Patenting Diagnostic Methods – Part 2Written By: Dr. Angela Keuling, Patent AgentIn Part 1 of this article, we looked at the Canadian approach to determining patent eligibility of diagnostic methods. In Part 2, we’ll consider the approach in the United States.U.S. Approach to Patent EligibilityIn 2012, the patent eligibility of diagnostic methods was addressed by the U.S. Supreme Court in Mayo Collaborative Services v. Prometheus Laboratories, Inc., 566 U.S. 66 (2012). The claimed method in this case involved steps for determining the level of a specific drug metabolite in the blood and using that level to indicate if the drug dosage should be increased or decreased. The court found that the method was directed to a natural law (i.e. the relationship between the metabolite and the efficacy and toxicity of the drug). In addition, the court found that the additional steps in the method were only routine and conventional activities and therefore were not enough to make the overall method patent eligible.Since the Mayo case, several other U.S. court cases have found diagnostic method claims to be invalid based on a similar patent eligibility analysis as used in Mayo. In addition, diagnostic method patent applications have frequently been rejected by the U.S. Patent Office for being directed to patent ineligible subject matter.However, more recently, U.S. courts have provided some potential paths forward for the patent eligibility of diagnostic methods. In Vanda Pharm. Inc. v. West-Ward Pharm. Int’l Ltd. 887 F.3d 1117 (Fed. Cir. 2018), a claimed method was found to be patent eligible that involved performing a genotyping assay on a biological sample taken from a patient and then administering a drug at certain dosages based on the patient’s genotype. In particular, it was the inclusion of a step for administering a drug that led the court to find that the claims were not merely directed to a natural law. The court concluded that a “novel method of treating a disease” is patent eligible subject matter as opposed to a diagnostic method as in the Mayo case.This conclusion is also reflected in the U.S. Patent Office’s 2019 Revised Patent Subject Matter Eligibility Guidance in which “a particular treatment or prophylaxis” is provided as an example of an additional element that can render a claim patent eligible even if it’s found to be directed to a natural law.In 2020, in Illumina, Inc. v. Ariosa Diagnostics, Inc., No. 2019-1419 (Fed. Cir. 2020), the court provided another potential strategy for patenting diagnostic methods. The method in this case involved preparing a particular DNA fraction from a blood or plasma sample and then analyzing the DNA for genetic alterations. The court found that the claimed method was not directed to a natural law or phenomenon as the method produced a DNA fraction that does not exist in nature. The court therefore appeared to create another “bucket” of patent eligible subject matter, namely methods for preparing biological samples. As stated in the decision: “This is not a diagnostic case. And it is not a method of treatment case. It is a method of preparation case.”Patenting Diagnostic Methods in the United StatesAs in Canada, patent eligibility issues remain a hurdle for obtaining patent protection on diagnostic methods in the United States. However, recent court decisions, along with revised subject matter eligibility guidelines provided by the U.S. Patent Office, present possible strategies for potentially obtaining patent eligible claims. A diagnostic method that can be claimed as a method of treatment (e.g. by including a step for administering a particular treatment) or a method of preparing samples (e.g. by including novel sample preparation steps) may potentially be patent eligible in the U.S.Thus, inventors of new diagnostic methods should consider their intellectual property strategy carefully and not rule out patent protection as a means to protect their invention in both Canada and the U.S. If you are interested in potentially patenting a diagnostic invention, our intellectual property team is happy to help you navigate this space.Disclaimer: This article is to be used for educational and non-commercial purposes only. Parlee McLaws LLP does not intend for this article to be a source of legal advice. Please seek the advice of a lawyer before choosing to act on any of the information contained in this article.