Abstract 5420: DPYD enhancer variant confers increased risk of severe toxicity in 5-FU chemotherapy

Genetic variants in the DPYD gene that are deleterious to dihydropyrimidine dehydrogenase (DPD) enzyme function have demonstrated clinical validity as predictive biomarkers for severe (i.e., CTCAE grade ≥3) and potentially lethal toxicity to fluorouracil (5-FU) and capecitabine chemotherapies. Variants within the coding region only explain 5-10% of 5-FU-related toxicities; and GWAS approaches have been unable to identify validated predictive biomarkers to date. Our previous studies demonstrated that DPD expression was controlled by multiple epigenetic processes; considerable variation was also noted in liver DPYD/DPD levels. Using CRISPR-interference (CRISPRi) and CRISPR-activation (CRISPRa), we identified functional enhancer regions within liver tissues and cells. Epigenetic status at these regions was shown to correlate with DPYD expression in cell models and human liver tissues. Chromosome conformation capture (3C) confirmed direct promoter-enhancer interactions. A multi-omics analysis of >1000 human liver specimens identified a proximal eQTL for DPYD expression within an enhancer, with a global minor allele frequency of 27%. This variant was subsequently shown to directly alter DPYD expression in knock-in cell line models. The variant disrupts transcription factor binding at the DPYD enhancer, leading to reduced enhancer-promoter interaction, reduced DPD expression, and increased cellular sensitivity to 5-FU. Collectively, our data suggest that the variant could represent a novel predictive biomarker for severe 5-FU toxicity. The evaluation of this marker in the clinical setting is currently underway.

Citation Format: Ting Zhang, Alisa Ambrodji, Huixing Huang, Kelly Bouchonville, Amy Etheridge, Remington Schmidt, Jose Cardiel Nunez, Zoey Temesgen, Federico Innocenti, Robert Diasio, Carlo Largiadèr, Steven M. Offer. DPYD enhancer variant confers increased risk of severe toxicity in 5-FU chemotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5420.

Therapeutic Drug Monitoring in Oncology: International Association of Therapeutic Drug Monitoring and Clinical Toxicology Recommendations for 5-Fluorouracil Therapy

5-Fluorouracil (5-FU) is dosed by body surface area, a practice unable to reduce the interindividual variability in exposure. Endorsed by the International Association of Therapeutic Drug Monitoring and Clinical Toxicology (IATDMCT), we evaluated clinical evidence and strongly recommend TDM for the management of 5-FU therapy in patients with colorectal or head-and-neck cancer receiving common 5-FU regimens. Our systematic methodology provides a framework to evaluate published evidence in support of TDM recommendations in oncology.

Abstract B49: Histone H3K27 tri-methylation regulates DPYD expression and cellular sensitivity of 5-fluorouracil

Dihydropyrimidine dehydrogenase (DPD) is a major determinant of the efficacy and toxicity of 5-fluorouracil in various cancer therapies. Single nucleotide polymorphisms (SNPs) within DPYD have been studied extensively for years. However, known SNPs do not explain most cases of altered DPD activity and response to 5-FU. Furthermore, variations of DPYD expression in cancer patients have been reported; however, the underlying molecular mechanism is unclear. This suggests that regulation of DPYD expression may be an additional mechanism to control DPD activity. In this study, we focused on epigenetic regulation of DPD and specifically investigated the role of histone methylation on DPYD expression. Inhibition of the H3K27 methyl-transferase Ezh2 by either GSK-126 or a dominant-negative histone H3 mutant significantly increased DPYD expression in various cell lines. The expression of thymidylate synthetase, a major target of 5-fluorouracil toxicity, was not altered. Consistent with elevated DPYD expression, cells that lost H3K27me3 were more resistant to 5-fluorouracil. Furthermore, we demonstrated that Ezh2 and H3K27me3 were enriched on the promoter and the first exon of DPYD in low-DPD expressing cells, but not in cell lines with high DPD levels. Additionally, the enrichment of H3K27me3 on the DPYD promoter was negatively correlated with cellular DPD activity in peripheral mononuclear cells from healthy volunteers. Finally, CRISPR/Cas9-mediated targeting of Ezh2 to the DPYD promoter artificially increased H3K27me3 and suppressed DPYD expression. Collectively, these data suggest that histone methylation can regulate DPYD expression, providing a previously unrecognized mechanism of 5-fluorouracil sensitivity. The tri-methylation of H3K27 is a potential biomarker for guiding individualized 5-FU therapy.

Citation Format: Rentian Wu, Steven Offer, Calvin Jerde, Garrett Dunlap, Robert Diasio. Histone H3K27 tri-methylation regulates DPYD expression and cellular sensitivity of 5-fluorouracil. [abstract]. In: Proceedings of the AACR Special Conference on Chromatin and Epigenetics in Cancer; Sep 24-27, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2016;76(2 Suppl):Abstract nr B49.

