timing

Specific survival outcomes may vary by type of cancer but generally, 1- to 2-year survival is a short-term outcome and 5- and 10-year survival is a long-term outcome. Treatment-related morbidity can be acute toxicity (≤14 days) or late toxicity (>14 days).

Setting

Patients would be tested in the oncology setting. Also, referral for genetic counseling is important for the explanation of the genetic disease, heritability, genetic risk, test performance, and possible outcomes.

Technically Reliable

Assessment of technical reliability focuses on specific tests and operators and requires a review of unpublished and often proprietary information. Review of specific tests, operators, and unpublished data are outside the scope of this policy, and alternative sources exist. This policy focuses on the clinical validity and clinical utility.

Clinically Valid

A test must detect the presence or absence of a condition, the risk of developing a condition in the future, or treatment response (beneficial or adverse).

Toxicity

A number of studies have evaluated the association between variants in the DPYD and/or TYMS genes and 5-FU toxicity. Cancer types and specific variants studied differed across these reports. Several meta-analyses have been published. Li et al (2014) identified 7 cohort studies with a total of 946 patients with CRC.^18, A pooled analysis of study findings found that DPYD variants correlated significantly with an increased risk of 5-FU-related toxicity. Also, Rosmarin et al (2014) identified 16 studies with a total of 4855 patients with CRC who were treated with capecitabine and other fluorouracil-based treatment regimens.^19, Capecitabine toxicity was significantly associated with several DPYD alleles and several TYMS single nucleotide variants.

A key study was published by Schwab et al (2008).^20, Trialists enrolled 683 patients who were receiving 5-FU for colon or other gastrointestinal cancers, cancers of unknown primary, or breast cancer in a genotype study. Seven different 5-FU regimens (monotherapy or in combination with folate or levamisole [not approved by the Food and Drug Administration]) administered by bolus or by infusion were included. Patients were genotyped for the DPYD splice site variant DPYD*2A (IVS14+ 1G>A), which leads to a nonfunctional enzyme, and for TYMS tandem repeats. Sensitivity, specificity, and positive and negative predictive values for overall toxicity, diarrhea, mucositis, and leukopenia were calculated (seeTable 1). Although heterozygosity for DPYD*2A had 99% specificity for serious toxicity, sensitivity ranged from 6% to 13%. Tandem repeats in TYMS were neither sensitive nor specific indicators of serious toxicity. Clinical factors also were examined for association with toxicity. Overall and in the group of 13 patients who were heterozygous for DPYD*2A, women were more likely than men to develop severe toxicity (overall odds ratio, 1.9; 95% CI, 1.26 to 2.87; p=0.002), most commonly mucositis. Bolus administration of 5-FU was a significant, independent predictor of severe toxicity overall.

Table 1. Grade 3 and 4 Adverse Events and DPYD and TYMS Genotypes

Toxicity	DPYD*2Aa (n=13), %	TYMS VNTR 2/3 or 3/3b (n=521),%
Overall toxicity
Sensitivity	6	65
Specificity	99	21
Positive predictive value	46	14
Negative predictive value	85	76
Diarrhea
Sensitivity	NR	57
Specificity	NR	22
Positive predictive value	NR	6
Negative predictive value	NR	84
Mucositis
Sensitivity	8	NR
Specificity	99	NR
Positive predictive value	31	NR
Negative predictive value	93	NR
Leukopenia
Sensitivity	13	NR
Specificity	99	NR
Positive predictive value	31	NR
Negative predictive value	96	NR

Adapted from Schwab et al (2008).^20,
NR: not reported; VNTR: variable number of tandem repeats.

^aHeterozygousDPYD*2Avs wt/wt.

^b Homozygous (3R/3R) or mixed heterozygous (2R/3R) triple repeats vs homozygous double repeats (2/2).

Vásquez et al (2017) prospectively evaluated 197 patients who were treated with 5-FU between 2013 and 2015.²² All patients were given the European Organization for Research and Treatment of Cancer quality of life assessment; there was a significant link between low European Organization for Research and Treatment of Cancer scores and the patient’s risk of developing severe toxicity. However, no significant association between variants in methylenetetrahydrofolate reductase (MTHFR) or TYMS tandem repeats and severe toxicity could be identified.

Nahid et al (2017) prospectively evaluated 161 patients with CRC who were treated with 5-FU-based chemotherapy.^22, Of these patients, clinical follow-up was available for 139 patients. Within this population, DPYD*2A was significantly associated with grade 3 or 4 toxicity (p=0.023). The MTHFR C677T variant was associated with increased efficacy of treatment (p=0.006). The authors recommended confirmation of these findings in a larger population.

Efficacy

A meta-analysis by Wang et al (2013) included 11 studies that assessed the association between TYMS variants (5¢ tandem repeats and a single nucleotide substitution [G>C] within triplet repeats) and survival outcomes.^23, Patients had gastric cancer or CRC and received 5-FU with or without leucovorin with or without levamisole. Three studies (n=311 patients) were eligible for pooled analysis of overall survival (OS). Statistical heterogeneity was not assessed. Patients who were homozygous for triplet repeats (3R/3R) had longer OS than patients who were homozygous for doublet repeats (2R/2R) or compound heterozygous (2R/3R).

