Patenting diagnostic methods post-Myriad
Patents claiming diagnostic methods that use natural phenomena must recite more than conventional and existing detection steps to satisfy the US Supreme Court’s patent-eligibility standard set forth in Association for Molecular Pathology v Myriad Genetics, the Northern District of California held in Ariosa Diagnostics, Inc v Sequenom, Inc on October 30.
The decision, the first by a US trial court applying the Myriad decision, provides guidance to those seeking to patent diagnostic methods that correlate a natural phenomenon, such as a biomarker or chemical analyte, to the presence or absence of disease or to a treatment decision.
The court’s decision arose from a declaratory judgment action brought by plaintiff Ariosa. Ariosa asked the court to declare that its non-invasive prenatal test (the Harmony test) using cell-free foetal DNA circulating in the blood of pregnant women does not directly infringe or contribute to infringe US patent no. 6,258,540 (the ‘540 patent) exclusively licensed by defendant Sequenom.
In response, Sequenom filed a counterclaim for patent infringement and motion for preliminary injunction to stop the sale or use of the Harmony test. The district court denied the motion and Sequenom appealed. On appeal, the Federal Circuit vacated the district court’s denial and, among other issues, remanded the case with directions to examine subject matter eligibility of the asserted claims in the first instance in light of the Supreme Court’s Myriad decision.
The ‘540 patent
Sequenom is the exclusive licensee of the ‘540 patent. The claims are based on the discovery that cell-free foetal DNA (cffDNA) is detectable in maternal serum or plasma samples. The patent noted that using cffDNA allows for a better detection rate than using prior art nucleated blood cell DNA extracted from a comparable volume of whole blood. The three independent claims of the ‘540 patent recite:
1. A method for detecting a paternally inherited nucleic acid of foetal origin performed on a maternal serum or plasma sample from a pregnant female, which method comprises (i) amplifying a paternally inherited nucleic acid from the serum or plasma sample, and (ii) detecting the presence of a paternally inherited nucleic acid of foetal origin in the sample.
24. A method for detecting a paternally inherited nucleic acid on a maternal blood sample, which method comprises (i) removing all or substantially all nucleated and anucleated cell populations from the blood sample, (ii) amplifying a paternally inherited nucleic acid from the remaining fluid, and (iii) subjecting the amplified nucleic acid to a test for the paternally inherited foetal nucleic acid.
25. A method for performing a prenatal diagnosis on a maternal blood sample, which method comprises (i) obtaining a non-cellular fraction of the blood sample, (ii) amplifying a paternally inherited nucleic acid from the non-cellular fraction, and (iii) performing nucleic acid analysis on the amplified nucleic acid to detect paternally inherited foetal nucleic acid.
Questions of patent-eligibility
Ariosa argued that the patent claims were invalid because the cffDNA is a natural phenomenon and the ‘540 patent merely added well-understood, routine, conventional activity in the field to that natural phenomenon. Sequenom countered that the claimed methods were patentable because they are novel uses of a natural phenomenon, rather than a patent on the natural phenomenon itself. Sequenom noted that in addition, the claims are patentable because the claims do not preempt all uses of cffDNA.
“Claims to prenatal non-invasive screening methods were not patent-eligible because the claimed methods merely appended conventional steps, specified at a high level of generality, to patent-ineligible mental steps.”
The parties agreed that neither cffDNA nor the discovery of cffDNA in maternal plasma or serum is patentable because the presence of cffDNA in maternal plasma or serum is a natural phenomenon. However, the district court conceded that the patent claims are not drawn to the cffDNA itself; but rather a method for detecting the cffDNA. As such, the issue before the court was whether the steps of the claimed methods, applied to that natural phenomenon, are sufficient to render the claims patentable.
The district court determined that the additional steps were insufficient to render the claims patent-eligible. The court agreed with Ariosa that the additional limitations in the claims either apply well-understood, routine, and conventional activity to the natural phenomenon or limit the natural phenomenon to specific types of natural phenomenon which are also unpatentable.
The court also looked to the patent specification and testimony by Sequenom’s own expert, Dr Evans, who stated that the amplification and detection of DNA sequences in plasma or serum was well known prior to the filing date of the application that matured into the patent. The specification of the ‘540 patent also stated that the preparation of serum of plasma from the maternal blood sample is carried out by standard techniques.
The court stated: “Sequenom attempts to argue that its patent claims an inventive method of using cffDNA. But, based on the undisputed facts before the court, the only inventive part of the patent is that the conventional techniques of DNA detection known at the time of the invention are applied to paternally inherited cffDNA as opposed to other types of DNA. Thus, the only inventive concept contained in the patent is the discovery of cffDNA, which is not patentable.”
The court also addressed whether the claims of the ‘540 patent pose a risk of preempting a law of nature, natural phenomenon or abstract idea. The court dismissed Sequenom’s argument that because alternative methods of detecting cffDNA exist, the claims are not preemptive. The court determined that even though alternative methods existed, they were not commercially viable and the effect of the ‘540 patent in practice was preemptive.
The district court decision is not surprising in that it is consistent with the Federal Circuit’s non-precedential PerkinElmer, Inc v Intema Ltd decision in 2012. In Intema, the Federal Circuit applied the US Supreme Court’s earlier Mayo Collaborative Servs v Prometheus Labs, Inc ruling and held that claims to prenatal non-invasive screening methods were not patent-eligible because the claimed methods merely appended conventional steps, specified at a high level of generality, to patent-ineligible mental steps.
Conventional techniques are not enough
The Ariosa decision clearly set the discussion around the technology applied to practise a method that may include a natural phenomenon or law of nature. In the court’s view, application of conventional techniques to the use of a law of nature or natural phenomenon will not satisfy Myriad or Prometheus.
Thus, under Ariosa, use of techniques such as polymerase chain reaction (PCR) or immunohistochemistry will not rescue a claim which recites only a natural phenomenon or law of nature. However, modification of an existing technology in an unconventional manner, or the application of a new technology (such as a novel antibody or technique), would appear to be a move toward satisfying the new patent-eligibility standard and could distinguish this holding.
References are available on request to the author.
Antoinette Konski is a partner at Foley & Lardner LLP in Palo Alto. She can be contacted at: akonski@foley.com
