Blood gene expression biomarkers of response to anti-TNF drugs in pediatric inflammatory bowel diseases before initiation of treatment.

BACKGROUND/AIMS: Changes in gene expression profiles among individuals with inflammatory bowel diseases (IBDs) could potentially influence the responsiveness to anti-TNF treatment. The aim of this study was to identify genes that could serve as predictors of early response to anti-TNF therapies in pediatric IBD patients prior to the initiation of treatment. METHODS: We conducted a prospective, longitudinal, and multicenter study, enrolling 24 pediatric IBD patients aged less than 18 years who were initiating treatment with either infliximab or adalimumab. RNA-seq from blood samples was analyzed using the DESeq2 library by comparing responders and non-responders to anti-TNF drugs. RESULTS: Bioinformatic analyses unveiled 102 differentially expressed genes, with 99 genes exhibiting higher expression in responders compared to non-responders prior to the initiation of anti-TNF therapy. Functional enrichment analyses highlighted defense response to Gram-negative bacteria (FDR = 2.3 ×10-7) as the most significant biological processes, and hemoglobin binding (FDR = 0.002), as the most significant molecular function. Gene Set Enrichment Analysis (GSEA) revealed notable enrichment in transcriptional misregulation in cancer (FDR = 0.016). Notably, 13 genes (CEACAM8, CEACAM6, CILP2, COL17A1, OLFM4, INHBA, LCN2, LTF, MMP8, DEFA4, PRTN3, AZU1, and ELANE) were selected for validation, and a consistent trend of increased expression in responders prior to drug administration was observed for most of these genes, with findings for 4 of them being statistically significant (CEACAM8, LCN2, LTF2, and PRTN3). CONCLUSIONS: We identified 102 differentially expressed genes involved in the response to anti-TNF drugs in children with IBDs and validated CEACAM8, LCN2, LTF2, and PRTN3. Genes participating in defense response to Gram-negative bacterium, serine-type endopeptidase activity, and transcriptional misregulation in cancer are good candidates for anticipating the response to anti-TNF drugs in children with IBDs.

Polymorphisms indicating risk of inflammatory bowel disease or antigenicity to anti-TNF drugs as biomarkers of response in children.

Few genetic polymorphisms predict early response to anti-TNF drugs in inflammatory bowel disease (IBD), and even fewer have been identified in the pediatric population. However, it would be of considerable clinical interest to identify and validate genetic biomarkers of long-term response. Therefore, the aim of the study was to analyze the usefulness of biomarkers of response to anti-TNFs in pediatric IBD (pIBD) as long-term biomarkers and to find differences by type of IBD and type of anti-TNF drug. The study population comprised 340 children diagnosed with IBD who were treated with infliximab or adalimumab. Genotyping of 9 selected SNPs for their association with early response and/or immunogenicity to anti-TNFs was performed using real-time PCR. Variants C rs10508884 (CXCL12), A rs2241880 (ATG16L1), and T rs6100556 (PHACTR3) (p value 0.049; p value 0.03; p value 0.031) were associated with worse long-term response to anti-TNFs in pIBD. DNA variants specific to disease type and anti-TNF type were identified in the pediatric population. Genotyping of these genetic variants before initiation of anti-TNFs would enable, if validated in a prospective cohort, the identification of pediatric patients who are long-term responders to this therapy.

Association between HLA DNA Variants and Long-Term Response to Anti-TNF Drugs in a Spanish Pediatric Inflammatory Bowel Disease Cohort.

The genetic polymorphisms rs2395185 and rs2097432 in HLA genes have been associated with the response to anti-TNF treatment in inflammatory bowel disease (IBD). The aim was to analyze the association between these variants and the long-term response to anti-TNF drugs in pediatric IBD. We performed an observational, multicenter, ambispective study in which we selected 340 IBD patients under 18 years of age diagnosed with IBD and treated with anti-TNF drugs from a network of Spanish hospitals. Genotypes and failure of anti-TNF drugs were analyzed using Kaplan-Meier curves and Cox logistic regression. The homozygous G allele of rs2395185 and the C allele of rs2097432 were associated with impaired long-term response to anti-TNF drugs in children with IBD after 3 and 9 years of follow-up. Being a carrier of both polymorphisms increased the risk of anti-TNF failure. The SNP rs2395185 but not rs2097432 was associated with response to infliximab in adults with CD treated with infliximab but not in children after 3 or 9 years of follow-up. Conclusions: SNPs rs2395185 and rs2097432 were associated with a long-term response to anti-TNFs in IBD in Spanish children. Differences between adults and children were observed in patients diagnosed with CD and treated with infliximab.

