Pharmacokinetics and Safety of Lurbinectedin Administrated with Itraconazole in Cancer Patients: A Drug-Drug Interaction Study

This open-label, two-part, phase Ib drug-drug interaction study investigated whether the pharmacokinetic (PK) and safety profiles of lurbinectedin (LRB), a marine-derived drug, are affected by co-administration of itraconazole (ITZ), a strong CYP3A4 inhibitor, in adult patients with advanced solid tumors. In Part A, three patients were sequentially assigned to Sequence 1 (LRB 0.8 mg/m2, 1-h intravenous [IV] + ITZ 200 mg/day oral in Cycle 1 [C1] and LRB alone 3.2 mg/m2, 1 h, IV in Cycle 2 [C2]). In Part B, 11 patients were randomized (1:1) to receive either Sequence 1 (LRB at 0.9 mg/m2 + ITZ in C1 and LRB alone in C2) or Sequence 2 (LRB alone in C1 and LRB + ITZ in C2). Eleven patients were evaluable for PK analysis: three in Part A and eight in Part B (four per sequence). The systemic total exposure of LRB increased with ITZ co-administration: 15% for Cmax, area under the curve (AUC) 2.4-fold for AUC0-t and 2.7-fold for AUC0-∞. Co-administration with ITZ produced statistically significant modifications in the unbound plasma LRB PK parameters. The LRB safety profile was consistent with the toxicities described in previous studies. Co-administration with multiple doses of ITZ significantly altered LRB systemic exposure. Hence, to avoid LRB overexposure when co-administered with strong CYP3A4 inhibitors, an LRB dose reduction proportional to CL reduction should be applied.

Impact of a Moderate CYP3A4 Inducer (Bosentan) on Lurbinectedin Pharmacokinetics and Safety in Patients with Advanced Solid Tumors: An Open-Label, Two-Way, Crossover, Phase Ib Drug-Drug Interaction Study

This open-label, two-way, crossover, phase Ib drug-drug interaction study investigated whether the pharmacokinetics (PKs) and safety profile of lurbinectedin (LRB) are affected by co-administration of a moderate CYP3A4 inducer (bosentan, BOS) in adult patients with advanced solid tumors. Eleven patients were randomly assigned to Sequence 1 (LRB + BOS in Cycle 1 [C1] and LRB alone in Cycle 2 [C2]) or Sequence 2 (LRB alone in C1 and LRB + BOS in C2), and finally, eight patients (four per sequence) were considered evaluable for PK assessment. LRB (3.2 mg/m2, 1 h [h], intravenous) was administered alone or combined with multiple BOS administration (125 mg/12 h oral; 5.5 days). Co-administration with BOS decreased the systemic total exposure (area under the curve, AUC) of LRB by 21% for AUC0-t and 20% for AUC0-∞ and increased clearance by 25%. Co-administration with BOS did not significantly modify the unbound plasma LRB PK parameters. BOS increased the conversion of LRB to its metabolite M1, with no changes on its metabolite M4. The LRB safety profile was consistent with the toxicities previously described for this drug. No differences in terms of toxicity were found between LRB with and without BOS. In summary, the magnitude of the observed changes precludes a clinically relevant effect of BOS co-administration on LRB exposure and its safety profile.

A model-based head-to-head comparison of single-agent lurbinectedin in the pivotal ATLANTIS Study

Introduction

Lurbinectedin is a selective inhibitor of oncogenic transcription U.S. Food and Drug Administration (FDA)-approved for patients with relapsed small cell lung cancer (SCLC) as monotherapy at 3.2 mg/m² every 3 weeks (q3wk). ATLANTIS was a phase 3 study in SCLC with lurbinectedin 2.0 mg/m² plus doxorubicin 40 mg/m² q3wk vs physician's choice, with overall survival (OS) as the primary endpoint and objective response rate (ORR) as the secondary endpoint. This work aimed to dissect the contribution of lurbinectedin and doxorubicin to antitumor effects in SCLC, and to predict the efficacy of single-agent lurbinectedin at 3.2 mg/m² in ATLANTIS to allow for a head-to-head comparison with the control arm.

Methods

The dataset included exposure and efficacy data from 387 patients with relapsed SCLC (ATLANTIS, n=288; study B-005, n=99). Patients in the ATLANTIS control arm (n=289) were used for comparison. Unbound plasma lurbinectedin area under the concentration-time curve (AUC_u) and total plasma doxorubicin area under the concentration-time curve (AUC_DOX) were used as exposure metrics. Univariate and multivariate analyses were conducted to determine the best predictors and predictive model for OS and ORR. OS baseline hazard was best described by a log-logistic distribution, with chemotherapy-free interval (CTFI), lactate dehydrogenase, albumin, brain metastases, neutrophils/lymphocytes ratio, AUC_u, and the interaction between AUC_u and AUC_DOX as predictors. Effect of AUC_u on ORR best fitted to a sigmoid-maximal response (E_max) logistic model, where E_max was dependent on CTFI.