Smyth et al (2017) published a randomized phase 3 trial of 456 patients treated for gastroesophageal cancer either with surgery alone or with surgery augmented with 5-FU chemotherapy.^24, Of these patients, genetic tests were performed for 289 patients. The primary outcome was any association between ten germline variants, including tandem repeats in the TYMS gene, and response rates, survival, or toxicity. Of the genes evaluated, none showed a variant significantly associated with chemotherapy-related toxicity. Of patients who received chemotherapy, there was a significant association between the TYMS 2R/2R genotype and longer survival: for these patients, median OS was not reached during the study, while patients with TYMS 2R/3R or 3R/3R genotypes, respectively, had a median OS of 1.44 or 1.60 years (p=0.005). Trialists noted that patients with TYMS 2R/2R genotype seemed to benefit from the chemotherapy treatment, with a significant interaction between treatment arm and genotype (p=0.029). No relationship between genotype and chemotherapy toxicity was noted. The trial was limited by the lack of tissue samples for all patients.

Section Summary: Clinically Valid

A number of observational studies and meta-analyses of these studies have found that DPYD variants and/or TYMS single nucleotide variants correlated significantly with an increased risk of 5-FU-related toxicity. A meta-analysis of three studies found a significant association between TYMS gene variants and longer OS. In a separate study, a different variant of TYMS was significantly associated with longer OS. The available studies reported statistical associations and did not prospectively evaluate health outcomes in patients with genetic variants.

Clinically Useful

A test is clinically useful if the use of the results informs management decisions that improve the net health outcome of care. The net health outcome can be improved if patients receive correct therapy, or more effective therapy, or avoid unnecessary therapy, or avoid unnecessary testing.

Direct Evidence

Direct evidence of clinical utility is provided by studies that have compared health outcomes for patients managed with and without the test. Because these are intervention studies, the preferred evidence would be from RCTs.

A TEC Assessment (2010) concluded that DPYD and TYMS variant testing did not meet TEC criteria.^25, The Assessment noted that the tests had “poor ability to identify patients likely to experience severe 5-FU toxicity. Although genotyping may identify a small fraction of patients for whom serious toxicity is a moderate to a strong risk factor, most patients who develop serious toxicity do not have variants in DPD or TS genes.”^25,

Several recent prospective observational studies have reported safety and effectiveness outcomes in patients who received genetic testing prior to receiving a 5-FU-based chemotherapy regimen. Characteristics and results of these studies are shown in Tables 2 and 3. Three of these, conducted by the same research group in the Netherlands, used historical controls,^26,27,28, and one also included a matched-pairs analysis using previously-collected data.^27, The others were single-arm, uncontrolled studies.^29,30,31, No prospective trials comparing efficacy and safety outcomes using concurrent control groups with or without pretreatment DPYD and/or TYMS testing were identified.

Henricks et al (2019) included 3 comparison groups in a prospective cohort study in which patients received genotyping prior to treatment as part of routine care.^27, Group 1 (n=40) were DPYD*2A carriers treated with an approximately 50% reduced fluoropyrimidine dose. Group 2 (n=1606) were wild-type patients who had been identified as part of an earlier study (Deenan et al [2016];^26, discussed below) and treated with a standard dose. Group 3 (n=86) were DPYD*2A carriers, identified from the literature, treated with a standard dose. Safety outcomes of the first 18 of the 40 patients in Group 1 were previously reported in Deenan et al (2016).^26, Patients in Group 1 were matched to those in Group 2 for the primary analysis for covariables known to influence treatment outcome. The primary effectiveness endpoint was OS. Secondary endpoints were progression-free survival and tumor response.

In matched-pair comparisons, Groups 1 and 2 did not differ on OS (hazard ratio 0.82; 95% CI 0.47 to 1.43; P=0.47), progression-free survival (hazard ratio 0.83; 95% CI 0.47 to 1.50; p=0.54), or  tumor response (0% vs 5% complete response; 20% vs 34% partial response; p>0.99), suggesting that the lower dose did not have a detrimental effect on treatment response in DPYD*2A carriers. The incidence of treatment-related toxicity, including overall toxicity, gastrointestinal toxicity, hematological toxicity, and hand-foot syndrome, was higher in the genotype-guided dosing group compared to wild-type patients, but differences were not statistically significant. Compared to the historical literature cohort who had received standard dosing, Group 1 patients had a lower risk of severe toxicity (77% vs 18%; P<0.001). There were no treatment-related deaths in the genotype-guided group, compared to 7 of 86 (8%) in the historical cohort. This study had several methodological limitations. Although patients were prospectively genotyped, data collection of outcomes was retrospective. A historical control group was used for the assessment of adverse events. There was a relatively large amount of missing data, small sample size, and the study was underpowered. Because it was conducted at a single-institution, its results may not be generalizable to other settings.

