Seeds of Doubt: PTAB Rejects Plant Patent Challenge, Citing Genetic Uncertainty

by Dennis Crouch

In a recent post-grant review decision, the PTAB sided with the patentee and denied  institution of a PGR challenge to U.S. Patent No. 11,696,545 (“the ‘545 patent”), which claims an inbred maize variety designated PH4CYJ. Inari Agriculture, Inc. v. Pioneer Hi-Bred International, Inc., PGR2024-00023, Paper 15 (P.T.A.B. Oct. 15, 2024).  The case is interesting for several reasons — most notably because it upholds a utility patent covering a plant line developed through simple cross breeding.  In my post, I point to two deficiencies in the Board’s decision (1) its lack of reasoning for a determinative claim construction; and (2) its conclusion that a parent-line of maize  used in the cross breeding was not prior art because it was not publicly available at the time.

• Read the Decision: PGR2024-00023 DI – Final

Background: Pioneer’s utility patent claims a “seed, plant, plant part, or plant cell of inbred maize variety PH4CYJ, representative seed of the variety having been deposited under NCMA accession number 202212062.” The patent discloses that PH4CYJ was developed by what appears to be simple crossing of two parental inbred lines, followed by several generations of selection and self-pollination.

Inari challenged the claims on several grounds, including obviousness over various prior art references.  One problem though was that the prior art only taught one of the parental lines.  Importantly, the other parent line (“PH1VNA”) was not publicly available.

In its decision, the PTAB recognized that the prior art did provide close phenotypic similarity (observable characteristics), but recognized that the claimed invention encompasses both the phenotype and the genotype (genetic material) of the plant, as described by the exemplary seed deposit.  So, Inari’s failure to address the invention’s genotype was a significant weakness in its case.

The unavailability of the parent PH1VNA as prior art posed two main problems for Inari’s obviousness challenge:

1. Lack of complete starting material: Without access to both parent lines, a person of ordinary skill in the art would not have had all the necessary genetic material to arrive at the claimed line whose genome, the Board noted, “is derived from its parents.” Inari failed to explain how a PHOSITA could produce the claimed seed, including its unique genotype, without access to the parental line.
2. Unpredictability in breeding outcomes: Even if PH1VNA were known, the PTAB highlighted the inherent unpredictability in plant breeding. Every child is unique. The Board relied upon testimony that a plant breeder “would not expect that a cross of the same parents will produce the same child. The genome of a progeny plant is the result of the random recombination in the F1 plant of the two parental genomes and the chance of the exact same child resulting from that cross is infinitesimally small.”  In other words, Inari failed to show a reasonable expectation of success.

Not Available to the Public: One intriguing aspect of this decision is the PTAB’s leap in concluding that the parental line was not prior art.  The Board notes that the PH1VNA parent line was “not publicly available at the relevant time” and was a “proprietary inbred line.” While these statements suggest that PH1VNA was maintained secretly, we have to recognize that the courts have repeatedly recognized that secret information can still qualify as prior art — especially in the circumstances where the secrets are held by the patentee.

The ambiguity here lies in the possibility of some commercial use or secret sales of the parent PH1VNA by Pioneer. If PH1VNA was used in commercial hybrid seed production or was subject to confidential sales offers/agreements, these activities could trigger prior art status under § 102(a)(1), even if the line itself was not publicly disclosed. The PTAB’s decision does not address these nuances, leaving open questions about the true prior art status of PH1VNA.

Claim Construction: The second interesting element of this case for me is the PTAB’s construction of the claims as covering both genotype and phenotype. While the Board cited Enzo Biochem, Inc. v. Gen-Probe Inc., 323 F.3d 956 (Fed. Cir. 2002) to support its interpretation, that case is distinguishable as it involved claims explicitly directed to genetic characteristics. Here, the claims of Pioneer’s ‘545 patent are directed to a “seed, plant, plant part, or plant cell of inbred maize variety PH4CYJ,” with reference to a “representative” deposit of plant material. The PTAB did not delve deeply into whether this language necessarily incorporates genotypic limitations.

While a seed deposit can demonstrate possession of genetic material for written description purposes, it does not automatically follow that the genotype is claimed absent language to that effect. The term “representative” could be interpreted as referring solely to phenotypic characteristics, which are typically the focus of plant variety claims.

I recognize my criticisms here were directed at the Board, I have not reviewed the briefs filed by the parties and recognize that the Board is bound to decide the case based upon the issues presented.

Other Notable Aspects of the Decision

While the unavailable parental line issue was central to the PTAB’s obviousness analysis, the decision also addressed several other interesting points:

1. Utility under 35 U.S.C. § 101: The PTAB rejected Inari’s argument that the claimed invention lacked utility, finding that the ‘545 patent’s disclosure of various uses for maize grain and plant material was sufficient to satisfy the utility requirement.

2. Written description and enablement: The PTAB found that the combination of phenotypic information, breeding history, and the seed deposit was sufficient to satisfy both the written description and enablement requirements of 35 U.S.C. § 112(a).

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Scott McKeown (Wolf Greenfield) and his team of Oona Johnstone, Thomas Foley, and Zhiyun Ge represented the petitioner; Michael Kane, Katie Hyma, Dexter Whitley, Yong (Lucien) Wang, and Jonathan Singer (all from Fish & Richardson) for the patent owner.

The opinion was authored by APJ Jeffrey Abraham and joined by Ulrike Jenks, and Zhenyu Yang.