Clinical Relevance of Novel Polymorphisms in the Dihydropyrimidine Dehydrogenase (DPYD) Gene in Patients with Severe Fluoropyrimidine Toxicity: A Spanish Case-Control Study.

Among cancer patients treated with fluoropyrimidines, 10-40% develop severe toxicity. Polymorphism of the dihydropyrimidine dehydrogenase (DPYD) gene may reduce DPD function, the main enzyme responsible for the metabolism of fluoropyrimidines. This leads to drug accumulation and to an increased risk of toxicity. Routine genotyping of this gene, which usually includes DPYD *HapB3, *2A, *13 and c.2846A > T (D949V) variants, helps predict approximately 20-30% of toxicity cases. For DPD intermediate (IM) or poor (PM) metabolizers, a dose adjustment or drug switch is warranted to avoid toxicity, respectively. Societies such as the Spanish Society of Pharmacogenetics and Pharmacogenomics (SEFF), the Dutch Pharmacogenetics Working Group (DPWG) or the Clinical Pharmacogenetics Implementation Consortium (CPIC) and regulatory agencies (e.g., the Spanish Medicines Agency, AEMPS) already recommend DPYD routine genotyping. However, the predictive capacity of genotyping is currently still limited. This can be explained by the presence of unknown polymorphisms affecting the function of the enzyme. In this case-control work, 11 cases of severe fluoropyrimidine toxicity in patients who did not carry any of the four variants mentioned above were matched with 22 controls, who did not develop toxicity and did not carry any variant. The DPYD exome was sequenced (Sanger) in search of potentially pathogenic mutations. DPYD rs367619008 (c.187 A > G, p.Lys63Glu), rs200643089 (c.2324 T > G, p.Leu775Trp) and rs76387818 (c.1084G > A, p.Val362Ile) increased the percentage of explained toxicities to 38-48%. Moreover, there was an intronic variant considered potentially pathogenic: rs944174134 (c.322-63G > A). Further studies are needed to confirm its clinical relevance. The remaining variants were considered non-pathogenic.

Comparison of a new rapid method for determination of serum anti-adalimumab and anti-infliximab antibodies with two established ELISA kits.

BACKGROUND: Adalimumab (ADL), infliximab (IFX) and their biosimilars are widely used biological drugs. Some patients, however, generate neutralizing antibodies that hamper the effectiveness of these drugs. Evidence shows therapeutic drug monitoring of serum levels ADL/IFX and anti-drug antibodies (ADA) is useful to improve treatment effectiveness. We evaluated a new rapid quantitative method, Quantum Blue (QB), for determining serum anti-ADL and anti-IFX antibodies (Research Use Only labelling) by comparing it with two established ELISA kits, Promonitor (PM) and Lisa-Tracker (LT). METHODS: Eighty samples (40 for each drug type) were analysed. Percentage of agreement and kappa statistic were used to compare positive/negative ADA results. Clinical implications for drug treatment in the patients with discordant results were evaluated. The Chi-square test was used to analyze differences for ADA detection in patients with disease flare and without concomitant immunosuppressant treatment. RESULTS: Agreement exceeded 80 % among anti-ADL methods. Although LT ELISA showed a lower capacity in detecting anti-ADL antibodies, discrepancies were found for levels close to the cut-off concentration, thus having minimal impact on clinical decisions. Conversely, QB anti-IFX displayed low agreement with PM and LT ELISA kits (67.5 % and 50 %, respectively), and was unable to detect high levels of antibodies, therefore having major clinical implications. Agreement between PM and LT ELISA anti-IFX kits was 82.5 % with all discordant results being undetected for PM and slightly positive for LT. CONCLUSION: QB anti-ADL shows similar performance to ELISA kits while QB anti-IFX needs further improvements to achieve reliable antibody detection.