Deenan et al (2016) compared outcomes for pretreatment DPYD*2A testing with historical controls.^26, The study included cancer patients intending to undergo treatment with fluoropyrimidine-based therapy (5-FU or capecitabine).^26, Genotyping for DPYD*2A was performed before treatment, and dosing was adjusted based on the alleles identified. Patients with heterozygous variant alleles were treated with a reduced (i.e., ≥50%) starting dose of fluoropyrimidine for 2 cycles, and dosage was then individualized based on tolerability. No homozygous variant allele carriers were identified. Safety outcomes were compared with historical controls. Twenty-two (1.1%) of 2038 patients were heterozygous for DPYD*2A. Eighteen (82%) of these 22 patients were treated with reduced doses of capecitabine. Five (23%; 95% CI, 10% to 53%) patients experienced grade 3 or higher toxicity. In historical controls with DPYD*2A variant alleles, the rate of grade 3 or higher toxicity was 73% (95% CI, 58% to 85%). The historical controls were more likely to be treated with 5-FU-based therapy than with capecitabine-based therapy. Trial limitations included lack of randomization to a management strategy and use of historical, rather than concurrent, controls.

Henricks et al (2018) conducted a prospective study of adult patients with cancer who were intended to start fluoropyrimidine-based therapy.^28, Patients were enrolled from 17 hospitals in the Netherlands. Dose reductions were based on genotyping: Heterozygous DPYD variant allele carriers received an initial dose reduction of either 25% (for c.2846A>T and c.1236G>A) or 50% (for DPYD*2A and c.1679T>G). The researchers compared adverse events in the prospectively genotyped group who received genotype-based dosing, wild-type patients identified through prospective genotyping, and a historical control group of patients from a previously published meta-analysis who were DPYD variant carriers but did not receive genotype-guided dosing. The primary outcome was the frequency of severe treatment-related toxicity. Survival and response were not assessed. There was a higher incidence of grade 3 or higher toxicity in the genotype-dosing group compared to wild-type patients (39% vs 23%; p=0.0013).The relative risk for severe toxicity in DPYD*2A carriers who did not have genotype-guided dosing was 2.87 (95% CI 2.14 to 3.86), compared to 1.31 (0.63 to 2.73) in the cohort that received genotype-based dosing. The main limitation of this study is its use of a historical control group, with no control for confounders in the analysis.

Cremolini et al (2018)^31, reported chemotherapy-related adverse events experienced by patients with metastatic colon cancer who were enrolled in the phase III RCT and treated with first-line FOLFOXIRI plus bevacizumab or FOLFIRI plus bevacizumab. Of 508 randomized patients, 443 (87%) were genotyped for DPYD and UGT1A1 variants. All received study treatments as planned; dosage was not adjusted based on genotyping. All patients received study treatments at planned doses. Overall eight of ten patients who were DPYD carriers experienced grade 3 or higher adverse events. An advantage of this study was that it used prospectively and systematically collected data on adverse events. It is limited by the lack of a comparison group and because genotype-based dosing was not used.

Goff et al (2014) prospectively genotyped 42 adults who had gastric or gastroesophageal junction cancer for TSER tandem repeats.^29, Twenty-five patients who had TSER 2R/2R or 2R/3R genotypes received a modified 5-FU chemotherapy regimen until unacceptable toxicity or disease progression (median, 5.5 cycles); patients homozygous for triplet repeats (3R/3R) were excluded. The overall response rate in 23 evaluable patients was 39% (9 partial responses, no complete responses), which was worse than a 43% historical overall response rate in unselected patients. The overall response rate in 6 patients homozygous for doublet repeats (2R/2R) was 83% (5 partial responses, no complete responses). Median OS and progression-free survival in the entire cohort (secondary outcomes) was 11.3 months and 6.2 months, respectively; these rates were similar to those reported in unselected populations. The study was stopped before meeting target enrollment (minimum 75 patients) due to insufficient funding.

Magnani et al (2013) reported on 180 cancer patients receiving fluoropyrimidines (5-FU or capecitabine) who underwent DPYD analysis for the 1905+1 G>A variant by high-performance liquid chromatography.^30, Four patients were heterozygous carriers. Of these, 3 patients received a dose reduction of 50% to 60% but still experienced severe toxicities requiring hospitalization. One patient did not receive chemotherapy based on DPYD genotype and the presence of other variants found in mismatch repair genes.

Table 2. Summary of Key Nonrandomized Trials Characteristics

Study	Study Type	Country	Dates	Participants	Treatment
Henricks (2019)27,	Prospective screening, retrospective data collection, historical control groups	Netherlands	2007-2015	Patients intended to be treated with FU-based chemotherapy (n=1732)	Genotyping for DPYD*2A
Henricks (2018)28,	Prospective, with historical control	Netherlands	2015-2017	Patients intended to be treated with FU-based chemotherapy (n=1181)	Genotyping for DPYD*2A,
Cremolini (2018)31,	Prospective, uncontrolled	Italy	2008-2011	Patients with metastatic colorectal cancer who were treated with 5-FU and irinotecan-based chemotherapy in an RCT (n=443)	Genotyping for DPYD*2A
Deenen (2016)26,	Prospective, with historical control	Netherlands	2007-2011	Patients intended to be treated with FU-based chemotherapy (n=2038)	Genotyping for DPYD*2A
Goff (2014)29,	Prospective, uncontrolled	US	2008-2010	Adults with gastric or gastroesophageal junction cancer (n=25)	Genotyping for TSER tandem repeats
Magnani (2013)30,	Prospective, uncontrolled	Italy	2011-2012	Patients diagnosed with gastrointestinal, breast, head and neck, and other tumors (n=180)	DPYD analysis

