Giuseppe Corona

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.

Effect of methylenetetrahydrofolate reductase 677C-->T polymorphism on toxicity and homocysteine plasma level after chronic methotrexate treatment of ovarian cancer patients.

MTHFR is a critical enzyme that regulates the metabolism of folate and methionine, both of which are important factors in DNA methylation and synthesis. Subjects with the 677C→T variant have impaired remethylation of Hcy to methionine that could determine hyperhomocysteinemia. Remethylation of Hcy into methionine and DNA methylation are also affected by MTX treatment. Thus, a combined effect between MTX and reduced activity of the MTHFR 677C→T polymorphism could occur, leading to toxicity. In a clinical trial, 43 ovarian cancer patients were treated with low doses of MTX. During MTX therapy, 12 patients (27.9%) developed G3/4 WHO toxicity. In these 12 patients, we observed 6 G3/4 thrombocytopenias, 1 G3 neutropenia, 1 G3 anemia, 9 G3 mucositis cases and 1 G4 mucositis case. A significant association was observed between toxicity and TT MTHFR 677 genotype (p < 0.0001). G3/4 toxicity occurred in 10 of 13 (77%), 1 of 17 (6%) and 1 of 13 (8%) patients with the TT, CT and CC MTHFR genotypes, respectively. According to the logistic regression model, patients with the TT genotype had a relative risk of 42.0 (95% CI 4.2–418.6) of developing G3/4 toxicity compared to patients with the CC and CT genotypes. Patients with the TT genotype had Hcy plasma levels after MTX therapy significantly (p = 0.0001) higher than basal levels (mean ± SD = 16.71 ± 4.72 vs. 12.48 ± 3.57 μmol/l); moreover, they also had higher Hcy plasma levels after MTX than patients with other MTHFR 677 genotypes (CC mean ± SD = 9.87 ± 3.61 μmol/l and CT mean ± SD = 11.48 ± 3.13 μmol/l). Finally, significant associations were observed between G3/4 WHO toxicity and higher Hcy plasma levels after MTX treatment (p = 0.0004). In conclusion, our data suggest that the TT MTHFR 677 genotype is associated with marked MTX‐induced hyperhomocysteinemia and could represent a pharmacogenetic marker for toxicity after chronic treatment with low doses of MTX.

Role of folate receptor and reduced folate carrier in the transport of 5‐methyltetrahydrofolic acid in human ovarian carcinoma cells

Folate receptor‐α (FR‐α) is generally over‐expressed in non‐mucinous human ovarian carcinomas. The meaning of FR‐α over‐expression and its role in the 5‐methyltetrahydrofolic acid (N5‐CH3‐H4PteGlu) transport in such tumors is not clear, especially compared with the reduced folate carrier (RFC), the other known folate transporter. In this study, we analyzed molecular FR‐α and RFC expression in 16 ovarian carcinoma tissues and in 5 ovarian carcinoma cell lines using competitive PCR. Co‐expression of the 2 transporters was found both in vivo and in vitro. FR‐α mRNA expression in the cell lines was in good agreement with the corresponding protein expression evaluated by cellular folic acid binding and immunofluorescence analysis, using a specific monoclonal antibody (MAb) (MOv18). Moreover, RFC mRNA expression levels were consistent with the selective cellular binding of N‐hydroxysuccinimide of [3H]‐methotrexate (NHS‐MTX). The 5 ovarian carcinoma cell lines (IGROV‐1, SW‐626, SKOV‐3, OVCAR‐3 and OAW‐42), grown at physiological N5‐CH3‐H4PteGlu concentrations (20 nM) and expressing FR‐α and RFC levels superimposable to those observed in vivo, were used as in vitro cellular model to evaluate the different contribution of FR‐α and RFC to the transport of N5‐CH3‐H4PteGlu. The cytoplasmic N5‐CH3‐[3H]H4PteGlu accumulation observed in each cell line was approximately linear over 4 hr of incubation, but there was no correlation between the rate of folate internalization and FR‐α and RFC expression levels. Furthermore, the selective inhibition of FR‐α and RFC functionality allowed us to distinguish their differential role on the overall N5‐CH3‐[3H]H4PteGlu intracellular delivery. Treatment with the N‐hydroxysuccinimide of folic acid, which blocks FR‐α activity, showed only a partial inhibition (about 20%) of folate internalization in all the cell lines. In contrast, the inhibition of RFC by NHS‐MTX, under conditions that did not affect FR‐α functionality, generally reduced folate accumulation by more than 70%. Only one cell line (IGROV‐1) showed a comparable contribution of the 2 transport systems. Our findings suggest that in ovarian carcinomas, in spite of its over‐expression, FR‐α generally plays a minor role in N5‐CH3‐H4PteGlu transport compared with RFC. Int. J. Cancer 75:125–133, 1998.© 1998 Wiley‐Liss, Inc.