Whole Transcription Profile of Responders to Anti-TNF Drugs in Pediatric Inflammatory Bowel Disease.

BACKGROUND: Up to 30% of patients with pediatric inflammatory bowel disease (IBD) do not respond to anti-Tumor Necrosis Factor (anti-TNF) therapy. The aim of this study was to identify pharmacogenomic markers that predict early response to anti-TNF drugs in pediatric patients with IBD. METHODS: An observational, longitudinal, prospective cohort study was conducted. The study population comprised 38 patients with IBD aged < 18 years who started treatment with infliximab or adalimumab (29 responders and nine non-responders). Whole gene expression profiles from total RNA isolated from whole blood samples of six responders and six non-responders taken before administration of the biologic and after two weeks of therapy were analyzed using next-generation RNA sequencing. The expression of six selected genes was measured for purposes of validation in all of the 38 patients recruited using qPCR. RESULTS: Genes were differentially expressed in non-responders and responders (32 before initiation of treatment and 44 after two weeks, Log2FC (Fold change) >0.6 or <-0.6 and p value < 0.05). After validation, FCGR1A, FCGR1B, and GBP1 were overexpressed in non-responders two weeks after initiation of anti-TNF treatment (Log2FC 1.05, 1.21, and 1.08, respectively, p value < 0.05). CONCLUSION: Expression of the FCGR1A, FCGR1B, and GBP1 genes is a pharmacogenomic biomarker of early response to anti-TNF agents in pediatric IBD.

Regulatory CDH4 Genetic Variants Associate With Risk to Develop Capecitabine-Induced Hand-Foot Syndrome.

Capecitabine-induced hand-foot syndrome (CiHFS) is a common dermatological adverse reaction affecting around 30% of patients with capecitabine-treated cancer, and the main cause of dose reductions and chemotherapy delays. To identify novel genetic factors associated with CiHFS in patients with cancer, we carried out an extreme-phenotype genomewide association study in 166 patients with breast and colorectal capecitabine-treated cancer with replication in a second cohort of 85 patients. We discovered and replicated a cluster of four highly correlated single-nucleotide polymorphisms associated with susceptibility to CiHFS at 20q13.33 locus (top hit = rs6129058, hazard ratio = 2.40, 95% confidence interval = 1.78-3.20; P = 1.2 × 10-8 ). Using circular chromosome conformation capture sequencing, we identified a chromatin contact between the locus containing the risk alleles and the promoter of CDH4, located 90 kilobases away. The risk haplotype was associated with decreased levels of CDH4 mRNA and the protein it encodes, R-cadherin (RCAD), which mainly localizes in the granular layer of the epidermis. In human keratinocytes, CDH4 downregulation resulted in reduced expression of involucrin, a protein of the cornified envelope, an essential structure for skin barrier function. Immunohistochemical analyses revealed that skin from patients with severe CiHFS exhibited low levels of RCAD and involucrin before capecitabine treatment. Our results uncover a novel mechanism underlying individual genetic susceptibility to CiHFS with implications for clinically relevant risk prediction.

Genetic Predictors of Long-term Response to Antitumor Necrosis Factor Agents in Pediatric Inflammatory Bowel Disease.

OBJECTIVES: Inflammatory bowel disease (IBD) is more complex in children and they will have to live with the disease for much longer. For this reason, it is necessary to optimize treatment. The polymorphisms associated with the response to anti-tumor necrosis factor (TNF) drugs in adults with IBD have not been analyzed in children. The aim of the study was to identify genetic variants associated with the long-term response to anti-TNF drugs in children with IBD. METHODS: An observational, longitudinal, ambispective cohort's study was conducted. We recruited 209 anti-TNF-treated children diagnosed with IBD and genotyped 21 polymorphisms previously studied in adults with Crohn disease (CD) using real-time PCR. The association between single-nucleotide polymorphisms (SNPs) and time-to-failure was analyzed using the log-rank test. RESULTS: After multivariate analysis, 3 SNPs in IL10, IL17A and IL6 were significantly associated with response to anti-TNF treatment among patients diagnosed with CD (rs1800872-HR, 4.749 (95% confidence interval [CI] 1.156-19.517), P value < 0.05; rs2275913-HR, 0.320 [95% CI 0.111-0.920], P value  < 0.05; and rs10499563-HR, 0.210 [95% CI 0.047-0.947], P value 0.05, respectively). None of these SNPs were associated with response to infliximab in adults diagnosed with CD. Among patients diagnosed with ulcerative colitis (UC), 1 SNP in LY96 was significantly associated with response to anti-TNF treatment (rs-11465996-HR, 10.220 [95% CI 1.849-56.504] P value < 0.05). CONCLUSIONS: Genotyping of these DNA variants before starting treatment may help to identify children who are long-term responders to anti-TNF drugs, and thus tailor treatment of pediatric IBD.