FU: fluoropyrimidine

Table 3. Summary of Key Nonrandomized Trials Results

Study	Heterozygous Carrier  Patients	Grade 3 Toxicity	Overall Response Rate	Median Overall Survival
Henricks (2019)27,;
Group 1: DPYD*2A carriers, reduced dose (n=40)	40	7/40 (18%)	0% complete response, 20% partial response, 40% stable	27 months (range 1-83 months)
Group 2: Wild-type,standard dose (n= 1606)	NA	372/1606 (23%)	5% complete response, 29% partial response, 14% stable	24 months (range 0.7 to 97 months)
Group 3: DPYD*2A carriers, standard dose (n= 86)	86	66/86 (77%)	NR
Hazard ratio (95% CI)				Group 1 vs Group 2 0.82 (0.47 to 1.43)
p-value		Group 1 vs Group 2: 0.57 Group 1 vs group 3: <0.001	Group 1 vs Group 2: >0.99	Group 1 vs Group 2: 0.47
Henricks (2018)28,			NR	NR
DPYD*2A carriers, genotype-guided dosing	85/1181 (7.7%)	33/85 (39%) RR 1.31 (95% CI 0.63 to 2.73)
Historical control (DPYD*2A carriers, standard dose)		RR 2.87 (95% CI 2.14 to 3.86)
Relative risk (95% CI)
Historical control (wild-type, standard dosing)		231/1018 (23%); p<0.0013 vs genotype guided dosing cohort	NR	NR
Cremolini (2018)31,	10/439 (2.2%)	8/10 (80%)	NR	NR
Deenen (2016)26,	22/2038  (1.1%)	28%	NR	NR
P-value		<0.001
Goff (2014)29,	NR	NR	39.1% (9 partial responses, no complete responses)	11.3 months; 6.2 months
95% CI			22.2-59.2
Magnani (2013)30,	4 (2.2%)	NR	NR	NR

CI: confidence interval; NR: not reported; NA: not applicable; RR: relative risk

The purpose of the limitations tables (see Tables 4 and 5) is to display notable limitations identified in each study.

Table 4. Relevance Limitations

Study	Populationa	Interventionb	Comparatorc	Outcomesd	Duration of Follow-Upe
Henricks (2019)27,			historical control group
Henricks (2018)28,			historical control group	1. no effectiveness outcomes
Cremolini (2018)31,		3. genotype-based dosing not used	no control group	1. no effectiveness outcomes
Deenen (2016)26,			historical control group	1. no effectiveness outcomes
Goff (2014)29,			no control group
Magnani (2013)30,			no control group	1. no effectiveness outcomes

The study limitations stated in this table are those notable in the current review; this is not a comprehensive limitations assessment.

 ^a Population key: 1. Intended use population unclear; 2. Clinical context is unclear; 3. Study population is unclear; 4. Study population not representative of intended use.

^bIntervention key: 1. Classification thresholds not defined; 2. Version used unclear; 3. Not intervention of interest.

^c Comparator key: 1. Classification thresholds not defined; 2. Not compared to credible reference standard; 3. Not compared to other tests in use for same purpose.

^d Outcomes key: 1. Study does not directly assess a key health outcome; 2. Evidence chain or decision model not explicated; 3. Key clinical validity outcomes not reported (sensitivity, specificity and predictive values); 4. Reclassification of diagnostic or risk categories not reported; 5. Adverse events of the test not described (excluding minor discomforts and inconvenience of venipuncture or noninvasive tests).

^e Follow-Up key: 1. Follow-up duration not sufficient with respect to natural history of disease (true-positives, true-negatives, false-positives, false-negatives cannot be determined).

Table 5. Study Design and Conduct Limitations

Study	Selectiona	Blindingb	Delivery of Testc	Selective Reportingd	Data Completenesse	Statisticalf
Henricks (2019)27,	2 not randomized	1 not blinded			2, 3
Henricks (2018)28,	2 not randomized	1 not blinded			2, 3
Cremolini (2018)31,	2. convenience sample	1 not blinded			2, 3	2 no comparator
Deenen (2016)26,	2 not randomized	1 not blinded			2, 3
Goff (2014)29,	2 convenience sample	1 not blinded			2, 3	2 no comparator
Magnani (2013)30,	2 convenience sample	1 not blinded			2, 3	2 no comparator

The study limitations stated in this table are those notable in the current review; this is not a comprehensive limitations assessment. 

^a Selection key: 1. Selection not described; 2. Selection not random or consecutive (i.e., convenience).

^bBlinding key: 1. Not blinded to results of reference or other comparator tests.

^cTest Delivery key: 1. Timing of delivery of index or reference test not described; 2. Timing of index and comparator tests not same; 3. Procedure for interpreting tests not described; 4. Expertise of evaluators not described.

^d Selective Reporting key: 1. Not registered; 2. Evidence of selective reporting; 3. Evidence of selective publication.

^e Data Completeness key: 1. Inadequate description of indeterminate and missing samples; 2. High number of samples excluded; 3. High loss to follow-up or missing data.

^f Statistical key: 1. Confidence intervals and/or p values not reported; 2. Comparison with other tests not reported.

