A PK-PD model linking biomarker dynamics to progression-free survival in patients treated with everolimus and sorafenib combination therapy, EVESOR phase I trial.

PURPOSE: The objective was to develop a pharmacokinetic-pharmacodynamic (PK-PD) model linking everolimus and sorafenib exposure with biomarker dynamics and progression-free survival (PFS) based on data from EVESOR trial in patients with solid tumors treated with everolimus and sorafenib combination therapy and to simulate alternative dosing schedules for sorafenib. PATIENTS AND METHODS: Everolimus (5-10 mg once daily, qd) and sorafenib (200-400 mg twice daily, bid) were administered according to four different dosing schedules in 43 solid tumor patients. Rich PK and PD sampling for serum angiogenesis biomarkers was performed. Baseline activation of RAS/RAF/ERK (MAPK) pathway was assessed by quantification of mRNA specific gene panel in tumor biopsies. The PK-PD modeling was performed using NONMEM® software. RESULTS: An indirect response PK-PD model linking sorafenib plasma exposure with soluble vascular endothelial growth factor receptor 2 (sVEGFR2) dynamics was developed. Progression-free survival (PFS) was described by a parametric time-to-event model. Higher decreases in sVEGFR2 at day 21 and higher baseline activation of MAPK pathway were associated with longer PFS (p = 0.002 and p = 0.007, respectively). The simulated schedule sorafenib 200 mg bid 5 days-on/2 days-off + continuous everolimus 5 mg qd was associated with median PFS of 4.3 months (95% CI 1.6-14.4), whereas the median PFS in the EVESOR trial was 3.6 months (95% CI 2.7-4.2, n = 43). CONCLUSION: Sorafenib 200 mg bid 5 days-on/2 days-off + everolimus 5 mg qd continuous was selected for an additional arm of EVESOR trial to evaluate whether this simulated schedule is associated with higher clinical benefit. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01932177.

EVESOR, a model-based, multiparameter, Phase I trial to optimize the benefit/toxicity ratio of everolimus and sorafenib.

AIM: This novel multiparameter Phase I study aimed to optimize doses/dosing schedules of everolimus and sorafenib drug combination, based on modeling/simulation (NCT01932177). PATIENTS & METHODS: About 26 patients with solid tumors were treated in four different dosing schedules. Everolimus once daily + sorafenib twice daily were given continuously in arms A and B, and intermittently in arms C (alternating every other week) and D (everolimus continuous and sorafenib 3 days on/4 days off). RESULTS: Continuous schedules exhibited higher toxicity risks than intermittent schedules (64.1 vs 35.9%; p < 0.0001), and trends for lower disease control rates (80 vs 100%). No significant pharmacokinetic interaction was identified. CONCLUSION: Feasibility of EVESOR trial is demonstrated. Intermittent schedules might provide better tolerance and efficacy than continuous schedules.

Multiparameter Phase I trials: a tool for model-based development of targeted agent combinations--example of EVESOR trial.

Optimal development of targeted drug combinations is one of the future challenges to be addressed. Computerization and mathematical models able to describe biological phenomena and to simulate the effects of changes in experimental conditions may help find solutions to this issue. We propose the concept of 'multiparameter trials', where biological, radiological and clinical data required for modeling purpose are collected and illustrated by the ongoing academic EVESOR trial. The objective of the model-based work would be the determination of the optimized doses and dosing schedules of everolimus and sorafenib, offering the maximization of the predicted modeled benefit/toxicity ratio in patients with solid tumors. It may embody the 'proof of concept' of model-based drug development of anticancer agent combinations.

A validated method for quantifying atractyloside and carboxyatractyloside in blood by HPLC-HRMS/MS, a non-fatal case of intoxication with Atractylis gummifera L.

Atractyloside (ATR) and carboxyatractyloside (CATR) are diterpene glycosides that are responsible for the toxicity of several Asteraceae plants around the world. Mediterranean gum thistle (Atractylis gummifera L.) and Zulu impila (Callilepis laureola DC.), in particular, are notoriously poisonous and the cause of many accidental deaths, some suicides and even some murders. There is no current method for measuring the two toxins in biological samples that meet the criteria of specificity required in forensic medicine. We have endeavored to fill this analytical gap. Analysis was carried out using a solid-phase extraction and a high-performance liquid chromatography coupled with high-resolution tandem mass spectrometry detection. The method was validated in the whole blood with quantification limits of 0.17 and 0.15 µg/L for ATR and CATR, respectively. The method was applied to a non-fatal case of intoxication with A. gummifera. To the best of the authors' knowledge, this is the first time that a concentration of ATR and CATR in blood (883.1 and 119.0 µg/L, respectively) and urine (230.4 and 140.3 µg/L, respectively) is reported. ATR and CATR were quantified in A. gummifera roots by the standard method addition (3.7 and 5.4 mg/g, respectively).

A template model for studying anticancer drug efflux transporter inhibitors in vitro.

