The two recent high-profile US Supreme Court decisions on patent eligibility — Association for Molecular Pathology versus Myriad (see Nature Rev. Drug Discov. 12, 570–571; 2013) and Mayo versus Prometheus (see Nature Rev. Drug Discov. 11, 344; 2012) — changed the rules on what type of inventions were eligible for patent protection. Namely, the long-standing precedent that products that are isolated from natural sources could be patented was thrown out, and certain methods of determining optimal drug doses were also deemed to be patent eligible.

Credit: Jacques Jangoux/Alamy

In response to these changes, the US Patent and Trademark Office has now issued guidance to help patent examiners (and indeed patentees) determine whether applications are patent eligible.

The publication details several examples of hypothetical patent applications and whether they should be permissible. For instance, if a cancer-combating compound was isolated and purified from plant leaves, it would not be eligible because it would not be substantially different from the natural product that is present in the leaves. However, a derivative that was structurally and functionally different could be patent eligible, as could a method of using the isolated purified natural product to treat colon cancer.

Whether the new guidelines mean that a greater proportion of applications are rejected — and potentially appealed — remains to be seen. But it has been noted that several historically patented products, such as adrenaline and streptomycin, would fail to meet the new eligibility guidelines.

US Patent and Trademark Office guidelines: http://www.uspto.gov/patents/law/exam/myriad-mayo_qrs.pdf; http://www.uspto.gov/patents/law/exam/myriad-mayo_guidance.pdf

PATENT ADVISORS

Daniel M. Becker: Dechert, Mountain View, CA, USA.

Luke Kempton: Wragge & Co., London, UK.

Leslie Meyer-Leon: IP Legal Strategies, Boston, MA, USA.

George W. Schlich: Schlich & Co., London, UK.

John A. Tessensohn: Shusaku Yamamoto, Osaka, Japan.

Philip Webber: Dehns, London, UK.