The Court of Appeals for the Federal Circuit ruled last Friday that medical diagnostic tests are patentable. In the past, the law in this field was a bit unclear, because such tests were sometimes viewed as abstract ideas or natural phenomena, which are not patentable. However, the court here in Prometheus Laboratories Inc. v. Mayo Collaborative Services (on remand by the Supreme Court) noted that a method claim involving a diagnostic test may be patented if it is an application of an abstract idea or natural phenomenon, and if it is tied to a specific machine or transforms an article into a different state or thing.

Prometheus obtained patents containing method claims for finding the most effective dosages of thiopurine drugs to treat particular stomach diseases. These tests consist of administering a particular thiopurine drug to a patient, and then determining the levels of the drug’s metabolites in the blood. These measurements then indicate whether the drug dosage should be increased or decreased.

The Mayo Clinic planned to use a similar diagnostic test that would infringe upon Prometheus’ patents. However, Mayo asserted that it had the right to use the tests because Prometheus’ patents were invalid for claiming natural phenomena. Mayo said that the correlation between chemical levels in the blood and the most effective dosage of a drug is a naturally occurring relationship, and thus should not be patentable.

The court held that even though natural phenomena cannot be patented, applications of such phenomena may be patentable. Prometheus’ method claims were found to consist of a proper application of natural correlations between levels of metabolites in the blood and drug efficacy. Furthermore, the court noted that the claims did not encompass only the correlations, but also specific steps to treat a disease by administering drugs to a patient and then assessing metabolite levels in the blood.

The court also noted that the machine-or-transformation test could be used here to further prove that Prometheus’ claims were valid. In the recent Bilski ruling, this test was found to be a useful tool in determining the patentability of method claims (although it is not the only test that can be used). According to the machine-or-transformation test, if the claim is tied to a specific machine, or transforms something into a different state or thing, it may be patentable. The court found that the human body is necessarily transformed when the drugs of Prometheus’ patent claims are administered to patients, thus the claims pass the test.

This ruling should have an interesting effect in the biotech industry, which conducts and produces various types of medical diagnostic tests. Now, more of these tests may be found patentable, which could change the way some companies go about their diagnostic test research and business. For example, this ruling could prove favorable to entities like Myriad Genetics Inc. Myriad is currently appealing a decision made earlier this year that invalidated patent claims for methods of looking at specific DNA sequences to determine whether a woman has an increased risk of developing breast cancer. If Myriad can show that its method claims pass the machine-or-transformation test and consist of applications of natural phenomena, it could win its case on appeal. However, this could all depend on what exactly the court decides is an “application” of a natural phenomenon, and how broadly the Prometheus ruling will be construed.

Furthermore, it’s a definite possibility that Mayo may appeal this holding, and that the case could go to the Supreme Court. This could be an opportunity for the Supreme Court to narrow and clarify its tenets regarding method patents after Bilski, or to distinguish the business method patents discussed in Bilski from medical and biological method patents that are more likely to affect the biotech industry.

Jane Kim, SLS ’12, CLB Student Fellow