Results

Head-to-head comparisons with predicted 3.2 mg/m² lurbinectedin resulted in a positive outcome in ATLANTIS, with hazard ratio (95% prediction intervals [95% PI]) for OS of 0.54 (0.41, 0.72), and odds ratio (95% PI) for ORR of 0.35 (0.25, 0.5).

Conclusion

These results support the superiority of lurbinectedin monotherapy for relapsed SCLC over other approved therapies.

Quantitative determination of lurbinectedin, its unbound fraction and its metabolites in human plasma utilizing ultra-performance LC-MS/MS

AIMS

Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) methods to quantify total lurbinectedin, its plasma protein binding to derive the unbound fraction and its main metabolites 1',3'-dihydroxy-lurbinectedin (M4) and N-desmethyl-lurbinectedin (M6) in human plasma, were developed and validated.

MATERIALS & METHODS

For lurbinectedin, sample extraction was performed using supported liquid extraction. For metabolites, liquid-liquid extraction with stable isotope-labeled analogue internal standards was used. Plasma protein binding was evaluated using rapid equilibrium dialysis. In vitro investigations at different plasma protein concentrations were carried out to estimate dissociation rate constants to albumin and alpha-1-acid glycoprotein (AAG).

RESULTS

Calibration curves displayed good linearity over 0.1 to 50 ng/mL for lurbinectedin and 0.5 to 20 ng/mL for the metabolites. Methods were validated in accordance with established guidance. The inter-day precision and accuracy ranged from 5.1% to 10.7%, and from -5% to 6% (lurbinectedin in plasma); from 3.1% to 6.6%, and from 4% to 6% (lurbinectedin in plasma:PBS); from 4.5% to 12.9%, and from 4% to 9% (M4); and from 7.5% to 10.5%, and from 6% to 12% (M6). All methods displayed good linearity (r2 >0.99). Recovery was evaluated for lurbinectedin in plasma:PBS (66.4% to 86.6%), M4 (7.82% to 13.4%) and M6 (22.2% to 34.3%). The method for lurbinectedin in plasma has been applied in most clinical studies, while the plasma:PBS and metabolites methods were used to evaluate the impact of special conditions on lurbinectedin PK. Lurbinectedin plasma protein binding was 99.6% and highly affected by AAG concentration.

CONCLUSIONS

These UPLC-MS/MS methods enable the rapid and sensitive quantification of lurbinectedin and its main metabolites in clinical samples.

Anti-cancer drug combinations approved by US FDA from 2011 to 2021: main design features of clinical trials and role of pharmacokinetics

During the last decade, the treatment for many cancer indications has evolved due to intensive clinical research into anti-tumor agents' combination. In most instances, new combination treatments consist of an add-on to the standard of care (SOC), which then demonstrate a substantial gain in efficacy and no detrimental effect in tolerability. In the era of targeted therapies, for which maximum tolerated dose (MTD)-based dosing strategies are no longer applicable, early stage studies exploring new combinations are often conducted in the population of interest, expediting the collection of preliminary safety data, to be promptly expanded to collect preliminary efficacy data. Nevertheless, rule-based dose-finding studies are still a prevailing approach for early stage cancer, especially for chemotherapy (CT)-containing combinations. Pharmacokinetic (PK) assessments play a key role throughout the clinical development of drug combinations, informing potential PK interactions. But most importantly, they allow the development of innovative exposure-response (E-R) models aimed at exploring the contribution of each agent to the overall effect of the combination therapy. This review identifies 81 new drug combinations approved by the United States Food and Drug Administration (FDA) for hemato-oncology during the 2011-2021 period and summarizes the main design features of clinical trials and the role of PK assessments.

Preclinical and randomized phase I studies of plitidepsin in adults hospitalized with COVID-19

Plitidepsin, a marine-derived cyclic-peptide, inhibits SARS-CoV-2 replication at nanomolar concentrations by targeting the host protein eukaryotic translation elongation factor 1A. Here, we show that plitidepsin distributes preferentially to lung over plasma, with similar potency against across several SARS-CoV-2 variants in preclinical studies. Simultaneously, in this randomized, parallel, open-label, proof-of-concept study (NCT04382066) conducted in 10 Spanish hospitals between May and November 2020, 46 adult hospitalized patients with confirmed SARS-CoV-2 infection received either 1.5 mg (n = 15), 2.0 mg (n = 16), or 2.5 mg (n = 15) plitidepsin once daily for 3 d. The primary objective was safety; viral load kinetics, mortality, need for increased respiratory support, and dose selection were secondary end points. One patient withdrew consent before starting procedures; 45 initiated treatment; one withdrew because of hypersensitivity. Two Grade 3 treatment-related adverse events were observed (hypersensitivity and diarrhea). Treatment-related adverse events affecting more than 5% of patients were nausea (42.2%), vomiting (15.6%), and diarrhea (6.7%). Mean viral load reductions from baseline were 1.35, 2.35, 3.25, and 3.85 log10 at days 4, 7, 15, and 31. Nonmechanical invasive ventilation was required in 8 of 44 evaluable patients (16.0%); six patients required intensive care support (13.6%), and three patients (6.7%) died (COVID-19-related). Plitidepsin has a favorable safety profile in patients with COVID-19.

