Challenges

Personalised medicine will require the development of targeted medicines. By definition, these are likely to be used by fewer patients than ‘blockbuster’ medicines for common conditions. As medicine development costs are extremely high, there has been concern about whether the pharmaceutical industry can make the development of targeted medicines profitable.

However, it is being seen that one advantage of developing targeted medicines is an increase in the efficiency of clinical trials. For example, fewer new medicines should fail at each stage of the development process if they are targeted at a known cause of the disease. As explained earlier in this topic, the use of biomarkers is key to this work, and this is also explained in detail in the EUPATI biomarkers topic .

Technical and Regulatory Challenges

Using biomarkers can be a complex approach in medicines development, but is key to personalised medicine. In some cases, new reliable ways to collect and manage large amounts of data are needed. New techniques to make sure specific biomarkers are suitable (‘ validation’) also have to be in place before medicines developed in this way can be authorised.

The specific field of pharmacogenetics or pharmacogenomics is the study of how one type of biomarker (genetic or genomic information) affects patients’ responses to treatment. The challenges for these developments are discussed later in the Pharmacogenetics / pharmacogenomics topic.

Companion Diagnostics

More and more often, new medicines, particularly for cancer, are authorised together with an accompanying diagnostic test. The use of these tests ensures that the medicine is appropriate for the patient being treated - therefore personalising the use of the medicine. If a diagnostic test performance is poor, varies or is not properly checked (validated), the medicine may be given inappropriately. This could, for example, cause an adverse reaction, or be ineffective for that patient, or both. Therefore, proper design and validation of the diagnostic test is essential to get the best outcome from the medicine and for the patient.

• Show who is likely to respond to the medicine (‘responders’ and ‘non-responders’).
• identify patients at high risk for adverse reactions.
• Help the doctor to select an appropriate dose - that is both safe and effective.

Companion diagnostics may include tests directly on the patient such as electrocardiography (ECG) or diagnostic imaging such as MRI. Tests carried out on samples taken from a patient (such as DNA tests) are generally considered to provide the most valid evidence by Regulatory Authorities. 

Companion diagnostics should have an ‘intended use’ or ‘indications for use’. They are often both referred to under the umbrella term of 'intended use' (of a treatment). They should generally include the following elements:

• What is measured, identified or detected (such as a specific gene or protein).
• What kind of measurement the test makes (including whether the test is quantitative (it looks at numbers), or semi‑quantitative and qualitative (it looks at observations and descriptions).
• The sample type and where it is from (e.g. whole blood,  CSF (cerebrospinal fluid)).
• The setting in which the diagnostic device is meant to be used (whether it will be done in a laboratory or at ‘point-of-care’, i.e. near the patient).
• Exactly what type of equipment is required to perform the test.
• The target condition (a particular disease, disease stage, health status, or any other identifiable condition or event, or an observation that should prompt clinical action such as the initiation (starting), modification (changing) or termination (ending) of treatment).
• Why the measurement is being done - the ‘clinical purpose’ (such as to help with diagnosis, assess how the disease is likely to develop (prognosis) and monitoring).
• The target population for whom the test is intended (such as individuals with particular genotypes (genetic make-up) or phenotypes (characteristics)).

Ethical Challenges