The role of pharmacogenetics in capecitabine efficacy and toxicity

Capecitabine is an oral prodrug of 5-fluorouracil (5-FU) and approved for treatment of various malignancies. Hereditary genetic variants may affect a drug’s pharmacokinetics or pharmacodynamics and account for differences in treatment response and adverse events among patients. In this review we present the current knowledge on genetic variants, commonly single-nucleotide polymorphisms (SNPs), tested in cohorts of cancer patients and possibly useful for prediction of capecitabine efficacy or toxicity. Capecitabine is activated to 5-FU by CES, CDA and TYMP, of which SNPs in CDA and CES2 were found to be associated with efficacy and toxicity. In addition, variants in genes of the 5-FU metabolic pathway, including TYMS, MTHFR and DPYD also influenced capecitabine efficacy and toxicity. In particular, well-known SNPs in TYMS and DPYD as well as putative DPYD SNPs had an association with clinical outcome as well as adverse events. Inconsistent findings may be attributable to factors related to ethnic differences, sample size, study design, study endpoints, dosing schedule and the use of multiple agents. Of the SNPs described in this review, dose reduction of fluoropyrimidines based on the presence of DPYD variants ^*2A (rs3918290), ^*13 (rs55886062), −2846A>T (rs67376798) and −1236G>A/HapB3 (rs56038477) has already been recommended. Other variants merit further validation to establish their definite role in explanation of interindividual differences in the outcome of capecitabine-based therapy.     

Rs895819 in MIR27A improves the predictive value of DPYD variants to identify patients at risk of severe fluoropyrimidine‐associated toxicity

The objective of this study was to determine whether genotyping of MIR27A polymorphisms rs895819A>G and rs11671784C>T can be used to improve the predictive value of DPYD variants to identify patients at risk of severe fluoropyrimidine‐associated toxicity (FP‐toxicity). Patients treated previously in a prospective study with fluoropyrimidine‐based chemotherapy were genotyped for rs895819 and rs11671784, and DPYD c.2846A>T, c.1679T>G, c.1129‐5923C>G and c.1601G>A. The predictive value of MIR27A variants for early‐onset grade ≥3 FP‐toxicity, alone or in combination with DPYD variants, was tested in multivariable logistic regression models. Random‐effects meta‐analysis was performed, including previously published data. A total of 1,592 patients were included. Allele frequencies of rs895819 and rs11671784 were 0.331 and 0.020, respectively. In DPYD wild‐type patients, MIR27A variants did not affect risk of FP‐toxicity (OR 1.3 for ≥1 variant MIR27A allele vs. none, 95% CI: 0.87–1.82, p = 0.228). In contrast, in patients carrying DPYD variants, the presence of ≥1 rs895819 variant allele was associated with increased risk of FP‐toxicity (OR 4.9, 95% CI: 1.24–19.7, p = 0.023). Rs11671784 was not associated with FP‐toxicity (OR 2.9, 95% CI: 0.47?18.0, p = 0.253). Patients carrying a DPYD variant and rs895819 were at increased risk of FP‐toxicity compared to patients wild type for rs895819 and DPYD (OR 2.4, 95% CI: 1.27–4.37, p = 0.007), while patients with a DPYD variant but without a MIR27A variant were not (OR 0.3 95% CI: 0.06?1.17, p = 0.081). In meta‐analysis, rs895819 remained significantly associated with FP‐toxicity in DPYD variant allele carriers, OR 5.4 (95% CI: 1.83–15.7, p = 0.002). This study demonstrates the clinical validity of combined MIR27A/DPYD screening to identify patients at risk of severe FP‐toxicity.     

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

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

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

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

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

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

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

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

Implementing DPYD*2A Genotyping in Clinical Practice: The Quebec,Canada, Experience

