Patent Rights and Cell-Free DNA cancer testing

by Dennis Crouch
I have been following the ongoing case of Natera v. NeoGenomics that is currently on appeal before the Federal Circuit. Docket No. 24-1324. The technology in these cases has amazing potential and I have several friends who have used these techniques to detect early stage cancer.
The particular litigation here centers on Natera’s US Patent No. 11,519,035 issued on December 6, 2022 that covers a method of detecting cancer through analysis of cell-free DNA (cfDNA) obtained from blood samples.  The basic idea is that small fragments of DNA that are released into the bloodstream by cells, including cancer cells. High throughput extraction and sequencing technologies can then be used to detect mutations and their potential associated risk factors, including the presence of cancer and the specific type of cancer. cfDNA cancer screening has lots of advantages, most notably, it is almost non-invasive (blood sample) and provides potential early across the entire body.  It can be particularly effective for detecting reemergence of cancer for someone in remission because the particular mutation is already known.  This is known as a “tumor-informed” test.

Natera’s ‘035 patent is directed to methods for amplifying and sequencing cell-free DNA (cfDNA) to detect cancer. The claimed invention involves three key steps: (1) tagging cfDNA with universal adaptors, (2) amplifying 25-2,000 single nucleotide polymorphism (SNP) loci in a single reaction volume, and (3) performing massively parallel sequencing.  Each of these steps were known in the prior art, but the combination of all three appears to be new. NeoGenomics is accused of infringing through its use of its RaDaR, an independently developed cancer-detection test that purportedly employs a similar process for analyzing cfDNA to provide highly sensitive detection of cancerous mutations. NeoGenomics disagrees, arguing the claims require the tagging and targeted amplification to occur in separate PCR reactions with different primer sets, and that its approach combines this process.
The district court case is still pending in the Middle District of North Carolina (23-CV-629), with the present appeal set-up by the district court’s issuance of a preliminary injunction barring NeoGenomics from utilizing its RaDaR test.
The District Court’s Preliminary Injunction Ruling
In its preliminary injunction order, the district court sided with Natera. It found that Natera “made a strong showing that the RaDaR test made and sold by NeoGenomics uses the method claimed in the ‘035 patent and infringes.” The result then is that NeoGenomics is barred from offering or marketing its product to new patients.  In its December 2023 order, the district court made an exception for existing patients and clinical studies already in process — those uses can continue.
In an ordinary case, an accused infringer can keep doing what it has been doing throughout a lawsuit, and is only required to change its behavior upon final judgment, and only if the court orders it to do so.  Some accused infringers try to take some voluntary steps immediately in order to avoid building up potential damages, but many do not.  A patentee who wants to stop ongoing infringement at the start of the case can petition for preliminary injunctive relief, a judicial equitable remedy that can prohibit the accused infringer from making and selling the allegedly infringing product or service before a trial on the merits.  The patent act does not particularly identify preliminary injunctions as an available remedy, but does state that courts “may grant injunctions in accordance with the principles of equity to prevent the violation of any right secured by patent, on such terms as the court deems reasonable.” 35 U.S.C. § 283.
Under the “principles of equity”, the Supreme Court has identified a general four-part test for preliminary relief. The test is substantially the same as the eBay test for permanent injunction with one key difference – the requirement of showing a likelihood of success on the merits. This is required since, unlike permanent injunctions, this is preliminary relief and a jury has not yet decided whether the patent is valid and infringed.  Thus, to obtain relief a patentee must demonstrate:

a likelihood of success on the merits,
irreparable harm in the absence of an injunction,
the balance of hardships favors the patentee, and
an injunction is in the public interest.

Abbott Labs. v. Sandoz, Inc. , 544 F.3d 1341 (Fed. Cir. 2008).  The likelihood of success factor requires the patentee to show “that it will likely prove infringement, and that it will likely withstand challenges, if any, to the validity of the patent.” Titan Tire Corp. v. Case New Holland, Inc. , 566 F.3d 1372 (Fed. Cir. 2009).  If the accused infringer raises a “substantial question” regarding validity or infringement, a preliminary injunction should not issue.  Importantly, the issuance of a preliminary injunction within the district court’s reasonable discretion, even if the patentee makes the required showing.  The decision to grant or deny a preliminary injunction is reviewed on appeal for abuse of discretion.
The District Court’s Reasoning: 
On validity, the court rejected NeoGenomics’ obviousness challenge, finding its prior art arguments “appear to show hindsight bias more than they support a substantial question of obviousness.” The court emphasized the “challenges associated with cfDNA” that made it “unlikely a person skilled in the art would have been motivated” to apply the prior art techniques with “anticipated success.” Turning to irreparable harm, the court stressed that Natera and NeoGenomics are “direct competitors” in the concentrated tumor-informed minimal residual disease (MRD) testing market. Without an injunction, Natera would likely lose “customers, profits, business relationships, and clinical opportunities,” amounting to irreparable harm.
Key Issues on Appeal
On appeal, the Federal Circuit has been asked to scrutinize the district court’s application of the preliminary injunction factors. The central issues include:
1. Claim Construction: Did the court err by not explicitly construing the tagging and amplification limitations? NeoGenomics contends the claims require separate PCR reactions for each step, while Natera maintains they only require the steps to occur sequentially.
2. Obviousness: Did the court demand too much for obviousness and improperly focus on unclaimed features? NeoGenomics argues Natera’s admissions in other cases show that using the claimed DNA processing steps on cfDNA was routine.  Although Natera’s product is successful, those results are not claimed — only the process in broad terms.  NeoGenomic argues that the lower court erred by focusing on these unclaimed results.
3. Irreparable Harm: Did Natera show a sufficient causal nexus between the alleged harm and infringement? NeoGenomics attacks the irreparable harm finding as based on unclaimed tumor-informed testing, not the specific claim limitations. This argument seems odd – it is essentially that the patent claims are so broad that there can be no irreparable harm associated with Neo’s narrow use.
4. Public Interest: Did the court properly balance the interests of cancer patients and researchers? NeoGenomics contends RaDaR’s unique attributes make it essential for certain clinical uses in a way Natera’s competing product (Signatera) cannot match.
In the case, the Federal Circuit appears to be moving quite quickly and I expect a quick decision from the panel – especially if the court overturns the injunction.
The panel here includes Chief Judge Moore and Judges  Taranto and Chen. Arguing counsel: Deanne Maynard for NeoGenomics Laboratories, Inc. and Jeffrey A. Lamken for Natera, Inc.
The district court case is ongoing with trial date set for March 2025.

PI Order
NateraNeoGen – Opening Brief
NateraNeoGen – Responsive Brief
NateraNeoGen – Reply Brief