USA: Showing of lack of written description requirement (Amgen v. Sanofi – CAFC)

Wide claims must be supported by a representative number of examples. The person skilled in the art should be able to carry out the invention on the priority date. Evidence to prove whether or not the person skilled in the art was able to carry out the invention in view of the state of the art must lie before the priority date. A court of first instance in the US had rejected post-priority evidence as a matter of principle. The Court of appeals ruled more differentiated.

Amgen began studying PCSK9 inhibitors in 2005 to develop a new treatment for elevated cholesterol levels. On January 9, 2008, Amgen filed a patent application for a monoclonal antibody and received two patents in 2014. The corresponding drug Repatha ™ was launched in 2015.

The patent very broadly claimed a monoclonal antibody which on the one hand binds to a larger number of specifically mentioned residues and on the other hand blocks the binding of PCSK9 to LDL-R.

The patent specification describes a trial-and-error process which Amgen has used to generate certain antibodies and then test them for their function (screening). According to the patent specification, screening 3000 human monoclonal antibodies for the desired function using this method, resulted in 85 functioning specimens. For two of these variants, the antibodies have been described on the basis of their three-dimensional structure. One of these two antibodies is used in the drug Repatha ™.

Sonofi / Regeneron started developing their drug Praluent ™ in September 2007. They also used the mechanism to prevent PCSK9 from binding and destroying LDL-R proteins. They applied for a patent for their specific solution, which was granted in November 2011. The claim is specifically directed to the active ingredient used in Praluent and defines its amino acid sequence.

In 2014, Amgen filed suit against Sanofi / Regeneron for patent infringement. Although Sanofi acknowledged that Praluent ™ fell under Amgen's claim, it attacked Amgen’s patent for insufficient disclosure and for obviousness. In order to prove insufficient disclosure, Sanofi proffered documents from his own research, which had been carried out after the priority date of the Amgen Patent.

The District Court did not admit the post-priority evidence. Such evidence would not document the state of the art at the time of priority and is therefore not relevant to the assessment of sufficient disclosure. The court held the patent valid and affirmed the infringement.

Sanofi appealed to the Court of Appeals for the Federal Circuit (CAFC). The CAFC remands the first-instance judgment and orders that the trial of the first instance be re-opened in order to examine Sanofi's evidence.

The CAFC reasoned his decision as follows:

The requirement of sufficient disclosure is meant to ensure that the inventor actually possessed the invention he claims. The ownership becomes apparent by disclosing “a representative number of species falling within the scope of the genus or structural features common to the members of the genus so that one of skill in the art can ‘visualize or recognize’ the members of the genus"-

In the present dispute, the central issue is whether or not to use evidence and understanding developed after the priority date in order to assess whether or not a "representative number of embodiments" is disclosed.

The CAFC confirms that the sufficient disclosure is to be judged on the basis of the prior art at the time of priority.

However, it is also true that the "representative examples" of the claimed genus can probably only be assessed on the basis of evidence produced after the priority date. If the non-disclosed examples belong to the state of the art, the genre could not be claimed because of a lack of novelty.

The CAFC addresses two earlier decisions.

In the earlier judgment in AbbVie v. Janssen the written description requirement was insufficient for the functional claim because the functional claim covered an embodiment that was significantly different from the examples in the patent in suit. (This alternative embodiment was just the embodiment used by the alleged infringer.) In the judgment at that time, it was only clear that the infringement was after AbbVie's invention date. Whether the infringement occurred before or after the priority date of the patent application was not discussed.

The earlier decision in re Hogan referred to the question of whether to allow post-priority evidence to prove the state of the art after the priority date. This had rightly been denied. However, the ruling did not address the issue now under discussion as to whether to use post-priority evidence to assess the "representative number of examples".

The previous case law therefore does not preclude the consideration of post-priority evidence to determine the "representative number". Therefore, the judgment of the District Court should be set aside and the case remanded to the first instance for reassessment.

Note: Attempts are often made to extend the scope protection far beyond the actual invented embodiments by formulating broad functional claims. However, this can lead to the claim being invalid in the event of a dispute. Therefore, in formulating the patent application, it should be noted that the claim is supported by a reasonable number of different embodiments in the description.