Pharmacokinetic Optimisation of Treatment with Oral Etoposide

Etoposide is a derivative of podophyllotoxin widely used in the treatment of several neoplasms, including small cell lung cancer, germ cell tumours and non-Hodgkin’s lymphomas. Prolonged administration of etoposide aims for continuous inhibition of topoisomerase II, the intracellular target of etoposide, thus preventing tumour cells from repairing DNA breaks. However, the clinical advantages of extended schedules as compared with conventional short-term infusions remain unclear.Oral administration of etoposide represents the most feasible and economic strategy to maintain effective concentrations of drug for extended times. Nevertheless, the efficacy of oral etoposide therapy is contingent on circumventing pharmacokinetic limitations, mainly low and variable bioavailability. Inhibition of small bowel and hepatic metabolism of etoposide with specific cytochrome P450 inhibitors or inhibition of the intestinal P-glycoprotein efflux pump have been attempted to increase the bioavailability of oral etoposide, but the best results were obtained with daily oral administration of low etoposide doses (50–100 mg/day for 14–21 days). Saturable absorption of etoposide was reported for doses greater than 200 mg/day, whereas lower doses were associated with increased bioavailability, although they were characterised by high inter- and intrapatient variability.Pharmacokinetic parameters such as plasma trough concentration between two oral administrations (C24, trough), drug exposure time above a threshold value and area under the plasma concentration-time curve have been correlated with the pharmacodynamic effect of oral etoposide. Pharmacokinetic-pharmacodynamic relationships indicate that severe toxicity is avoided when peak plasma concentrations do not exceed 3–5 mg/L and C24,trough is under the threshold limit of 0.3 mg/L. To maintain effective etoposide plasma concentrations during prolonged oral administration, pharmacokinetic variability must be monitored in each patient, taking account of factors from many pharmacokinetic studies of etoposide, including absorption, distribution, protein binding, metabolism and elimination.Dosage reduction is generally useful to avoid haematological toxicity in patients with renal dysfunction (creatinine clearance <50 mL/min). The need for dosage adjustment based on liver function in patients with liver dysfunction is not completely defined, but generally is not indicated in patients with minor liver dysfunction. Adaptive dosage adjustment based on individual pharmacokinetic parameters, estimated using limited sampling strategies and population pharmacokinetic models, is more appropriate. This approach has been used with success in different clinical trials to increase the etoposide dosage, without significantly increasing toxicity.Various pharmacodynamic models have been proposed to guide etoposide oral dosage. However, they lack precision and accuracy and need to be refined by considering other predictor variables in order to extend their application in current clinical practice.