BackgroundFluoropyrimidines are used in chemotherapy combinations for multiple cancers. Deficient dihydropyrimidine dehydrogenase activity can lead to severe life‐threatening toxicities. DPYD*2A polymorphism is one of the most studied variants. The study objective was to document the impact of implementing this test in routine clinical practice.MethodsWe retrospectively performed chart reviews of all patients who tested positive for a heterozygous or homozygous DPYD*2A mutation in samples obtained from patients throughout the province of Quebec, Canada.ResultsDuring a period of 17 months, 2,617 patients were tested: 25 patients tested positive. All were White. Twenty‐four of the 25 patients were heterozygous (0.92%), and one was homozygous (0.038%). Data were available for 20 patients: 15 were tested upfront, whereas five were identified after severe toxicities. Of the five patients confirmed after toxicities, all had grade 4 cytopenias, 80% grade ≥3 mucositis, 20% grade 3 rash, and 20% grade 3 diarrhea. Eight patients identified with DPYD*2A mutation prior to treatment received fluoropyrimidine‐based chemotherapy at reduced initial doses. The average fluoropyrimidine dose intensity during chemotherapy was 50%. No grade ≥3 toxicities were observed. DPYD*2A test results were available in an average of 6 days, causing no significant delays in treatment initiation.ConclusionUpfront genotyping before fluoropyrimidine‐based treatment is feasible in clinical practice and can prevent severe toxicities and hospitalizations without delaying treatment initiation. The administration of chemotherapy at reduced doses appears to be safe in patients heterozygous for DPYD*2A.Implications for PracticeFluoropyrimidines are part of chemotherapy combinations for multiple cancers. Deficient dihydropyrimidine dehydrogenase activity can lead to severe life‐threatening toxicities. This retrospective analysis demonstrates that upfront genotyping of DPYD before fluoropyrimidine‐based treatment is feasible in clinical practice and can prevent severe toxicities and hospitalizations without delaying treatment initiation. This approach was reported previously, but insufficient data concerning its application in real practice are available. This is likely the first reported experience of systematic DPYD genotyping all over Canada and North America as well.     

Impact of DPYD,DPYS, and UPB1 gene variations on severe drug‐related toxicity in patients with cancer

Cancer treatment with a fluoropyrimidine (FP) is often accompanied by severe toxicity that may be dependent on the activity of catalytic enzymes encoded by the DPYD, DPYS, and UPB1 genes. Genotype‐guided dose individualization of FP therapy has been proposed in western countries, but our knowledge of the relevant genetic variants in East Asian populations is presently limited. To investigate the association between these genetic variations and FP‐related high toxicity in a Japanese population, we obtained blood samples from 301 patients who received this chemotherapy and sequenced the coding exons and flanking intron regions of their DPYD, DPYS, and UPB1 genes. In total, 24 single nucleotide variants (15 in DPYD, 7 in DPYS and 2 in UPB1) were identified including 3 novel variants in DPYD and 1 novel variant in DPYS. We did not find a significant association between FP‐related high toxicity and each of these individual variants, although a certain trend toward significance was observed for p.Arg181Trp and p.Gln334Arg in DPYS (P = .0813 and .087). When we focused on 7 DPYD rare variants (p.Ser199Asn, p.IIe245Phe, p.Thr305Lys, p.Glu386Ter, p.Ser556Arg, p.Ala571Asp, p.Trp621Cys) which have an allele frequency of less than 0.01% in the Japanese population and are predicted to be loss‐of‐function mutations by in silico analysis, the group of patients who were heterozygous carriers of at least one these rare variants showed a strong association with FP‐related high toxicity (P = .003). Although the availability of screening of these rare loss‐of‐function variants is still unknown, our data provide useful information that may help to alleviate FP‐related toxicity in Japanese patients with cancer.     

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

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

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

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

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

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

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

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

Gene polymorphisms predict toxicity to neoadjuvant therapy in patients with rectal cancer

BACKGROUND

Toxicity from neoadjuvant chemoradiation therapy (NT) increases morbidity and limits therapeutic efficacy in patients with rectal cancer. The objective of this study was to determine whether specific polymorphisms in genes associated with rectal cancer response to NT were correlated with NT‐related toxicity.

METHODS

One hundred thirty‐two patients with locally advanced rectal cancer received NT followed by surgery. All patients received 5‐fluorouracil (5‐FU) and radiation (RT), and 80 patients also received modified infusional 5‐FU, folinic acid, and oxaliplatin chemotherapy (mFOLFOX‐6). Grade ≥3 adverse events (AEs) that occurred during 5‐FU/RT and during combined 5‐FU/RT + mFOLFOX‐6 were recorded. Pretreatment biopsy specimens and normal rectal tissues were collected from all patients. DNA was extracted and screened for 22 polymorphisms in 17 genes that have been associated with response to NT. Polymorphisms were correlated with treatment‐related grade ≥3 AEs.