Integrated exposure-response analysis of efficacy and safety of lurbinectedin to support the dose regimen in small-cell lung cancer

Purpose

These exposure–response (E–R) analyses integrated lurbinectedin effects on key efficacy and safety variables in relapsed SCLC to determine the adequacy of the dose regimen of 3.2 mg/m² 1-h intravenous infusion every 3 weeks (q3wk).

Methods

Logistic models and Cox regression analyses were applied to correlate lurbinectedin exposure metrics (AUC_tot and AUC_u) with efficacy and safety endpoints: objective response rate (ORR) and overall survival (OS) in SCLC patients (n = 99) treated in study B-005 with 3.2 mg/m² q3wk, and incidence of grade 4 (G4) neutropenia and grade 3–4 (G ≥ 3) thrombocytopenia in a pool of cancer patients from single-agent phase I to III studies (n = 692) treated at a wide range of doses. A clinical utility index was used to assess the appropriateness of the selected dose.

Results

Effect of lurbinectedin AUC_u on ORR best fitted to a sigmoid-maximal response (E_max) logistic model, where E_max was dependent on chemotherapy-free interval (CTFI). Cox regression analysis with OS found relationships with both CTFI and AUC_u. An E_max logistic model for G4 neutropenia and a linear logistic model for G ≥ 3 thrombocytopenia, which retained platelets and albumin at baseline and body surface area, best fitted to AUC_tot and AUC_u. AUC_u between approximately 1000 and 1700 ng·h/L provided the best benefit/risk ratio, and the dose of 3.2 mg/m² provided median AUC_u of 1400 ng·h/L, thus maximizing the proportion of patients within that lurbinectedin target exposure range.

Conclusions

The relationships evidenced in this integrated E–R analysis support a favorable benefit-risk profile for lurbinectedin 3.2 mg/m² q3wk.

Trial registration

Clinicaltrials.gov: NCT02454972; registered May 27, 2015.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00280-021-04366-3.

Population Pharmacokinetic-Pharmacodynamic Modeling and Covariate Analyses of Neutropenia and Thrombocytopenia in Patients With Solid Tumors Treated With Lurbinectedin

Lurbinectedin is a selective inhibitor of oncogenic transcription. Reversible myelosuppression is its most relevant toxicity. Pharmacokinetic-pharmacodynamic analyses were conducted to characterize the time course of absolute neutrophil count and platelet count recovery and to detect and quantify the effect of relevant covariates in patients with advanced solid tumors treated with lurbinectedin. Absolute neutrophil count, platelet count, and lurbinectedin total plasma concentration were assessed in 244 patients treated with lurbinectedin with varied dosing schedules and doses. A reference extended semimechanistic pharmacokinetic-pharmacodynamic model of myelosuppression was used. Granulocyte colony-stimulating factor (G-CSF) administration was modeled as a dichotomous covariate, and platelet transfusions were included as a bolus dose into the last compartment of the model, representing the central circulation. Final models were suitable to describe the time course of absolute neutrophil count and platelet count recovery. A lurbinectedin dose of 3.2 mg/m² every 3 weeks can be administered without primary prophylaxis with G-CSF. G-CSF followed by ≤2 dose reductions of 20%, if needed, gradually reduced grade 4 neutropenia from cycle 3 onward. BSA-based dosing reduced the incidence of grade ≥ 3 thrombocytopenia. One-week dose delays because of low absolute neutrophil count occurred in 3.5% of patients, thus supporting every-3-week administration. CYP3A inhibitors produced absolute 11.0% and 6.2% increases in grade ≥ 3 neutropenia and thrombocytopenia, respectively. Neutropenia and thrombocytopenia after lurbinectedin administration to cancer patients are noncumulative, reversible, short lasting, and clinically manageable with secondary prophylaxis of G-CSF or platelet transfusion and, if needed, dose reductions.

Plitidepsin has a positive therapeutic index in adult patients with COVID-19 requiring hospitalization

Plitidepsin is a marine-derived cyclic-peptide that inhibits SARS-CoV-2 replication at low nanomolar concentrations by the targeting of host protein eEF1A (eukaryotic translation-elongation-factor-1A). We evaluated a model of intervention with plitidepsin in hospitalized COVID-19 adult patients where three doses were assessed (1.5, 2 and 2.5 mg/day for 3 days, as a 90-minute intravenous infusion) in 45 patients (15 per dose-cohort). Treatment was well tolerated, with only two Grade 3 treatment-related adverse events observed (hypersensitivity and diarrhea). The discharge rates by Days 8 and 15 were 56.8% and 81.8%, respectively, with data sustaining dose-effect. A mean 4.2 log10 viral load reduction was attained by Day 15. Improvement in inflammation markers was also noted in a seemingly dose-dependent manner. These results suggest that plitidepsin impacts the outcome of patients with COVID-19.

