Sufficiency is a general requirement of UK patent law and under the European Patent Convention that requires the patentee to show that a notional skilled person can make the patented product using the disclosure in the patent in conjunction with the common general knowledge available at the time of the priority date.
Where a patentee claims patent protection for a range of products, sufficiency requires that it be possible for a skilled person to make the full range of products for which the claim is made. However, this requirement applies only to a “relevant” range. A range is “relevant” if the variable creating the range affects the utility of the product for achieving its intended purpose.
The scope of this relevant range was recently considered by the UK Supreme Court. Regeneron had alleged infringement of its patents directed generally to transgenic mice suitable for developing antibodies for human medical use. However, humans tend to reject mouse antibodies, and implanting human antibody genes into mice compromises their immune systems, limiting the usefulness of the mice in antibody development. The idea underlying Regeneron’s patents offered a solution to these two problems. Regeneron’s patents contemplated the development of a hybrid gene structure consisting of both human and mouse elements termed the human variable region and murine constant region, respectively.
In defending the infringement action, Kymab challenged the validity of the patents, arguing that the patents were invalid for lack of sufficiency.
The trial court and Court of Appeal acknowledged that the patents extended to a range of products in the form of transgenic mice implanted with different amounts of human gene segments in the human variable region of the hybrid gene structure. The court held that this range was “relevant” for the purposes of the sufficiency principle as the higher the amount of human gene segments in the human variable region within the hybrid gene structure, the greater the quality and diversity of antibodies the mouse is able to produce for eventual use in treating human diseases.
However, at the priority date, the disclosure of the patents, in conjunction with the common general knowledge, did not enable the creation of transgenic mice containing more than a very small amount of human gene segments in the human variable region of the hybrid gene structure. As of the priority date, it was impossible, without taking further inventive steps, to create transgenic mice at the more valuable end of the product range. The ability to create such a mouse is, as of today, possible but dependent on further inventions developed years after Regeneron’s priority date.
At trial, the court held that infringement had been proved, but Regeneron’s claims were invalid for lack of sufficiency.
The Court of Appeal came to a different conclusion. While acknowledging that the disclosure in Regeneron’s patents would enable creation of only some, but not all, of the claimed products, the Court of Appeal held that Regeneron’s patents were valid, and that its invention consisted of a new, generally applicable principle. In the Court of Appeal’s view, such a principle contributes to the public by its use in products that can be made immediately, and also in products that are only capable of being made in the future. The Court of Appeal reasoned that, in being granted a monopoly limited only to products that can be made immediately, a patentee would get a raw deal by receiving no reward for the public benefit derived from the invention’s use in future products.
In a 4-1 decision, the UKSC, citing Exxon/Fuel Oils and Unilever/Detergents, overturned the Court of Appeal’s decision. The UKSC held that the disclosure, coupled with the common general knowledge available at the priority date, must enable the creation of substantially all products within the scope of the product claim:
 What matters is that it is settled law, in relation to a product claim, that sufficiency requires substantially the whole of the range of products within the scope of the claim to be enabled to be made by means of the disclosure in the patent, and this both reflects and applies the principle that the contribution to the art is to be measured by the products which can thereby be made as at the priority date, not by the contribution which the invention may make to the value and utility of products, the ability to make which, if at all, lies in the future.
Since the two Regeneron patents, in conjunction with the common general knowledge, did not enable a skilled person to create transgenic mice with a hybrid gene structure containing more than a small amount of human gene segments in the human variable region, Regeneron’s claimed monopoly exceeded the contribution made to the art at the priority date.
Lord Briggs held that Regeneron’s patents failed for insufficiency and allowed Kymab’s appeal.
The decision can be found here.