Novelty and inventive step of enantiomer patents come under scrutiny of Italian courts.

Nebivolol is an active compound used for the treatment of hypertension and covered by claim 6 of EP 0 334 429. It consists of a mixture of the enantiomers l-Nebivolol (RSSS) and d-Nebivolol (SRRR).

The Court of Rome held that Nebivolol was not novel and not inventive over prior art, in particular Janssen Pharmaceutica's U.S. patent 4,654,362, which described a compound (compound no. 84) made of the racemic mixture RSSS + SRRR and RSRR + SRSS.

The cases are of particular interest since they are among the first cases decided by Italian courts on the validity of inventions which are based on the selection of a specific enantiomer or racemate from a known racemate or racemic mixture.

According to the Court of Rome, in these cases the principle of a selection invention, developed by the Italian Supreme Court, could be applied. In particular, the validity of a selection invention could be established if the identification of the specific compound - among the many others covered in the general formula - was non-obvious for the person skilled in the art. For this purpose, not only the process of selecting the specific compound should be considered but also possible unexpected properties thereof.

With regard to undisclosed properties of a known compound, the Court of Rome referred to the criteria developed by the Italian case law concerning the so called "translation inventions", i.e. an invention where a device, process or use already known in a particular technical field is applied in a totally different field.1 In particular, the court referred to an earlier precedent decision by the Supreme Court which had held that "there is no (valid) translation invention if there is neither a new function pursued by it, i.e. a further use in a field different from the field the original invention relates to, nor if the original invention covers any uses thereof but only those described or obvious in the light of the patent specification."

With regard to the case at issue, the Court of Rome held that "the discovery of the potentiating efficacy of the isomer l- Nebivolol on the efficacy of the blood pressure's reducing agent d-Nebivolol does not imply a patentable translation" and therefore a "new use" of the compound 84, which contains both of them.

The court further considered whether the Nebivolol racemates RSSS+SRRR actually lead to a potentiating effect (or an improvement) in respect of the racemic mixture of compound 84 or whether it contained merely a description of already known effects. It excluded the potentiating effect not already achieved by compound 84.

Finally, the Court of Rome found that the identification of the RSSS enantiomer as a potentiating agent could not be considered inventive. A person skilled in the art would need to undertake a "top-down" approach by first separating the racemates RSSS+SRRR from RSRR + SRSS of compound 84, which would have led to the discovery that Nebivolol (RSSS+SRRR) was the most active compound. As a further step, the skilled person would need to separate the enantiomers composing the racemate and would then obviously have concluded that the enantiomer RSSS plays the role of a potentiating agent as claimed by the patent at issue.