ONE-SENTENCE SUMMARY

Plitidepsin, an inhibitor of SARS-Cov-2 in vitro , is safe and positively influences the outcome of patients hospitalized with COVID-19.

First-in-human study of PM14 in patients with advanced solid tumors

3078

Background: PM14 is a new chemical entity that forms DNA adducts which specifically inhibit RNA synthesis and block active transcription of protein-coding genes. Antitumor activity has been demonstrated in vitro in several cell lines (e.g. lung, kidney, prostate), and in vivo in mice bearing xenografted human-derived tumors (soft tissue sarcoma, small cell lung cancer, ovarian, gastric, breast and renal cancer). Methods: Open-label, dose-escalating, phase I trial of PM14 administered as a 3-hour infusion i.v. every 3 weeks (q3wk) in patients (pts) with advanced solid tumors, adequate organ function and ECOG PS score of 0-1. Two schedules were explored: Schedule A (Day 1 [D1], Day 8 [D8]) and Schedule B (D1). Results: 37 pts were treated (Schedule A/B: 28/9 pts). Baseline characteristics of pts (A/B): median age 56/47 years; male 57%/56%; ECOG PS 0: 57%/56%; median of prior lines (range): 3 (1-8)/4 (1-10). Most common tumor types (A + B): STS (n=7 pts), ovarian (n=6), pancreatic (n=4), prostate cancer (n=3). The maximum tolerated dose was 4.5 mg/m2 for A (dose-limiting toxicities [DLTs]: D8 omission due to lack of recovery of lab parameters for re-treatment [n=2 pts]) and 5.6 mg/m2 (DLTs: G4 febrile neutropenia [n=1], G4 transaminase increase [n=1]) for B. The recommended dose (RD) was 3.0 mg/m2 on D1,D8 (A), and 4.5 mg/m2 on D1 (B). No DLTs were present at the RDs. Most common toxicities were hematological abnormalities and transaminase increase. Main toxicities at the RDs are shown below. Antitumor activity comprised stable disease ≥4 months in 7 heavily pretreated pts (6 in A; 1 in B) at all dose levels. Linear pharmacokinetics were observed for PM14 at tested doses (0.25-5.6 mg/m²), with geometric mean (CV%) total plasma clearance 5.9 L/h (88%), volume of distribution 128 L (81%) and median (range) terminal half-life 15.9 h (7.5-34.3 h). Less than 1.6% of administered dose was recovered in urine. Conclusions: RDs were determined for two PM14 schedules in pts with advanced solid tumors. At the RDs, PM14 is well tolerated and has a manageable safety profile. An expansion phase in specific tumor types, with an optional Bayesian continual reassessment method for RD fine-tuning, is ongoing with both schedules.[Table: see text]

Population-Pharmacokinetic and Covariate Analysis of Lurbinectedin (PM01183), a New RNA Polymerase II Inhibitor, in Pooled Phase I/II Trials in Patients with Cancer

BACKGROUND AND OBJECTIVES

Lurbinectedin is an inhibitor of RNA polymerase II currently under clinical development for intravenous administration as a single agent and in combination with other anti-tumor agents for the treatment of several tumor types. The objective of this work was to develop a population-pharmacokinetic model in this patient setting and to elucidate the main predictors to guide the late stages of development.

METHODS

Data from 443 patients with solid and hematologic malignancies treated in six phase I and three phase II trials with lurbinectedin as a single agent or combined with other agents were included in the analysis. The potential influence of demographic, co-treatment, and laboratory characteristics on lurbinectedin pharmacokinetics was evaluated.

RESULTS

The final population-pharmacokinetic model was an open three-compartment model with linear distribution and linear elimination from the central compartment. Population estimates for total plasma clearance, and apparent volume at steady state were 11.2 L/h and 438 L, respectively. Inter-individual variability was moderate for all parameters, ranging from 20.9 to 51.2%. High α-1-acid glycoprotein and C-reactive protein, and low albumin reduced clearance by 28, 20, and 20%, respectively. Co-administration of cytochrome P450 3A inhibitors reduced clearance by 30%. Combinations with other anti-tumor agents did not modify the pharmacokinetics of lurbinectedin significantly.

CONCLUSION

The population-pharmacokinetic model indicated neither a dose nor time dependency, and no clinically meaningful pharmacokinetic differences were found when co-administered with other anticancer agents. A chronic inflammation pattern characterized by decreased albumin and increased C-reactive protein and α-1-acid glycoprotein levels led to high lurbinectedin exposure. Co-administration of cytochrome P450 3A inhibitors increased lurbinectedin exposure.

Effects of aripiprazole on pupillometric parameters related to pharmacokinetics and pharmacogenetics after single oral administration to healthy subjects

BACKGROUND

Pupillometry is used for the detection of autonomic dysfunction related to numerous diseases and drug administration. Genetic variants in cytochrome P450 ( CYP2D6, CYP3A4), dopamine receptor ( DRD2, DRD3), serotonin receptor ( HTR2A, HTR2C) and ATP-binding cassette subfamily B ( ABCB1) genes were previously associated with aripiprazole response.

