Epirubicin Clearance Research Articles

A Uridine Glucuronosyltransferase 2B7 Polymorphism Predicts Epirubicin Clearance and Outcomes in Early-Stage Breast Cancer

BackgroundEpirubicin is metabolized by uridine glucuronosyltransferase 2B7 (UGT2B7), an enzyme rich in single nucleotide polymorphisms (SNPs). We studied whether the −161 C > T germline SNP in UGT2B7 was related to epirubicin metabolism and whether differences exist in the toxicity and efficacy of epirubicin-based chemotherapy among patients who were TT homozygotes, CT heterozygotes, and CC homozygotes. Patients and MethodsA total of 132 women with non–metastatic breast cancer receiving FEC (5-fluorouracil 500 mg/m2, epirubicin 100 mg/m2, cyclophosphamide 500 mg/m2) were prospectively enrolled. Toxicity was assessed in cycle 1 using the National Cancer Institute Common Toxicity Criteria, version 2.0. ResultsThe sequence at −161 was studied in 132 subjects; 37 were TT homozygotes, 63 were CT heterozygotes, 26 were CC homozygotes, and 6 could not be genotyped. The CC genotype patients had decreased epirubicin clearance (median, 103.3 L/hr) compared with the CT/TT genotype patients (median, 134.0 L/hr; P = .002). The CC homozygous patients had an increased risk of grade 3 to 4 leukopenia compared with the TT homozygotes or heterozygotes (P = .038 and P = .032, respectively). TT homozygotes or heterozygotes had an increased risk of early recurrence (P = .039; χ2 test). ConclusionThe results of the present prospective pharmacogenetic study suggest that the UGT2B7 −161 C > T SNP correlate with drug metabolism, toxicity, and efficacy in patients receiving epirubicin chemotherapy. Further studies of this UGT2B7 SNP as a predictor of epirubicin toxicity and efficacy are warranted.

Abstract P3-06-48: Pharmacogenetic dosing of epirubicin in FEC chemotherapy

Abstract Background: Epirubicin dosing affects important clinical outcomes in breast cancer, with higher dose regimens improving efficacy but producing more myelosuppression. Epirubicin is metabolized by uridine glucuronosyltransferase 2B7 (UGT2B7). We previously reported relationships between UGT2B7’s promoter polymorphisms and epirubicin clearance and clinical outcomes in the (neo)adjuvant breast cancer setting; we identified a trend for increased grade 3/4 neutropenia but better efficacy outcomes in patients having at least one deficient allele (i.e. CT or CC) vs. patients who were wild type homozygotes. Patients homozygous for the deficient allele (CC) were at statistically significant increased risk for leucopenia compared to patients who were wild type homozygotes or heterozygotes. In this study we hypothesized patients with CT and TT genotypes would tolerate a higher epirubicin dose compared to CC genotype patients. We designed this study to determine the safety of pharmacogenetic-guided epirubicin dosing for each UGT2B7 genotype. Methods: Female breast cancer patients with histologically confirmed non-metastatic invasive breast cancer scheduled to receive at least three cycles of FE100C in the (neo)adjuvant setting were enrolled into the study. Peripheral blood was analyzed for UGT2B7 genotype. Patients received standard dose IV FE100C during the first 21 day cycle. Based on genotype, epirubicin dosing was escalated in the 2nd and 3rd cycles. Epirubicin Dose Escalation SchemeDose of Epirubicin per Cycle (mg/m2)CycleGenotype123CC100100100CT100115130TT100120140 Results: To date 32 patients are evaluable for pharmacogenetic guided epirubicin dosing (8 CC genotypes, 14 CT genotypes and 10 TT genotypes). All 32 patients received epirubicin100 mg/m2 in cycle one and a single patient in each of the CC and CT genotypes experienced grade 3 febrile neutropenia and were not dose escalated. All other patients with CT and TT genotypes were dose escalated in cycle 2 and all but two patients in the CT and TT genotypes were dose escalated in cycle 3. The incidence of febrile neutropenia was not dose dependent as all three genotypes had similar incidence in each cycle whereas leucopenia was genotype and dose dependent. The incidence of leukopenia increased in patients with CT and TT genotypes as their dose was increased and cycle 3 leukopenia rates were similar to patients with the CC genotype receiving standard dose epirubicin. Conclusions: Pharmacogenetic guided epirubicin dosing is well tolerated. This study is ongoing and updated data will be presented. Citation Format: John R Mackey, Edith Pituskin, Ann Vlahadamis, Katia Tonkin, Karen King, Sanraj Basi, Maria Ho, Judith Meza-Junco, Anil Joy, Dick Au, Sambasivarao Damaraju, Michael B Sawyer. Pharmacogenetic dosing of epirubicin in FEC chemotherapy [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-06-48.

