What is the best time to file a patent?
Katherine Wright, pharmaceutical patent attorney, comments on the risks of filing a patent application too early as recently highlighted in Regeneron v Kymab & Novo Nordisk.
Determining the best time to file a patent application is one of the first and sometimes one of the most difficult questions that patent applicants face, and its importance should not be overlooked.
Two criteria which a patent application must meet are novelty (the invention is not made public before the application is filed) and sufficiency (the application would enable a person skilled in the technical field to practise the invention). When filing a patent application, a balance must be found between filing earlier, when adequate data to ensure sufficiency may not be available, and filing later, when more data is available but there is a greater risk that a third party will have got there first.
The risks of filing a patent application too early have recently been highlighted in Regeneron v Kymab & Novo Nordisk  EWCA Civ 671.
Regeneron’s European patents EP1360287 and EP2264163 relate to transgenic mice that produce partially humanised monoclonal antibodies. Monoclonal antibodies are widely used for the treatment of an extensive range of diseases, including cancer and autoimmune diseases. Regeneron developed a method for developing humanised antibodies using transgenic mice in which parts of the mouse genes are replaced with the equivalent parts of the human genes. This technology became the basis for Regeneron’s commercially successful VelocImmune technology.
During an attempt to enforce their patents against an alleged infringement by Kymab and Novo Nordisk, it became clear from expert evidence that the method of carrying out the invention taught in Regeneron’s patents would not work as described. This might have occurred because the method had not been confirmed by experiment before the patent application was filed, for example. The High Court found that Regeneron’s patents did not enable the invention to be put into practice and found the patents invalid for lack of sufficiency.
Regeneron appealed, arguing that the patents were sufficient as the described method could be used if several adjustments were made, and these adjustments would have been common general knowledge for a person working in this field at the filing date of Regeneron’s patents. The Court of Appeal agreed, and decided that a skilled team would have found it obvious and technically feasible to modify the described method as indicated. The Court therefore found Regeneron’s patents sufficient.
Regeneron were fortunate in that the deficiencies in their described method could be rectified using knowledge commonly available at the filing date, but this is likely to be a rare circumstance for technical processes that have not been confirmed by experiment before a patent application was filed.
While it is certainly desirable to file a patent application as early as possible, it is nevertheless advisable to delay filing until you are in a position to describe a specific method for putting the invention into effect that you know works, together with evidential data to support a claimed chemical or biological effect, if appropriate.