AIMS

Our aim was to evaluate if aripiprazole affects pupil contraction and its relationship with pharmacokinetics and pharmacogenetics.

METHODS

Thirty-two healthy volunteers receiving a 10 mg single oral dose of aripiprazole were genotyped for 15 polymorphisms in ABCB1, CYP2D6, DRD2, DRD3, HTR2A and HTR2C genes by reverse transcription polymerase chain reaction. Aripiprazole and dehydro-aripiprazole plasma concentrations were measured by high-performance liquid chromatography tandem mass spectrometry. Pupil examination was performed by automated pupillometry.

RESULTS

Aripiprazole caused pupil constriction and reached the peak value at C_max. HTR2A rs6313 T allele carriers and HTR2C rs3813929 C/T subjects showed higher maximum constriction velocity and maximum pupil diameter. Besides, Gly/Gly homozygotes for DRD3 rs6280 showed significantly lower maximum constriction velocity values. A/G heterozygotes for DRD2 rs6277 showed higher total time taken by the pupil to recover 75% of the initial resting size values. CYP2D6 intermediate metabolisers showed higher area under the curve, C_max and T_1/2 than extensive metabolisers. ABCB1 G2677T/A A/A homozygotes had greater T_1/2 in comparison with C/C homozygotes. ABCB1 C3435T T allele carriers and C1236T C/T subjects showed greater area under the curve than C/C homozygotes.

CONCLUSIONS

Aripiprazole affects pupil contraction, which could be a secondary effect through dopamine and serotonin receptors. Pupillometry could be a useful tool to assess autonomic nervous system activity during antipsychotic treatment.

Metabolite profiling of the novel anti-cancer agent, plitidepsin, in urine and faeces in cancer patients after administration of 14C-plitidepsin

PURPOSE

Plitidepsin absorption, distribution, metabolism and excretion characteristics were investigated in a mass balance study, in which six patients received a 3-h intravenous infusion containing 7 mg ¹⁴C-plitidepsin with a maximum radioactivity of 100 µCi.

METHODS

Blood samples were drawn and excreta were collected until less than 1% of the administered radioactivity was excreted per matrix for two consecutive days. Samples were pooled within-patients and between-patients and samples were screened for metabolites. Afterwards, metabolites were identified and quantified. Analysis was done using Liquid Chromatography linked to an Ion Trap Mass Spectrometer and offline Liquid Scintillation Counting (LC-Ion Trap MS-LSC).

RESULTS

On average 4.5 and 62.4% of the administered dose was excreted via urine over the first 24 h and in faeces over 240 h, respectively. Most metabolites were found in faeces.

CONCLUSION

Plitidepsin is extensively metabolised and it undergoes dealkylation (demethylation), oxidation, carbonyl reduction, and (internal) hydrolysis. The chemical formula of several metabolites was confirmed using high resolution mass data.

Development and validation of a liquid chromatography-tandem mass spectrometry assay for the quantification of lurbinectedin in human plasma and urine

Lurbinectedin is a novel highly selective inhibitor of RNA polymerase II triggering caspase-dependent apoptosis of cancerous cells. This article describes the development and validation of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay to quantify lurbinectedin in human plasma and urine. Plasma samples were pre-treated with 1 M aqueous ammonia after which they were brought onto supported liquid extraction (SLE) columns. Lurbinectedin was eluted from the columns using tert-butyl methyl ether (TBME). Urine was first diluted in plasma and lurbinectedin was extracted from this matrix by liquid-liquid extraction using TBME. Samples were measured by LC-MS/MS in the positive electron ion spray mode. The method was linear over 0.1-100 ng/mL and 1-1000 ng/mL in plasma and urine, respectively, with accuracies and precisions within ±15% (20% for LLOQ) and below 15% (20% for LLOQ), respectively. The method was developed to support a mass balance study in which patients received a dose of 5 mg lurbinectedin.

Association of nicotine metabolism and sex with relapse following varenicline and nicotine replacement therapy

Nicotine is metabolized into cotinine and then into trans-3'-hydroxycotinine, mainly by cytochrome P450 2A6. Recent studies reported better effectiveness of varenicline in women and in nicotine normal metabolizers phenotypically determined by nicotine-metabolite ratio. Our objective was to study the influence of nicotine-metabolite ratio, CYP2A6 genotype and sex on the response to nicotine replacement therapy and varenicline. Data were extracted from a longitudinal study which included smokers participating in a smoking cessation program. Response to treatment was defined by the absence of relapse when a set threshold of reduction in cigarettes per day relative to the week before the study was no more reached. The analysis considered total and partial reduction defined by a diminution of 100% and of 90% in cigarettes per day, respectively. The hazard ratio of relapsing was estimated in multivariate Cox regression models including the sex and the nicotine metabolism determined by the phenotype or by CYP2A6 genotyping (rs1801272 and rs28399433). In the normal metabolizers determined by phenotyping and in women, the hazard ratio for relapsing was significantly lower with varenicline for a partial decrease (HR = 0.33, 95% CI [0.12, 0.89] and HR = 0.20, 95% CI [0.04, 0.91], respectively) and nonsignificantly lower for a total cessation (HR = 0.45, 95% CI [0.20, 1.0] and HR = 0.38, 95% CI [0.14, 1.0]). When compared with the normal metabolizers determined by phenotyping, the hazard ratio for a partial decrease was similar in the normal metabolizers determined by genotyping (HR = 0.42, 95% CI [0.18, 0.94]) while it was significantly lower with varenicline for a total cessation (HR = 0.50, 95% CI [0.26, 0.98]). Women and normal nicotine metabolizers may benefit more from varenicline over nicotine replacement therapy. (PsycINFO Database Record