A TEC Assessment (2010) concluded that DPYD and TYMS variant testing had a poor ability to identify patients likely to experience severe 5-FU toxicity. Since the publication of the TEC Assessment, no prospective trials comparing the efficacy and toxicity outcomes in patients who did and did not undergo pretreatment DPYD and/or TYMS testing have been published. Three prospective observational studies used a historical control group and one also used a matched-pairs analysis to compare outcomes in patients who received genotype-based dosing to those who received standard dosing. No differences in OS, progression-free survival, or tumor progression were observed. Risk of serious toxicity was higher in DPYD allele carriers who received genotype-based dosing compared to wild-type patients but lower when compared to historical controls who were carriers but received standard dosing. The evidence is limited by retrospective data collection, use of historical control groups, small sample sizes, and missing data.

Summary of Evidence

For individuals who have cancer for whom treatment with 5-FU is indicated who receive laboratory assays to determine 5-FU AUC, the evidence includes RCTs, observational studies, and systematic reviews. The relevant outcomes are OS, disease-specific survival, test accuracy and validity, and treatment-related morbidity. Several analyses of patients with CRC have evaluated clinical validity. One study, for example, found the rate of severe toxicity was significantly lower in patients with stage II and III cancer who chose pharmacokinetic monitoring vs BSA monitoring but progression-free survival did not differ between groups in patients with stage IV or recurrent cancer. No RCTs or nonrandomized comparative studies were identified comparing health outcomes in cancer patients who did and did not have 5-FU dose adjustment using the My5-FU assay and who were treated with chemotherapy regimens used in current clinical practice. A systematic review of the available literature found a significantly higher response rate with BSA-based monitoring and no significant difference in toxicity. Most data derived from observational studies and the RCTs were conducted in the 1980s when different chemotherapy protocols were used. The evidence is insufficient to determine the effects of the technology on health outcomes.

For individuals who have cancer for whom treatment with 5-FU is indicated who receive genetic testing for variants (e.g., in DPYD and TYMS) affecting 5-FU metabolism, the evidence includes observational studies and systematic reviews. The relevant outcomes are OS, disease-specific survival, test accuracy and validity, and treatment-related morbidity. A TEC Assessment (2010) concluded that DPYD and TYMS variant testing had poor prognostic capacity to identify patients likely to experience severe 5-FU toxicity. Since the publication of that Assessment, no prospective trials comparing the efficacy and toxicity outcomes in patients who did and did not undergo pretreatment DPYD and/or TYMS testing have been published. Three prospective observational studies used a historical control group and one also used a matched-pairs analysis to compare outcomes in patients who received genotype-based dosing to those who received standard dosing. No differences in OS, progression-free survival, or tumor progression were observed. Risk of serious toxicity was higher in DPYD allele carriers who received genotype-based dosing compared to wild-type patients but lower when compared to historical controls who were carriers but received standard dosing. The evidence is limited by retrospective data collection, use of historical control groups, small sample sizes, and missing data. The evidence is insufficient to determine the effects of the technology on health outcomes.

SUPPLEMENTAL INFORMATION

Practice Guidelines and Position Statements

National Comprehensive Cancer Network Guidelines

Although current National Comprehensive Cancer Network guidelines acknowledge that the “selection, dosing, and administration of anticancer agents and the management of associated toxicities are complex,”^32, The Network does not recommend use of area under the curve guidance for 5-fluorouracil (5-FU) dosing or genetic testing for DPYD and/or TYMS variants in patients with colon,^33, rectal,^34, breast,^32, gastric,^35, pancreatic cancer,^36, or head and neck cancers.^37,

Clinical Pharmacogenetics Implementation Consortium

The CPIC (2009) was formed as a shared project between PharmGKB, an internet research tool developed by Stanford University, and the Pharmacogenomics Research Network of the National Institutes of Health. The CPIC (2013) published evidence-based guidelines for DPYD genotype and fluoropyrimidine dosing.^3, The guidelines did not address testing.

Anupdate to the CPIC (2017) guidelines was published by Amstutz et al (2018).^38, As in 2013, the primary focus of the guidelines was on the DPYD genotype and implications for dosing of fluoropyrimidine. In the update, the CPIC (2017) noted that genetic testing for DPYD may include “resequencing of the complete coding regions” or may be confined to analysis of particular risk variants, among which CPIC listed the c.190511G>A, c.1679T>G, c.2846A>T, and c.1129-5923C>G variants, as affecting 5-FU toxicity. The guideline further noted that, while other genes (TYMS,MTHFR) may be tested for variants, the clinical utility of such tests is yet unproven. In patients who have undergone genetic testing and who are known carriers of a DPYD risk variant, the guidelines recommended that caregivers strongly reduce the dosage of 5-FU-based treatments, or exclude them, depending on the patient’s level of DPYD activity. CPIC advised follow-up therapeutic drug monitoring to guard against underdosing and cautioned that genetic tests could be limited to known risk variants and, therefore, not identify other DPYD variants.