Genome-wide association study identifies variants at 16p13 associated with survival in multiple myeloma patients

Here we perform the first genome-wide association study (GWAS) of multiple myeloma (MM) survival. In a meta-analysis of 306 MM patients treated at UCSF and 239 patients treated at the Mayo clinic, we find a significant association between SNPs near the gene FOPNL on chromosome 16p13 and survival (rs72773978; P=6 × 10(-10)). Patients with the minor allele are at increased risk for mortality (HR: 2.65; 95% CI: 1.94-3.58) relative to patients homozygous for the major allele. We replicate the association in the IMMEnSE cohort including 772 patients, and a University of Utah cohort including 318 patients (rs72773978 P=0.044). Using publicly available data, we find that the minor allele was associated with increased expression of FOPNL and increased expression of FOPNL was associated with higher expression of centrosomal genes and with shorter survival. Polymorphisms at the FOPNL locus are associated with survival among MM patients.

Fatty acid binding protein 3 (fabp3) is associated with insulin, lipids and cardiovascular phenotypes of the metabolic syndrome through epigenetic modifications in a Northern European family population

Background

Fatty acid-binding proteins (FABPs) play regulatory roles at the nexus of lipid metabolism and signaling. Dyslipidemia in clinical manifestation frequently co-occurs with obesity, insulin resistance and hypertension in the Metabolic Syndrome (MetS). Animal studies have suggested FABPs play regulatory roles in expressing MetS phenotypes. In our family cohort of Northern European descent, transcript levels in peripheral white blood cells (PWBCs) of a key FABPs, FABP3, is correlated with the MetS leading components. However, evidence supporting the functions of FABPs in humans using genetic approaches has been scarce, suggesting FABPs may be under epigenetic regulation. The objective of this study was to test the hypothesis that CpG methylation status of a key regulator of lipid homeostasis, FABP3, is a quantitative trait associated with status of MetS phenotypes in humans.

Methods

We used a mass-spec based quantitative method, EpiTYPER®, to profile a CpG island that extends from the promoter to the first exon of the FABP3 gene in our family-based cohort of Northern European descent (n=517). We then conducted statistical analysis of the quantitative relationship of CpG methylation and MetS measures following the variance-component association model. Heritability of each methylation and the effect of age and sex on CpG methylation were also assessed in our families.

Results

We find that methylation levels of individual CpG units and the regional average are heritable and significantly influenced by age and sex. Regional methylation was strongly associated with plasma total cholesterol (p=0.00028) and suggestively associated with LDL-cholesterol (p=0.00495). Methylation at individual units was significantly associated with insulin sensitivity, lipid particle sizing and diastolic blood pressure (p<0.0028, corrected for multiple testing for each trait). Peripheral white blood cell (PWBC) expression of FABP3 in a separate group of subjects (n=128) negatively correlated with adverse profiles of metabolism (β_WHR = −0.72; β_LDL-c = −0.53) while positively correlated with plasma adiponectin (β=0.24). Further, we show that differential methylation of FABP3 affects binding activity with nuclear proteins from heart tissue. This region that we found under methylation regulation overlaps with a region actively modified by histone codes in the newly available ENCODE data.

Conclusions

Our findings suggest that DNA methylation of FABP3 strongly influences MetS, and this may have important implications for cardiovascular disease.

EGFR somatic mutations in lung tumors: radon exposure and passive smoking in former- and never-smoking U.S. women

BACKGROUND

Patients with lung cancer with mutations in EGF receptor (EGFR) tyrosine kinase have improved prognosis when treated with EGFR inhibitors. We hypothesized that EGFR mutations may be related to residential radon or passive tobacco smoke.

METHODS

This hypothesis was investigated by analyzing EGFR mutations in 70 lung tumors from a population of never and long-term former female smokers from Missouri with detailed exposure assessments. The relationship with passive smoking was also examined in never-smoking female lung cancer cases from the Mayo clinic.

RESULTS

Overall, the frequency of EGFR mutation was 41% [95% confidence interval (CI), 32%-49%]. Neither radon nor passive-smoking exposure was consistently associated with EGFR mutations in lung tumors.

CONCLUSIONS

The results suggest that EGFR mutations are common in female, never-smoking lung cancer cases from the United States, and EGFR mutations are unlikely due to exposure to radon or passive smoking.

Associations of common variants at 1p11.2 and 14q24.1 (RAD51L1) with breast cancer risk and heterogeneity by tumor subtype: findings from the Breast Cancer Association Consortium

