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CareDx, Stanford Sue Natera for Patent Infringement

This article has been updated with a statement from Natera.

NEW YORK (GenomeWeb) – CareDx and Stanford University today filed suit against Natera in the United States District Court for Delaware, claiming that Natera has infringed on US Patents 9,845,497 and 8,703,652, which are exclusively licensed to CareDx from Stanford University. 

The patents cover methods of cell-free DNA analysis for noninvasive monitoring of organ transplant rejection, which CareDx uses as the basis for its AlloSure organ transplant diagnostics. CareDx is asserting that Natera has infringed on that intellectual property through its marketing and performance of a kidney transplant rejection test, which it performs at its CLIA-certified laboratory in San Carlos, California, to analyze cell-free DNA from transplant patients to inform rejection.

According to the suit, in mid-2018, Natera began developing the kidney transplant test, which works by measuring the donor-derived cell-free DNA (dd-cfDNA) in the recipient's blood in order to gauge possible injury to the transplanted organ. Natera also claimed at the time that the assay would be using its core SNP-based massively multiplexed PCR technology to more accurately measure dd-cfDNA levels without the need for donor genotyping.

In December, the suit continues, Natera began a clinical trial titled, "Utility of a Novel Dd-cfDNA Test to Detect Injury in Renal Post-Transplant Patients," and published an article in the Journal of Clinical Medicine entitled, "Optimizing Detection of Kidney Transplant Injury by Assessment of Donor-Derived Cell-Free DNA Via Massively Multiplex PCR."

Finally, CareDx claims, this February, Natera announced a partnership to begin distributing the transplant test and to accelerate the company's entry into the transplant diagnostics market.

Based on Natera's claims, CareDx said it believes the firm has infringed the '497 patent through its performance of the kidney transplant rejection test.

"First, a plasma sample containing cell-free DNA (cfDNA) from a kidney transplant recipient (post-transplant) is genotyped to obtain a SNP profile," the suit noted. "This involves three steps: (i) cfDNA is extracted from the recipient's plasma sample, (ii) cfDNA is amplified via massively multiplex PCR (mmPCR), and (iii) the amplified SNPs are then subject to next-generation sequencing (NGS). Finally, the amount of donor-derived cfDNA (dd-cfDNA) in the post-transplant recipient's plasma is determined by detecting a homozygous or a heterozygous SNP within the donor-specific circulating cell-free nucleic acids."

According to CareDx, these steps are identical to the intellectual property protected under Claim 1 of the '497 patent. This is only one example of infringement of this patent, the company added.

Similarly, CareDx claims that Natera infringes the '652 patent through its activities connected to its performance of the kidney transplant rejection test, adding that the company's activities around genotyping transplant recipients specifically impinge on Claim 1 of that patent.

CareDx has levied two counts of infringement against Natera in its suit, and has asked the court to grant it a judgement either saying that infringement has occurred or that the '497 and '652 patents are valid. CareDx is also asking for damages or other monetary relief, court costs, attorneys' fees, and an order enjoining Natera from further infringement of the two patents.

"If intellectual property is disrespected, it is the transplant community that is impacted," CareDx CEO Peter Maag said in a statement. "The intellectual property behind AlloSure was developed with substantial involvement from leading transplant researchers. We are filing this suit to support future innovation in transplantation. We will continue to monitor activities in the transplant field and vigorously defend our intellectual property where appropriate to protect our substantial investments and leadership position."

For its part, Natera issued a statement today acknowledging the suit. The company said it is confident in its ability to prevail in court and doesn't anticipate that the case will interfere with its commercialization plans or operations in any way. 

"We are not surprised that CareDx would attempt to disrupt the imminent commercialization of Natera's innovative organ transplant rejection test, which does not require donor genotyping, and will compete with CareDx's older test," Natera added. "In recently published analytical and clinical validation studies, Natera's test demonstrated industry-leading performance."