Federal Circuit Elaborates on Obviousness Standard Under 35 U.S.C. § 103
In the United States, one of the reasons a patent claim may not be obvious over various prior art references is if one of those references “teaches away” from the modification or combination needed to arrive at the claim. The standard for what constitutes “teaching away” was addressed in a recent decision of the U.S. Court of Appeals for the Federal Circuit[1] in an appeal from an inter partes review (IPR), which is a post-grant proceeding conducted by the Patent Trial and Appeal Board (PTAB) of the United Stated Patent and Trademark Office.
In the Ravgen IPR, petitioner Labcorp challenged validity of a Ravgen patent and asserted that a combination of prior art references would render the challenged patent obvious. As there was no explicit statement in any of the references that the combination could or should not be made, Labcorp posited that the combination of art could be considered. Labcorp’s assertion rested, however, on an older more restrictive standard for the sort of prior art disclosure that sufficiently “teaches away” from a proposed combination of references. In the final written decision in the Ravgen IPR, the PTAB applied a more recently articulated standard of “teaching away” when it determined that the claims of Ravgen’s patent had not been shown by Labcorp to be obvious over the prior art.
As explained by the Federal Circuit in its 2017 Arctic Cat decision,[2] even if the prior art does not explicitly “teach away” from making a particular modification or combination of prior art, evidence that a person of ordinary skill in the art may be “dissuaded” from doing so may be sufficient to negate obviousness of the proposed modification or combination. In Arctic Cat, patent challenger Bombardier argued that certain patent claims would have been obvious by combining a thrust steering system from one of Bombardier's jet boats with an existing personal watercraft (PWC). While there were SAE safety reports identifying Bombardier’s jet boat steering system as a potential solution to PWC steering problems, generally, those same safety reports raised significant safety concerns about implementing the combination. The Federal Circuit explained that even though the evidence did not explicitly “teach away,” the concerns raised were substantial enough to dissuade a person of ordinary skill in the art from combining the two prior art disclosures in the way posited by Bombardier. The 2017 Arctic Cat decision made it easier in some situations for patent owners to defeat validity challenges based on obviousness.
Ravgen’s patent relates to non-invasive fetal DNA testing methods that use cell lysis inhibitors to analyze cell-free fetal DNA and detect genetic disorders in a fetus. The patent provides a list of formaldehyde compounds as potential agents, including formaldehyde, formaldehyde derivatives, and formalin. The claims require a sample containing free fetal DNA and an agent that inhibits the lysis of cells, which may be, in some embodiments, one of these potential agents as the cell lysis inhibitor.
Labcorp filed IPR petitions to challenge Ravgen’s patent. Labcorp argued that the claims in question are obvious under 35 U.S.C. § 103 over a combination of prior art references, including Chiu, Bianchi, and Rao, asserting that a person skilled in the art would have been motivated to combine the references to arrive at the claimed invention. More particularly, one of the asserted references disclosed one or more of the claim cell lysis inhibitors, and another disclosed a method similar to that recited in Ravgen’s patent.
The PTAB reviewed the petitions and concluded that Labcorp failed to show a motivation to combine Chiu, Bianchi, and Rao. Specifically, Bianchi discloses uses of paraformaldehyde as an agent which causes gaps in the membrane of cell and leads to a leakage of the maternal DNA. Additionally, formaldehyde is well known to cause damage to nucleic acids, such as cffDNA. After weighing competing expert testimony, the PTAB determined that a person skilled in the art would not be motivated to use paraformaldehyde and formaldehyde disclosed in one prior art reference in a method disclosed in another reference relied on by Labcorp.
Labcorp appealed the PTAB’s final written decision, arguing that the PTAB required an unattainable standard for providing a motivation to combine the references, namely, that the combination must be perfect rather than simply desirable. Labcorp further argued that a combination resulting in both advantages and disadvantages does not necessarily lead to motivation against making the combination, i.e., teaching away from the asserted combination. The Federal Circuit disagreed with Labcorp and concluded that a person skilled in the art would have been discouraged to combine the use of paraformaldehyde disclosed by Bianchi and the method for detecting cffDNA disclosed by Chiu. Specifically, since Chiu discloses cell leakage, and cell leakage of maternal DNA is -- according to Labcorp’s own expert -- “something you do not want to happen,” there was sufficient “teaching away” from the proposed combination.
Labcorp also asserted in the appeal that the PTAB failed to consider the prior art references for everything that they teach. Specifically, Labcorp argued that the PTAB ignored prior art disclosures that small amounts of maternal DNA leakage do occur and that paraformaldehyde is “frequently used for fixing and stabilizing tumor cells in blood.” According to Labcorp, despite the shortcomings of paraformaldehyde, it is still frequently used to stabilize tumor cells in blood and a person skilled in the art would have been readily aware of those concerns. The PTAB explicitly acknowledged both teachings but, on the entire record, was still not persuaded.
Key Takeaways
Labcorp argued on appeal to the Federal Circuit that the PTAB’s focus on possible DNA leakage ignored the fact that simultaneous advantages and disadvantages do not necessarily eliminate a motivation to combine references, that is, they do not necessarily teach away from the asserted combination of references. The PTAB responded, however, that a POSITA would have been dissuaded from using paraformaldehyde disclosed in the prior art in another prior art method to arrive at the claimed invention of Ravgen’s patent, as use of paraformaldehyde may result in gaps in the cell membranes, thus providing a means for maternal DNA to escape into the sample. Labcorp’s own expert conceded that maternal DNA leakage was undesirable. The PTAB indicated that rising to the level of explicitly “teaching away” was not necessary in this case because, consistent with Arctic Cat, dissuasion from making the modification was sufficient.
Thus, it is important to remember that mere dissuasion may be enough to overcome a proposed combination or modification of prior art references raised in an obviousness challenge.
Explained slightly differently, a prima facie case of obviousness may be rebutted by showing that the art, in any material respect, teaches away from the claimed invention. Typically, the evidence utilized in a “teaching away” argument is an explicit statement in the prior art indicating that adding a feature from a second prior art reference to a first prior art reference would undermine or disparage that which is disclosed in the first prior art reference. According to the validity challenge or claim rejection, this demonstrates that the prior art cannot be combined as proposed to achieve the claimed invention.
However, in the Ravgen decision, as found by the PTAB and affirmed by the Federal Circuit, evidence demonstrating mere dissuasion from making a specific combination, as opposed to an explicit statement, was sufficient to establish that the prior art cannot be combined to achieve the claimed invention, as had been proposed by Labcorp. This decision is consistent with Arctic Cat.