Sarcopenia and Acute Severe Toxicity in Sarcoma Patients Treated with Doxorubicin-Based Chemotherapy

ABSTRACT Aim: Lean body mass (LBM) better than body surface area (BSA), predicts epirubicin's clearance and its toxicity in breast cancer patients (pts) (Prado et al, 2010). Since the dose-intensity of anthracycline-based chemotherapy may be critical in sarcoma pts, we studied whether sarcopenia was associated with the occurrence of acute severe toxicity (AT) in this population. Methods: Sarcoma pts treated with doxorubicin-based chemotherapy and having a CT scan at the 3rd lumbar vertebrae prior chemotherapy were selected. Skeletal muscle cross-sectional area were measured and sarcopenia was defined using standardized thresholds (Antoun et al, 2010.). Acute severe toxicity was defined as any grade 4 toxicity or febrile neutropenia (FN) or grade≥3 gastrointestinal (GI) toxicity, according to the NCI-CTC occurring at 1st cycle. Sarcopenic and non-sarcopenic pts were compared (k-2 test or Fischer's exact test for qualitative data). Results: 42 consecutive soft tissue (n=24; 57%) and bone sarcoma (n=18; 43%) pts were eligible (57.1% males, median age 48yrs, range 22-68), and received a median doxorubicin dose of 112 mg at first cycle (range 84-148). 24 pts (57.1%) were sarcopenic at baseline. 13 (54%) of the sarcopenic patients had a normal body mass index (BMI), 11 (46%) were overweight. During the first cycle, AT were hematologic (11 pts 26.2%), FN (8 pts 19.0%), and GI toxicity (6 pts 14.3%). Sarcopenic pts had significantly more ATs (11/24 versus 3/18, p=0.04), more grade 4 hematotoxicity (9/24 versus 2/18, p=0.05), more FN (7/24 versus 1/18, p=0.05). Pts with sarcopenia and BMI Conclusions: The evaluation of sarcopenia prior to doxorubicin-based chemotherapy in sarcoma patients identifies patients with high-risk of acute toxicity. Disclosure: All authors have declared no conflicts of interest.

An exploratory study of body composition as a determinant of epirubicin pharmacokinetics and toxicity

Although body composition has emerged as an important predictor of drug efficacy and toxicity, explanations for this association are unclear. Our goal was to investigate relationships between lean body mass (LBM), liver size/function and epirubicin pharmacokinetics (PK) and toxicity. Data from a clinical study (n = 24) of patients with breast cancer receiving adjuvant intravenous FE(100)C chemotherapy were used to examine relationships between LBM, liver size, and epirubicin clearance. Muscle tissue and liver mass were measured by analysis of computerized tomography cross-sectional images, and an extrapolation of muscle mass to total LBM compartment was employed. Population PK analysis of epirubicin was undertaken to test effects of body composition on epirubicin clearance and area under the curve (AUC). Estimated LBM was extremely variable in this cohort ranging from 32.9 to 67.3 kg. LBM was associated with neutrophil nadir (r = 0.5, P = 0.023), and mean LBM was lower for patients presenting with toxicity compared to those where toxicity was absent (41.6 vs. 56.2 kg, P = 0.002); 33% of variance in clearance was explained by LBM and aspartate aminotransferase (AST). Liver mass was not related to epirubicin clearance likely due to larger livers presenting with larger fat content, but liver attenuation (degree of fat infiltration) and AST were associated with AUC. To our knowledge, this is the first study to examine relationships between LBM, liver mass/function and epirubicin PK and toxicity. This exploratory work investigates the notion of organs and tissues having distinctive contributions to the distribution and metabolism of antineoplastic drugs.