National Institute for Health and Care Excellence

The National Institute of Health and Care Excellence (2014) published evidence-based diagnostics guidance on the 5-FU assay for 5-FU chemotherapy dose adjustment.^39, The guidance stated: “The My5-FU assay is only recommended for use in research for guiding dose adjustment in people having fluorouracil chemotherapy by continuous infusion. The My5-FU assay shows promise and the development of robust evidence is recommended to demonstrate its utility in clinical practice.”

U.S. Preventive Services Task Force Recommendations

Not applicable.

Ongoing and Unpublished Clinical Trials

Some currently ongoing and unpublished trials that might influence this policy are listed in Table 6.

Table 6. Summary of Key Trials

NCT No.	Trial Name	Planned Enrollment	Completion Date
Ongoing
AUC-guided dosing of 5-FU
NCT00943137	The Optimisation of 5-Fluorouracil Dose by Pharmacokinetic Monitoring in Asian Patients With Advanced Stage Cancer	55	Jun 2017 (unknown)
NCT02055560a	Retrospective Data Comparison of Toxicity and Efficacy in Colorectal Cancer (CRC) Patients Managed With and Without 5-FU Exposure Optimization Testing	350	Dec 2017 (unknown)
DPYD and/or TYMS testing before use of fluoropyrimidines
NCT02324452	Safety, Feasibility and Cost-effectiveness of Genotype-directed Individualized Dosing of Fluoropyrimidines	1250	Mar 2018 (ongoing)
NCT00131599	Thymidylate Synthase Polymorphisms as a Predictor of Toxicity to 5-Fluorouracil Based Chemotherapy in Stage III Colon C	104	July 2017 (ongoing)
NCT02138617	Genotype-Directed Phase II Study Of Higher Dose Of Irinotecan In First-Line Metastatic Colorectal Cancer Patients Treated With Folfiri Plus Bevacizumab	100	May 2022

AUC: area under the curve; 5-FU: 5-Fluorouracil; NCT: national clinical trial.

^a Denotes industry-sponsored or cosponsored trial.]
________________________________________________________________________________________

Horizon BCBSNJ Medical Policy Development Process:

This Horizon BCBSNJ Medical Policy (the “Medical Policy”) has been developed by Horizon BCBSNJ’s Medical Policy Committee (the “Committee”) consistent with generally accepted standards of medical practice, and reflects Horizon BCBSNJ’s view of the subject health care services, supplies or procedures, and in what circumstances they are deemed to be medically necessary or experimental/ investigational in nature. This Medical Policy also considers whether and to what degree the subject health care services, supplies or procedures are clinically appropriate, in terms of type, frequency, extent, site and duration and if they are considered effective for the illnesses, injuries or diseases discussed. Where relevant, this Medical Policy considers whether the subject health care services, supplies or procedures are being requested primarily for the convenience of the covered person or the health care provider. It may also consider whether the services, supplies or procedures are more costly than an alternative service or sequence of services, supplies or procedures that are at least as likely to produce equivalent therapeutic or diagnostic results as to the diagnosis or treatment of the relevant illness, injury or disease. In reaching its conclusion regarding what it considers to be the generally accepted standards of medical practice, the Committee reviews and considers the following: all credible scientific evidence published in peer-reviewed medical literature generally recognized by the relevant medical community, physician and health care provider specialty society recommendations, the views of physicians and health care providers practicing in relevant clinical areas (including, but not limited to, the prevailing opinion within the appropriate specialty) and any other relevant factor as determined by applicable State and Federal laws and regulations.

___________________________________________________________________________________________________________________________

Index:
Laboratory and Genetic Testing for Use of 5-Fluorouracil in Patients With Cancer
Laboratory Testing to Allow Area Under the Curve (AUC) Targeted 5-Fluorouracil (5-FU) Dosing for Patients Administered 5-FU for Cancer
Area Under the Curve (AUC) Targeted 5-Fluorouracil (5-FU) Dosing for Patients Administered 5-FU for Cancer
Targeted 5-Fluorouracil (5-FU) Dosing for Patients Administered 5-FU for Cancer
OnDose
My5-FU
TheraGuide

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3. Caudle KE, Thorn CF, Klein TE, et al. Clinical Pharmacogenetics Implementation Consortium guidelines for dihydropyrimidine dehydrogenase genotype and fluoropyrimidine dosing. Clin Pharmacol Ther. Dec 2013;94(6):640-645. PMID 23988873

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5. Kline CL, Schiccitano A, Zhu J, et al. Personalized dosing via pharmacokinetic monitoring of 5-fluorouracil might reduce toxicity in early- or late-stage colorectal cancer patients treated with infusional 5-fluorouracil-based chemotherapy regimens. Clin Colorectal Cancer. Jun 2014;13(2):119-126. PMID 24461492

6. Saam J, Critchfield GC, Hamilton SA, et al. Body surface area-based dosing of 5-fluorouracil results in extensive interindividual variability in 5-fluorouracil exposure in colorectal cancer patients on FOLFOX regimens. Clin Colorectal Cancer. Sep 2011;10(3):203-206. PMID 21855044

7. Gamelin E, Boisdron-Celle M, Delva R, et al. Long-term weekly treatment of colorectal metastatic cancer with fluorouracil and leucovorin: results of a multicentric prospective trial of fluorouracil dosage optimization by pharmacokinetic monitoring in 152 patients. J Clin Oncol. Apr 1998;16(4):1470-1478. PMID 9552054

