• Narendra Vaish

Patent Eligibility Of A Diagnostic Patent At the Federal Circuit

Since the Supreme Court decision, Mayo Collaborative Servs. v. Prometheus Labs, in 2012 that struck down method of treatment claims for being directed to a law of nature (the relationship between metabolite concentrations in blood and whether a particular dose will be effective or harmful), it has been challenging to obtain claims to diagnostic inventions in the U.S.A.


In March, the United States Court of Appeals for the Federal Circuit (CAFC) held Illumina’s patents (U.S. 9,580,751 and U.S. 9,738,931) for diagnosing Down’s Syndrome to be patent-eligible, reversing a lower court decision that the claims were ineligible under 35 U.S.C. § 101 as being directed to a natural phenomenon. In August, the Federal Circuit denied a petition for rehearing en banc and issued a modified opinion upholding the patents. An exemplary claim of the Illumina’s patents is:


1. A method for preparing a deoxyribonucleic acid (DNA) fraction from a pregnant human female useful for analyzing a genetic locus involved in a fetal chromosomal aberration, comprising:

(a) extracting DNA from a substantially cell-free sample of blood plasma or blood serum of a pregnant human female to obtain extracellular circulatory fetal and maternal DNA fragments;

(b) producing a fraction of the DNA extracted in (a) by:

(i) size discrimination of extracellular circulatory DNA fragments, and

(ii) selectively removing the DNA fragments greater than approximately 500 base pairs,

wherein the DNA fraction after (b) comprises a plurality of genetic loci of the extracellular circulatory fetal and maternal DNA; and

(c) analyzing a genetic locus in the fraction of DNA produced in (b).

The Court held that the claims were not directed to a natural phenomenon because the claims included “ physical process steps that changed the composition of the mixture” (i.e., increasing the relative amount of fetal DNA compared to maternal DNA). In contrast, the Court asserted that the contested claims in Ariosa Diagnostics, Inc. v. Sequenom, Inc. set forth detecting or observing a property of a previously-prepared sample.


The Court also distinguished this case from Association for Molecular Pathology v. Myriad Genetics, Inc. (“a naturally occurring DNA segment is a product of nature and not patent eligible merely because it has been isolated”), and concluded that, in this case, separated DNA is not claimed but rather a method to unconventionally separate DNA.

The Court decision in the current case gives way forward for patenting diagnostic claims. For example, a novel method of diagnosis, a novel manufacturing process for diagnostic kits and devices, an improvement of a prior method, and a novel diagnostic target such as a gene expression profile or a biomarker may provide ways to patent a diagnostic method. Structuring a diagnostic claim as a therapeutics claim (i.e., a method of treatment claim) may also help in patenting a diagnostic invention.


Further readings:

https://www.ipwatchdog.com/2020/08/04/en-banc-rehearing-denied-illumina-patents-again-upheld-on-rehearing/id=123811/

https://www.ipwatchdog.com/2020/08/13/rethinking-way-patent-diagnostics/id=124063/

https://www.lexology.com/r.ashx?l=94BX8VA


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