Uridine glucuronosyltransferase 2B7 pharmacogenetics predicts epirubicin clearance and myelosuppression

2504 Background: Epirubicin (EPI) is widely used to treat breast cancer. EPI is predominantly metabolized by uridine glucuronosyltransferase (UGT) 2B7 to inactive glucuronides. We previously showed that a UGT enhancer single nucleotide polymorphism (SNP) at position -161 T to C correlated with rates of morphine glucuronidation. Methods: We performed a prospective pharmacogenetic study of effects of this SNP on EPI metabolism in M0 breast cancer patients (PTS) receiving adjuvant or neoadjuvant FEC100 (5-fluorouracil 500 mg/m2, EPI 100 mg/m2 and cyclophosphamide 500 mg/m2) given every 3 wks. PTS with ALT and AST ≤ upper limit of normal (ULN), a total bilirubin ≤ ULN, and normal renal and cardiac function were eligible. EPI levels were drawn at approximately 1 and 24 hrs. Cycle 1 toxicities were assessed using NCIC CTG toxicity criteria. Results: 123 PTS entered this study, mean (range): age 51 (28 - 74), sex 122 F/ 1 M, baseline AST 24 U/L (13–66), ALT 22 U/L (5–90), bilirubin 8 μmol/L (2–26), creatinine 74 μmol/L (50 - 126). PTS were genotyped using Pyrosequencing; 26 PTS were TT homozygotes, 59 were CT heterozygotes, and 33 were CC homozygotes. 5 PTS could not be genotyped. A three compartment population pharmacokinetic model in NONMEM V 1.1 for EPI was used incorporating all PTS. The baseline objective function was 1817, and inclusion of genotype significantly improved the objective function to 1764; CC genotype PTS had decreased EPI clearance 88.9 L/hr compared to CT/TT genotype PTS 129 L/hr, p<0.001. Rates of first cycle grade 3/4 leucopenia were 78% in CC PTS and 48% in CT/TT PTS; consistent with the pharmacokinetic analysis. Conclusions: A SNP in UGT 2B7 is common and appears to predicts EPI clearance and myelosuppresion in non-metastatic breast cancer PTS and may form the basis for a method to individualize EPI treatment. No significant financial relationships to disclose.

Assessment of the validity of a population pharmacokinetic model for epirubicin

The aim of this study was to evaluate a population model for epirubicin clearance using internal and external validation techniques. Jackknife samples were used to identify outliers in the population dataset and individuals influencing covariate selection. Sensitivity analyses were performed in which serum aspartate transaminase (AST) values (a covariate in the population model) or epirubicin concentrations were randomly changed by +/-10%. Cross-validation was performed five times, on each occasion using 80% of the data for model development and 20% to assess the performance of the model. External validation was conducted by assessing the ability of the population model to predict concentrations and clearances in a separate group of 79 patients. Structural parameter estimates from all jackknife samples were within 7.5% of the final population estimates and examination of log likelihood values indicated that the selection of AST in the final model was not due to the presence of outliers. Alteration of AST or epirubicin concentrations by +/-10% had a negligible effect on population parameter estimates and their precision. In the cross-validation analysis, the precision of clearance estimates was better in patients with AST concentrations>150 U l-1. In the external validation, epirubicin concentrations were over-predicted by 81.4% using the population model and clearance values were also poorly predicted (imprecision 43%). The results of internal validation of population pharmacokinetic models should be interpreted with caution, especially when the dataset is relatively small.

Maximum a posteriori Bayesian estimation of epirubicin clearance by limited sampling.

