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.     

Screening for dihydropyrimidine dehydrogenase deficiency: to do or not to do, that's the question

The treatment of cancer patients with 5-fluorouracil (5FU)-based chemotherapy can be accompanied by severe and sometimes lethal toxicity. Dihydropyrimidine dehydrogenase (DPD) plays a pivotal role in the metabolism of 5FU and as such, a deficiency of DPD has been recognized as an important risk factor, predisposing patients to the development of severe 5FU-associated toxicity. To date, screening of patients for the presence of a DPD deficiency prior to the treatment is not yet routinely performed. Taking into account the relatively small impact of adjuvant 5FU-based chemotherapy on survival, patients should be informed about the risks of the therapy and should be offered the possibility of testing for the presence of a DPD deficiency in advance of receiving such treatment.     

High Expression of Thymidylate Synthase Leads to Resistance to 5-Fluorouracil in Biliary Tract Carcinoma in vitro

To evaluate the effect of chemotherapy of 5-fluorouracil (5-FU) in human biliary tract carcinoma, we studied 5-FU sensitivity, thymidylate synthase (TS) content, and dihydropyrimidine dehydroge-nase (DPD) activity in 4 human biliary tract carcinoma cell lines compared to 12 various digestive carcinoma cell lines of human organs in vitro. 5-FU sensitivity in the cell lines was analyzed by MTT assay. TS content was analyzed by the [6-³H]FdUMP binding assay method, and DPD activity was analyzed by thin-layer chromatography (TLC). 5-FU lC₅₀ values of biliary tract carcinoma cell lines were significantly higher than those of the carcinoma cell lines of the other digestive organs: 97, 45, 119, and 194 tunes the concentration of the other digestive, pancreas, colon, and gastric carcinoma cell lines, respectively. TS content of biliary tract carcinoma cell lines was also significantly greater than that of the carcinoma cell lines of the other organs. No difference in DPD activity, however, was recognized between the carcinoma cell lines of each organ. TS content in the cell lines significantly correlated with 5-FU sensitivity, but DPD activity did not. Therefore, in the present study, TS expression was concluded to influence the high resistance to 5-FU of biliary tract carcinoma in comparison with the carcinomas of the other digestive organs.     

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.     

Severe 5-fluorouracil-induced toxicity due to decreased dihydropyrimidine dehydrogenase activity: report of a patient survival and urinary pyrimidine and dihydropyrimidine levels

We report a Japanese woman who survived severe 5-fluorouracil (5-FU) toxicity after receiving 5′-deoxy-5-fluoro-uridine (5′DFUR) for the treatment of breast cancer (pt2n1m1); the toxicity was due to decreased dihydropyrimidine dehydrogenase (DPD) activity. Pharmacokinetic investigation showed very high and prolonged plasma 5-FU concentrations after termination of the oral administration of 5′DFUR. The DPD activity in all plasma samples was below 30 pmol/min per mg protein. Her urinary thymine and uracil levels were high, and the ratios of urinary dihydrothymine/thymine and dihydrouracil/uracil were very low compared with the ratios in healthy people. These findings suggest that determination of urinary pyrimidine and dihydropyrimidine levels would be an appropriate urinary screening sytem that may be useful for evaluating DPD activity before 5-FU treatment is initiated. Received: January 14, 1998 / Accepted: October 29, 1998     

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.     

Changes in thymidylate synthase and its inhibition rate and changes in dihydropyrimidine dehydrogenase after the administration of 5-fluorouracil with cisplatin to nude mice with gastric cancer xenograft SC-1-NU

