Erika Cecchin

The role of UGT1A1*28 polymorphism in the pharmacodynamics and pharmacokinetics of irinotecan in patients with metastatic colorectal cancer

PURPOSE UGT1A1*28 polymorphism has been associated with decreased glucuronidation of SN38, the active metabolite of irinotecan. This could increase toxicity with this agent. PATIENTS AND METHODS In a prospective study, 250 metastatic colorectal cancer patients were treated with irinotecan, fluorouracil, and leucovorin as first-line treatment. UGT1A1*28 polymorphism was investigated with respect to the distribution of hematologic and nonhematologic toxicity, objective response rate, and survival. Pharmacokinetics was investigated in a subgroup of patients (71 of 250) who had been analyzed with respect to toxicity and efficacy. RESULTS UGT1A1*28 polymorphism was associated with a higher risk of grade 3 to 4 hematologic toxicity (odds ratio [OR], 8.63; 95% CI, 1.31 to 56.55), which was only relevant for the first cycle, and was not seen throughout the whole treatment period for patients with both variant alleles TA7/TA7 compared with wild-type TA6/TA6. The response rate was also higher in TA7/TA7 patients (OR, 0.32; 95% CI, 0.12 to 0.86) compared with TA6/TA6. A nonsignificant survival advantage was observed for TA7/TA7 when compared with TA6/TA6 patients (hazard ratio, 0.81; 95% CI, 0.45 to 1.44). Higher response rates were explained by a different pharmacokinetics with higher biliary index [irinotecan area under the curve (AUC)x(SN38 AUC/SN38G AUC)] and lower glucuronidation ratio (SN38G AUC/SN38 AUC) associated with the TA7/TA7 genotype and a higher response rate, indicating that the polymorphism is functionally relevant. CONCLUSION The results indicate that UGT1A1*28 polymorphism is of some relevance to toxicity; however, it is less important than discussed in previous smaller trials. In particular, the possibility of a dose reduction for irinotecan in patients with a UGT1A1*28 polymorphism is not supported by the result of this analysis.

Predictive Role of the UGT1A1, UGT1A7, and UGT1A9 Genetic Variants and Their Haplotypes on the Outcome of Metastatic Colorectal Cancer Patients Treated With Fluorouracil, Leucovorin, and Irinotecan

PURPOSE UGT1A1*28 is considered the main pharmacogenetic predictor of the toxicity outcome of irinotecan-treated patients. We evaluated the effect of other UGT1A variants and haplotypes involved in 7-ethyl-10-hydroxycamptothecin (SN-38) glucuronidation on severe toxicity and efficacy of fluorouracil, leucovorin, and irinotecan (FOLFIRI). PATIENTS AND METHODS In addition to UGT1A1*28, UGT1A1*60, UGT1A1*93, UGT1A7*3, and UGT1A9*22 were genotyped in 250 metastatic colorectal cancer patients, and associations with severe hematologic and nonhematologic toxicity, objective response, time to progression (TTP), and overall survival were evaluated. In a subset of 71 patients, pharmacokinetic data were also available. RESULTS UGT1A7*3 was the only marker of severe hematologic toxicity after the first cycle (odds ratio [OR], 3.94; 95% CI, 1.05 to 14.82; P = .04) in a multivariate analysis. It was also associated with glucuronidation ratio (SN-38G area under the curve [AUC]/SN-38 AUC) and biliary index (irinotecan AUC) x (SN-38 AUC/SN-38G AUC). Haplotype I (all the reference sequence alleles but UGT1A9*22) was a predictor of severe hematologic toxicity during the entire course of therapy (OR, 0.39; 95% CI, 0.19 to 0.82; P = .01), together with sex (OR, 2.08; 95% CI, 1.01 to 4.28; P = .05). In addition to UGT1A1*28, haplotype II (all the variant alleles but UGT1A9*22) was associated with a response rate (OR, 8.61; 95% CI, 1.75 to 42.38; P = .01). UGT1A1*28 was the only marker associated with TTP. CONCLUSION We propose that UGT1A variants additional to UGT1A1*28 might improve the prediction of the outcome of colorectal cancer patients treated with FOLFIRI. A UGT1A haplotype-based approach might be an efficacious strategy to achieve treatment individualization of FOLFIRI.

