December 2011
Amending chemical patent applications at the European Patent Office
Introduction
An applicant may not amend a European patent application or patent to include subject matter that was not in the original application. However, whether an amendment adds new subject matter is a subjective test.
A recent decision (T783/09) of the European Patent Office (EPO) Technical Boards of Appeal (TBA) addresses amendments to patent applications and patents for chemical inventions.
Background
To assess if an amendment adds subject matter to the original application, the EPO decides if a skilled person would derive the proposed amendment “directly and unambiguously” from the original text.
In chemistry cases, compounds are often described by a generic structural formula, such as:
It is usually possible to shorten the lists for X and Y, as long as each list still contains more than one option. This is because the amendment still covers a group of compounds, just a smaller group than originally disclosed.
However, reducing the lists to a single option in each can add subject matter to the application, if the combination of options was not set out in the original application. Such an amendment singles out a specific compound, that was previously undisclosed. For example, if X is reduced to just H and Y to just Cl, the amendment will add subject matter if the specific combination of H and Cl was not explicitly disclosed in the original application.
The decision addressed the question of whether these rules also apply to patent applications for combination medicines, comprising “Drug A” and “Drug B”. Can the lists be shortened without adding subject matter?
The decision
The decision looked at a patent in which claim 1 was amended to combination of a compound called LAF237 with a second compound from a list of pioglitazone, rosiglitazone or troglitazone. The original application disclosed LAF237 in combination with 22 compounds, including all the three compounds of pioglitazone, rosiglitazone or troglitazone.
The first question that the TBA addressed was whether the skilled person could derive, directly and unambiguously from the original application, the combinations of LAF237 with just the three other compounds.
All of the 22 compounds were described as being “very preferred”. The TBA was satisfied that the original application disclosed the three claimed combinations from final claim 1 as part of a list of 22 disclosed combinations.
However, the TBA also had to decide whether the original application also taught only the three claimed combinations from the list of “very preferred” 22 combinations, or whether their selection added subject matter.
The TBA concluded that the application taught all 22 combinations as being of equal value –“very preferred embodiments”. The choice of the three combinations in amended claim 1 did not “single out” any specific subject matter that was not originally taught. Instead the amendment reduced the originally–disclosed group to a smaller group, which EPO practice allows.
The TBA decided that the amendment was acceptable.
The effect of the decision
The decision provides clear guidance for applicants having to amend chemical claims by choose only some possibilities from two lists.
Where an original application lists options, and the applicant wants to reduce the number of options in the list, this should be possible if the original application is clear that those options have equal value.
We are of the opinion that this decision may also be applied to patent applications for chemical compounds. In the example given above if X is amended to be just H, this new decision would allow the applicant to amend Y to be Cl or Br, but not F or I, assuming that the original application taught that all four were of equal value.