A genome-wide association study (GWAS) identified single-nucleotide polymorphisms (SNPs) at 1p11.2 and 14q24.1 (RAD51L1) as breast cancer susceptibility loci. The initial GWAS suggested stronger effects for both loci for estrogen receptor (ER)-positive tumors. Using data from the Breast Cancer Association Consortium (BCAC), we sought to determine whether risks differ by ER, progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), grade, node status, tumor size, and ductal or lobular morphology. We genotyped rs11249433 at 1p.11.2, and two highly correlated SNPs rs999737 and rs10483813 (r(2)= 0.98) at 14q24.1 (RAD51L1), for up to 46 036 invasive breast cancer cases and 46 930 controls from 39 studies. Analyses by tumor characteristics focused on subjects reporting to be white women of European ancestry and were based on 25 458 cases, of which 87% had ER data. The SNP at 1p11.2 showed significantly stronger associations with ER-positive tumors [per-allele odds ratio (OR) for ER-positive tumors was 1.13, 95% CI = 1.10-1.16 and, for ER-negative tumors, OR was 1.03, 95% CI = 0.98-1.07, case-only P-heterogeneity = 7.6 × 10(-5)]. The association with ER-positive tumors was stronger for tumors of lower grade (case-only P= 6.7 × 10(-3)) and lobular histology (case-only P= 0.01). SNPs at 14q24.1 were associated with risk for most tumor subtypes evaluated, including triple-negative breast cancers, which has not been described previously. Our results underscore the need for large pooling efforts with tumor pathology data to help refine risk estimates for SNP associations with susceptibility to different subtypes of breast cancer.

Methylation of the human pendrin promoter

Inspection of the nucleotide sequence of the human pendrin promoter revealed the presence of a CpG island. We investigated the ability of IL-4 to stimulate pendrin message expression in two separate cell lines: the NCI-H292 lung epithelial cell line and the human embryonic kidney (HEK)-Blue cell line. The expression of pendrin mRNA was significantly increased in both cells types after 4, 24, 48 and 72 hours treatment with IL-4, and interestingly, the increase in pendrin mRNA was greater in the NCI-H292 cells. Methylation of CpG sites within the promoter regions of genes can affect activities of gene promoters and have either positive or negative implications on the transcription and mRNA expression of the particular gene. We quantitatively analyzed the methylation status of 35 CpG sites within the human pendrin promoter in both cell lines. The basal methylation pattern was statistically different at multiple CpG sites between the NCI-H292 and HEK-Blue cells. We propose that the difference in basal methylation between the two cell types may determine a cell-specific response to IL-4 in terms of pendrin mRNA expression.

A phase I clinical trial of vorinostat in combination with sFULV2 in patients with refractory solid tumors

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Background: Thymidylate synthase (TS) over-expression is associated with 5-FU resistance. Pre-clinical studies demonstrate that vorinostat down-regulates intra-tumor TS in a dose-dependent fashion and augments 5-FU antitumor activity in xenograft models. We conducted a phase I clinical trial of an intermittent schedule of QD x 3 vorinostat in combination with a fixed dose of fluorouracil (5-FU) and leucovorin (LV) in patients (pts) with refractory solid tumors. Methods: Vorinostat was escalated in a standard 3 x 3 design in combination with a fixed dose of 5-FU and LV (simplified de Gramont regimen, sFULV2). Vorinostat was given QD x 3 on an every-2-week cycle. sFULV2 started on day 2 of vorinostat and consisted of leucovorin 400 mg/m2 i.v. over 2 hrs followed by 5-FU 400 mg/m2 bolus and 5-FU 2400 mg/m2 over 46 hrs. Results: 24 pts were enrolled: Male/Female: 11/13; ECOG 0/1: 6/18; Age: median 60 (range 42–77) yrs. 21 pts had colorectal cancer (CRC), 1 had gastric, 1 had esophageal, and 1 had anal cancer. Vorinostat dose-levels (DL) were 600 mg, 800 mg, 1000 mg, 1200 mg, 1400 mg, 1700 mg, and 2000 mg. Dose-limiting toxicities (DLT), consisting of fatigue and hand-and-foot syndrome (H&F), were seen in 2 of 3 pts at the 2000 mg DL. None of the 6 pts at the 1700 mg DL had a DLT. Cycle 1 grade 3/4 toxicities consisted of thrombocytopenia, GI bleeding, fatigue, and H&F in 2 pts at the 2000 mg DL and a non-DLT G3 diarrhea (lasted <24 hrs) in 1 pt at the 1700 mg DL. Grade 2 nausea, fatigue, and anorexia were common; especially at DL ≥ 1700 mg. Antitumor activity was noted in pts with CRC despite prior refractoriness to 5-FU and failure to oxaliplatin, irinotecan, and cetuximab in all pts. 12/21 CRC pts had a confirmed SD (11) or PR (1). CRC pts had a median PFS of 4 months, a ≥ 6 months PFS rate of 43%, and a ≥ 8 months PFS rate of 33%. Conclusions: The maximum tolerated dose (MTD) of vorinostat in combination with sFULV2 is 1700 mg PO QD x 3 every 2 weeks. This combination is associated with considerable activity in pts with 5-FU-refractory CRC and warrants further investigation. An expanded MTD cohort is accruing to investigate 5-FU-vorinostat PK interaction and intra-tumor TS down-regulation. (This work was supported by a grant from CTEP and the ACS.)

No significant financial relationships to disclose.

Long-term survival on capecitabine in two gemcitabine refractory pancreatic cancer patients. Is there a pharmacogenetic explanation?

CONTEXT

Capecitabine has shown efficacy in treatment of metastatic pancreatic cancer. Several researchers have identified thymidine phosphorylase, dihydropyrimidine dehydrogenase, or their ratio as indicators of response to capecitabine in various cancers.

