In a recent study published in The Lancet – the Pharmacogenomic Testing for Preventing Adverse Drug Reactions (PREPARE) study – a 12-gene pharmacogenetic panel, which has been referred to as a “DNA medication pass”, was used to tailor and inform the treatment of patients. The results showed that this pre-emptive genotyping strategy significantly reduced the occurrence of clinically relevant adverse drug reactions (by approx. 30%).
Moreover, this study was designed as an open-label, multicentre, controlled, cluster-randomised, crossover implementation trial, involving 6944 patients. It was conducted in 18 hospitals, 9 community health centres and 28 community pharmacies across 7 European countries, including Austria, Greece, Italy, the Netherlands, Slovenia, Spain, and the UK. This study is one of the first to not only demonstrate the clinical utility of genetically-guided treatment, but also support the feasibility of bringing precision medicine to the clinic on a large scale.
The promise of precision medicine
The era of precision medicine (which promises to transform healthcare through personalized treatment plans that consider patients’ genes, lifestyles, and environments) has been “right around the corner” for many years now. Indeed, despite growing scientific evidence and rapid advancements in genomics technology, the implementation of precision medicine has been slow. The one-size-fits-all approach to treatment, where doctors prescribe treatments based on the expected responses of an average patient, still dominates.
There are several reasons for the slow implementation of precision medicine in the clinic. These include lack of standardization, limited resources and technology, funding shortages, privacy and security concerns, and the healthcare system structure. Additionally, the limited number of real-world studies has made it difficult to fully demonstrate the potential benefits of precision medicine.
However, despite all this, the momentum for precision medicine continues to build, attracting attention from researchers, healthcare providers and the public. The results from the PREPARE study are a promising step forward – by not only proving the effectiveness of treatment guided by genetic information, but also showing that precision medicine can be successfully implemented in clinical settings on a large scale.
PREPARE-ing for the future
The PREPARE study was conducted across seven European countries and included 6944 patients. The results found that genetically-guided prescribing of treatment using the 12-gene pharmacogenetic panel significantly reduced the incidence of clinically relevant adverse drug reactions by around 30% compared to patients receiving standard treatment. This study represents one of the largest efforts to implement pharmacogenetics in a real-world setting and highlights the potential benefits of integrating pharmacogenetic testing into routine clinical practice. Its results show the benefits of a standardised, validated, and harmonised pharmacogenetic-test system, and the turnaround time for genotyping results ranged from 1 to 7 days. Additionally, patients holding a DNA medication pass expressed “great satisfaction” and according to researchers the pass gave patients sense of empowerment as they felt more engaged and actively involved in their personalized treatment.

The study had some limitations, such as relying on patient-reported adverse drug reactions and only enrolling patients with European, Mediterranean, or Middle Eastern ancestry. However, its practical design across multiple countries and diseases makes it a valuable contribution to the field and show that pharmacogenetic testing has the potential to significantly improve the safety and efficacy of drug treatment in patients. The PREPARE study was coordinated by Henk -Jan Guchelaar, who said, “For the first time we have proven that a tailored strategy works at a large scale within clinical practice. There is now enough evidence for us to proceed with implementation.”