8. Boisdron-Celle M, Craipeau C, Brienza S, et al. Influence of oxaliplatin on 5-fluorouracil plasma clearance and clinical consequences. Cancer Chemother Pharmacol. Mar 2002;49(3):235-243. PMID 11935216

9. Ychou M, Duffour J, Kramar A, et al. Individual 5-FU dose adaptation in metastatic colorectal cancer: results of a phase II study using a bimonthly pharmacokinetically intensified LV5FU2 regimen. Cancer Chemother Pharmacol. Oct 2003;52(4):282-290. PMID 12827293

10. Milano G, Etienne MC, Renee N, et al. Relationship between fluorouracil systemic exposure and tumor response and patient survival. J Clin Oncol. Jun 1994;12(6):1291-1295. PMID 8201391

11. Santini J, Milano G, Thyss A, et al. 5-FU therapeutic monitoring with dose adjustment leads to an improved therapeutic index in head and neck cancer. Br J Cancer. Feb 1989;59(2):287-290. PMID 2930694

12. Gamelin EC, Danquechin-Dorval EM, Dumesnil YF, et al. Relationship between 5-fluorouracil (5-FU) dose intensity and therapeutic response in patients with advanced colorectal cancer receiving infusional therapy containing 5-FU. Cancer. Feb 1 1996;77(3):441-451. PMID 8630950

13. Gamelin E, Delva R, Jacob J, et al. Individual fluorouracil dose adjustment based on pharmacokinetic follow-up compared with conventional dosage: results of a multicenter randomized trial of patients with metastatic colorectal cancer. J Clin Oncol. May 1 2008;26(13):2099-2105. PMID 18445839

14. Andre T, Boni C, Navarro M, et al. Improved overall survival with oxaliplatin, fluorouracil, and leucovorin as adjuvant treatment in stage II or III colon cancer in the MOSAIC trial. J Clin Oncol. Jul 1 2009;27(19):3109-3116. PMID 19451431

15. de Gramont A, Figer A, Seymour M, et al. Leucovorin and fluorouracil with or without oxaliplatin as first-line treatment in advanced colorectal cancer. J Clin Oncol. Aug 2000;18(16):2938-2947. PMID 10944126

16. Fety R, Rolland F, Barberi-Heyob M, et al. Clinical impact of pharmacokinetically-guided dose adaptation of 5- fluorouracil: results from a multicentric randomized trial in patients with locally advanced head and neck carcinomas. Clin Cancer Res. Sep 1998;4(9):2039-2045. PMID 9748117

17. Yang R, Zhang Y, Zhou H, et al. Individual 5-fluorouracil dose adjustment via pharmacokinetic monitoring versus conventional body-area-surface method: a meta-analysis. Ther Drug Monit. Feb 2016;38(1):79-86. PMID 26309030

18. Li Q, Liu Y, Zhang HM, et al. Influence of DPYD genetic polymorphisms on 5-fluorouracil toxicities in patients with colorectal cancer: a meta-analysis. Gastroenterol Res Pract. Jan 2014;2014:827989. PMID 25614737

19. Rosmarin D, Palles C, Church D, et al. Genetic markers of toxicity from capecitabine and other fluorouracil- based regimens: investigation in the QUASAR2 study, systematic review, and meta-analysis. J Clin Oncol. Apr 1 2014;32(10):1031-1039. PMID 24590654

20. Schwab M, Zanger UM, Marx C, et al. Role of genetic and nongenetic factors for fluorouracil treatment-related severe toxicity: a prospective clinical trial by the German 5-FU Toxicity Study Group. J Clin Oncol. May 1 2008;26(13):2131-2138. PMID 18299612

21. Boige V, Vincent M, Alexandre P, et al. DPYD genotyping to predict adverse events following treatment with fluorouracil-based adjuvant chemotherapy in patients with stage III colon cancer: a secondary analysis of the PETACC-8 Randomized Clinical Trial. JAMA Oncol. Jan 21 2016;2(5):655-662. PMID 26794347

22. Nahid NA, Apu MNH, Islam MR, et al. DPYD*2A and MTHFR C677T predict toxicity and efficacy, respectively, in patients on chemotherapy with 5-fluorouracil for colorectal cancer. Cancer Chemother Pharmacol. Jan 2018;81(1):119-129. PMID 29134491

23. Wang YC, Xue HP, Wang ZH, et al. An integrated analysis of the association between Ts gene polymorphisms and clinical outcome in gastric and colorectal cancer patients treated with 5-FU-based regimens. Mol Biol Rep. Jul 2013;40(7):4637-4644. PMID 23645036

24. Smyth E, Zhang S, Cunningham D, et al. Pharmacogenetic analysis of the UK MRC (Medical Research Council) MAGIC Trial: association of polymorphisms with toxicity and survival in patients treated with perioperative epirubicin, cisplatin, and 5-fluorouracil (ECF) chemotherapy. Clin Cancer Res. Dec 15 2017;23(24):7543-7549. PMID 28972045

25. Blue Cross and Blue Shield Association Technology Evaluation Center (TEC). Pharmacogenetic Testing to Predict Serious Toxicity From 5-Fluorouracil (5-FU) for Patients Administered 5-FU-Based Chemotherapy for Cancer. TEC Assessments. 2010;24:Tab 13.