RESULTS

Overall, 27 of 132 patients (20%) had grade ≥3 AEs; 18 patients had a complication associated only with 5‐FU/RT, 3 patients experienced toxicity only during mFOLFOX‐6, and 6 patients had grade ≥3 AEs associated with both treatments before surgery. Polymorphisms in the genes x‐ray repair complementing defective repair in Chinese hamster cells 1 (XRCC1), xeroderma pigmentosum group D (XPD), and tumor protein 53 (TP53) were associated with grade ≥3 AEs during NT (P < .05). Specifically, 2 polymorphisms—an arginine‐to‐glutamine substitution at codon 399 (Q399R) in XRCC1 and a lysine‐to‐glutamine substitution at codon 751 (K751Q) in XPD—were associated with increased toxicity to 5‐FU/RT (P < .05), and an arginine‐to‐proline substitution at codon 72 (R72P) in TP53 was associated with increased toxicity to mFOLFOX‐6 (P = .008).

CONCLUSIONS

Specific polymorphisms in XRCC1, XPD, and TP53 were associated with increased toxicity to NT in patients with rectal cancer. The current results indicated that polymorphism screening may help tailor treatment for patients by selecting therapies with the lowest risk of toxicity, thus increasing patient compliance. Cancer 2013. © 2012 American Cancer Society.     

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

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

Impact of the introduction of rituximab in first‐line follicular lymphoma: a retrospective study of 247 unselected patients referred to a single institution with a long‐term follow‐up

Rituximab was approved in France in 2004, following randomized trials that demonstrated efficacy in newly diagnosed high tumour burden follicular lymphoma (FL). This retrospective study compared the management and outcome of FL in unselected patients treated in a single institution before and after rituximab approval. Two hundred and forty‐seven adult patients were referred with first‐line FL between 1996 and 2010 and are included in this study. The 103 pre‐rituximab patients comprising cohort 1 were diagnosed between January 1996 and December 2003; cohort 2 includes the 144 patients diagnosed after the approval of rituximab between January 2004 and December 2010. Baseline clinical and biological data, type of therapy, treatment response, progression‐free survival (PFS) and overall survival (OS) rates were compared. There were no statistically significant differences between the two cohorts with respect to baseline clinical and disease characteristics, including FL International Prognostic Index score. The major difference between the two cohorts is the use of rituximab in first line. Seventy‐one per cent of patients in cohort 2 received rituximab (19% alone, 52% with chemotherapy) versus 10% in cohort 1 (2% alone, 8% with chemotherapy; p < 0.0001). The objective response rate (ORR) was significantly higher for cohort 2 (ORR 84% compared with 72% for cohort 1; p = 0.03). The PFS and OS rates were also significantly better: 3‐year PFS 72% [95% confidence interval (CI) 64–80%] versus 55% (95% CI 45–64%), p = 0.0039 and 3‐year OS 98% (95% CI 94–99%) versus 83% (95% CI 74–90%), p = 0.0007. Effect of period of study is significant when using multivariate analysis on PFS and OS and lactate dehydrogenase level (PFS and OS) and age (OS). These data from everyday practice confirm the benefit for patients with FL treated in the last decade through availability of rituximab in first line used alone or in association with various chemotherapy regimens. Copyright © 2014 John Wiley & Sons, Ltd.     

Outcomes of patients ≥65 years old with advanced cancer treated on phase I trials at MD ANDERSON CANCER CENTER

Patients ≥65 years with cancer remain underrepresented in clinical trials, particularly in phase I clinical trials. We analyzed the clinical course of patients ≥65 years treated on phase I clinical trials with particular emphasis on toxicities. We identified 347 consecutive patients ≥65 years with advanced cancer in our phase I clinic from 01/2004‐12/2009 and analyzed disease characteristics, toxicities, survival and response. Overall, 251 patients received a targeted agent, of whom 241 (96%) received an investigational, non‐FDA‐approved drug. Clinical benefit (complete response + partial response + stable disease ≥ 6 months) was noted in 61 patients (18%). Eighty‐nine patients (26%) had grade 3/4 toxicity, commonly hematologic, including 6 dose‐limiting toxicities and 1 treatment‐related death (<0.01%). Median overall survival from first Phase I Clinic visit was 8.8 months (95% CI: 7.8–10.6); median time to treatment failure was 1.9 months (95% CI: 1.8–2.1). Multivariable analyses revealed 4 indicators of lack of clinical benefit (liver metastases, performance status [PS] >1, prior radiation, ≥5 prior treatments; p <0.0001). Patients age 70–79 years had a greater risk of grade 3/4 toxicities when treated with combinations (≥2 drugs) compared to monotherapy (p = 0.006). Predictors of shorter time to treatment failure and overall survival included PS >1, thrombocytosis, >2 metastatic sites, and elevated lactate dehydrogenase (p <0.05). Our results suggest that phase I clinical trials are well tolerated in patients ≥65 years. Additionally, we identified risk factors that may facilitate patient selection for clinical trial participation.     