CASE REPORT

We report two patients with metastatic pancreatic carcinoma who had long-term survivals on capecitabine after gemcitabine failure. These two cases prompted us to measure thymidine phosphorylase and dihydropyrimidine dehydrogenase levels to facilitate discourses regarding their relationship with efficacy of capecitabine. We also describe a novel method of measuring thymidine phosphorylase level from serum without an invasive tissue biopsy. One patient is alive as of today, with improved performance status, 50 months after capecitabine was started. CA 19-9 and CT scans remained stable during 57 cycles. Her thymidine phosphorylase level was 1.77 compared to a control level of 1.00. Dihydropyrimidine dehydrogenase level was 4.14 compared to a control level of 1.00. Their ratio was 0.43. The other patient was alive on capecitabine for 24 months. His performance status, bilirubin, AST, and ALT improved on capecitabine. CT scans and CA 19-9 remained stable during this period. He had thymidine phosphorylase level of 5.56, dihydropyrimidine dehydrogenase level of 2.74, and their ratio of 2.03.

CONCLUSION

Capecitabine resulted in long term survivals in two patients with metastatic pancreatic cancer after gemcitabine failure. The use of capecitabine as second-line treatment in metastatic pancreatic cancer should be further explored along with the role of thymidine phosphorylase and dihydropyrimidine dehydrogenase levels in its activity. A non-invasive method of thymidine phosphorylase measurement we described should be validated in larger trials.

Priorities in colorectal cancer research: recommendations from the Gastrointestinal Scientific Leadership Council of the Coalition of Cancer Cooperative Groups

Emerging technologies have greatly expanded our ability to detect, characterize, and treat colorectal cancer. The Coalition of Cancer Cooperative Groups convened a multidisciplinary panel, the Scientific Leadership Council in GI cancer, to discuss and advise on the priorities and opportunities to advance current and future approaches into the clinical arena to impact most rapidly the morbidity and mortality from this disease. The Council's recommendations for research priorities are the result of engagement of community and academic oncologists, patient advocacy groups, and other stakeholders including the pharmaceutical industry and governmental agencies. We detail some key prospects for investigation in the areas of colon cancer detection, prevention, and surgical and medical management. Many are in early or definitive clinical trials, and a focus on rapid accrual is urged. The implementation of biology-directed laboratory investigations, both in association with ongoing clinical trials and as a separate developmental strategy for targeted therapies, is supported as the route to individualized therapy.

Identification of potentially useful combinations of epidermal growth factor receptor tyrosine kinase antagonists with conventional cytotoxic agents using median effect analysis

Targeted therapy for breast carcinoma has achieved a major advance with the use of trastuzumab in Her2/neu-positive tumors. The epidermal growth factor receptor superfamily thus becomes an attractive target for therapeutic agents. As the epidermal growth factor receptor tyrosine kinase family has a conformational binding site, which allows small molecules to interfere with its function, we have explored the effects of a dual kinase (epidermal growth factor receptor-1 and epidermal growth factor receptor-2) inhibitor (GW282974X) with a variety of cytotoxic agents looking for synergistic effects in vitro. Using a median effect model in four breast cancer cell lines in vitro, cytotoxic agents commonly used in treatment of human malignant disease were combined with trastuzumab or one of two epidermal growth factor receptor tyrosine kinase inhibitors in a 72-h culture and then analyzed for cytotoxic effect by 3-[26]-2,5-diphenyl-tetrazolium bromide assay. Combination index values within one standard deviation of unity were considered additive, less than unity as synergistic and more than unity as antagonistic. Synergistic results were confirmed by curve shift analysis and by an enzyme-linked immunosorbent assay measuring apoptosis by cytoplasmic histone-associated DNA fragments. Quantitative real-time polymerase chain reaction analysis was used to measure the expression of three of the critical enzymes in 5'-deoxy-5-fluorouridine metabolism and activity: thymidine phosphorylase, dihydropyrimidine dehydrogenase and thymidine synthase. 5'-Deoxy-5-fluorouridine with GW282974X demonstrated global synergy, both in high and low expressing epidermal growth factor receptor breast cancer cell lines. These results were confirmed by apoptosis assay and cell counts. RNA quantification following treatment with the dual kinase inhibitor suggested reduction in thymidine synthase levels to be a potential mechanism of synergy. The triplet of trastuzumab, GW282974X and 5'-deoxy-5-fluorouridine, and the triplet of GW282974X, epirubicin and 5'-deoxy-5-fluorouridine were highly synergistic in low expression cells (MCF7/wt) and high expression cells (MCF7/adr). These experiments suggest further studies of the dual kinase inhibitor with selected cytotoxics such as 5'-deoxy-5-fluorouridine are warranted.