Background Although 5-fluorouracil (5-FU) and cis-diamminedichloroplatinum (cisplatin) in combination have synergistic cytotoxicity against both murine and human neoplasms, the precise mechanism of the synergism, and the effects on thymidylate synthase and its percent inhibition, and the effects on dihydropyrimidine dehydrogenase (DPD) remained to be elucidated.Methods Experimental chemotherapy was performed using SC-1-NU, a human gastric carcinoma xenograft. SC-1-NU was maintained by serial transplantation in male BALB/c nude mice. The nude mice received various chemotherapeutic regimens consisting of 5-FU and/or cisplatin, with different dosages and periods of administration. After the treatment, we examined the in vivo effects of 5-FU and cisplatin in each regimen on thymidylate synthase and its percent inhibition, and the effects on DPD, in addition to the observation of tumor growth inhibition.Results The combined use of 5-FU (20mg/kg per day) and cisplatin (either 1.5 or 7.5mg/kg per day) showed a synergistic antitumor effect, regardless of the different doses of cisplatin. The long-term administration of 5-FU significantly increased both total thymidylate synthase and the percent thymidylate synthase inhibition rate. The short-term administration of 5-FU significantly decreased DPD. Nevertheless, these changes showed no relation to the combined use of cisplatin.Conclusion Combined administration of cisplatin with 5-FU did not further increase thymidylate synthase inhibition over that occurring with 5-FU alone, which does not support the hypothesis that cisplatin combined with 5-FU modulates thymidylate synthase inhibition in enhancing the anticancer effect of 5-FU. Changes in DPD after the administration of 5-FU may provide an insight into tumor sensitivity and resistance to 5-FU.     

Predicting 5-FU sensitivity using human colorectal cancer specimens: comparison of tumor dihydropyrimidine dehydrogenase and orotate phosphoribosyl transferase activities with in vitro chemosensitivity to 5-FU

Background: In tumor cells, the enzyme orotate phosphoribosyl transferase (OPRT) contributes to 5-fluorouracil (5-FU) phosphorylation and another enzyme, dihydropyrimidine dehydrogenase (DPD), is associated with 5-FU catabolic action. We measured OPRT and DPD activities and, to determine whether their levels might serve as indicators of 5-FU sensitivity, simultaneously assayed in vitro chemosensitivity to 5-FU. Methods: Tissue specimens were obtained from colorectal cancer patients and in vitro chemosensitivity was tested using fluorescein diacetate assay (FDA) or histoculture drug response assay (HDRA). DPD and OPRT activities were measured by radioassay. Results: The chemosensitivity assay was performed on 62 colorectal cancer specimens. Results were evaluable in 29 of 30 cases (96.7%) for FDA and 30 of 32 cases (98.3%) for HDRA. The positive sensitivity rate was 37.9% by FDA assay and 30% by HDRA assay. In positive specimens, the mean DPD activity was 44.9 ± 32.6 pmol/min per mg protein, and in negative specimens, it was 53.8 ± 33.7 pmol/min per mg protein (P = 0.875). In contrast, the mean OPRT value was significantly higher in positive specimens (0.418 ± 0.180 nmol/min per mg protein) than in negative specimens (0.325 ± 0.153 nmol/min per mg protein; P < 0.05). The chemosensitivity test proved positive in 60% of the specimens with ORPT activity of 0.413 or above and 50% of those with DPD activity of 30 or below. Of the patient specimens showing OPRT activity of 0.413 or above and DPD activity of 30 or below, 88.9% were positive for 5-FU sensitivity, suggesting the possibility that the combination of these two levels may be predictive of 5-FU positive sensitivity. Conclusion: DPD and OPRT activities within cancer cells may predict positive sensitivity to 5-FU. Received: February 6, 2002 / Accepted: August 7, 2002 Correspondence to:K. Isshi     

