What impact will personalised medicine have on pharmacy?

Until just over 15 years ago, the medical and pharmaceutical communities took a standardised approach to drug therapy in that we treated all patients as if ‘one size fits all’. This approach was challenged in 2003 when Allen Roses, then worldwide president of genetics at GlaxoSmithKline (GSK) stated that, “the vast majority of drugs – more than 90% – only work in 30–50% of the people”. In other words, while we have effective drugs, they do not work in everyone.

Roses pointed out that a better understanding of pharmacogenetics would remove much of the uncertainty and variability in drug response and toxicity. This observation resonated with the increasingly wide use of the term “personalised medicine” and its aim to select “the right dose of the right drug for the right indication for the right patient at the right time”.

More recently, the US National Institutes of Health has defined the closely related term “precision medicine” as “an emerging approach for disease treatment and prevention that takes into account individual variability in genes, environment, and lifestyle for each person”. This concept is anticipated to allow healthcare professionals to predict more accurately which treatment and prevention strategies for a particular disease will work in which groups of people, and to identify those treatments that are most likely to produce toxicity in susceptible individuals (for example, severe skin reactions associated with carbamazepine or phenytoin treatment in individuals of Han Chinese or Thai origin possessing the human leucocyte antigen [HLA] B*1502 allele).

Another example relates to the enzyme thiopurine methyltransferase, which metabolises thiopurine drugs (azathioprine, mercaptopurine, tioguanine). The risk of myelosuppression (a condition in which bone marrow activity is decreased) is increased in patients with reduced activity of the enzyme, particularly for the few individuals in whom TPMT activity is undetectable. These latter individuals should therefore not receive azathioprine, mercaptopurine or tioguanine therapy.

Very recently, a blood test has been developed that accurately and reliably predicts whether depressed patients will respond to common antidepressants. It has been shown that individuals with two biomarkers (a naturally occurring molecule, gene, or characteristic by which a particular pathological or physiological process or disease can be identified), macrophage migration inhibitory factor (MIF) and interleukin IL-1β, above specified thresholds are unlikely to respond to conventional, commonly prescribed antidepressants. On the other hand, patients with levels of these biomarkers below the suggested threshold are expected to respond to first-line antidepressants^[1]
.

The impact of personalised medicine on pharmacists and other healthcare professionals is becoming increasingly important. These medicines are typically macromolecular biopharmaceuticals that require particular care in their handling, administration (usually by parenteral injection or infusion) and storage (often requiring refrigeration). The selection of patients and the appropriate dosing necessitates the intervention of a diagnostic test in many cases and parenteral administration always requires specialist care and observation. The complexity of the treatment also demands that the pharmacist has well-honed communication skills to explain clearly and confidently why a treatment may or may not be appropriate for a particular individual.

As a consequence, in addition to the provision of blood pressure checks and lifestyle advice, pharmacists in the NHS are playing an increasingly important role in health technology appraisal and medicines optimisation, helping to ensure that patients have timely access to clinically effective and cost-effective personalised medicine.

Hence, the RPS Pharmaceutical Sciences External Advisory Panel (PSEAP) emphasises the need to ensure that we have pharmacists with the right skills and educational background to match the advances in personalised/precision medicines: an objective underscored by the Association of the British Pharmaceutical Industry in a recent report that highlighted the fact that the UK life sciences industry faces a skills shortage in this regard
^[2]
. In response, the PSEAP has established a working group on personalised medicines, reflecting its determination to ensure that the pharmacist plays a central role in providing patients with “the right dose of the right drug for the right indication for the right patient at the right time and at the right price”.