PHARMACOGENOMICS

To advocate that pharmacists take a leadership role in pharmacogenomics-related patient testing, based on current or anticipated medication therapy; further,

To advocate for the inclusion of pharmacogenomic test results in medical and pharmacy records in a format that clearly states the implications of the results for drug therapy and facilitates availability of the genetic information throughout the continuum of care and over a patient’s lifetime; further,

To encourage health systems to support an interprofessional, evidenced-based effort to implement appropriate pharmacogenomics services and to identify and determine appropriate dissemination of actionable information to appropriate healthcare providers for review; further,

To encourage pharmacists to educate prescribers and patients about the use of pharmacogenomic tests and their appropriate application to drug therapy management; further,

To advocate that all health insurance policies provide coverage for pharmacogenomic testing to optimize patient care; further,

To advocate that drug product manufacturers and researchers conduct and report outcomes of pharmacogenomic research to facilitate safe and effective use of medications; further,

To encourage research into the economic and clinical impact of preemptive pharmacogenomic testing; further,

To encourage pharmacy workforce education on the use of pharmacogenomics and its application to therapeutic decision-making.

Rationale

Clinical pharmacogenomics is the practice of using genetic information to guide optimal drug selection and drug dosing for patients to maximize therapeutic effects, improve outcomes, and minimize toxicity. Currently, pharmacogenomic testing is used for specific drug-gene pairs in patients currently taking a medication associated with gene or prior to initiating therapy. Pharmacists are especially prepared to take a leadership role in selecting appropriate tests as they have an understanding of pharmacokinetic and pharmacodynamics properties of drugs in specific diseases and patient populations.

Over the past 10 years, the Clinical Pharmacogenetics Implementation Consortium (CPIC) has published over 23 guidelines that cover 19 genes and 46 drugs across several therapeutic areas as well as resources to facilitate the implementation of pharmacogenomics into routine clinical practice and the electronic health record. These guidelines include indications for which drugs and genes are most likely to be clinically useful based on current evidence. However, barriers such as prioritizing testing, interpretation for actionable results, incorporation of genomic data into the electronic health record, and reimbursement remain. Furthermore, there is also the challenge of how to ensure that the results of pharmacogenomic tests stay with the patient throughout their health journey. Implementation of pharmacogenomic testing has the potential to improve patient care by decreasing failed treatment attempts due to medication ineffectiveness or adverse effects and by increasing effectiveness of improperly dosed medications.

The advent of widely available pharmacogenomic tests, many of which are also marketed to the public, introduces another layer of complexity. The Food and Drug Administration (FDA) has alerted patients and healthcare providers that claims for many genetic tests to predict a patient's response to specific medications have not been reviewed by the FDA and may not have the scientific or clinical evidence to support their use. Changing drug treatment based on the results from such a test could lead to inappropriate treatment decisions and potentially serious health consequences for the patient. It is imperative to identify clinically significant drug-gene pairs, as these may prevent adverse events, and such identification should be performed preemptively, as with DPYD genotyping prior to starting patients on fluoropyrimidines. There may also be a role for the FDA to provide incentives for manufacturers to conduct pharmacogenomic testing to optimize drug-gene patient paring.

Another barrier that many providers and patients encounter is insurance coverage of pharmacogenomic testing. A 2019 JAPhA article found that coverage and payments of pharmacogenomics varied by the company and gene-drug pairs and remain suboptimal. The article found that, of gene-drug indication group (GDIG), 50% were mentioned in policies but were covered less than 20% of the time. When mentioned in a policy, 7 GDIGs were uniformly covered, and 11 GDIGs were uniformly not covered. Overall, insurance companies covered approximately 40% of GDIGs mentioned in their policies. Additionally, preemptive pharmacogenomics suffers from a lack of economic and outcomes data supporting its more widespread adoption into practice. Such data would provide impetus for reimbursement from third-party payers. The number of genes tested in preemptive testing is typically greater than for reactive testing, meaning the number of actionable pharmacotherapeutic interventions made will increase. To ensure a sustainable preemptive pharmacogenomic testing system, clinical decision support is crucial for the implementation of evidence-based treatment decisions because it will become less feasible for a clinician specializing in pharmacogenomics to provide a recommendation for each pharmacogenomically actionable medication.

Furthermore, the ASHP Statement on the Pharmacist’s Role in Clinical Pharmacogenomics states that pharmacogenomics has an essential place in pharmacy education because pharmacists should be educated to be able to recommend pharmacogenomic testing for drug and dosage selection; design patient-specific drug and dose regimens based on the patient’s pharmacogenomic profile and other pertinent information; educate patients, pharmacists, and other healthcare professionals about pharmacogenomic principles and appropriate indications for clinical pharmacogenomic testing; and communicate pharmacogenomic-specific drug therapy recommendations to the healthcare team.