结直肠癌患者DPD水平与5-FU血药浓度、疗效及毒性的相关性研究

背景与目的:以相同的FOLFOX6方案治疗晚期结直肠癌患者,疗效和不良反应却明显不同。二氢嘧啶脱氢酶(DPD)是影响5鄄FU化疗疗效及不良反应的主要因素之一。本研究主要探讨结直肠癌患者外周血DPD水平与标准FOLFOX6方案治疗后患者5鄄FU血药浓度、不良反应及疗效的相关性。方法:应用高效液相色谱法(HPLC)检测结直肠癌患者化疗前DPD水平,按标准的FOLFOX6方案给药后,检测5鄄FU稳态血药浓度(HPLC法),同时观察化疗不良反应和疗效。结果:DPD在72例结直肠癌患者中呈正态分布,从1.55～5.94不等;5鄄FU稳态血药浓度在结直肠癌患者之间具有较大的变异,从141.1μg/L到1741.9μg/L,不呈正态分布。DPD水平和5鄄FU血药浓度呈负相关(r=-0.460,P<0.01),5鄄FU血药浓度≤600μg/L时不良反应较小,>600μg/L时不良反应明显增加,差异具有显著性(P<0.05)。不同治疗反应组的平均血药浓度之间差异具有显著性(P<0.05)。DPD水平和口腔粘膜炎、腹泻等具有相关性,DPD水平和疗效没有相关性(r=0.312,P=0.078)。结论:DPD水平和5鄄FU稳态血药浓度在结直肠癌患者之间具有较大的差异。DPD水平和5鄄FU血药浓度及毒性呈负相关,5鄄FU稳态血药浓度和不良反应以及治疗反应呈正相关。     

Radiation recall phenomenon secondary to capecitabine: possible role of thymidine phosphorylase

Background: The first reported case of radiation (XRT) recall related to capecitabine described dermatitis in a previously radiated field in a breast cancer patient (Ortman; JCO). We previously reported the first case of recall syndrome manifesting as diffuse gastritis and duodenitis related to capecitabine with prior XRT with 5-FU in a pancreatic cancer patient (Saif; JARCET). We report here another pancreatic cancer patient with a radiation recall receiving capecitabine following capecitabine-XRT. Patients and methods: From April 2004 to June 2005, 20 patients with locally advanced pancreatic adenocarcinoma were treated with capecitabine 1,600 mg/m² daily with concomitant radiation (5040cGy) Monday–Friday (weekends off) for a total of 6 weeks, followed by capecitabine 2,000 mg/m² daily for 14 days every 3 weeks. One male patient with tumor in the neck and body of pancreas and not infiltrating the duodenum dropped hemoglobin to 7.3 g/dl at the end of the ninth week, and melena on rectal examination. Specimen of primary pancreatic ductal adenocarcinoma was obtained via EUS-guided biopsy before starting XRT on day 1 and utilized for RNA extraction. TP mRNA level was determined by real-time quantitative PCR (RT-Q-PCR). Results: Upper endoscopy revealed gastritis consistent with radiation toxicity. Colonoscopy was negative. Transfusion of three units of packed red blood cells (PRBCs) was given. The dose of capecitabine was reduced by 25%. His anemia continued to progress, a CT scan revealed 39% decrease in the tumor size (PR). Analysis of tumor specimen prior to the start of capecitabine-XRT showed TP expression of 183.16 (high). In addition to TP, DPD was 7.40, and TNF-alpha 4,114.56. Conclusion: We believe this case to be the second case of radiation recall presenting as diffuse gastritis in a patient receiving capecitabine after previous treatment with XRT. Further studies, including the role of TP are warranted into the pathogenesis of this unique phenomenon.     

Prevention of 5-fluorouracil-induced early severe toxicity by pre-therapeutic dihydropyrimidine dehydrogenase deficiency screening: Assessment of a multiparametric approach