New DPYD variants causing DPD deficiency in patients treated with fluoropyrimidine.

PURPOSE: Several clinical guidelines recommend genetic screening of DPYD, including coverage of the variants c.1905 + 1G>A(DPYD*2A), c.1679T>G(DPYD*13), c.2846A>T, and c.1129-5923C>G, before initiating treatment with fluoropyrimidines. However, this screening is often inadequate at predicting the occurrence of severe fluoropyrimidine-induced toxicity in patients. METHODS: Using a complementary approach combining whole DPYD exome sequencing and in silico and structural analysis, as well as phenotyping of DPD by measuring uracilemia (U), dihydrouracilemia (UH2), and the UH2/U ratio in plasma, we were able to characterize and interpret DPYD variants in 28 patients with severe fluoropyrimidine-induced toxicity after negative screening. RESULTS: Twenty-five out of 28 patients (90%) had at least 1 variant in the DPYD coding sequence, and 42% of the variants (6/14) were classified as potentially deleterious by at least 2 of the following algorithms: SIFT, Poly-Phen-2, and DPYD varifier. We identified two very rare deleterious mutations, namely, c.2087G>A (p.R696H) and c.2324T>G (p.L775W). We were able to demonstrate partial DPD deficiency, as measured by the UH2/U ratio in a patient carrying the variant p.L775W for the first time. CONCLUSION: Whole exon sequencing of DPYD in patients with suspicion of partial DPD deficiency can help to identify rare or new variants that lead to enzyme inactivation. Combining different techniques can yield abundant information without increasing workload and cost burden, thus making it a useful approach for implementation in patient care.

Gene Signatures of Early Response to Anti-TNF Drugs in Pediatric Inflammatory Bowel Disease.

Around a 20-30% of inflammatory bowel disease (IBD) patients are diagnosed before they are 18 years old. Anti-TNF drugs can induce and maintain remission in IBD, however, up to 30% of patients do not respond. The aim of the work was to identify markers that would predict an early response to anti-TNF drugs in pediatric patients with IBD. The study population included 43 patients aged <18 years with IBD who started treatment with infliximab or adalimumab. Patients were classified into primary responders (n = 27) and non-responders to anti-TNF therapy (n = 6). Response to treatment could not be analyzed in 10 patients. Response was defined as a decrease in over 15 points in the disease activity indexes from week 0 to week 10 of infliximab treatment or from week 0 to week 26 of adalimumab treatment. The expression profiles of nine genes in total RNA isolated from the whole-blood of pediatric IBD patients taken before biologic administration and after 2 weeks were analyzed using qPCR and the 2-∆∆Ct method. Before initiation and after 2 weeks of treatment the expression of SMAD7 was decreased in patients who were considered as non-responders (p value < 0.05). Changes in expression were also observed for TLR2 at T0 and T2, although that did not reach the level of statistical significance. In addition, the expression of DEFA5 decreased 1.75-fold during the first 2 weeks of anti-TNF treatment in responders, whereas no changes were observed in non-responders. Expression of the SMAD7 gene is a pharmacogenomic biomarker of early response to anti-TNF agents in pediatric IBD. TLR2 and DEFA5 need to be validated in larger studies.

Differential Expression of SMAD Genes and S1PR1 on Circulating CD4+ T Cells in Multiple Sclerosis and Crohn's Disease.

