Recommendations for pharmacogenetic testing in clinical practice guidelines in the US

Navigating Pharmacogenomic Testing in Practice: Who to Test and When to Test

There is increasing attention on the clinical utility and value of pharmacogenetic (PGx) testing to individualize medication management. Most clinical practice guidelines from medical professional societies do not recommend routine PGx testing, with a few key exceptions. Inconsistent recommendations across clinical practice guidelines, FDA product labeling, and payer reimbursement policies have hampered widespread adoption of testing. Multiple resources exist to aid in the adoption and use of actionable PGx test results in clinical practice; however, most of these resources do not provide guidance on who should receive PGx testing and when-a critical question the clinical community continues to struggle with. There are multiple considerations when answering this question beyond the clinical validity of the drug-gene interaction itself, such as the actionable result frequency, severity of the adverse clinical outcome, predictive power of the PGx test, suitability of alternative treatments, cost, and turnaround time of test results. This perspective discusses these considerations and models for testing including preemptive screening, pretreatment testing, and reactive testing, highlighting advantages and disadvantages of each approach. The authors provide their perspectives on identifying candidates for PGx testing in the current real-world environment and how that differs from a clinically ideal scenario.

Clopidogrel transfer into human milk: case series - a contribution from the ConcePTION project

Introduction

Implementation of breastfeeding recommendations is hampered by-among others-lacking information regarding medicine safety during breastfeeding. This article describes the clinical and pharmacokinetic data of breastfeeding mothers using clopidogrel (CLP) as secondary prevention following (suspicion of) a cerebrovascular accident.

Methods

A 29-year-old and 42-year-old woman were chronically treated with 75 mg CLP once daily. Human milk samples were collected at 7 and 9 months (patient 1), and at 14 months postpartum (patient 2). Each sampling period, two maternal blood samples as well as one infant blood sample were collected. Concentrations of CLP, clopidogrel carboxylic acid (CCA) and clopidogrel active metabolite (CAM) derivatized were analyzed using liquid chromatography with tandem mass spectrometry.

Results

The average steady-state concentration in human milk was 0.96 and 7.40 ng/mL for CLP and CCA, respectively. CAM concentrations in all but two milk samples were below the limit of detection (LOD; 0.004 ng/mL). In the infant plasma sample, CCA level was 0.05 ng/mL but CLP and CAM were undetectable (CLP LOD: 0.003 ng/mL). The mean daily infant dosage (DID) was 82.3, 585.6 and 1.5 ng/kg/day for CLP, CCA and CAM, respectively, and the relative infant dose (RID) for CLP-related exposure remained well below 1%.

Discussion

The estimated infant exposure to CLP and its metabolites via human milk was low in both cases. Although this low exposure was supported by the observed infant plasma concentration, additional studies should confirm CLP safety via human milk, especially considering known variable pharmacokinetics and ontogeny of metabolizing enzymes in infants.

Integrating Pharmacogenomics into the Broader Construct of Genomic Medicine: Efforts by the ClinGen Pharmacogenomics Working Group (PGxWG)

Pharmacogenomics (PGx) is focused on the relationship between an individual's genetic makeup and their response to medications, with the overarching aim of guiding prescribing decisions to improve drug efficacy and reduce adverse events. The PGx and genomic medicine communities have worked independently for over 2 decades, developing separate standards and terminology, making implementation of PGx across all areas of genomic medicine difficult. To address this issue, the Clinical Genome Resource (ClinGen) Pharmacogenomics Working Group (PGxWG) was established by the National Institutes of Health (NIH)-funded ClinGen to initially create frameworks for evaluating gene-drug response clinical validity and actionability aligned with the ClinGen frameworks for evaluating monogenic gene-disease relationships, and a framework for classifying germline PGx variants similar to the American College of Medical Genetics (ACMG) and Association of Molecular Pathology (AMP) system for interpretation of disease-causing variants. These frameworks will leverage decades of work from well-established PGx resources facilitating buy-in among PGx stakeholders. In this report, we describe the background and major activities of the ClinGen PGxWG, and how this initiative will facilitate the critical inclusion of PGx into the larger context of genomic medicine.

The Pharmacogenomics Global Research Network Implementation Working Group: global collaboration to advance pharmacogenetic implementation

Pharmacogenetics promises to optimize treatment-related outcomes by informing optimal drug selection and dosing based on an individual's genotype in conjunction with other important clinical factors. Despite significant evidence of genetic associations with drug response, pharmacogenetic testing has not been widely implemented into clinical practice. Among the barriers to broad implementation are limited guidance for how to successfully integrate testing into clinical workflows and limited data on outcomes with pharmacogenetic implementation in clinical practice. The Pharmacogenomics Global Research Network Implementation Working Group seeks to engage institutions globally that have implemented pharmacogenetic testing into clinical practice or are in the process or planning stages of implementing testing to collectively disseminate data on implementation strategies, metrics, and health-related outcomes with the use of genotype-guided drug therapy to ultimately help advance pharmacogenetic implementation. This paper describes the goals, structure, and initial projects of the group in addition to implementation priorities across sites and future collaborative opportunities.