5-Fluorouracil (5-FU)–based treatments can lead to early-onset severe (4%–5%) even fatal (0.3%) toxicities in patients with dihydropyrimidine dehydrogenase (DPD) deficiency. This multicenter prospective cohort study aimed to assess the clinical benefit of pretherapeutic screening for DPD deficiency using a multiparametric approach. Two parallel cohorts of patients treated with 5-FU–based chemotherapy for colorectal carcinoma were compared in a prospective nonrandomized study. In arm A, patients had DPD deficiency screening before treatment, whereas in arm B no pretherapy screening was performed. Dosing was based on 5-FU administration guidelines of each institution. DPD deficiency screening was performed using a combined multiparametric approach (5-FU^{ODPM Tox}). The frequency of early grade 4–5 toxic events potentially induced by 5-FU was compared in the two groups. At total of 1,142 patients (n = 1,116 evaluable) were enrolled. In arm A, out of 718 evaluable patients, nine grade 4 early toxicities potentially related to 5-FU were reported in nine patients (1.2%) with no toxic death despite one complete DPD deficiency and 24 partial deficiencies. The 24 patients with partial deficiency had safe pharmacokinetics (PK)-monitored 5-FU. In arm B, among 398 evaluable patients, 17 grade 4–5 toxic early events potentially related to 5-FU were reported in 12 patients (4.2%). The incidence of early severe toxicity was significantly higher in arm B (P = .0019), confirming the positive impact of pretherapeutic DPD assessment. The percent of patients with a toxicity grade 3 or higher observed in arm A was 10.8% (n = 78) compared to 17.55% (n = 69)  in arm B (P = .0497). The percentage of death was reduced from 2.5/1,000 in arm B to 0 in arm A. The time to occurrence of all grade ≥3 toxicities was determined in both arms and the difference between the two arms was significant (P = .047). Overall, one patient with complete DPD deficiency confirmed retrospectively died within 13 days from grade 5 multivisceral toxicity. Enrollment was prematurely closed after external experts’ decision. In conclusion, multiparametric pretherapeutic DPD deficiency screening significantly lowered the risk of early severe toxicity and avoided an early toxic death. This approach should be used for safe administration of 5-FU–based treatments.     

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.     

The Prevalence of DPYD*9A (c.85T&gt;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.     

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.     

Increased risk of grade IV neutropenia after administration of 5-fluorouracil due to a dihydropyrimidine dehydrogenase deficiency: high prevalence of the IVS14+1g>a mutation

Dihydropyrimidine dehydrogenase (DPD) is the initial and rate-limiting enzyme in the catabolism of 5-fluorouracil (5-FU), and it is suggested that patients with a partial deficiency of this enzyme are at risk of developing severe 5-FU-associated toxicity. We evaluated the importance of DPD deficiency, gender and the presence of the IVS14+1G>A mutation in the etiology of 5-FU toxicity. In 61% of cases, decreased DPD activity could be detected in peripheral blood mononuclear cells. Furthermore, the number of females (65%) in the total group of patients appeared to be higher than the number of males (35%) (p = 0.03). Patients with partial DPD deficiency appeared to have a 3.4-fold higher risk of developing grade IV neutropenia than patients with normal DPD activity. Analysis of the DPYD gene of patients suffering from grade IV neutropenia for the presence of the IVS14+1G>A mutation showed that 50% of the patients investigated were heterozygous or homozygous for the IVS14+1G>A mutation. Adopting a threshold level for DPD activity of 70% of that observed in the normal population, 14% of the population is prone to the development of severe 5-FU-associated toxicity. Below this threshold level, 90% of individuals heterozygous for a mutation in the DPYD gene can be identified. Considering the common use of 5-FU in the treatment of cancer, the severe 5-FU-related toxicities in patients with low DPD activity and the apparently high prevalence of the IVS14+1G>A mutation, screening of patients at risk before administration of 5-FU is warranted.     

Predicting clinical outcome of 5-fluorouracil-based chemotherapy for colon cancer patients: is the CpG island methylator phenotype the 5-fluorouracilresponsive subgroup?