Influence of two variants of CYP450 oxidoreductase on the stable dose of acenocoumarol in a Spanish population

AIM

To evaluate the influence of two variants of P450 oxidoreductase (POR), rs2868177 and POR*28, on the stable dosage of acenocoumarol.

PATIENTS & METHODS

For this observational, cross-sectional study, patients were undergone stable anticoagulant treatment with acenocoumarol. Univariate and multiple regression analyses were performed to assess the influence of POR polymorphisms.

RESULTS

About 340 patients were enrolled. Multiple regression had a coefficient of determination (R²) of 51.5% and an Akaike information criterion of 234.22. The inclusion of POR*28 polymorphisms increased the R² to 52.0% and reduced the Akaike information criteria to 230.58. The POR*28 heterozygote showed statistical significance in the algorithm.

CONCLUSION

The POR*28 heterozygote appears to be associated with the stable dose of acenocoumarol, but its clinical contribution to the prediction of the dosing of this drug is minimal.

A New Pharmacogenetic Algorithm to Predict the Most Appropriate Dosage of Acenocoumarol for Stable Anticoagulation in a Mixed Spanish Population

There is a strong association between genetic polymorphisms and the acenocoumarol dosage requirements. Genotyping the polymorphisms involved in the pharmacokinetics and pharmacodynamics of acenocoumarol before starting anticoagulant therapy would result in a better quality of life and a more efficient use of healthcare resources. The objective of this study is to develop a new algorithm that includes clinical and genetic variables to predict the most appropriate acenocoumarol dosage for stable anticoagulation in a wide range of patients. We recruited 685 patients from 2 Spanish hospitals and 1 primary healthcare center. We randomly chose 80% of the patients (n = 556), considering an equitable distribution of genotypes to form the generation cohort. The remaining 20% (n = 129) formed the validation cohort. Multiple linear regression was used to generate the algorithm using the acenocoumarol stable dosage as the dependent variable and the clinical and genotypic variables as the independent variables. The variables included in the algorithm were age, weight, amiodarone use, enzyme inducer status, international normalized ratio target range and the presence of CYP2C9*2 (rs1799853), CYP2C9*3 (rs1057910), VKORC1 (rs9923231) and CYP4F2 (rs2108622). The coefficient of determination (R2) explained by the algorithm was 52.8% in the generation cohort and 64% in the validation cohort. The following R2 values were evaluated by pathology: atrial fibrillation, 57.4%; valve replacement, 56.3%; and venous thromboembolic disease, 51.5%. When the patients were classified into 3 dosage groups according to the stable dosage (<11 mg/week, 11-21 mg/week, >21 mg/week), the percentage of correctly classified patients was higher in the intermediate group, whereas differences between pharmacogenetic and clinical algorithms increased in the extreme dosage groups. Our algorithm could improve acenocoumarol dosage selection for patients who will begin treatment with this drug, especially in extreme-dosage patients. The predictability of the pharmacogenetic algorithm did not vary significantly between diseases.

Contribution of genetic background, traditional risk factors, and HIV-related factors to coronary artery disease events in HIV-positive persons

BACKGROUND

Persons infected with human immunodeficiency virus (HIV) have increased rates of coronary artery disease (CAD). The relative contribution of genetic background, HIV-related factors, antiretroviral medications, and traditional risk factors to CAD has not been fully evaluated in the setting of HIV infection.

METHODS

In the general population, 23 common single-nucleotide polymorphisms (SNPs) were shown to be associated with CAD through genome-wide association analysis. Using the Metabochip, we genotyped 1875 HIV-positive, white individuals enrolled in 24 HIV observational studies, including 571 participants with a first CAD event during the 9-year study period and 1304 controls matched on sex and cohort.

RESULTS

A genetic risk score built from 23 CAD-associated SNPs contributed significantly to CAD (P = 2.9 × 10(-4)). In the final multivariable model, participants with an unfavorable genetic background (top genetic score quartile) had a CAD odds ratio (OR) of 1.47 (95% confidence interval [CI], 1.05-2.04). This effect was similar to hypertension (OR = 1.36; 95% CI, 1.06-1.73), hypercholesterolemia (OR = 1.51; 95% CI, 1.16-1.96), diabetes (OR = 1.66; 95% CI, 1.10-2.49), ≥ 1 year lopinavir exposure (OR = 1.36; 95% CI, 1.06-1.73), and current abacavir treatment (OR = 1.56; 95% CI, 1.17-2.07). The effect of the genetic risk score was additive to the effect of nongenetic CAD risk factors, and did not change after adjustment for family history of CAD.