To develop a limited sampling strategy for estimation of epirubicin clearance. The data set comprised 1051 concentrations measured in 105 patients with advanced or metastatic breast cancer treated with epirubicin alone. Ten limited sampling designs comprising two or three blood samples were proposed, taken at times identified by D-optimality from population pharmacokinetic parameter estimates. The data set was then truncated to include the sampling times for each of the designs. MAP Bayesian estimates of clearance were generated for each design and compared with clearance estimates obtained using all the data. The limited sampling designs were also validated using a separate data set obtained from 18 patients with either breast cancer or hepatocellular carcinoma. The sensitivity of the best limited sampling designs to sample time recording errors of 0-10% or 10-20% was then assessed using a simulated data set including 200 patients. The optimum sampling times were: end of the injection and 18 min, 40 min, 3 h, 10 h and 48 h after the start of the injection. The best three-sample design included samples at 40 min, 3 h and 48 h and gave unbiased estimates of clearance with an imprecision of 9.1% (95% CI 7.3, 10.5). The best two sample design included samples at 3 and 48 h and gave unbiased estimates of clearance with an imprecision of 12.4% (95% CI 9.6, 14.6). Using the validation data set, these two and three sample designs gave unbiased estimates of clearance with an imprecision of 5.6% (95% CI 3.7, 7.0) and 4.2% (95% CI 2.6, 5.3), respectively. Simulations that included 0-10% or 10-20% errors in the recording of the blood sampling times had negligible effects on the bias and imprecision of clearance estimates. Limited sampling designs have been identified and validated that estimate epirubicin clearance with adequate precision and without bias from two or three blood samples. These designs also allow flexibility in blood sample collection and are robust with regard to sample time recording errors.

Epirubicin in patients with liver dysfunction: development and evaluation of a novel dose modification scheme

This study aimed to develop an epirubicin dose modification scheme in women with breast cancer and liver dysfunction. We first identified target areas under the concentration-time curve (AUCs) of 2400 and 1600 ng/ml.h from pharmacokinetic studies in 15 women with normal liver tests. In a second group of 16 women with abnormal liver biochemistry, the relationship between raised asparate aminotransferase (AST) and epirubicin clearance was: dose=AUC (97.5−34.2×log AST). Adaptive dosing was evaluated prospectively in a third group of 41 women with serum AST ⩾2×normal±raised bilirubin. The median AUCs were 2444 and 1608 ng/ml.h, close to the high and low target AUCs, respectively. Variability in AUC was lower with adaptive dosing than in a fourth group given an unadjusted dose of epirubicin (coefficient of variation=25.8, 30.0 and 46.5%, respectively; P=0.06). Epirubicin dosing based on AST is safe and may reduce pharmacokinetic variability.

Docetaxel in combination with epirubicin in metastatic breast cancer: pharmacokinetic interactions

Epirubicin (75 mg/m 2) and docetaxel (75 mg/m 2) were administered to 16 patients affected by metastatic breast cancer following two different schedules: (1) docetaxel as infusion administered 1 h after epirubicin administration (schedule A); and (2) docetaxel as infusion immediately (10 min) after the end of epirubicin i.v. bolus administration (schedule B). Experimental non-compartmental analyses such as AUC and Css, were affected very little by the drug combination, irrespective of whether the administration of docetaxel was immediately after the epirubicin bolus (10 min) or delayed (1 h). However, serum levels showed evidence of transient drug interaction: in schedule A, docetaxel infusion was associated with a transient increase of plasma epirubicin in correspondence with Css max of docetaxel. Bi-compartmental analysis showed a significant difference in epirubicin clearance between protocols A and B. It is suggested that polysorbate 80, used in minimal amounts to formulate docetaxel, may interfere with epirubicin plasma level.