Genotype-Driven Phase I Study of Irinotecan Administered in Combination With Fluorouracil/Leucovorin in Patients With Metastatic Colorectal Cancer

PURPOSE We aimed to identify the maximum-tolerated dose (MTD) of irinotecan in patients with cancer with UGT1A1*1/*1 and *1/*28 genotypes. We hypothesize that the patients without the *28/*28 genotype tolerate higher doses of irinotecan. PATIENTS AND METHODS Patients undergoing first-line treatment for metastatic colorectal cancer (CRC) eligible for treatment with irinotecan plus infusional fluorouracil/leucovorin (FOLFIRI) were screened for the UGT1A1*28/*28 genotype and excluded from the study. Fifty-nine white patients with either the *1/*1 or the *1/*28 genotype were eligible for dose escalation of irinotecan. The starting dose of biweekly irinotecan was 215 mg/m(2) for both genotype groups, whereas the dose of infusional fluorouracil was fixed. Pharmacokinetic data of irinotecan and metabolites were also obtained. Results The dose of irinotecan was escalated to 370 mg/m(2) in patients with the *1/*28 genotype and to 420 mg/m(2) in those with the *1/*1 genotype. Dose-limiting toxicities (DLTs) were observed in two of four of *1/*28 patients at 370 mg/m(2) and in two of three of *1/*1 patients at 420 mg/m(2). No DLTs were observed in 10 *1/*28 patients at 310 mg/m(2) and in 10 *1/*1 patients at 370 mg/m(2); hence these dose levels were the MTD for each genotype group. The most common grade 3 to 4 toxicities were neutropenia and diarrhea. The pharmacokinetics of irinotecan and SN-38 exhibit linear kinetics. CONCLUSION The recommended dose of 180 mg/m(2) for irinotecan in FOLFIRI is considerably lower than the dose that can be tolerated when patients with the UGT1A1*28/*28 genotype are excluded. Prospective genotype-driven studies should test the efficacy of higher irinotecan doses in the FOLFIRI schedule.

Tumor response is predicted by patient genetic profile in rectal cancer patients treated with neo-adjuvant chemo-radiotherapy

The aim of the study was the identification of a pharmacogenetic profile predictive of the tumor regression grade (TRG), considered as tumor response parameter, after neo-adjuvant treatment in rectal cancer patients. A total of 238 rectal cancer patients treated in a neo-adjuvant setting by a fluoropyrimidines-based chemo-radiotherapy (RT) were genotyped for 25 genetic polymorphisms in 16 genes relevant for treatment-associated pathways. Two polymorphisms were associated with TRG in a multivariate analysis: hOGG1-1245C>G, which can affect radiosensitivity and MTHFR-677C>T, which is involved in fluoropyrimidines action. Patients bearing at least one variant allele had a lower chance to get TRG⩽2 (OR=0.46 95% CI 0.23–0.90, P=0.024; and OR=0.48 95% CI 0.24–0.96, P=0.034; respectively). An association trend was observed for ABCB1-3435C>T, which is responsible for the multi-drug resistance (odds ratio (OR)=1.96, 95% confidence interval (CI) 0.98–3.95, P=0.057). Exploratory classification and regression tree (CART) analysis highlighted high-order gene–gene and gene–environment interactions and a genetic signature associated with differential response, with hOGG1-1245C>G as the most predictive factor. Other significant variables were: ABCB1-3435C>T, MTHFR-677C>T, ERCC1-8092C>A, ABCC2-1249G>A, XRCC1-28152G>A, XRCC3-4541A>G and patients gender. On the basis of CART results, patients were categorized into three groups according to tumor response probability: intermediate and high profiles had a higher probability to get TRG⩽2 as compared with low profiles (OR=4.12 95% CI 1.46–11.65, P<0.001 and OR=12.44, 95% CI 5.52–28.04, P<0.0001, respectively). This study evidences a major role of hOGG1-1245C>G and MTHFR-677C>T polymorphisms in the tumor response of rectal cancer patients treated with chemo-RT in neo-adjuvant setting, and shows the relevance of gene–gene and gene–environment interactions for complex phenotypes as tumor response.

