The United States District Court for the District of Delaware recently held that claims covering methods for evaluating organ transplant rejection are invalid under 35 U.S.C. § 101.

The patents at issue disclose methods to assess organ transplant rejection without the need for invasive biopsies. This is accomplished by detecting particular concentrations of donor cell-free DNA (cfDNA) in the blood of transplant recipients. The disclosed methods have four steps for detecting a donor’s cfDNA in a transplant recipient: “1. ‘obtaining’ or ‘providing’ a ‘sample’ from the recipient that contains cfDNA; 2. ‘genotyping’ the transplant donor and/or recipient to develop ‘polymorphism’ or ‘SNP’ ‘profiles’; 3. ‘sequencing’ the cfDNA from the sample using ‘multiplex’ or ‘high-throughput’ sequencing; or performing ‘digital PCR’; and 4. ‘determining’ or ‘quantifying’ the amount of donor cfDNA.”

In 2019, plaintiffs sued defendants for allegedly infringing the asserted patents by making and selling certain organ transplant tests. The defendants each filed a motion for summary judgment of invalidity of the asserted patents under § 101 and in December 2020 the court denied those motions. Later, the court sua sponte raised the § 101 validity issue under Fed. R. Civ. P. 56(f)(3). According to the court, it was uncontested that the claims were directed to detecting natural phenomena. The court determined, therefore, that the dispositive question under both steps of the Alice/Mayo framework for patent eligibility was whether the claimed methods used only standard/conventional detection techniques.

To answer this question, the court examined the specifications. Language in each specification stated that the “invention employs, unless otherwise indicated, conventional techniques . . . which are within the skill of the art.” (emphasis added). The court held that since the specifications never indicated “otherwise,” they conclusively established that standard/conventional detection methods were used. The court in reaching its decision rejected plaintiffs’ argument that, because this language “appears verbatim in myriad patents,” including patents not directed to DNA sequencing technology, it would be unfair to read this “widely repeated passage” as an admission that the claimed steps were conventional. In doing so, the court emphasized the fundamental principle that a “patentee is bound by the words it uses in its patent[.]” The court further explained that patent applicants often represent that techniques are conventional in order to meet § 112 requirements and, having done that here, plaintiffs “cannot now avoid the consequences that flow from its representation.”

The court rejected several other arguments by plaintiffs that these detection techniques were not conventional. Specifically, the plaintiffs pointed to disclosure in the patents as allegedly indicating that sequencing techniques used in the methods—including digital polymerase chain reaction (PCR) and “next generation sequencing”—were not conventional, routine or well-understood. The court found that plaintiffs’ alleged evidence “mischaracterized the written description” and that its assertions that these sequencing techniques are nonconventional was “simply false.” The court also determined that extrinsic evidence plaintiff relied on failed to establish that the detection techniques were nonconventional. According to the court, “[p]ermitting [plaintiffs] to now nullify with extrinsic evidence an unambiguous representation it made to the PTO to secure its patents and exclude competitors like Defendants from making or using the claimed invention would be fundamentally at odds with the basic principles underlying our patent system.” Having found no genuine disputes of material fact that the asserted patents claim patent-ineligible subject matter, the court entered summary judgment of invalidity for defendants.

Practice Tip: When considering whether to characterize any disclosed technique or method in a patent as “conventional” or “routine,” a patent applicant should carefully weigh any possible benefits of including such language (e.g., to meet § 112 requirements) against any potential risk that the statements could be used later in litigation to show that the claims are invalid under § 101.

CareDx, Inc. et al. v. Natera, Inc., No. CV 19-0567-CFC-CJB, 2021 WL 4439600 (D. Del. Sept. 28, 2021).