Personalised medicine patents disputed at US Supreme Court

A patent for a diagnostic test is currently under consideration by the US Supreme Court. The eventual decision may have profound implications for the burgeoning personalised medicine industry which often relies on DNA tests to guide physicians in choosing tailored therapies for patients.

In the current case, the Mayo Clinic, based in Minnesota, is challenging a patent held by Swiss-based, Nestlé-owned Prometheus Laboratories in an intellectual property spat that has been going on for seven years. The test under consideration helps doctors determine the optimum individual dosage of the drug thiopurine, used to treat autoimmune illnesses, such as Crohn's disease and lupus. After the patient has been given thiopurine, a blood sample is taken to measure the number of metabolites, and the results compared against predetermined ranges — the doctor can then decide whether to alter the dose of the drug.

The Mayo Clinic previously used Prometheus' test but developed their own allegedly more accurate test in 2004 and Prometheus Laboratories sued the Mayo Clinic for breaching their patent protection. However, a federal court judge ruled that the original Prometheus patent was invalid, on grounds that it was based on a natural phenomenon and mental processes, neither of which is patentable. The decision was overturned by the US Court of Appeals, leading the Mayo Clinic to the present appeal to the Supreme Court.

The legal issue is, in the words of Justice Stephen Breyer of the Supreme Court: 'What has to be added to a law of nature to make it a patentable process?' And by extension, has Prometheus Laboratories successfully done that?

Fellow Supreme Court Justice Elena Kagan thinks not: 'This is not a treatment protocol, it's not a treatment regimen… All you have done is pointed out a set of facts that exist in the world [...] and are claiming protection for something that anybody can try to make use of in any way, and you are saying, "You have to pay us"'.

Representing Prometheus Laboratories, Mr Richard Bress, said: 'The idea that we are not novel because people took some of the same steps along the way to invention that we actually succeeded in is wrong'. Furthermore, argued Bress, 'the court has never suggested that there is an extra-statutory limitation that prevents patents on developing useful information, even if they have a mental step at the end'.

The Obama administration openly supports Mayo Clinic's position. Solicitor General Donald Verrilli stated: 'You can't get a patent by tacking a mental step onto an utterly conventional process for administering drugs and testing their effects'.

This case is about more than the determining the boundaries of the legal test for a medical patent, and ascertaining whether those conditions have been met by Prometheus. There are broader concerns around the impact on innovation in personalised medicine and the possible creation of market and knowledge monopolies. Mr Stephen Shapiro, representing Mayo Clinic, argued that Prometheus' patent was so wide as to prevent a patient seeking a 'second opinion…[using] a better metabolite test with more accurate numbers' from the Mayo Clinic.

The case was heard by a full Supreme Court, who will deliver their ruling next year.