The Th17 immune response plays a key role in autoimmune diseases such as multiple sclerosis (MS) and inflammatory bowel disease (IBD). Expression of Th17-related genes in inflamed tissues has been reported in autoimmune diseases. However, values are frequently obtained using invasive methods. We aimed to identify biomarkers of MS in an accessible sample, such as blood, by quantifying the relative expression of 91 Th17-related genes in CD4+ T lymphocytes from patients with MS during a relapse or during a remitting phase. We also compared our findings with those of healthy controls. After confirmation in a validation cohort, expression of SMAD7 and S1PR1 mRNAs was decreased in remitting disease (-2.3-fold and -1.3-fold, respectively) and relapsing disease (-2.2-fold and -1.3-fold, respectively). No differential expression was observed for other SMAD7-related genes, namely, SMAD2, SMAD3, and SMAD4. Under-regulation of SMAD7 and S1PR1 was also observed in another autoimmune disease, Crohn's disease (CD) (-4.6-fold, -1.6-fold, respectively), suggesting the presence of common markers for autoimmune diseases. In addition, expression of TNF, SMAD2, SMAD3, and SMAD4 were also decreased in CD (-2.2-fold, -1.4-fold, -1.6-fold, and -1.6-fold, respectively). Our study suggests that expression of SMAD7 and S1PR1 mRNA in blood samples are markers for MS and CD, and TNF, SMAD2, SMAD3, and SMAD4 for CD. These genes could prove useful as markers of autoimmune diseases, thus obviating the need for invasive methods.

Evaluating the role of ENOSF1 and TYMS variants as predictors in fluoropyrimidine-related toxicities: An IPD meta-analysis.

To assess the proposed associations of the c.742-227G>A (rs2612091) polymorphism within the Enolase Superfamily Member 1 gene (ENOSF1) and two variants in the adjacent Thymidylate Synthase gene (TYMS): the 5'VNTR 28bp-repeat (rs45445694) and 3'UTR 6bp-indel (rs11280056) with severe toxicity in fluoropyrimidine-treated cancer patients, we performed an individual patient data meta-analysis. Only studies investigating all three-abovementioned variants with fluoropyrimidine-related toxicities were considered for meta-analysis. Associations were tested individually for each study using multivariate regression. Meta-analysis was performed using a random-effects model. One-stage multivariate regressions including tests for independent SNP effects were applied to investigate individual effects of the variants. Multivariate haplotype regression analyses were performed on a pooled dataset to test multi-SNP effects. Of four studies including 2'067 patients, 1'912 were eligible for meta-analysis. All variants were exclusively associated with severe hand-foot-syndrome (HFS) (TYMS 2R: OR = 1.50, p = 0.0002; TYMS 6bp-ins: OR = 1.42 p = 0.0036; ENOSF1 c.742-227G: OR = 1.64 p < 0.0001, per allele). We observed independent effects for ENOSF1 c.742-227G>A and the TYMS 28bp-repeat: each toxicity-associated allele increased the risk for severe HFS (OR = 1.32 per allele, p < 0.0001). Patients homozygous for both variants were at the 3-fold higher risk for severe HFS compared to wild-type patients. Our results confirm an essential role for ENOSF1 c.742-227G and TYMS 2R-alleles in the development of fluoropyrimidine-related HFS. This suggests an important function of these genes in the development of severe HFS. Furthermore, these variants might help stratify patients in studies investigating measures of HFS prevention.

Genetic predictors of long-term response and trough levels of infliximab in crohn's disease.