Pharmacokinetics of oral etoposide in patients with hepatocellular carcinoma

Abstract Etoposide dosage in patients with liver dysfunction remains controversial. Since etoposide has a hepatic component to its clearance (CL) and shows a high degree of protein binding, hepatic impairment could affect etoposide disposition. However, the empiric recommendation that the dose of etoposide be decreased in such patients may reduce systemic exposure and be detrimental to its antitumor activity. To address these issues we studied the pharmacokinetics (PK) of etoposide in patients with hepatocellular carcinoma (HCC) and underlying cirrhosis (n= 17) treated with daily oral etoposide. Unbound etoposide was obtained by ultrafiltration. Etoposide concentrations (total and free drug) were measured by high-performance liquid chromatography (HPLC) and analyzed by noncompartmental equations. The patients had mild or moderate liver dysfunction. Albuminemia was in the normal range for all the patients. Creatininemia was normal in all but two patients. PK results (mean and range) showed that etoposide disposition was unchanged in patients with liver dysfunction. We found slightly high etoposide bioavailability [F, 61% (17–95%)] and clearance [CL, 1.1 (0.7–2.3) l h−1 m−2] resulting in a normal degree of systemic exposure (AUCoral 27 μg h ml−1). Normal protein binding [PB 93.2% (84.4–98.1%)] contributed to a normal level of exposure to free drug (AUCf, oral 1.9 μg h ml−1). The distribution volume [VSS 8.4 (6.1–13.2) l/m2] and the effective half-life [t1/2eff, 5.1 (3.0–9.6) h] were normal. Median CL and protein binding did not differ in the seven patients with total bilirubin value of >1.2 mg/dl as compared with the ten patients with total bilirubin levels of ≤1.2 mg/dl (1.3 versus 1.0 l h−1 m−2 and 92.5% versus 93.4%, respectively). In agreement with this PK finding, we observed no clinical evidence of increased toxicity in patients with hyperbilirubinemia as compared with patients with normal bilirubinemia (mean WBC decrease 38% versus 47%). The only case of severe (grade 4) hematological toxicity was observed in one patient with reduced glomerular filtration. Since the pharmacological effects of etoposide correlate with the level of systemic exposure to the free drug, our data suggest that no dose reduction is needed in patients with HCC. It is even possible to increase the dose intensity in patients with favorable PK parameters under appropriate hematological and therapeutic drug monitoring.

Pharmaco-metabolomics: an emerging "omics" tool for the personalization of anticancer treatments and identification of new valuable therapeutic targets.

In the post‐genomics era, metabolomics represents a new “omics” approach that in the last decade has received increased attention in the field of oncology. Metabolomics is based on the holistic study of the metabolic profile that characterizes a specific phenotype in a biological system. The metabolic profile provides a readout of the metabolic state of an individual that cannot be obtained directly from DNA genotyping, gene expression, or proteomic profiling analyses. The translational value of metabonomics in the oncology field has been demonstrated by the identification of diagnostic and prognostic biomarkers. The so‐called pharmaco‐metabolomic approach that is currently emerging aims to identify the individual metabolomic characteristics able to predict drug effectiveness and/or toxicity. This review presents the potential role of pharmaco‐metabolomics in the future of anticancer pharmacology to achieve customized anticancer treatments and new, targeted therapeutic approaches. J. Cell. Physiol. 227: 2827–2831, 2012.

Lopinavir-ritonavir dramatically affects the pharmacokinetics of irinotecan in HIV patients with Kaposi's sarcoma

The coadministration of protease inhibitors with anticancer drugs in the management of human immunodeficiency virus‐related malignancies can cause potential drug–drug interactions. The effect of lopinavir/ritonavir (LPV/RTV) on the pharmacokinetics of irinotecan (CPT11) has been investigated in seven patients with Kaposis sarcoma. Coadministration of LPV/RTV reduces the clearance of CPT11 by 47% (11.3±3.5 vs 21.3±6.3 l/h/m2, P=0.0008). This effect was associated with an 81% reduction (P=0.02) of the AUC (area under the curve) of the oxidized metabolite APC (7‐ethyl‐10‐[4‐N‐(5‐aminopentanoic‐acid)‐1‐piperidino]‐carbonyloxycamptothecin). The LPV/RTV treatment also inhibited the formation of SN38 glucuronide (SN38G), as shown by the 36% decrease in the SN38G/SN38 AUCs ratio (5.9±1.6 vs 9.2±2.6, P=0.002) consistent with UGT1A1 inhibition by LPV/RTV. This dual effect resulted in increased availability of CPT11 for SN38 conversion and reduced inactivation on SN38, leading to a 204% increase (P=0.0001) in SN38 AUC in the presence of LPV/RTV. The clinical consequences of these substantial pharmacokinetic changes should be investigated.

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.