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Federal Circuit Affirms PTAB Decision Regarding DNA Sampling Patent
01/22/2025On January 6, 2025, the United States Court of Appeals for the Federal Circuit (“CAFC”) affirmed the decision of the Patent Trial and Appeal Board (“PTAB”) rejecting a challenge to U.S. Patent No. 7,332,277 (“the ‘277 patent”) by Laboratory Corporation of America Holdings (“Labcorp”). The CAFC held that the PTAB correctly found that Labcorp failed to demonstrate that a person of ordinary skill in the art would have been motivated to combine the prior art references at issue. Lab’y Corp. of America Holdings v. Ravgen, Inc., No. 2023-1342, 2023-1345 (Fed. Cir. Jan. 6, 2025).
Ravgen, Inc. (“Ravgen”) owns U.S. Patent 7,332,277 (“the ’277 patent”), which is directed to “non-invasive methods for sampling DNA and detection of genetic disorders in a fetus.” In 2022, Ravgen sued Labcorp in federal court for infringing the ‘277 patent and was awarded $272.5 million by the jury. Subsequently, Labcorp challenged certain claims of the ’277 patent as obvious under 35 U.S.C. § 103 in two inter partes review petitions, arguing that a person of ordinary skill in the art would have been motivated to combine the maternal blood processing method disclosed in a 2001 Clinical Chemistry article (“Chiu”) with the formaldehyde compounds disclosed in U.S. Patent 5,648,220 (“Bianchi”) or in International Patent Application Publication WO 03/018757 (“Rao”). The PTAB disagreed, finding that the prior art in fact showed that a person of ordinary skill in the art likely would have been dissuaded from the combination.
On appeal, Labcorp argued that the PTAB’s motivation to combine analysis was flawed because it (i) required a heightened and untenable standard for proving a motivation to combine, (ii) did not adhere to precedents that require reading each reference in its entirety, and (iii) engaged in post hoc claim construction to read additional limitations into the claims.
With respect to the first argument, Labcorp asserted, inter alia, that the PTAB’s focus on “a miniscule amount of maternal DNA” leakage as opposed to the benefits of cell stabilization disclosed in Bianchi was erroneous because it demanded the most desirable combination. The CAFC disagreed, noting that the PTAB evaluated the disclosures of Bianchi and found that a person of ordinary skill in the art “would have been dissuaded from adding Bianchi’s paraformaldehyde [to the cffDNA detection method of Chiu] because the [person of ordinary skill in the art] would have expected Bianchi’s paraformaldehyde to create gaps in the cell membranes, providing a means for maternal DNA to escape into the sample.” Further, the PTAB recognized that Bianchi preferably retains 99% or more of the DNA in the cell but found that a person of ordinary skill in the art would recognize that releasing 1% of cellular DNA in a sample in Chiu would result in “a negative effect on Chiu’s fetal cell-free DNA analyses.” The CAFC held that these findings were factual—not legal—and therefore did not require an improperly heightened standard for obviousness.
Second, Labcorp argued that the PTAB legally erred by failing to consider the entirety of Bianchi and Rao’s teachings. With respect to Bianchi, Labcorp argued that the PTAB ignored the teaching that 99% or more of the DNA should remain in the cells. With respect to Rao, Labcorp argued that the PTAB ignored the teaching that paraformaldehyde is “frequently used for fixing and stabilizing tumor cells in blood” despite its shortcomings and that handling those concerns would be “readily apparent to one skilled in cell biology.” The CAFC disagreed, emphasizing the PTAB’s acknowledgement of the teachings in the final written decisions. Further, the CAFC noted that, even if the PTAB’s consideration of the teachings were unclear, CAFC precedent has indicated, “numerous times, failure to explicitly discuss every fleeting reference or minor argument does not alone establish that the Board did not consider it.”
Third, Labcorp asserted that the PTAB engaged in improper post hoc claim construction by, inter alia, “read[ing] into the claims additional limitations prohibiting DNA damage and requiring a certain degree of cell stabilization.” The CAFC disagreed, emphasizing that (i) neither party identified terms in need of construction during IPR proceedings, (ii) the PTAB did not deem it necessary to expressly construe any terms, and (iii) there was no indication that the PTAB engaged in implicit claim construction at any time. Instead of requiring a certain degree of cell stabilization, the PTAB properly relied on the claims’ recitation of a method for “determining the sequence of a locus of interest on free fetal DNA isolated from a sample” as it assessed the motivation to combine inquiry on cffDNA-related issues.
Labcorp also argued that the PTAB’s factual findings were unsupported by substantial evidence, but the CAFC disagreed, finding that the [PTAB] “thoroughly considered the references and expert testimony provided by both parties” and that “Labcorp [] failed to identify any factual finding … that was not reasonably supported by substantial evidence.”