Hand-Foot Syndrome Variant in a Dihydropyrimidine Dehydrogenase–Deficient Patient Treated with Capecitabine

We present a case with dihydropyrimidine dehydrogenase (DPD) deficiency that manifested a variant of hand-foot syndrome (HFS). A 52-year-old man received capecitabine for adjuvant treatment of rectal cancer. On the ninth day of the first cycle, he presented to the clinic with a rash on the dorsum of both hands accompanied by symptoms of pain, erythema, swelling, and desquamation consistent with grade 3 HFS. The palms of his hands and soles of his feet were only tender with no apparent rash or discoloration. Dihydropyrimidine dehydrogenase activity was evaluated by radio assay using peripheral blood mononuclear cells. Dihydropyrimidine dehydrogenase activity was below normal: 0.12 nmol/minute/mg protein. Capecitabine was not resumed, and the rash resolved in 3 weeks with the use of pyridoxine and Udderly Smooth balm. Interestingly, HFS is rarely seen with 5-fluorouracil regimens containing selective DPD-inhibitors. This patient with DPD deficiency manifested a variant of HFS. The pharmacologic basis for the development of HFS in DPD-deficient patients warrants further investigation. Dihydropyrimidine dehydrogenase deficiency, if undiagnosed, can lead to death. In addition to severe to life-threatening toxicities akin to 5-fluorouracil, capecitabine can lead to unusual variants of common toxicities, including HFS, in DPD-deficient patients.

Hand-foot syndrome (HFS) in patients treated with capecitabine (CAP) and the role of thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD)

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Background: HFS is the most common toxicity of CAP. Preclinical studies have shown that radiation (XRT) up-regulates TP, which may in turn increase efficacy of CAP. CAP is degraded by DPD, and a deficiency in this enzyme may increase toxicity of CAP. However, effect of XRT on frequency of HFS and association with TP and DPD has not been fully characterized. Methods: Toxicity data were collected from pts with LA pancreatic cancer enrolled in 3 clinical trials conducted at UAB between Apr 2001 and Jul 2005. Overall results of these trials have been reported elsewhere. Pts received XRT (50.4 Gy) with CAP (1,200–1,600 mg/m2 BID M-F) followed CAP (2,000 mg/m2 BID x 14 days). Pts were classified into 2 groups to evaluate HFS: CAP-XRT and CAP. Roche grading was used to assess HFS. Dose modifications were according to drug insert. Pts received prophylactic udder cream and pyridoxine. Tumor specimens were procured in 36 pts by EUS-FNA 1 wk pre- and 2 wks post XRT to evaluate TP and DPD. Age, race, sex, and PS were evaluated as prognostic factors. Results: Median duration of CAP was 6 wks (range: 3–6) for CAP-XRT and 2.5 cycles (range: 0–17) for CAP. Among 58 pts, 14 developed HFS (24%). CAP group had a higher incidence of HFS than CAP-XRT (17.2 % vs. 10.3 %; P = 0.12). Grade 2/3 HFS was observed in 15.5 % of CAP and 1.7 % of CAP-XRT (P = 0.0078). Median cumulative dose of CAP for first development of HFS was 235,000 mg/m2 in CAP-XRT group and 3,185,000 mg/m2 in CAP, with relative frequency of an event occurring in CAP-XRT vs. CAP of 0.59. HFS occurred at a median of 5 wks in CAP-XRT and 6 wks in CAP. Log-rank test showed neither age, sex, ECOG PS, or race was associated with development of HFS. There was no difference in tumor responses of pts with vs. without HFS. Mean tumor TP was higher among pts with vs. without HFS (275.77 vs. 215.29; P = 0.32). Mean tumor DPD was lower among pts with vs. without HFS (55.18 vs. 63.58; P = 0.49). Mean TP:DPD ratio was higher among pts with vs. without HFS (10.29 vs. 3.04; P = 0.31). Conclusions: This study suggests that incidence, severity, and time to occurrence of HFS with CAP-XRT < CAP, indicating no effect of XRT. No significant association of HFS with higher tumor TP or lower tumor DPD was found. Pharmacological basis for HFS with CAP needs to be explored.

[Table: see text]

Is capecitabine safe in patients with gastrointestinal cancer and dihydropyrimidine dehydrogenase deficiency?

Patients with cancer with dihydropyrimidine dehydrogenase (DPD) deficiency are at significant risk for severe 5-fluorouracil (5-FU) toxicity, including the risk of death. Data regarding the toxicity of capecitabine, an oral fluoropyrimidine, in patients with DPD deficiency are scarce. From 2004 to 2005, 2 patients with gastrointestinal (GI) malignancies (of the pancreas and liver) experienced severe to even life-threatening toxicities during capecitabine therapy, which resulted in death for 1 patient. A DPD enzyme assay was performed as previously defined in our laboratory. Both patients were DPD deficient upon evaluation for toxicity. Capecitabine can lead to severe and sometimes life-threatening toxicities akin to toxicities caused by 5-FU in patients with DPD deficiency. In cases of unexpected severe toxicity during capecitabine treatment, DPD deficiency should be considered. We suggest that capecitabine should not be used in patients with DPD deficiency. Screening should be considered in view of the widespread use of capecitabine and 5-FU, the severe toxicity that can develop in patients with low DPD activity, and the prevalence of the mutation.