INTRODUCTION: Several factors, such as trough serum anti-TNF levels, have been associated with response to therapy in Crohn's disease. However, this association is observed after initiation of treatment. Identifying DNA variants may prove useful for predicting long-term response or failure to these drugs before initiation of treatment. OBJECTIVE: To identify genetic variants associated with long-term response to infliximab and trough levels in Crohn's disease. PATIENTS AND METHODS: An observational, longitudinal study was conducted. We analyzed blood samples from 132 infliximab-treated patients diagnosed with Crohn's disease from 2 hospitals. We genotyped 21 polymorphisms previously related to anti-TNF response in genes involved in the NFkB-mediated inflammatory response, TNFα-signaling and cytokines regulated by NFkB, using real-time PCR. Trough infliximab levels were measured using ELISA. The association between SNPs and time-to-failure (defined as the time from the initiation of induction therapy to the date of treatment withdrawal due to a primary or secondary failure) was analyzed using log-rank test. The association between SNPs and supra-(>7 µg/mL) or infratherapeutic (<3 µg/mL) infliximab trough levels was analyzed using a linear-by-linear association chi-squared test. RESULTS: Two SNPs in TLR2, rs1816702 and rs3804099, and 1 SNP in TNFRSF1B, rs1061624, were associated with long-term response (up to ten years follow-up) to infliximab (HR, 0.13 [95%CI, 0.02-1.00], p < 0.05; HR, 0.39 [95%CI, 0.18-0.88], p < 0.05; and HR, 0.04 [95%CI, 0.18-0.92] p > 0.05, respectively). In addition, IL6 rs10499563 C and IL10 rs1800872 A were associated with supratherapeutic trough infliximab levels; IL10 rs3024505 T was associated with infratherapeutic levels (p < 0.05). CONCLUSION: Genotyping of the variants identified in the genes encoding TLR2, TNFRSF1B, IL6 and IL10 reported herein represent a promising tool for the identification and selection of those patients who will benefit most from infliximab.

Clinical utility of ABCB1 genotyping for preventing toxicity in treatment with irinotecan.

Preventing severe irinotecan-induced adverse reactions would allow us to offer better treatment and improve patients' quality of life. Transporters, metabolizing enzymes, and genes involved in the folate pathway have been associated with irinotecan-induced toxicity. We analyzed 12 polymorphisms in UGT1A1, ABCB1, ABCG2, ABCC4, ABCC5, and MTHFR in 158 patients with metastatic colorectal cancer treated with irinotecan and studied the association with grade >2 adverse reactions (CTCAE). Among the most frequent ADRs, the SNPs rs1128503, rs2032582, and rs1045642 in ABCB1 and rs1801133 in MTHFR were associated with hematological toxicity and overall toxicity. The SNP rs11568678 in ABCC4 was also associated with overall toxicity. After correction of P values using a false discovery rate, only ABCB1 variants remained statistically significant. Haplotype analysis in ABCB1 showed an 11.3-fold and 4.6-fold increased risk of hematological toxicity (95% CI, 1.459-88.622) and overall toxicity (95% CI, 2.283-9.386), respectively. Consequently, genotyping of the three SNPs in ABCB1 can predict overall toxicity and hematological toxicity with a diagnostic odds ratio of 4.40 and 9.94, respectively. Genotyping of ABCB1 variants can help to prevent severe adverse reactions to irinotecan-based treatments in colorectal cancer.

Use of exome sequencing to determine the full profile of genetic variants in the fluoropyrimidine pathway in colorectal cancer patients affected by severe toxicity.

AIM: To identify genetic variants associated with capecitabine toxicity in fluoropyrimidine pathway genes using exome sequencing. PATIENTS & METHODS: Exomes from eight capecitabine-treated patients with severe adverse reactions (grade >2), among a population of 319, were sequenced (Ion Proton). SNPs in genes classified as potentially damaging (Sorting Intolerant from Tolerant and Polymorphism Phenotyping v2) were tested for association with toxicity in a validation cohort of 319 capecitabine-treated patients. RESULTS: A total of 17 nonsynonymous genetic variants were identified. Of these, five putative damaging SNPs in DPYD, ABCC4 and MTHFR were genotyped in the validation cohort. DPYD rs1801160 was associated with the risk of toxicity (p = 0.029) and MTHFR rs1801133 with delayed administration of chemotherapy due to toxicity (p = 0.047). CONCLUSION: Exome sequencing revealed two specific biomarkers of the risk of toxicity to capecitabine.

Identification of new SNPs associated with severe toxicity to capecitabine.

