In what may be another blow to diagnostic patents, the US Court of Appeals for the Federal Circuit affirmed the patent ineligibility of claims that it held to be directed to detecting natural phenomena by conventional techniques. CareDx, Inc. v. Natera, Inc., Case No. 2022-1027 (Fed. Cir. July 18, 2022) (Lourie, Bryson, Hughes, JJ.)

CareDx is the exclusive licensee of three Stanford University patents directed to diagnosing or predicting organ transplant status by using methods to detect a donor’s cell-free DNA (cfDNA). When an organ transplant is rejected, the recipient’s body destroys the donor cells, releasing cfDNA from the donated organ’s dying cells into the blood. Detecting the naturally increased levels of donor cfDNA (due to the deteriorating organ condition) can be used to diagnose the likelihood of an organ transplant rejection.

The representative claims were summarized as having 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”
4. “Determining” or “quantifying” the amount of donor cfDNA.

CareDx filed two lawsuits, one alleging that Natera’s kidney transplant rejection test infringed the patents, and another alleging that Eurofins Viracor’s various organ transplant rejection tests infringed one of the patents. Natera and Eurofins moved to dismiss the complaints for failing to state a claim because of a lack of patent-eligible subject matter under 35 U.S.C. § 101. The magistrate judge who reviewed the motions recommended that they be denied, finding that the claims were a “purportedly new, unconventional combination of steps” to detect natural phenomena. Although the recommendation was vacated with regard to Natera because the complaint was amended, the district court adopted the magistrate’s recommendation as to Eurofins with modified reasoning that the patent “specifications raise doubts about the patents’ validity” by suggesting that the steps were neither new nor unconventional. Still, the district court was wary of ruling prematurely and denied the motion so that the parties could conduct discovery to develop the record on what was considered conventional in the art.

Following expert discovery relating to § 101 eligibility, Natera and Eurofins moved for summary judgment on patent ineligibility. The district court denied summary judgment, citing a factual dispute as to the conventionality of the techniques for performing the claimed methods. Natera and Eurofins moved for certification of interlocutory appeals of the district court’s denial. After conferring with the parties, the district court agreed to reconsider its decision in view of case law raised in the certification motion. After reconsideration, the district court granted the summary judgment motions of ineligibility, finding that the asserted claims were directed to the detection of natural phenomena—specifically, the presence of donor cfDNA in a transplant recipient and the correlation between donor cfDNA and transplant rejection—and concluding that based on the specification’s many admissions, the claims recited only conventional techniques.

CareDx appealed, arguing [...]

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