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.

A Retrospective Study of Coagulation Abnormalities in Patients Receiving Concomitant Capecitabine and Warfarin

BACKGROUND

The extent and complications of the interaction between capecitabine and warfarin are not fully known.

PATIENTS AND METHODS

A retrospective study of 77 patients who received capecitabine was performed to analyze coagulation abnormalities with or without warfarin.

RESULTS

Twenty-one patients received warfarin with capecitabine. Twelve were on an average warfarin dosage of 19.4 mg per week (range, 7-35 mg) before capecitabine treatment, with a stable international normalized ratio (INR; range, 0.9-3.3). The dose of capecitabine ranged from 1.6 g/m2 to 2 g/m2 per day. Thirteen patients (11 on warfarin) had an INR > 3 (range, 3.23-11.5), resulting in a probability of an INR > 3 of 32% in the warfarin group versus 4% for those not on warfarin (P = 5.1 x 10(-14)) at 130 days. Six patients required a warfarin dose reduction (1-2.5 mg decrease). There were 7 episodes of bleeding (all gastrointestinal; 5 with warfarin). Seven patients who experienced bleeding had INRs ranging from 1.06 to 8 (average, 3.31) at the time bleeding occurred. Of the 7 bleeding episodes, 5 patients required transfusions, averaging 3.25 units of red blood cells and 2.4 units of fresh frozen plasma. The incidence of bleeding at 130 days of treatment with capecitabine was 18% with warfarin versus 2% without (P = 4 x 10(-13)). Bleeding episodes were not significantly different between patients with or without liver involvement (4 of 40 episodes vs. 3 of 37 episodes, respectively; P = 0.12). Patients with an INR > 3 were evenly distributed between those with or without liver involvement (6 of 40 patients vs. 7 of 37 patients, respectively). No INR increases persisted after discontinuation of capecitabine.

CONCLUSION

This study confirms a clinically significant interaction between warfarin and capecitabine-based chemotherapy akin to that already known for 5-fluorouracil. In addition to altered coagulation parameters, bleeding can be a complication. These events occurred in patients with and without liver metastases. We recommend weekly monitoring of coagulation parameters for all patients receiving concomitant warfarin and capecitabine, with an appropriate adjustment of warfarin dose. The nature and extent of this interaction requires further investigation.

Analysis of the DPYD gene implicated in 5-fluorouracil catabolism in a cohort of Caucasian individuals

PURPOSE

Complete or partial loss of dihydropyrimidine dehydrogenase (DPD) function has been described in cancer patients with intolerance to fluoropyrimidine drugs like 5-fluorouracil (5-FU) or Xeloda. The intention of this population study is to assess and to evaluate gene variations in the entire coding region of the dihydropyrimidine dehydrogenase gene (DPYD), which could be implicated in DPD malfunction.

EXPERIMENTAL DESIGN

A cohort of 157 individuals was genotyped by denaturing high-performance liquid chromatography; 100 of these genotypes were compared with functional studies on DPD activity and mRNA expression.

RESULTS

Twenty-three variants in coding and noncoding regions of the DPYD gene were detected, giving rise to 15 common haplotypes with a frequency of >1%. Rare sequence alterations included a frameshift mutation (295-298delTCAT) and three novel point mutations, 1218G>A (Met406Ile), 1236G>A (Glu412Glu), and 3067C>T (Pro1023Ser). DPD enzyme activity showed high variation in the analyzed population and correlated with DPD mRNA expression. In particular, the novel variants were not accompanied with decreased enzyme activity. However, a statistically significant deviation from the median DPD activity of the population was associated with the mutations 1601G>A (Ser534Asn) and 2846A>T (Asp949Val).

CONCLUSION

This work presents an analysis of DPYD gene variations in a large cohort of Caucasians. The results reflect the genetic and enzymatic variability of DPD in the population and may contribute to further insight into the pharmacogenetic disorder of DPD deficiency.

Simultaneous detection of variable number tandem repeats, single nucleotide polymorphisms, and allelic imbalance in the thymidylate synthase gene enhancer region using denaturing high-performance liquid chromatography

Polymorphisms in the thymidylate synthase enhancer region (TSER) have been reported to be associated with alterations in thymidylate synthase (TS) mRNA protein levels. The TSER is characterized by the presence of variable double (2R) and triple (3R) number tandem repeats (VNTRs). In addition to VNTRs, single nucleotide polymorphisms (SNPs) and allelic imbalance (AI), including loss of heterozygosity (LOH), have recently been associated with response to 5-fluorouracil (5-FU)-based chemotherapy. The aim of the current study was to develop a specific denaturing high-performance liquid chromatography (DHPLC) method for the rapid detection of these variations in the TSER in clinical samples. DHPLC analysis was validated in parallel with agarose gel electrophoresis (AGE), enzyme digestion, and quantitative reverse transcription-polymerase chain reaction (Q-RT-PCR). The optimized DHPLC method resolved 100% of the known TSER variations, differentiated between homozygous and heterozygous genotypes, and allowed the qualitative and quantitative detection of AI, including LOH, in tumor samples. This DHPLC method was developed to permit the rapid, sensitive, and accurate identification of the TSER genotype (VNTRs, SNPs, and AI) in clinical protocols where response to flouropyrimidines may be correlated with TSER polymorphisms.

