For readers unfamiliar with interference proceedings, the following is a (very) brief explanation of their functioning. In the US, until the entry into force, on 16 March 2013, of the first-to-file provisions contained in the America Invents Act, patent protection was granted under a first-to-invent system. An interference proceeding allowed the USPTO (and still does, for patent applications filed before 16 March 2013) to establish the priority of invention, if two parties each had a patentable claim to the same invention, to the effect that a patent application interfered with another patent application or an unexpired patent, respectively published or granted no more than one year before. According to 35 USC 135(a):
Whenever an application is made for a patent which, in the opinion of the Director, would interfere with any pending application, or with any unexpired patent, an interference may be declared and the Director shall give notice of such declaration to the applicants, or applicant and patentee, as the case may be. The Board of Patent Appeals and Interferences shall determine questions of priority of the inventions and may determine questions of patentability.In order to establish priority, the interference contest focused on two aspects of the act of invention, namely conception and reduction to practice (see Chapter 2300 of the USPTO's Manual of Patent Examining Procedure). The former concerned 'the formation, in the mind of the inventor, of a definite and permanent idea of the complete and operative invention' (Hybritech Inc. v Monoclonal Antibodies Inc.). The latter referred to the verification of that idea, the described and enabled anticipation of the subject matter of the count (which was 'the Board’s description of the interfering subject matter that sets the scope of admissible proofs on priority'). Reduction to practice could be actual (e.g. showing that the claimed invention worked as intended) or constructive (occurring on the filing of the patent). The proceedings were adjudged by the USPTO Board of Patent Appeals and Interferences, with appeals heard by either the US Court of Appeals for the Federal Circuit, or the District Court for the District of Columbia (according to 35 USC 146).
The Federal Circuit upheld the Board's decision, dismissing Sanofi's appeal, which maintained that knowledge of the full and correct nucleotide sequence was necessary to establish conception and reduction to practice. The court provided an interesting review of case law on the matter. According to the judges, Amgen Inc. v Chugai Pharmaceutical Co. had already established that, when a gene has been isolated and the inventor has knowledge of other characteristics sufficient to distinguish it from other genes, conception and reduction to practice can be established even if the inventor does not know its detailed constitution. Subsequent case law, as explained by the Board, did not change this perspective:
The Board distinguished Fiers v. Revel and Amgen as holding that conception and reduction to practice did not occur until the gene was isolated, for in those cases neither structure nor definitive properties had been established for the isolated gene. Burroughs Wellcome Co. v Barr Laboratories Inc. did not change these requirements, in holding that conception requires that the claimed DNA is possessed as a physical embodiment. Knowledge of the specific nucleotide sequence was not required in Burroughs Wellcome.
The decision noted that, in Enzo Biochem Inc. v Gen-Probe Inc., the court had upheld claims for DNA probes, even if the nucleotide sequence had not been determined. Similarly, in In re Wallach, it had clarified that the inventor can be said to be in possession of a protein, if he described a partial amino acid sequence in addition to other characteristics sufficient to identify the protein. In light of this case law, as the Board had already highlighted, knowledge of a complete sequence is not the only way to identify a composition precisely: to establish conception, it is sufficient that the party provides a description capable of distinguishing the composition from other materials, and of defining how to obtain it.
Accordingly, the court concluded that:
[T]he Board correctly based conception and reduction to practice on the possession of the isolated DNA segment that was shown to have the desired properties. When the subject matter is a DNA segment, conception requires possession and appreciation of the DNA segment that is claimed. [Invitrogen Corp. v Clontech Labs Inc.] [...] The Board found that Pfizer had successfully searched for and isolated the IL-13bc DNA segment, and possessed and appreciated the IL-13bc DNA before the Sanofi benefit date. [...] On these findings, the Board held that Pfizer had conceived and reduced to practice the isolated polynucleotide of Count 3 before the Sanofi benefit date. We conclude that the Board applied the correct law.