The CpG island methylator phenotype (CIMP+) of colorectal cancer (CRC) occurs predominantly in the proximal colon and is characterized by frequent hypermethylation of gene promoter regions. In this review, we present evidence suggesting CIMP+ represents the subgroup of colon cancers that are responsive to 5-fluorouracil (5-FU)-based treatments. CIMP+ has been associated with survival benefit from 5-FU in a clinical study of CRC, with additional evidence coming from studies on gastric cancer and tumor cell lines. Elevated concentrations of 5-10-methylene tetrahydrofolate (CH₂FH₄) occur in CIMP+ tumors and are probably due to low expression levels for γ-glutamyl hydrolase (GGH). Clinical and in vitro work has previously shown that high CH₂FH₄ and low GGH expression levels correlate with good response to 5-FU. Methylation-induced silencing of dihydropyrimidine dehydrogenase, the rate-limiting enzyme in 5-FU degradation, may also provide a link between CIMP+ and good response to 5-FU. The CIMP+-related phenotype referred to as microsatellite instability (MSI+) has been widely investigated as a predictive marker of response to 5-FU, with contradictory results. The interpretation of these studies is likely to be confounded by the fact that some MSI+ tumors occur in the background of CIMP+, but a significant proportion of others do not. Further studies on tumors from randomized clinical trials are required to confirm the value of CIMP+ and associated molecular features for the prediction of clinical outcome to 5-FU-based chemotherapy.     

Biweekly low-dose sequential gemcitabine, 5-fluorouracil, leucovorin, and cisplatin (GFP): a highly active novel therapy for metastatic adenocarcinoma of the exocrine pancreas

Phase II studies have suggested an improved response rate and acceptable toxicity profile associated with gemcitabine combinations compared to gemcitabine alone for treatment of metastatic adenocarcinoma of the pancreas. The GFP regimen (gemcitabine, 5-fluorouracil, leucovorin, and cisplatin) is based on laboratory evidence of disease-specific chemotherapy interaction.[8] This retrospective analysis examined the outcome of 49 consecutive patients with histologically confirmed metastatic pancreatic adenocarcinoma treated between July 1998 and September 2000. Day 1 treatment consisted of gemcitabine 500 mg/m² over 30 minutes and then leucovorin 300 mg bolus, 5-fluorouracil (5-FU) 400 mg/m² bolus, followed by infusional 5-FU 600 mg/m² over 8 hours. Day 2 consisted of leucovorin 300 mg bolus, 5-FU 400 mg/m² bolus, followed by cisplatin 50-75 mg/m² over 30 minutes and then infusional 5-FU 600 mg/m² over 8 hours. Treatment was administered every 2 weeks. Median patient age was 61.5 years, 74% were men, and 20 patients had refractory disease (11 patients had disease progression upon gemcitabine-based therapy). Grade 3-4 toxic effects (% patients) consisted of neutropenia (30%), thrombocytopenia (14%), anemia (8%), and neutropenic fever (2%). Grade 3-4 nonhematological toxicities (% patients) consisted of neuropathy (14%), ototoxicity (8%), nephrotoxicity (6%), nausea/vomiting (14%), and mucositis (10%). The majority of dose reductions were made for neuropathy or cytopenias. Filgrastim and erythropoietin were given as needed to promote dose intensity. Eight patients attained a partial response (PR) by RECIST criteria. Fourteen had stable disease (SD). Two patients attaining PR and two attaining SD had progressive disease with prior gemcitabine-based therapy. The median time to disease progression (TTP) from GFP start was 9 weeks. For all 49 patients, the median overall survival (OS) from GFP start was 10.6 months, 12-month survival was 46%, and 24-month survival was 30%. Notably, upon disease progression, 31 patients continued to receive the GFP regimen with irinotecan 80 mg/m² inserted on day 1 following gemcitabine, the G-FLIP regimen (gemcitabine, 5-fluorouracil, leucovorin, irinotecan, and cisplatin). Measured from G-FLIP initiation, the TTP for the 31 patients treated sequentially was 10 weeks, and for the 14 patients attaining SD or PR the TTP was 25 weeks. The median overall survival measured from GFP initiation was 11.8 months. The response rate, non-cross resistance, TTP, OS, and tolerability warrant prospective development of this novel combination. This experience also demonstrates that adding a single new drug such as irinotecan to the same first-line chemotherapy combination upon disease progression may be an important alternative for the treatment of relapsed/resistant cancer.