Effect of TP53 Arg72Pro and MDM2 SNP309 Polymorphisms on the Risk of High-Grade Osteosarcoma Development and Survival

Purpose: The germ-line polymorphisms TP53 Arg72Pro and MDM2 SNP309 T>G are risk factors for tumor development and affect response to chemotherapy and survival in several cancers, but their prognostic and predictive value in patients with high-grade osteosarcomas is not yet defined. The purpose of this study was to investigate the effect of the TP53 Arg72Pro and the MDM2 SNP309 on the risk of osteosarcoma development and survival. Experimental Design: The relative risk to develop osteosarcomas and the overall survival associated to TP53 Arg72Pro and MDM2 SNP309 polymorphisms were investigated in 201 patients. Correlations with event-free survival (EFS) were analyzed in a homogeneous subgroup of 130 patients with high-grade osteosarcomas of the limbs, nonmetastatic at diagnosis, which underwent neoadjuvant chemotherapy. Results: Multivariate analysis showed that the MDM2 polymorphism T309G was associated with an increased risk of developing osteosarcomas [GG versus TT; odds ratio, 2.09; 95% confidence interval (95% CI), 1.15-3.78]. A case/control gender approach evidenced a significant increased risk only for female osteosarcoma patients (GG versus TT; odds ratio, 4.26; 95% CI, 1.61-11.25). Subjects carrying the TP53 Arg72Pro polymorphism were found to have a significantly increased death risk (Pro/Pro versus Arg/Arg; hazard ratio, 2.90; 95% CI, 1.28-6.66). In the subgroup of 130 high-grade osteosarcomas, the TP53 Arg72Pro was an independent marker of EFS (Pro/Pro versus Arg/Arg; hazard ratio, 2.67; 95% CI, 1.17-6.11). Conclusion: The study provides evidence supporting the association of MDM2 SNP309 with high-grade osteosarcoma risk in females and shows that TP53 Arg72Pro has a prognostic value for overall survival and EFS in osteosarcoma patients.

A prospective validation pharmacogenomic study in the adjuvant setting of colorectal cancer patients treated with the 5-fluorouracil/ leucovorin/oxaliplatin (FOLFOX4) regimen

The discovery of pharmacogenomic markers in colorectal cancer (CRC) could be setting-specific. FOLFOX4 is employed in the adjuvant and metastatic setting in CRC. This prospective study is aimed to validate in the adjuvant setting the pharmacogenomic markers of toxicity reported in the metastatic setting (that is, GSTP1-rs947894, and -rs1138272; GSTM1-null genotype; AGXT-rs4426527, -rs34116584 and del-74 bp), and to discover additional markers. CRC patients (n=144) treated with adjuvant FOLFOX4 were genotyped for 57 polymorphisms in 29 genes. Grade ⩾2 neurotoxicity was associated (false discovery rate-adjusted q-value <0.1) with single-nucleotide polymorphisms in ABCC1 (rs2074087: odds ratio=0.43(0.22–0.86)), and ABCC2 (rs3740066: 2.99(1.16–7.70); rs1885301: 3.06(1.35–6.92); rs4148396: 4.69(1.60–13.74); rs717620: 14.39(1.63–127.02)). hMSH6-rs3136228 was associated with grade 3–4 neutropenia (3.23(1.38–7.57), q-value=0.0937). XRCC3-rs1799794 was associated with grade 3–4 non-hematological toxicity (8.90(2.48–31.97), q-value=0.0150). The markers previously identified in metastatic CRC were not validated. We have identified new markers of toxicity in genes of transport and DNA repair. If validated in other studies, they could help to identify patients at risk of toxicity.