Alteration in Epirubicin Pharmacokinetics and Metabolism by Dexverapamil: Results from a Phase II Study in Patients with Metastatic Breast Cancer

Background: To study the effect of the resistance-modifying agent (RMA) dexverapamil on the pharmacokinetics and metabolism of epirubicin. Methods: Nine women with metastatic breast cancer who received epirubicin (120 mg/m 2 ) as a 0.25-hour infusion without dexverapamil during the first treatment cycle and with dexverapamil (12 × 300 mg p. o. every 6 h) during the third treatment cycle were monitored with frequent plasma samples up to 48 h postinfusion. Epirubicin and its metabolites and dexverapamil and its main metabolite nordexverapamil were measured using a reverse-phase high-pressure liquid chromatography assay. Results: The concomitant administration of dexverapamil resulted in an increase in mean (±SD) epirubicin clearance from 1,408 (610) ml/min/m 2 to 2,004 (1,696) ml/min/m 2 , a decrease in epirubicin exposure (area under the curve (AUC)) from 2,968 (1,219) mg × h/ml to 1,901 (494) mg × h/ml, and an increase of the volume of distribution at steady state from 1,436 (1,231) l/m 2 to 2,425 (1,340) l/m 2 . The mean residence time and the elimination half-life were not different. There was a significant increase of epiglucuronide and the 7-deoxy-aglycones. At the time of epirubicin administration mean dexverapamil and nordexverapamil plasma levels were 790±409 and 755 ± 274 ng/ml, respectively. Conclusion: Dexverapamil had a significant effect on the pharmacokinetics and metabolism of epirubicin. However, other than observed in previous studies of RMAs and cytotoxic drugs, dexverapamil did not increase but reduce the AUC of epirubicin and had no effect on its toxicity. These data suggest that the type of pharmacologic interaction between RMAs and cytotoxic drugs can differ depending on the particular compounds used in combination.

Factors affecting epirubicin pharmacokinetics and toxicity: evidence against using body-surface area for dose calculation.

An exploratory study to test whether body-surface area (BSA) should be used for the calculation of epirubicin dose. The relationship between pretreatment characteristics and the effects of epirubicin were investigated in 20 chemotherapy-naive patients. Measurements of body size, renal and hepatic function, and other factors were correlated with epirubicin pharmacokinetics (PK) and epirubicin-induced neutropenia. All patients received 150 mg of epirubicin infused continuously over 120 hours, regardless of body size. Factors were analyzed by univariate and multivariate linear regression. There were no correlations between BSA or weight with any PK parameter or with the degree of neutropenia. In multivariate analysis, indicators of liver function were the only factors that correlated with neutropenia and epirubicin PK. Thus, correlations for neutropenia were seen with antipyrine clearance (P = .003), activated partial thromboplastin time (APTT) (P = .005) and serum transferrin (P = .01). Further, the area under the concentration-time curve (AUC) for epirubicin correlated with prothrombin index (P < .01), antipyrine clearance (P < .01), and serum bile salt concentration (P = .03), and there were similar correlations for epirubicin steady-state concentration (CpSS). Epirubicin clearance correlated with antipyrine clearance (P = .02). PK parameters for dihydroepirubicin correlated with prothombin index, serum transferrin, and bile salt concentrations (P < .001 for all correlations). Because of the number of statistical examinations performed, some of these correlations may be spurious. However, some are likely to be real, since the same variables repeatedly correlated with different epirubicin-associated outcomes. There were no correlations between epirubicin PK indices or neutropenia and serum aminotransferase levels or other biochemical liver function tests, creatinine, or any of the clinical factors examined. These results led us to question the use of BSA for epirubicin dose calculation. In contrast, quantitative liver function tests may give a better indication of drug handling and toxicity and may be useful to determine more accurate methods for dose calculation of epirubicin.

