Cost-Effectiveness Assessment of Monitoring Abiraterone Levels in Metastatic Castration-Resistant Prostate Cancer Patients

Evaluation of adherence to abiraterone therapy in prostate cancer patients based on a population pharmacokinetic model

AIMS

Abiraterone treatment requires regular drug intake under fasting conditions due to pronounced food effect, which may impact patient adherence. The aim of this prospective study was to evaluate adherence to abiraterone treatment in patients with prostate cancer. To achieve this aim, an abiraterone population pharmacokinetic model was developed and patients' adherence has been estimated by comparison of measured levels of abiraterone with population model-based simulations.

METHODS

A total of 1469 abiraterone plasma levels from 83 healthy volunteers collected in a bioequivalence study were analysed using a nonlinear mixed-effects model. Monte Carlo simulation was used to describe the theoretical distribution of abiraterone pharmacokinetic profiles at a dose of 1000 mg once daily. Adherence of 36 prostate cancer patients treated with abiraterone was then evaluated by comparing the real abiraterone concentration measured in each patient during follow-up visit with the theoretical distribution of profiles based on simulations. Patients whose abiraterone levels were ˂5th or ˃95th percentile of the distribution of simulated profiles were considered to be non-adherent.

RESULTS

Based on this evaluation, 13 patients (36%) have been classified as non-adherent. We observed significant association (P = .0361) between richness of the breakfast and rate of non-adherence. Adherent patients reported significantly better overall condition in self-assessments (P = .0384). A trend towards a higher occurrence of adverse effects in non-adherent patients was observed.

CONCLUSIONS

We developed an abiraterone population pharmacokinetic model and proposed an advanced approach to medical adherence evaluation. Due to the need for administration under fasting conditions, abiraterone therapy is associated with a relatively high rate of non-adherence.

Cost-effectiveness analysis of an orphan drug tebentafusp in patients with metastatic uveal melanoma and a call for value-based pricing

The normative regimens recommendations for treating metastatic uveal melanoma (mUM) are absent in the US. Recently, a phase III randomized clinical trial revealed that tebentafusp yielded a conspicuously longer overall survival than the control group. Based on the prominent efficacy, this study aimed to assess whether tebentafusp is cost-effective compared to the control group in patients with untreated mUM. A three-state partitioned survival model was developed to assess the costs, quality-adjusted life years (QALYs), and incremental cost-effectiveness ratio (ICER) from the perspective of US payers. Scenario analyses and sensitivity analyses were conducted to explore the conclusion uncertainty. Compared with control group, tebentafusp therapy yielded an additional 0.47 QALYs (1.19 vs. 0.72 QALYs) and an incremental cost of $444 280 ($633 822 vs. $189 542). The resultant ICER of $953 230/QALY far outweighed the willingness-to-pay threshold of $200 000/QALY. The ICER was always more than $750 000/QALY in all the univariable and probabilistic sensitivity analyses. Scenario analyses indicated that reducing the unit price of tebentafusp to $33.768/µg was associated with a favorable result of tebentafusp being cost-effective. For treatment-naive patients with mUM, the cost of tebentafusp therapy was not worth the improvement in survival benefits at the current price compared to the investigator's choice of therapy. The cost-effectiveness of tebentafusp could be promoted using value-based pricing.

Pharmacokinetic approach in therapeutic monitoring of antineoplastic drugs and the impact on pharmacoeconomics: A systematic review

OBJECTIVES

Therapeutic drug monitoring aims to quantify the concentration of a drug in a biological matrix. In oncology, the therapeutic arsenal is vast and therapeutic drug monitoring optimizes treatment and reduces costs. This review will analyze the financial impact of therapeutic monitoring of anticancer drugs in healthcare institutions.

METHODS

Keywords were selected using Decs (MeSH). Through the Pubmed, Scopus, and Virtual Health Library (VHL) databases, 74 articles were found, of which 4 meet the inclusion criteria. Methodological quality and risk of bias were assessed according to the Research Triangle Institute Item Bank (RTI-Item Bank) scale.

KEY FINDINGS

Therapeutic drug monitoring is an important tool for dose reduction or dose increase due to toxicity and lack of response, respectively. The main barriers are associated costs and lack of cost-benefit data. An alternative is to use population pharmacokinetic models, measured plasma concentration(s) and relevant patient characteristics, estimated individual pharmacokinetic parameters, and predicted drug concentrations at any point in the dosing range.

CONCLUSIONS

Therapeutic drug monitoring is understood as a technology that adds costs to payers. Future studies should generate clinical evidence of population pharmacokinetics from therapeutic drug monitoring studies.

Precision Dosing of Targeted Therapies Is Ready for Prime Time

Fixed dosing of oral targeted therapies is inadequate in the era of precision medicine. Personalized dosing, based on pharmacokinetic (PK) exposure, known as therapeutic drug monitoring (TDM), is rational and supported by increasing evidence. The purpose of this perspective is to discuss whether randomized studies are needed to confirm the clinical value of precision dosing in oncology. PK-based dose adjustments are routinely made for many drugs and are recommended by health authorities, for example, for patients with renal impairment or for drug-drug interaction management strategies. Personalized dosing simply extrapolates this paradigm from selected patient populations to each individual patient with suboptimal exposure, irrespective of the underlying cause. If it has been demonstrated that exposure is related to a relevant clinical outcome, such as efficacy or toxicity, and that exposure can be optimized by PK-guided dosing, it could be logically assumed that PK-guided dosing would result in better treatment outcomes without the need for randomized confirmatory trials. We propose a path forward to demonstrate the clinical relevance of individualized dosing of molecularly-targeted anticancer drugs.