Phase II Evaluation of Docetaxel-Modulated Capecitabine in Previously Treated Patients with Non–Small Cell Lung Cancer

PURPOSE

Based on the preclinical observation of upregulation of thymidine phosphorylase, the last enzymatic step in the conversion of capecitabine to 5-fluorouracil, by docetaxel along with good clinical tolerability of the combination of docetaxel and capecitabine using an optimized schedule in a previous phase I trial, we conducted this phase II study of this combination in patients with refractory or relapsed non-small cell lung cancer (NSCLC).

PATIENTS AND METHODS

Patients with NSCLC previously treated with at least one platinum- or paclitaxel-based regimen received docetaxel 36 mg/m(2) on days 1, 8, and 15 and capecitabine 625 mg/m(2) twice daily on days 5 to 18, every 4 weeks. The primary objective of the study was evaluation of progression-free survival (PFS) 26 weeks from initiation of treatment.

RESULTS

Thirty-six evaluable patients received 104 cycles of the combination. Severe toxicities were infrequent with only one patient requiring toxicity-related hospitalization. The 26-week PFS rate was 25% (95% confidence interval, 12-42) with an intent to treat median survival and 1-year survival rate of 9.1 months and 37%, respectively. Among 31 patients with measurable disease (Response Evaluation Criteria in Solid Tumors criteria), eight (26%; 95% confidence interval, 12-45) achieved partial responses.

CONCLUSION

The combination of capecitabine and weekly docetaxel is well tolerated in previously treated patients with NSCLC. The relatively high 26-week PFS and 1-year survival, as well as the high response rate observed, encourages further evaluation of this regimen in NSCLC, either in randomized trials for refractory patients or as a potential treatment option for chemotherapy naive patients.

Dihydropyrimidine Dehydrogenase Deficiency, a Pharmacogenetic Syndrome Associated with Potentially Life-Threatening Toxicity Following 5-Fluorouracil Administration

Dihydropyrimidine dehydrogenase (DPD) deficiency is a pharmacogenetic syndrome associated with potentially life-threatening toxicity following the administration of standard doses of 5-fluorouracil. This syndrome derives its importance from the fact that approximately 2 million patients receive the drug worldwide each year. Population studies have suggested that 4%-7% of the American population exhibit dose-limiting toxicity that might be associated with a genetic defect in the DPYD gene that encodes for the DPD enzyme. During the past several years it has become increasingly clear that genetics is a major determinant of the variability in drug response, accounting for the probability of drug efficacy and the likelihood of toxic drug reactions. This article briefly discusses the clinical presentation, laboratory diagnosis, pharmacokinetics, inheritance, and the clinical management options of DPD deficiency. The variability of DPD enzyme activity in population studies and the different DPYD alleles together with new phenotypic and genotypic methods of screening for DPD deficiency will also be reviewed.

Dihydropyrimidine dehydrogenase deficiency: impact of pharmacogenetics on 5-fluorouracil therapy

Through the use of pharmacogenetic studies, interindividual variability in response (efficacy and toxicity) to 5-fluorouracil (5-FU) chemotherapy has been linked to the rate-limiting enzyme in the drug's catabolic pathway, known as dihydropyrimidine dehydrogenase (DPD). This pharmacogenetic syndrome, known as "DPD deficiency," results in excessive amounts of 5-FU available to be anabolized to its active metabolites and is relatively undetectable by clinical observation prior to 5-FU administration. Extensive studies have associated both profound and partial deficiency in DPD activity with severe, unanticipated toxicity after 5-FU administration, while research on the molecular basis behind DPD deficiency has been linked to various sequence variants of the DPYD gene. Due to the widespread use of 5-FU, the severity of toxicity associated with DPD deficiency, and the prevalence of DPD deficiency in the population, extensive research is continually being performed to develop quick and accurate phenotypic and genotypic assays suitable for clinical settings that would allow clinicians to identify patients susceptible to adverse 5-FU reactions.

Denaturing high performance liquid chromatography analysis of the DPYD gene in patients with lethal 5-fluorouracil toxicity