CONCLUSIONS

In the setting of HIV infection, the effect of an unfavorable genetic background was similar to traditional CAD risk factors and certain adverse antiretroviral exposures. Genetic testing may provide prognostic information complementary to family history of CAD.

A preliminary model to avoid the overestimation of sample size in bioequivalence studies

Often the only available data in literature for sample size estimations in bioequivalence studies is intersubject variability, which tends to result in overestimation of sample size. In this paper, we proposed a preliminary model of intrasubject variability based on intersubject variability for Cmax and AUC data from randomized, crossovers, bioequivalence (BE) studies. From 93 Cmax and 121 AUC data from test-reference comparisons that fulfilled BE criteria, we calculated intersubject variability for the reference formulation and intrasubject variability from ANOVA. Lineal and exponential models (y=a(1-e-bx)) were fitted weighted by the inverse of the variance, to predict the intrasubject variability based on intersubject variability. To validate the model we calculated the coefficient of cross-validation of data from 30 new BE studies. The models fit very well (R2=0.997 and 0.990 for Cmax and AUC respectively) and the cross-validation correlation were 0.847 for Cmax and 0.572 for AUC. A preliminary model analyses allow us to estimate the intrasubject variability based on intersubject variability for sample size calculation purposes in BE studies. This approximation provides an opportunity for sample size reduction avoiding unnecessary exposure of healthy volunteers. Further modelling studies are desirable to confirm these results especially suggestions of the higher intersubject variability range.

An acenocoumarol dosing algorithm using clinical and pharmacogenetic data in Spanish patients with thromboembolic disease

Appropriate dosing of coumarins is difficult to establish, due to significant inter-individual variability in the dose required to obtain stable anticoagulation. Several genetic and other clinical factors have been associated with the coumarins dose, and some pharmacogenetic-guided dosing algorithms for warfarin and acenocoumarol have been developed for mixed populations. We recruited 147 patients with thromboembolic disease who were on stable doses and with an international normalized ratio (INR) between 2 and 3. We ascertained the influence of clinical and genetic variables on the stable acenocoumarol dose by multiple linear regression analysis in a derivation cohort (DC; n = 117) and developed an algorithm for dosing that included clinical factors (age, body mass index and concomitant drugs) and genetic variations of VKORC1, CYP2C9, CYP4F2 and APOE. For purposes of comparison, a model including only clinical data was created. The clinical factors explained 22% of the dose variability, which increased to 60.6% when pharmacogenetic information was included (p<0.001); CYP4F2 and APOE variants explained 4.9% of this variability. The mean absolute error of the predicted acenocoumarol dose (mg/week) obtained with the pharmacogenetic algorithm was 3.63 vs. 5.08 mg/week with the clinical algorithm (95% CI: 0.88 to 2.04). In the testing cohort (n = 30), clinical factors explained a mere 7% of the dose variability, compared to 39% explained by the pharmacogenetic algorithm. Considering a more clinically relevant parameter, the pharmacogenetic algorithm correctly predicted the real stable dose in 59.8% of the cases (DC) vs. only 37.6% predicted by the clinical algorithm (95% CI: 10 to 35). Therefore the number of patients needed to genotype to avoid one over- or under-dosing was estimated to be 5.

Association of pharmacogenetic markers with premature discontinuation of first-line anti-HIV therapy: an observational cohort study

BACKGROUND

Poor tolerance and adverse drug reactions are main reasons for discontinuation of antiretroviral therapy (ART). Identifying predictors of ART discontinuation is a priority in HIV care.

METHODS

A genetic association study in an observational cohort to evaluate the association of pharmacogenetic markers with time to treatment discontinuation during the first year of ART. Analysis included 577 treatment-naive individuals initiating tenofovir (n = 500) or abacavir (n = 77), with efavirenz (n = 272), lopinavir/ritonavir (n = 184), or atazanavir/ritonavir (n = 121). Genotyping included 23 genetic markers in 15 genes associated with toxicity or pharmacokinetics of the study medication. Rates of ART discontinuation between groups with and without genetic risk markers were assessed by survival analysis using Cox regression models.

RESULTS

During the first year of ART, 190 individuals (33%) stopped 1 or more drugs. For efavirenz and atazanavir, individuals with genetic risk markers experienced higher discontinuation rates than individuals without (71.15% vs 28.10%, and 62.5% vs 14.6%, respectively). The efavirenz discontinuation hazard ratio (HR) was 3.14 (95% confidence interval (CI): 1.35-7.33, P = .008). The atazanavir discontinuation HR was 9.13 (95% CI: 3.38-24.69, P < .0001).

CONCLUSIONS

Several pharmacogenetic markers identify individuals at risk for early treatment discontinuation. These markers should be considered for validation in the clinical setting.