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

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

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

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

Prognostic significance of histologic grade and Ki-67 proliferation index in follicular lymphoma

The prognostic value of histologic grading and the Ki-67 proliferation index in follicular lymphoma (FL) is controversial. This study investigated the clinical usefulness of these two factors in Asian FL patients. Four hundred and thirty-three patients diagnosed with FL were retrospectively reviewed with a median follow-up time of 47.0 months (range, 24.0-168.0). The 10-year overall survival (OS) rate and progression-free survival (PFS) rate were 91.0% and 47.1%, respectively. Grade 3B and grade 3B with diffuse large B cell lymphoma (DLBCL) showed a better PFS than grade 1-3A (P < 0.001), and similar findings were noted in patients who received rituximab-containing regimens (P = 0.002). In contrast, no significant differences in terms of OS or PFS were observed between grades 1-2 and 3A. In addition, patients with Ki-67 ≥ 30% had a significantly better PFS than patients with Ki-67 < 30% (P = 0.014), although the difference was eliminated in the multivariate analysis. Both grade and Ki-67 index had no impact on prognosis in patients who did not receive rituximab treatment. In conclusion, grade 3A is closely related to grade 1-2, as reflected by a similar indolent clinical course and a lower PFS rate than grade 3B/3B + DLBCL. In addition, a higher Ki-67 index seems to have a positive effect on PFS in FL patients.     

A phase 1 dose escalation study of bortezomib combined with rituximab, cyclophosphamide, doxorubicin, modified vincristine, and prednisone for untreated follicular lymphoma and other low-grade B-cell lymphomas

BACKGROUND:

Bortezomib has demonstrated efficacy in patients with relapsed B‐cell non‐Hodgkin lymphoma (NHL) both alone and in combination with other agents; however, limited data exist regarding its toxicity in combination with common frontline therapies for indolent NHL. A phase 1 study of bortezomib combined with rituximab, cyclophosphamide, doxorubicin, modified vincristine, and prednisone (R‐CHOP) was conducted in patients with untreated follicular lymphoma (FL) and other indolent NHLs.

METHODS:

Nineteen patients, including 10 patients with FL, were enrolled. The median patient age was 59 years (range, 29‐71 years). Seven patients had a FL International Prognostic Index score ≥3. R‐CHOP with the vincristine dose capped at 1.5 mg was administered on a 21‐day cycle for 6 to 8 cycles, and 1 of 3 dose levels of bortezomib (1.0 mg/m² [n = 1], 1.3 mg/m² [n = 6], or 1.6 mg/m² [n = 12]) was administered on days 1 and 8 of each cycle using a Bayesian algorithm for dose escalation.

RESULTS:

The maximum tolerated dose (MTD) of bortezomib with modified R‐CHOP was reached at 1.6 mg/m². Dose‐limiting toxicity was observed in 5 patients (1 patient at a bortezomib dose of 1.0 mg/m², 1 patient at a bortezomib dose of 1.3 mg/m², and 3 patients at a bortezomib dose of 1.6 mg/m²). Neuropathy occurred in 16 patients (84%), including 2 patients (11%) who experienced grade 3 sensory neuropathy. Grade 4 hematologic toxicity occurred in 4 patients. Of 19 evaluable patients, 100% responded, and the complete response rate was 68%. At a median follow‐up of 32 months, the 3‐year progression‐free survival rate was 89.5%.

CONCLUSIONS:

Bortezomib combined with modified R‐CHOP produced high response rates without substantial increases in toxicity. A phase 2 study of R‐CHOP and bortezomib given at this established MTD is currently ongoing. Cancer 2012;3538–3548. © 2012 American Cancer Society.