October 9, 2018

Primers and the Use of Naturally Occurring Position-Specific Signature Nucleotides are Patent Ineligible

By Bryan K. Wheelock, Principal

In Roche Molecular Systems, Inc., v. Cepheid, [2017-1690] (October 9, 2018), the Federal Circuit affirmed summary judgment of invalidity of claims of U.S. Patent No. 5,643,723 as directed to patent ineligible subject matter.

The ’723 patent is directed to methods for detecting the pathogenic bacterium Mycobacterium tuberculosis (MTB). The ’723 patent provides two types of claims: (1) composition-of-matter claims for the primers used in the polymerase chain reaction (PCR), which could hybridize to the rpoB gene of MTB at a site that includes at least one of the eleven signature nucleotides (“the primer claims”); and (2) process claims for methods for detecting MTB that include amplifying target sequences by PCR and detecting amplification products, which, if present, indicate the presence of MTB (“the method claims”).

As to the primer claims, the Federal Circuit held that In Re BRCA1 foreclosed Roche’s arguments for patentability. There, the Federal Circuit examined the subject matter eligibility of similar primer claims and held that those primers were not distinguishable from the isolated DNA found patent ineligible in Myriad, and thus are not patent-eligible. Primers necessarily contain the identical sequence of the nucleotide sequence directly opposite to the DNA strand to which they are designed to bind. The subject matter eligibility inquiry of primer claims hinges on comparing a claimed primer to its corresponding DNA segment on the chromosome — not the whole chromosome.

As to the method claims, the Federal Circuit said that the claims disclose a diagnostic test based on the observation that the presence of the eleven position-specific signature nucleotides of the naturally occurring MTB rpoB gene indicates the presence of MTB in a biological sample. The method claims are directed to a relationship between the eleven naturally occurring position-specific signature nucleotides and the presence of MTB in a sample.

In other words, the method claims assert that if an investigator detects a signature nucleotide from a sample, she knows the sample contains MTB. This relationship between the signature nucleotides and MTB is a phenomenon that exists in nature apart from any human action, meaning the method claims are directed to a natural phenomenon, which itself is ineligible for patenting.