26. Deenen MJ, Meulendijks D, Cats A, et al. Upfront genotyping of DPYD*2A to individualize fluoropyrimidine therapy: a safety and cost analysis. J Clin Oncol. Jan 20 2016;34(3):227-234. PMID 26573078

27. Henricks, LL, van Merendonk, LL, Meulendijks, DD, Deenen, MM, Beijnen, JJ, de Boer, AA, Cats, AA, Schellens, JJ. Effectiveness and safety of reduced-dose fluoropyrimidine therapy in patients carrying the DPYD*2A variant: A matched pair analysis. Int. J. Cancer, 2018 Nov 30;144(9). PMID 30485432

28. Henricks, LL, Lunenburg, CC, de Man, FF, Meulendijks, DD, Frederix, GG, Kienhuis, EE, Creemers, GG, Baars, AA, Dezentjé, VV, Imholz, AA, Jeurissen, FF, Portielje, JJ, Jansen, RR, Hamberg, PP, Ten Tije, AA, Droogendijk, HH, Koopman, MM, Nieboer, PP, van de Poel, MM, Mandigers, CC, Rosing, HH, Beijnen, JJ, Werkhoven, EE, van Kuilenburg, AA, van Schaik, RR, Mathijssen, RR, Swen, JJ, Gelderblom, HH, Cats, AA, Guchelaar, HH, Schellens, JJ. DPYD genotype-guided dose individualisation of fluoropyrimidine therapy in patients with cancer: a prospective safety analysis. Lancet Oncol., 2018 Oct 24;19(11). PMID 30348537

29. Goff LW, Thakkar N, Du L, et al. Thymidylate synthase genotype-directed chemotherapy for patients with gastric and gastroesophageal junction cancers. PLoS One. Sep 2014;9(9):e107424. PMID 25232828

30. Magnani E, Farnetti E, Nicoli D, et al. Fluoropyrimidine toxicity in patients with dihydropyrimidine dehydrogenase splice site variant: the need for further revision of dose and schedule. Intern Emerg Med. Aug 2013;8(5):417-423. PMID 23585145

31. Cremolini, CC, Del Re, MM, Antoniotti, CC, Lonardi, SS, Bergamo, FF, Loupakis, FF, Borelli, BB, Marmorino, FF, Citi, VV, Cortesi, EE, Moretto, RR, Ronzoni, MM, Tomasello, GG, Zaniboni, AA, Racca, PP, Buonadonna, AA, Allegrini, GG, Ricci, VV, Di Donato, SS, Zagonel, VV, Boni, LL, Falcone, AA, Danesi, RR. NA. Oncotarget, 2018 Mar 1;9(8). PMID 29487697

32. National Comprehensive Cancer Network (NCCN). NCCN Clinical Practice Guidelines in Oncology: Breast Cancer. Version 4.2017. http://www.nccn.org/professionals/physician_gls/pdf/breast.pdf. Accessed June 7, 2019.

33. National Comprehensive Cancer Network (NCCN). NCCN Clinical Practice Guidelines in Oncology: Colon Cancer. Version 1.2018. http://www.nccn.org/professionals/physician_gls/pdf/colon.pdf. Accessed June 7, 2019.

34. National Comprehensive Cancer Network (NCCN). NCCN Clinical Practice Guidelines in Oncology: Rectal Cancer. Version 4.2017. http://www.nccn.org/professionals/physician_gls/pdf/rectal.pdf. Accessed June 7, 2019.

35. National Comprehensive Cancer Network (NCCN). NCCN Clinical Practice Guidelines in Oncology: Gastric Cancer. Version 5.2017. http://www.nccn.org/professionals/physician_gls/pdf/gastric.pdf. Accessed June 7, 2019.

36. National Comprehensive Cancer Network (NCCN). NCCN Clinical Practice Guidelines in Oncology: Pancreatic Cancer. Version 3.2017. http://www.nccn.org/professionals/physician_gls/pdf/pancreatic.pdf. Accessed June 7, 2019.

37. National Comprehensive Cancer Network (NCCN). NCCN Clinical Practice Guidelines in Oncology: Head and Neck Cancer. Version 2.2017. http://www.nccn.org/professionals/physician_gls/pdf/head-and-neck.pdf. Accessed June 7, 2019.

38. Amstutz U, Henricks LM, Offer SM, et al. Clinical Pharmacogenetics Implementation Consortium (CPIC) guideline for dihydropyrimidine dehydrogenase genotype and fluoropyrimidine dosing: 2017 update. Clin Pharmacol Ther. Feb 2018;103(2):210-216. PMID 29152729

39. National Institute for Health and Care Excellence (NICE). Fluorouracil chemotherapy: The My5-FU assay for guiding dose adjustment [DG16]. 2014; https://www.nice.org.uk/guidance/dg16. Accessed June 7, 2019.

Codes:
(The list of codes is not intended to be all-inclusive and is included below for informational purposes only. Inclusion or exclusion of a procedure, diagnosis, drug or device code(s) does not constitute or imply authorization, certification, approval, offer of coverage or guarantee of payment.)

CPT*

81230
81231
81232
81346

S3722