A recent district court opinion clarified when a claimed diagnostic method is patent subject matter eligible. Unfortunately, in this instance the patent owner Caredx failed to meet these requirements with its allegedly infringed patents. Instead, the court granted Natera’s motion for summary judgment of patent invalidity, because there were no claimed non-conventional steps for detecting a donor’s genetic material during an organ transplant rejection.
All three of Caredx’s disputed patents disclosed methods for detecting an organ transplant rejection and by which physicians could assess rejection through blood tests instead of invasive biopsies. Instead, there were four overall steps to these claimed methods:
- obtaining a sample containing the specifically required genetic material;
- obtaining the transplant donor’s genetic profile;
- sequencing this donor genetic material; and
- quantifying the amount of this donor’s genetic material.
Under Alice and Mayo diagnostic methods are not patent subject matter eligible if they merely claim detection of a natural phenomenon. Both Caredx and Natera agreed that the relationship between organ rejection and the donor’s specific type of genetic material was a naturally occurring phenomenon. Therefore, Caredx’s claims were patent subject matter eligible only with unconventional method steps.
Caredx’s patents explicitly disclosed that the claimed methods designated conventional
procedures. However, Caredx’s position in the litigation was that the claimed methods were not conventional, and thereby Caredx squarely contradicted its own patent disclosures. The court concluded the patent disclosures were dispositive, because they comprised binding admissions that the methods exclusively comprised conventional steps. The court also concluded that new and useful steps were absent because there were only claimed standard detection techniques.
Although it is tempting to exclusively claim conventional subject matter, this approach could backfire under a patent subject matter eligibility challenge. Instead, attorneys should foresee future validity challenges and draft the patent application accordingly, so the client need not rely upon patent language which does not squarely support its litigation position.
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 See 35 U.S.C. 101.
 Caredx, Inc. et al. v. Natera, Inc. et al., 2021 U.S. Dist. LEXIS (D. Del. September 28, 2021)[hereinafter Caredx].TheLeland Stanford Jr. University was also a plaintiff in the lawsuit.
 Alice Corp. Pty. v. CLS Bank International, 573 U.S. 208, 216 (2014) [ hereinafter Alice]; Mayo Collaborative Services v. Prometheus Laboratories, Inc., 566 U.S. 63, 79-80(2012) [hereinafter Mayo]. Under both decisions evaluation of patent subject matter eligibility comprises (i)Step 1: Whether the claim is directed to patent eligible subject matter; and if not (ii) Step 2: Is there a claim element which is sufficient to transform an unpatentable natural law, abstract idea or natural phenomenon into patentable applications thereof. In this instance the court concluded that the claimed diagnostic methods were directed to a natural phenomenon, i.e., the relationship between the donor DNA and organ rejection.
 According to the court, to support its litigation position Caredx misrepresented the patents’ content in numerous instances.
 Id. at 9.
 Id. at note 4 supra.