Inconsistent quality of evidence for biomarker use on FDA drug labels

1. The majority of drug labels for drug-biomarker combinations did not provide convincing evidence for clinical validity or utility.

2. Of the drug labels that made recommendations for incorporating biomarker test results into therapeutic decision-making, only 30% provided convincing evidence for its clinical utility.

Evidence Rating Level: 2 (Good)

Study Rundown: Personalized medicine is an exciting prospect for the future of medicine. Studies have shown how differences in drug metabolism can alter drug levels and thus alter the drug’s safety and efficacy profiles. However the ultimate impact on clinical outcomes is unclear. Despite this, pharmacogenetic biomarker information and recommendations are included on FDA drug labels. Given the influence drug label information may have on physician therapeutic decision-making, this study sought to investigate the quality of evidence on existing drug labels for the use of pharmacogenetic biomarkers as well as the quality of citation of supporting studies.

This study found that the majority of drug labels of drug-biomarker combinations did not provide any evidence for clinical validity or utility. Moreover, of those labels that made recommendations for incorporating biomarkers into decision-making, only 30% provided evidence for its use. This study is the first to look at the quality of FDA drug-biomarker labeling given the significant consequences for physician therapeutic decision-making based on these labels. This study is limited by the information found on the publically available FDA websites. Overestimation of the quality of the cited evidence may also have occurred as the authors took the best of the clinical validity or utility to give the label their grade.

Click to read the study, published today in JAMA Internal Medicine

Relevant Reading: A Pharmacogenetic versus a Clinical Algorithm for Warfarin Dosing

In-Depth [descriptive study]: This descriptive study used publically available data from the Table of Pharmacogenomic Biomarkers in Drug Labeling, which contains all FDA-approved drugs and their labelling information. The extracted evidence was graded convincing, adequate or incomplete for clinical validity, utility and recommendations. The grading was based on the Evaluation of Genomic Application in Practice and Prevention Working Group’s guidelines.

In total, 119 drug-biomarker combinations were found, many of which were oncological drugs (31%). Only 36% provided convincing evidence for their clinical validity, and only 15% included convincing evidence for the improvement of clinical outcomes due to biomarker use, referred to as the clinical utility. An impressive 64% of labels did not provide convincing evidence for either clinical validity or utility. A total of 13 labels (10.9%) contained a full citation of supporting studies, whereas 36 did not mention any evidence to support the biomarker in question. Interestingly, of studies with no validity or utility evidence provided, 32% made recommendations on biomarker use in therapeutic decision-making. However, it is unclear how the information and biomarker use recommendations impact physician decision-making in practice.

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Image: PD

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