Clinical Pharmacokinetics of Epirubicin

Epirubicin (4'-epidoxorubicin) is a new anthracycline that has activity similar to doxorubicin (adriamycin) in a variety of solid neoplasms and haematologic malignancies. Importantly, epirubicin causes less cardiotoxicity than doxorubicin. There is extensive distribution of epirubicin into tissues and the elimination of the drug is predominantly biliary, with less than 15% of the drug excreted in the urine. The metabolism of epirubicin is characterised by complex biotransformation to relatively or totally inactive metabolites, including a 13-dihydro derivative, epirubicinol, 2 glucuronides and 4 aglycones. Quantitatively, the glucuronides of epirubicin and epirubicinol are very important, and this pathway, which is unique to epirubicin metabolism in humans, might explain the better tolerability of this drug compared with doxorubicin. Epirubicin pharmacokinetics may be described by a 3-compartment model, with median half-life values of 3.2 minutes, 1.2 and 32 hours for each phase. Total plasma clearance is 46 L/h/m2 and volume of distribution at steady-state is 1000 L/m2. The pharmacokinetics of epirubicin appears to be linear for doses up to the maximal tolerated dose of 150 to 180 mg/m2. Both intraperitoneal and intravesical administration of epirubicin are feasible, but remain of a rather restricted interest. The area under the plasma concentration-time curve of epirubicin is fairly well correlated with the relative kill of white blood cells. Therefore, epirubicin clearance can be used to predict haematological toxicity.

Lean body mass, body surface area and epirubicin kinetics

For a number of cytotoxics, a relationship between efficacy and plasma concentrations has recently been demonstrated. Lean body mass has been demonstrated to be a useful parameter for predicting drug clearance for a number of non-cytotoxic drugs. However, the role of lean body mass in predicting drug clearance for any cytotoxic drug has not been previously reported. Our purpose was to investigate lean body mass as a predictor of epirubicin clearance. Pharmacokinetic studies were performed in 10 patients receiving single agent epirubicin. Although preliminary, this study suggests that lean body should be further evaluated and tested in dose optimization studies.

Epirubicin in hepatocellular carcinoma: pharmacokinetics and clinical activity

The pharmacokinetics and clinical activity of epirubicin were investigated in 16 patients with hepatocellular carcinoma (HCC) who received epirubicin at 75 mg/m2; the drug was given intravenously to 7 patients and via the hepatic artery to 9 patients (7 of whom also underwent embolisation). Lignocaine (1 mg/kg) was also given intravenously to 15 patients, and the metabolite monoethylglycinexylidide (MEGX) was measured as an indicator of liver function. Epirubicin clearance correlated with serum aspartate aminotransferase (AST), albumin and bilirubin values in patients treated intravenously or intraarterially. Although the route of administration did not affect the median total plasma clearance of epirubicin, early- and intermediate-phase clearance was higher following intraarterial administration. MEGX levels correlated with serum bilirubin levels but there was no correlation with albumin or AST values or epirubicin clearance. The rate of response to epirubicin was 3/13 (23%; 95% confidence interval, 8%-50%). Intravenous epirubicin was tolerated well, but intraarterial treatment was associated with significant morbidity. These data confirm that although current recommended dose adjustments are based primarily on serum bilirubin levels, altered epirubicin pharmacokinetics correlate more strongly with AST and albumin values than with serum bilirubin concentrations. However, at this dose and schedule, epirubicin has only modest activity against HCC.

Clinical pharmacokinetics of epirubicin: the importance of liver biochemistry tests.

The influence of liver biochemistry tests on epirubicin pharmacokinetics has been investigated in 52 women with advanced breast cancer, 27 of whom had radiologically proven liver metastases. Patients received epirubicin 12.5-120 mg m-2 given as an i.v. bolus. Epirubicin levels were measured by HPLC following the first cycle of treatment. Epirubicin elimination, expressed as clearance (dose/AUC), in the 22 patients with normal AST and bilirubin was compared with that of 30 patients with a raised AST +/- raised bilirubin. Epirubicin clearance was significantly reduced in the patients with a raised AST, whether their serum bilirubin was normal (22 patients) or elevated (eight patients). In the 30 patients with a raised AST +/- raised bilirubin, epirubicin clearance correlated strongly with the level of AST (r = -0.72) but not with serum bilirubin, alkaline phosphatase, albumin or creatinine. Using a multiple regression analysis, AST was the only one of these biochemical variables predictive of epirubicin clearance (r2 = 0.47, P = 0.0006). We conclude that a raised serum AST is a more sensitive and reliable measure of abnormal epirubicin pharmacokinetics than increased bilirubin. These findings have implications for anthracycline treatment in patients with abnormal liver biochemistry.