The US Supreme Court has this month been considering whether it is legal for a company to hold a patent covering a biomarker test to determine the most appropriate levels of drug to use for treatment.
Prometheus Laboratories’ patent covers a method to determine the most effective dose of thiopurine drugs to treat gastrointestinal disorders, based on metabolite levels in patients’ blood. Both thiopurine drugs and tests to assess metabolite levels were already in existence, but the patents relate to the process for linking the drug dose and metabolite range.
Prometheus are claiming that a similar test from a Mayo Clinic company infringes their patent, whilst Mayo contests that the patent is invalid since the link between metabolite levels and drug action is based on a natural body process. The American Medical Association and others support the Mayo’s suit, arguing that the patent would interfere with normal medical practice by preventing doctors from assessing metabolite levels and adjusting drug dose in any manner.

Comment: The outcome of this case, expected in 2012, could have a major impact on companies developing products in the area of personalised medicine, such as genetic tests to identify individuals likely to need higher or lower doses of drugs.