Predicting individual risk of chemotherapy-induced severe adverse reaction is a critical issue when selecting the best treatment for cancer patients. SNPs have been identified in genes involved in the pharmacodynamics of fluoropyrimidines, and guidelines even recommend genotyping some DPYD variants in order to estimate the risk of toxicity. However, the predictive value of this approach remains insufficient, thus limiting its clinical implementation. The aim of the present study was to identify new genetic variants by selecting a group of tag SNPs in genes associated with the pharmacodynamics of fluoropyrimidines (CDA, DPYD, ENOSF1, CES1, TYMS, SLC22A7, TYMP, and UMPS). For this purpose, 23 selected SNPs were genotyped on an OpenArray™ platform in a cohort of 301 colorectal cancer patients receiving capecitabine-based chemotherapy. Univariate and multivariate statistical analysis by logistic regression revealed 10 SNPs associated with severe adverse reactions to capecitabine (P<0.05): rs1048977, rs12726436, and rs2072671 in CDA; rs12119882 in DPYD; rs2853741 in TYMS; rs699517 in TYMS/ENOSF1; rs2270860 and rs4149178 in SLC22A7; and rs2279199 and rs4678145 in UMPS. Except for rs2072671, no association had previously been reported between these SNPs and the risk of capecitabine-induced toxicity. The use of tag SNPs to find new polymorphisms related to adverse reactions to capecitabine was successful. These new variants could increase the predictive power of currently available tests and thus prevent severe adverse reactions to capecitabine.

Cost-effectiveness of screening for DPYD polymorphisms to prevent neutropenia in cancer patients treated with fluoropyrimidines.

AIM: To compare the cost of screening for three mutations in the dihydropyrimidine dehydrogenase gene and the costs of treating severe fluoropyrimidine-induced neutropenia. MATERIALS & METHODS: The polymorphisms rs3918290 (DPYD*2A), rs67376798 (DPYD 2846A>T) and rs55886062 (1679T>G, DPYD*13) were genotyped using real-time PCR, TaqMan probes and a rapid cell lysis to provide PCR-ready DNA. RESULTS: We found that genotyping 1000 patients in our center cost €6400 and that the mean cost of treating severe neutropenia was €3044. Therefore, if severe fluoropyrimidine-induced neutropenia is reduced by genotyping the three DPYD variations in at least 2.21 cases per 1000 treated patients, then DPYD genotyping will prove cost effective. CONCLUSION: We demonstrated that real-time DPYD genotyping using TaqMan probes is cost effective in all fluoropyrimidine-based treatments.

Clinical implementation of pharmacogenetics.

In the last decade, pharmacogenetic research has been performed in different fields. However, the application of pharmacogenetic findings to clinical practice has not been as fast as desirable. The current situation of clinical implementation of pharmacogenetics is discussed. This review focuses on the advances of pharmacogenomics to individualize cancer treatments, the relationship between pharmacogenetics and pharmacodynamics in the clinical course of transplant patients receiving a combination of immunosuppressive therapy, the needs and barriers facing pharmacogenetic clinical application, and the situation of pharmacogenetic testing in Spain. It is based on lectures presented by speakers of the Clinical Implementation of Pharmacogenetics Symposium at the VII Conference of the Spanish Pharmacogenetics and Pharmacogenomics Society, held in April 20, 2015.

Variants in CDA and ABCB1 are predictors of capecitabine-related adverse reactions in colorectal cancer.

Adverse reactions to capecitabine-based chemotherapy limit full administration of cytotoxic agents. Likewise, genetic variations associated with capecitabine-related adverse reactions are associated with controversial results and a low predictive value. Thus, more evidence on the role of these variations is needed. We evaluated the association between nine polymorphisms in MTHFR, CDA, TYMS, ABCB1, and ENOSF1 and adverse reactions, dose reductions, treatment delays, and overall toxicity in 239 colorectal cancer patients treated with capecitabine-based regimens. The ABCB1*1 haplotype was associated with a high risk of delay in administration or reduction in the dose of capecitabine, diarrhea, and overall toxicity. CDA rs2072671 A was associated with a high risk of overall toxicity. TYMS rs45445694 was associated with a high risk of delay in administration or reduction in the dose of capecitabine, HFS >1 and HFS >2. Finally, ENOSF1 rs2612091 was associated with HFS >1, but was a poorer predictor than TYMS rs45445694. A score based on ABCB1-CDA polymorphisms efficiently predicts patients at high risk of severe overall toxicity (PPV, 54%; sensitivity, 43%) in colorectal cancer patients treated with regimens containing capecitabine. Polymorphisms in ABCB1, CDA, ENOSF1,and TYMS could help to predict specific and overall severe adverse reactions to capecitabine.