Population Pharmacokinetic Analysis of Lanreotide Autogel® in Healthy Subjects: evidence for injection interval of up to 2 months

BACKGROUND AND OBJECTIVE: Lanreotide is a somatostatin analogue used for the treatment of acromegaly and neuroendocrine tumours. The objective of this study was to develop a pharmacokinetic model for the sustained-release formulation lanreotide Autogel after deep subcutaneous administration in healthy subjects, and to explore the potential effect of covariates, especially sex and dose. SUBJECTS AND METHODS: This was an open-label, single-centre, randomized, dose-ranging, parallel-group study, with a follow-up period of 4-7 months following drug administration in healthy subjects. Healthy Caucasian subjects aged 18-45 years were included. Subjects received a rapid intravenous bolus of 7 microg/kg of an immediate-release formulation of lanreotide (lanreotide IRF). After a 3-day washout period, participants were randomized to receive a single deep subcutaneous injection of lanreotide Autogel at a dose of 60, 90 or 120 mg. PHARMACOKINETIC AND STATISTICAL ANALYSIS: Blood samples for lanreotide determination were obtained during the first 12 hours after the intravenous bolus injection and during the 4- to 7-month follow-up period after deep subcutaneous administration of lanreotide Autogel. Data after intravenous and subcutaneous administration were fitted simultaneously using the population approach in NONMEM((R)) version VI software. The model was validated externally using data from patients with acromegaly. RESULTS: In total, 50 healthy subjects (24 women and 26 men) received a single intravenous dose of lanreotide IRF. Of these, 38 subjects (18 women and 20 men) received a single subcutaneous dose of lanreotide Autogel 3 days after intravenous lanreotide IRF. The disposition of lanreotide was described by a three-compartment open model. The estimates of the total volume of distribution and serum clearance were 15.1 L and 23.1 L/h, respectively. The estimates of interindividual variability were 0.05). CONCLUSIONS: Population analysis allows a full description of the disposition of lanreotide after rapid intravenous bolus administration of lanreotide IRF (7 microg/kg) and the pharmacokinetics of lanreotide Autogel after a single deep subcutaneous injection (60, 90 or 120 mg) in healthy subjects. The model-based simulations provide support for the feasibility of extending the dosing interval for lanreotide Autogel to 56 days when given at 120 mg. The absorption profile of lanreotide Autogel was independent of the dose and was not affected by sex

Predictive ability of a semi-mechanistic model for neutropenia in the development of novel anti-cancer agents: two case studies

Abstract In cancer chemotherapy neutropenia is a common dose-limiting toxicity. An ability to predict the neutropenic effects of cytotoxic agents based on proposed trial designs and models conditioned on previous studies would be valuable. The aim of this study was to evaluate the ability of a semi-mechanistic pharmacokinetic/pharmacodynamic (PK/PD) model for myelosuppression to predict the neutropenia observed in Phase I clinical studies, based on parameter estimates obtained from prior trials. Pharmacokinetic and neutropenia data from 5 clinical trials for diflomotecan and from 4 clinical trials for indisulam were used. Data were analyzed and simulations were performed using the population approach with NONMEM VI. Parameter sets were estimated under the following scenarios: (a) data from each trial independently, (b) pooled data from all clinical trials and (c) pooled data from trials performed before the tested trial. Model performance in each of the scenarios was evaluated by means of predictive (visual and numerical) checks. The semi-mechanistic PK/PD model for neutropenia showed adequate predictive ability for both anti-cancer agents. For diflomotecan, similar predictions were obtained for the three scenarios. For indisulam predictions were better when based on data from the specific study, however when the model parameters were conditioned on data from trials performed prior to a specific study, similar predictions of the drug related-neutropenia profiles and descriptors were obtained as when all data were used. This work provides further indication that modeling and simulation tools can be applied in the early stages of drug development to optimize future trials

A multi-centre dose-escalation and pharmacokinetic study of diflomotecan in patients with advanced malignancy

Diflomotecan, a homocamptothecin, targets DNA topoisomerase I. Previous clinical trials have demonstrated a variable degree of dose limiting toxicity. The purpose of this study was to further evaluate the safety and pharmacokinetic profile of a range of diflomotecan doses administered intravenously. Patients with advanced solid malignant tumours, refractory to standard therapies, with adequate haematologic, renal and hepatic function, received diflomotecan administered as a 20 min intravenous infusion every 21 days. Cohorts of six patients were recruited sequentially to one of three fixed starting dose groups-2, 4, or 7 mg, with drug administered by fixed-dose rather than dosing by body surface area. Pharmacokinetic analyses were performed on serial blood samples taken over the first 24 h after diflomotecan administration (cycles 1 and 2). Cytochrome P450 3A4 (CYP3A4) activity was determined by an erythromycin breath test (EBT) prior to diflomotecan administration in cycles 1 and 2. Thirteen patients, were treated with a starting dose of either 2 mg (n = 8) or 4 mg (n = 5) of diflomotecan. Dose limiting toxicities (DLTs) were observed in 1 patient in the 2 mg starting dose level (grade 4 neutropenia which lasted for 8 days), and in 2 of 5 patients enrolled at the 4 mg starting dose level (grade 4 neutropenia for 11 days; grade 4 neutropenia leading to withdrawal from the study), and no further dose escalation was performed. Pharmacokinetic analyses revealed a less than dose-proportional increase in diflomotecan and for the two metabolites BN80942 and P-20, with a magnitude of P-20 exposure similar to the parent drug. There was a high inter-patient variability in diflomotecan exposure similar to that observed with other camptothecin derivatives. One minor response was observed in a patient with oesophageal cancer. Diflomotecan administered as a 20-min intravenous infusion 3-weekly is characterised by a variable pharmacokinetic profile. Alternative oral dosing schedules of diflomotecan have been shown to display a more predictable PK/PD and safety profile and should be selected for further evaluation in Phase II clinical trials

Predictive ability of a semi-mechanistic model for neutropenia in the development of novel anti-cancer agents: two case studies

Abstract In cancer chemotherapy neutropenia is a common dose-limiting toxicity. An ability to predict the neutropenic effects of cytotoxic agents based on proposed trial designs and models conditioned on previous studies would be valuable. The aim of this study was to evaluate the ability of a semi-mechanistic pharmacokinetic/pharmacodynamic (PK/PD) model for myelosuppression to predict the neutropenia observed in Phase I clinical studies, based on parameter estimates obtained from prior trials. Pharmacokinetic and neutropenia data from 5 clinical trials for diflomotecan and from 4 clinical trials for indisulam were used. Data were analyzed and simulations were performed using the population approach with NONMEM VI. Parameter sets were estimated under the following scenarios: (a) data from each trial independently, (b) pooled data from all clinical trials and (c) pooled data from trials performed before the tested trial. Model performance in each of the scenarios was evaluated by means of predictive (visual and numerical) checks. The semi-mechanistic PK/PD model for neutropenia showed adequate predictive ability for both anti-cancer agents. For diflomotecan, similar predictions were obtained for the three scenarios. For indisulam predictions were better when based on data from the specific study, however when the model parameters were conditioned on data from trials performed prior to a specific study, similar predictions of the drug related-neutropenia profiles and descriptors were obtained as when all data were used. This work provides further indication that modeling and simulation tools can be applied in the early stages of drug development to optimize future trials