Efflux transporters play an important role in drug absorption and also in multidrug resistance. ABCG2 (BCRP) is an efflux transporter conferring cross-resistance to mitoxantrone (Mit), irinotecan (CPT11), and its active metabolite SN38. MBLI87, a new ABCG2 inhibitor has proven its efficacy against ABCG2-mediated efflux in vitro and in vivo. This work aimed at modeling and quantifying the cellular interaction between MBLI87 and different substrates using a mechanistic template model. An in vitro competition experiment study was carried out with HEK293 cells overexpressing ABCG2 exposed to fixed concentrations of substrates (Mit, CPT11, SN38) and to MBLI87 at several concentration levels. A nonlinear mixed-effects transport inhibition model was developed to fit intracellular drug concentrations. In this model, drugs cross the cell membrane through passive diffusion, active drug efflux is ABCG2 mediated, interaction between substrates and inhibitor occurs within the transporter. The interaction was found to be noncompetitive. The MBLI87 Ki was estimated to 141 nm for Mit, 289 nm for CPT11, and 1160 nm for SN38. The ratio of intrinsic transport clearance divided by diffusion clearance was estimated to 2.5 for Mit, 1.01 for CPT11, and 5.4 for SN38. The maximal increase in the intracellular substrate concentration that is possible to achieve by inhibition of the transporter was estimated to 1.5 for Mit, 0.1 for CPT11, and 4.4 for SN38. This mechanistic template model describes both drug accumulation and cellular transport, and the mixed-effects approach allows an estimation of intra- and interassay variability. This model is of great interest to study cytotoxic cellular pharmacokinetics.

Evaluation of miglustat treatment in patients with type III mucopolysaccharidosis: a randomized, double-blind, placebo-controlled study.

OBJECTIVE: To evaluate the efficacy and safety of oral miglustat treatment in patients with mucopolysaccharidosis type III. The primary outcome was efficacy with improvement or stabilization in at least two domains of Vineland Adaptative Behavior Scales at 6 months. The secondary outcome measured the evolution of other cognitive tests at 12 months. The safety and tolerability were assessed throughout the study. STUDY DESIGN: This was a randomized, double-blind, placebo-controlled, monocenter, institutional, phase IIb to III study. In case of efficacy at 6 months, the study would go on for another 6 months on an open design with all patients receiving miglustat. In the absence of efficacy at 6 months, the trial had to be continued for 6 more months with the initial design. RESULTS: After 6 months, efficacy was not superior in patients with miglustat. The independent review board confirmed continuing the study until 12 months. CONCLUSION: Miglustat treatment was not associated with any improvement/stabilization in behavior problems in patients with mucopolysaccharidosis type III. Miglustat has an acceptable safety profile. However, the study has confirmed that miglustat is able to pass through the blood-brain barrier without significantly decreasing ganglioside levels.

Fatal intoxication due to ackee (Blighia sapida) in Suriname and French Guyana. GC-MS detection and quantification of hypoglycin-A.

Between 1998 and 2001 the deaths of 16 Surinamese children were recorded along the Maroni River, which forms the border between Suriname and French Guyana. After a metabolic origin was eliminated, ethnobotanical research in the field led to a hypothesis of intoxication through the ingestion of ackee. Ackee (Blighia sapida) is a large green leafy tree of West African origin. Its unripe fruit contains large quantities of two toxic molecules: hypoglycin-A and hypoglycin-B, the former being the more toxic. We have developed a GC-MS procedure allowing us to demonstrate the presence of hypoglycin-A in the gastric fluid of one of the deceased children, and to compare the content of hypoglycin-A in fruit collected on the road to Paramaribo in Suriname (5.1mg/g) with samples from Burkina Faso (8.1mg/g) and Jamaica (9.2mg/g). Field research showed the misuse of this little-known plant by Maroon witch doctors. The Bushinengue witch doctors were informed about the dangers of ackee, and no new cases have been reported to date.

Population pharmacokinetics and pharmacodynamics of cisplatinum during hyperthermic intraperitoneal chemotherapy using a closed abdominal procedure.

The aim of this work was to study the pharmacokinetics of cisplatinum during closed abdominal hyperthermic intraperitoneal chemotherapy (HIPEC) using a population pharmacokinetics approach. Forty patients were treated between January 2003 and December 2004. Peritoneal and blood concentrations of cisplatinum were used to develop a pharmacokinetic model of the peritoneal and plasma compartments using NONMEM software. Different covariables were analyzed to identify those that explain part of the interindividual variability of the pharmacokinetic parameters. Relationships between the area under the concentration-time curve (AUC) and hematological and renal toxicity and efficiency were explored. The pharmacokinetics of cisplatinum were modeled with a 3-compartment model. Estimations of the plasma and peritoneal pharmacokinetic parameters were obtained. No clinical or biological covariates correlated with these parameters. No direct relationship between the AUC of the peritoneal or plasma and toxicity or efficiency was demonstrated. The pharmacokinetics during HIPEC could be modeled with a 3-compartment model using a population pharmacokinetics approach. This work is the basis of further studies. Notably, studies including new patients will analyze the impact of abdominal cavity volume and the variation of the abdominal pressure during HIPEC on the pharmacokinetics of cisplatinum.

Substrate reduction therapy with miglustat in chronic GM2 gangliosidosis type Sandhoff: results of a 3-year follow-up.

GM2 gangliosidosis type Sandhoff is caused by a defect of beta-hexosaminidase, an enzyme involved in the catabolism of gangliosides. It has been proposed that substrate reduction therapy using N-butyl-deoxynojirimycin (miglustat) may delay neurological progression, at least in late-onset forms of GM2 gangliosidosis. We report the results of a 3-year treatment with miglustat (100 mg t.i.d) in a patient with chronic Sandhoff disease manifesting with an atypical, spinal muscular atrophy phenotype. The follow-up included serial neurological examinations, blood tests, abdominal ultrasound, and neurophysiologic, cognitive, brain, and muscle MRI studies. We document some minor effects on neurological progression in chronic Sandhoff disease by miglustat treatment, confirming the necessity of phase II therapeutic trials including early-stage patients in order to assess its putative efficacy in chronic Sandhoff disease.