Efficacy of two vitamin E formulations in patients with abetalipoproteinemia and chylomicron retention disease.

Abetalipoproteinemia (ABL) and chylomicron retention disease (CMRD) are extremely rare recessive forms of hypobetalipoproteinemia characterized by intestinal lipid malabsorption and severe vitamin E deficiency. Vitamin E is often supplemented in the form of fat-soluble vitamin E acetate, but fat malabsorption considerably limits correction of the deficiency. In this crossover study, we administered two different forms of vitamin E, tocofersolan (a water-soluble derivative of RRR-α-tocopherol) and α-tocopherol acetate, to three patients with ABL and four patients with CMRD. The aims of this study were to evaluate the intestinal absorption characteristics of tocofersolan versus α-tocopherol acetate by measuring the plasma concentrations of α-tocopherol over time after a single oral load and to compare efficacy by evaluating the ability of each formulation to restore vitamin E storage after 4 months of treatment. In patients with ABL, tocofersolan and α-tocopherol acetate bioavailabilities were extremely low (2.8% and 3.1%, respectively). In contrast, bioavailabilities were higher in patients with CMRD (tocofersolan, 24.7%; α-tocopherol acetate, 11.4%). Plasma concentrations of α-tocopherol at 4 months were not significantly different by formulation type in ABL or CMRD. This study provides new insights about vitamin E status in ABL and CMRD and suggests the potential of different formulations as treatment options.

Time-to-Event Modeling of Left- or Right-Censored Toxicity Data in Nonclinical Drug Toxicology.

A time-to-event (TTE) model has been developed to characterize a histopathology toxicity that can only be detected at the time of animal sacrifice. The model of choice was a hazard model with a Weibull distribution and dose was a significant covariate. The diagnostic plots showed a satisfactory fit of the data, despite the high degree of left and right censoring. Comparison to a probabilistic logit model shows similar performance in describing the data with a slight underestimation of survival by the Logit model. However, the TTE model was found to be more predictive in extrapolating toxicity risk beyond the observation range of a truncated dataset. The diagnostic and comparison outcomes would suggest using the TTE approach as a first choice for characterizing short and long-term risk from nonclinical toxicity studies. However, further investigations are needed to explore the domain of application of this kind of approach in drug safety assessment.

Etoposide pharmacokinetics impact the outcomes of lymphoma patients treated with BEAM regimen and ASCT: a multicenter study of the LYmphoma Study Association (LYSA).

BACKGROUND: Relationships between pharmacokinetic (PK) parameters of etoposide and toxicity survivals were reported in cancer patients treated at standard doses. The clinical impact of PK variations of etoposide high doses has never been explored in lymphoma patients. PATIENTS AND METHODS: The primary objective of LYMPK study was to prospectively assess the impact of etoposide PK parameters on outcomes in lymphoma patients receiving high-dose chemotherapy regimen (carmustine, cytarabine, etoposide and melphalan) followed by autologous stem cell transplant (ASCT). Individual etoposide PK parameters were estimated with a previously reported bi-compartment model using NONMEM(®) program. The impact of PK parameters on toxicity and survival was assessed using univariate/multivariate analyses. RESULTS: A total of 91 patients with malignant lymphoma [non-Hodgkin's lymphoma (NHL): 79; Hodgkin's lymphoma: 12] at first line (n = 49) or relapse (n = 42) were enrolled in five centers. Large inter-individual variabilities in individual PK values were found for the same administration doses. In NHL patients, cumulative higher trough concentrations over the eight administrations of the first cycle (TotC min, categorized by the median 58.71 mg/L) had significant prognostic value regarding the 5-year progression-free survival (PFS: 73.6 vs 46.5 %, P = 0.015) and 5-year overall survival (OS: 74.0 vs 52.2 %, P = 0.034). Using a Cox model analysis, integrating disease settings (first line vs recurrent disease), simplified IPI and other prognostic factors, TotC min was the only significant independent prognostic factor influencing PFS, disease-specific survival and OS. CONCLUSION: This prospective study suggests survival of NHL patients treated with BEAM regimen and ASCT might be improved by increasing etoposide administration dose, or plasma concentration-based adjustment.

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.