Dihydropyrimidine dehydrogenase (DPD) enzyme deficiency is a pharmacogenetic syndrome with possible fatal outcome following 5-fluorouracil (5-FU) treatment. Several studies examining the molecular basis for DPD deficiency have identified over 30 sequence variations in the DPYD gene (which codes for the DPD enzyme). Our laboratory has recently developed and validated a denaturing high performance liquid chromatography method capable of identifying both known and unknown sequence variations in the DPYD gene. In the present study, we used this denaturing high performance liquid chromatography approach to examine the DPYD genotype of three patients who experienced lethal toxicity after administration of 5-FU. DPD enzyme activity could only be measured in one patient before death and demonstrated that lethal toxicity can occur in a partially DPD-deficient individual. Multiple heterozygous sequence variations (both known and unknown) were detected in all three patients including the novel variants 545T>A, M182K and 2329G>T, A777S. We conclude that (a) lethal toxicity can occur in partially DPD-deficient individuals after administration of 5-FU and is not exclusive to profoundly DPD-deficient individuals as suggested previously, (b) the complicated heterozygote genotype seen in these patients, combined with DPD deficiency being an autosomal codominant inherited syndrome, precludes the use of simple genotyping assays that identify only one or two mutations as a method for identifying DPD-deficient individuals; and (c) these multiple heterozygote genotypes (which are more difficult to accurately characterize) may be responsible for some of the conflicting reports which suggests a lack of correlation between phenotype and genotype.

Raltitrexed (Tomudex): an alternative choice in patients intolerant to 5-fluorouracil

Raltitrexed (Tomudex), a classical folate antagonist, is a selective inhibitor of thymidylate synthase (TS). It has significant single-agent activity in metastatic colorectal cancer. Severe life-threatening toxicity related to the administration of 5-fluorouracil and leucovorin is described in two patients, both of whom were not deficient in dihydropyrimidine dehydrogenase. Raltitrexed was administered to both patients with clinically acceptable side effects and allowed a TS inhibitor to be administered as part of an adjuvant program.

Phase I clinical and pharmacologic study of eniluracil plus fluorouracil in patients with advanced cancer

PURPOSE

To determine the highest dose of fluorouracil (5-FU) that could be safely administered with Eniluracil (776C85; Glaxo Wellcome Inc, Research Triangle Park, NC), an inactivator of dihydropyrimidine dehydrogenase (DPD), on a daily schedule for 5 days, and to define the toxicities of the combination and the pharmacokinetics of 5-FU when administered with 776C85.

PATIENTS AND METHODS

Patients with advanced solid tumors refractory to standard therapy were enrolled at two institutions. The study consisted of three periods designed to evaluate the safety, pharmacokinetics, and pharmacodynamics of 776C85 alone (period 1); the effects of 776C85 on the pharmacokinetics of 5-FU (period 2); and the maximum-tolerated dose (MTD) of 5-FU, with or without leucovorin, that could be safely administered with 776C85 (period 3). Cohorts of at least three patients each received oral 776C85 alone at doses of 3.7 mg/m2/d, 18.5 mg/m2/d and 0.74 mg/m2/d. After a 14-day washout period, each patient then received 776C85 daily for 3 days, with a single intravenous (i.v.) bolus dose of 5-FU 10 mg/m2 on day 2. After a second washout period, patients were treated with 776C85 daily for 7 days and 5-FU i.v. bolus on days 2 through 6. The starting dose of 5-FU 10 mg/m2/d was escalated until the MTD was determined. After determination of the MTD of 5-FU given with 776C85, oral leucovorin 50 mg/d on days 2 through 6 was added to determine the MTD of 5-FU with leucovorin in the presence of 776C85. Near the completion of the study, additional cohorts of patients were treated with 776C85 at 50 mg/d and oral 5-FU with or without leucovorin.

RESULTS

Sixty-five patients were enrolled onto the study and 60 were assessable for toxicity and response. Bone marrow suppression was the primary and dose-limiting toxicity of this regimen. Other toxicities included diarrhea, mucositis, anemia, anorexia, nausea, vomiting, and fatigue. 776C85 suppressed DPD activity in peripheral-blood mononuclear cells (PBMCs) by at least 90% for at least 24 hours at all dose levels tested. In the presence of 776C85, 5-FU half-life was prolonged, clearance was reduced, and the drug displayed linear pharmacokinetics. Recommended doses for further testing on a daily for 5-day schedule are 776C85 10 mg/d with i.v. 5-FU 25 mg/m2/d; 776C85 10 mg/d with i.v. 5-FU 20 mg/m2/d plus leucovorin 50 mg/d; 776C85 50 mg/d with 5-FU given orally at 15 mg/m2/d with leucovorin at 50 mg/d.

CONCLUSION

5-FU can be safely administered with 776C85; however, the MTDs are considerably lower than those conventionally used, caused, at least in part, by marked alterations in 5-FU plasma pharmacokinetics.

cis-Platinum in gynecologic cancer. III. Toxicity

The toxicity of cis-dichlorodiammineplatinum was evaluated in 41 patients who were treated for squamous cell carcinoma of the cervix or epithelial carcinoma of the ovary, with a dosage schedule of 60 mg/m2 every 3 weeks. Ototoxicity occurred in 33.3% of the patients serially tested, and anemia occurred in 48.8%. Leukopenia occurred in 29.9% and thrombocytopenia in 2.2% of courses administered. Nephrotoxicity was seen in 61% of patients as determined by evaluation of blood urea nitrogen and in 70.7% by serum creatinine elevation. Urine dipstick protein and 24 hour urinary protein determinations were evaluated. Suggestions are made in regard to the use of these determinations as a guide to modification of dose and duration of therapy.