Pharmacogenomics of intrinsic and acquired pharmacoresistance in colorectal cancer: Toward targeted personalized therapy

Colorectal cancer (CRC) represents one of the most common malignancies and is major cause of cancer-related deaths worldwide. A great improvement in response rate and patients survival was recently achieved through the introduction of new targeted agents including the anti-EGFR monoclonal antibodies cetuximab and panitumumab, the anti-angiogenic drugs bevacizumab and aflibercept, as well as the multi-kinase inhibitor regorafenib, in combination with standard fluoropyrimidines-based chemotherapeutic regimens. Intrinsic and acquired chemoresistance continue to be a major hindrance toward curative therapy. To overcome the obstacle of the currently unpredictable inter-individual variability in the therapy outcome, concentrated research efforts have been focused on elucidating the contribution of genetic variants predictive of pharmacoresistance in CRC. The occurrence of tumor somatic mutations in the RAS/RAF/MAPK and PI3K/PTEN/AKT pathways remains the main challenge for CRC treatment with the new biological agents. It has been recently proposed to consider a quadruple negative profile for CRC, based on the status of KRAS exon 2, BRAF-p.V600E, PI3KCA-exon 9 and PTEN, as tumor markers of sensitivity to anti-EGFR treatment. However, in the last years, great efforts have been devoted to address germline genetic profiles of pharmacoresistance. Heritable genetic variants in the ABC and SLC transport pathways; in the CYP450, GST, and UGT-mediated phase I and II metabolism; in the folate metabolic pathway; as well as in the EGF and VEGF signaling pathways, have been associated with a distinct tumor sensitivity phenotype in CRC patients treated with fluoropyrimidines combined with either irinotecan, oxaliplatin or targeted biological agents. More recently, computation of clinical-pharmacogenetic algorithms, combining multiple host polymorphisms with clinico-demographic features, appeared to be a more reliable strategy to test a complex phenomenon as tumor response to therapy. The final goal of the pharmacogenomics research in the domain of pharmacoresistance in CRC should be the definition of integrated somatic and germline genetic profiles of both intrinsic and acquired resistance. The aim of the present review is to provide a comprehensive update on the most important findings regarding the research of pharmacogenomics markers in the field of CRC treatment that could be integrated in clinical practice in order to accomplish an efficacious personalized treatment.

Pharmacology of epidermal growth factor inhibitors

Research into the molecular bases of malignant diseases has yielded the development of many novel agents with potential antitumor activity. Evidence for a causative role for the epidermal growth factor receptor (EGFR), which is now regarded as an excellent target for cancer chemotherapy in human cancer, leads to the development of EGFR inhibitors. Two classes of anti-EGFR agents are currently in clinical use: monoclonal antibodies directed at the extracellular domain of the receptor, and the low-molecular-weight receptor tyrosine kinase inhibitors acting intracellularly by competing with adenosine triphosphate for binding to the tyrosine kinase portion of the EGFR. The effect on the receptor interferes with key biological functions including cell cycle arrest, potentiation of apoptosis, inhibition of angiogenesis and cell invasion and metastasis. Cetuximab, a monoclonal antibody, and the receptor tyrosine kinase inhibitors gefitinib and erlotinib are currently approved for the treatment of patients with cancer. New agents with clinical activity are entering the clinic, and new combinatorial approaches are being explored with the aim of improving the potency and pharmacokinetics of EGFR inhibition, to increase the synergistic activity in combination with chemotherapy and overcome resistance to the EGFR inhibitors.

