CYP2C19 Genotype-Specific Dosing Plus TDM on Reaching Therapeutic Voriconazole Blood Levels

Summary

Invasive aspergillosis is a fungal infection which left untreated, is a significant cause of morbidity and mortality. Immunocompromised patient populations such as solid organ transplant and malignant hematology patients are especially susceptible to invasive fungal infections. Voriconazole is an anti-fungal agent that is frontline therapy for invasive aspergillosis. Treatment success is highly dependent on maintaining therapeutic voriconazole concentrations. The current published literature has established that treatment failure is associated with sub- and supra-therapeutic voriconazole concentrations.

Maintaining therapeutic voriconazole concentrations however, is challenging due to the high inter and intra-patient variability in voriconazole pharmacokinetics. The complex kinetics of voriconazole renders current manufacturers' dosing guidelines ineffective. Much of this complexity has been linked to genetic polymorphisms in the cytochrome P450 2C19 gene, and it has been found that CYP2C19 genotype plays an important role in determining voriconazole exposure levels. Therapeutic drug monitoring has been found to increase efficacy of voriconazole treatment through the monitoring of patients' voriconazole levels, allowing for dosage adjustments in response to supra- or sub-therapeutic levels.

There are few robust studies that have examined the effect of CYP2C19 genotype on voriconazole treatment outcomes. They have been unable to determine relationships between CYP2C19 genetic status, and clinical efficacy and safety. No studies to our knowledge have made dosing adjustments based on CYP2C19 genetic status.

The study aim is to explore the utility of voriconazole dosing that is based on the genetic status of the patient in conjunction with therapeutic drug monitoring. Over the course of one year, solid organ transplant recipients at Toronto General Hospital and malignant hematology patients at Princess Margaret Cancer Centre receiving voriconazole therapy will be randomized into one of two trial arms: a control arm receiving therapeutic drug monitoring only, or a treatment arm receiving genotype-specific dosing in conjunction with therapeutic drug monitoring. The investigators will compare the proportion of patients that achieve voriconazole therapeutic concentrations, the number of dose adjustments needed to achieve therapeutic voriconazole levels, and clinical outcomes between trial arms.

Conditions

• Aspergillosis Invasive
• Fungal Infection

Interventions

GENETIC

Voriconazole genotype-specific dosing

Those in the intervention arm will receive an experimental dosage regimen of voriconazole based on their genetic status. URM: 6 mg/kg voriconazole twice on the first day followed by 5 mg/kg twice daily, rounded to the nearest 50mg for oral formulations up to day 4 post-start of voriconazole therapy. EM: 6 mg/kg voriconazole twice on the first day followed by 4 mg/kg twice daily, rounded to the nearest 50mg for oral formulations up to day 4 post-start of voriconazole therapy. HEM and PM: 6 mg/kg voriconazole twice on the first day followed by 2 mg/kg twice daily, rounded to the nearest 50mg for oral formulations up to day 4 post-start of voriconazole therapy.

DRUG

Standard of Care

Participants are given 6 mg/kg voriconazole twice on the first day followed by 4 mg/kg twice daily, rounded to the nearest 50mg for oral formulations up to day 4 post-start of voriconazole therapy. After TDM is conducted on day 4 for all patients, dosing in both trial arms will adhere to the following in order to reach the target therapeutic window: 1.0-5.5 mg/L.

Sponsors & Collaborators

• University Health Network, Toronto

  lead OTHER

Principal Investigators

• Marisa Battistella, PharmD · University Health Network, Toronto

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

DOUBLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2018-01-10

Primary Completion

2019-08-31

Completion

2020-08-28

Countries

• Canada

Study Locations