Genetic polymorphisms of CYP1A2, CYP3A4, CYP3A5, pregnane/steroid X receptor and constitutive androstane receptor in 207 healthy Spanish volunteers

BACKGROUND

Variability of cytochrome P450 (CYP) in humans is largely related to the pharmacological and toxicological effects of drugs and chemicals. Identification of single nucleotide polymorphisms (SNPs) could be important for knowing their involvement in many drugs metabolism. The goal of this study was to analyze the genotype frequency of 10 SNPs related to mirtazapine metabolism [CYP3A4*17, CYP3A4*18, CYP3A5*3A, CYP1A2*1F, pregnane/steroid X receptor (PXR) (rs3814055, rs38114057, rs3814058) and constitutive androstane receptor (CAR) (rs4073054, rs2307424, rs2502815)].

METHODS

The study was carried out in 207 healthy Spanish volunteers that had participated in phase I clinical trials. Other studies were performed: Hardy-Weinberg equilibrium, haplotype estimation and linkage disequilibrium.

RESULTS

No mutation related to CYP3A4*17 and CYP3A4*18 was found. Therefore, we analyzed data for the other eight SNPs. Allele frequencies were in equilibrium with the Hardy-Weinberg equation. Six haplotypes were determined for three PXR SNPs, and four for CAR SNPs. Tests for linkage disequilibrium showed a high association between PXR (rs38114057) and PXR (rs3814058) (p= 0.001), and between the three CAR SNPs (p=0.001), which could be useful for identification of tag SNPs.

CONCLUSIONS

In the present study, the genotype frequencies of some SNPs related to mirtazapine metabolism in Spaniards were analyzed and showed that our study population is representative of HapMap European population. The results obtained could be analyzed with pharmacokinetic parameters of mirtazapine to elucidate the genotype-phenotype relationship, the involvement of these SNPs in metabolic reactions, drug interactions, and prediction of treatment response.

ADME pathway approach for pharmacogenetic studies of anti-HIV therapy

Pharmacogenetics holds promise in HIV treatment because of the complexity and potential toxicity of multidrug therapies that are prescribed for long periods. However, there has been limited success with the current approach where one or few candidate genes are examined for a limited number of allelic variants. A change in paradigm emerges from the availability of the HapMap, the wealth of data on less common genetic polymorphisms, and new genotyping technology. We present a comprehensive review of functional and putative functional variants in genes encoding absorption, distribution, metabolism and excretion (ADME) proteins relevant to HIV therapy. We propose an analytical array based on our review of the literature, web resources and use of bioinformatic analysis. We identified 126 genes with proven or potential role in HIV therapy. Variation in these genes can be characterized by 2428 SNPs (in Caucasians). On average, a gene is covered by 20 SNPs. This review compiles information for future analysis of the role of specific genes/variants in the exposure and response to antiretroviral therapy to generate a ranked list of new genetic variants for future studies.

Effect of opsonophagocytosis mediated by specific antibodies on the co-amoxiclav serum bactericidal activity against Streptococcus pneumoniae after administration of a single oral dose of pharmacokinetically enhanced 2000/125 mg co-amoxiclav to healthy volunteers

OBJECTIVES

To measure the effect of opsonophagocytosis mediated by complement activated by specific antibodies on the co-amoxiclav serum bactericidal activity against Streptococcus pneumoniae strains with reduced susceptibility to beta-lactams (amoxicillin MICs of 2, 4, 8 and 16 mg/L).

METHODS

An open Phase I study measuring ex vivo bactericidal activity after anti-pneumococcal vaccination and an oral dose of 2000/125 mg sustained-release co-amoxiclav was carried out. The ex vivo bactericidal activity was investigated through killing curves over 3 h [assuring polymorphonuclear neutrophil (PMN) viability] with serum samples collected 1.5 h and 5 h after dosing. Global killing was measured as the area under the killing curve (AUKC; log cfu x h/mL). The AUKC of the control growth curve of S. pneumoniae in Hanks' balanced salt solution (AUKC(K)) was used as control. The effect of the presence of complement and/or PMN was evaluated by the difference in the AUKC(K) and the different AUKCs obtained in the presence of inactivated serum (AUKC(IS)), active serum (AUKC(S)), inactivated serum plus PMN (AUKC(IS+PMN)) and active serum plus PMN (AUKC(S+PMN)).

RESULTS

Significant differences were found in all cases between the bactericidal activity of active serum+PMN (AUKC(K) - AUKC(S+PMN)) and that of inactivated serum (AUKC(K) - AUKC(IS)) with therapeutic indexes ranging from 0.56 to 3.04. At 1.5 h after dosing, a significantly higher bactericidal activity of co-amoxiclav was obtained when opsonophagocytosis occurred (samples with active serum and PMN) than when not occurring (killing curves with inactivated serum and without PMN), for all amoxicillin non-susceptible strains.

CONCLUSIONS

The results of this ex vivo study suggest that the collaboration of co-amoxiclav and complement-mediated opsonophagocytosis activated by specific antibodies may lay new approaches to overcome in vivo amoxicillin non-susceptibility.