Carboxylesterase isoform 2 mRNA expression in peripheral blood mononuclear cells is a predictive marker of the Irinotecan to SN38 activation step in colorectal cancer patients

Purpose: Irinotecan (CPT11) is a prodrug activated in humans mainly by carboxylesterase 2 (CES2) generating the SN38 metabolite responsible for the drug efficacy and toxicity. The interpatients variability in CPT11 activation step could cause unpredictable toxicity. To identify a predictive molecular marker for CPT11 activation in cancer patients, we investigated the CES2 mRNA expression in peripheral blood mononuclear cells (PBMC) and correlated it to CPT11 activation rate, toxic effects, and response. Experimental Design: Forty-five colorectal cancer patients were treated with a CPT11-including regimen (FOLFIRI). CES2 mRNA expression in PBMC was quantified by reverse transcription-PCR in real time. Plasma concentrations of CPT11, SN38, and SN38-glucuronide were determined by high-performance liquid chromatography and the pharmacokinetic variables calculated adopting the noncompartmental model. Toxicity was evaluated by the National Cancer Institute Common Toxicity Criteria scale and response by the WHO criteria. Results: A high interindividual variability in CES2 mRNA relative expression was observed (median, 1.45; range, 0.01-28.21). CES2 mRNA expression level was significantly associated with CPT11 activation ratio [(AUCSN38 + AUCSN38G)/AUCCPT11]. Patients with CES2 mRNA expression above the median cutoff value presented an activation ratio higher (median, 0.25; range, 0.15-0.42) than those with CES2 mRNA below the median (median, 0.20; range, 0.10-0.40; P = 0.013). This was associated with a nonsignificant trend of 1.34-fold increase of SN38 AUC in the group of patients with high CES2 mRNA expression (mean, 1.03 ± 0.62 versus 0.77 ± 0.32 μmol/L hour). Eight of 23 high CES2 mRNA–expressing patients (34.8%) developed grade 3 to 4 neutropenia or diarrhea compared with 2 of 22 (9.1%) in the low CES2-expressing group (P = 0.071). Conclusion: Our data support a predictive power of CES2 mRNA expression in PBMC for the activation rate of CPT11.

Pharmacogenetics of ABC and SLC transporters in metastatic colorectal cancer patients receiving first-line FOLFIRI treatment.

Objective Membrane transporters are widely recognized as important determinants of drug disposition and response, generating increasing interest on the pharmacological implications of their genetic variations. The aim of this study was to elucidate the predictive/prognostic role of ATP-binding cassette (ABC) and solute carrier (SLC) protein polymorphisms on irinotecan (FOLFIRI regimen) outcome. Patients and methods A total of 250 White metastatic colorectal cancer patients homogenously treated with a first-line FOLFIRI regimen were genotyped for a panel of variants in five transporter genes. The primary study endpoints were the response rate (partial or complete response), overall survival, and time to progression. Toxicity was considered a secondary endpoint. Irinotecan pharmacokinetic data of 71 patients were used for polymorphism functional analysis. Results Two variants of the ABCG2 (−15622C>T, rs7699188) gene were found to be predictive (P<0.01) of the response rate. High-order relationships of ABC/SLC markers with previously investigated genetic (UGT1A1 polymorphisms) and nongenetic (primary tumor site) factors that helped determine the response rate were highlighted. A prognostic effect of the ABCB1 rs2032582 variant on patient overall survival emerged (P=0.0074). The ABCG2 rs7699788 variant was also seen to be associated with grade 3–4 nonhematological toxicity (P=0.0012). The ABCG2 (−15622C>T, rs7699188) and ABCB1 (rs2032582) polymorphisms were not found to be associated with pharmacokinetic parameters. Conclusion This study showed that ABC/SLC polymorphisms have a crucial contribution toward the FOLFIRI outcome. This could represent a further step toward personalized therapy.