Patentability of intermediate chemical compounds – is it time for a change?

A 2011 decision of the Court of Turin addressed the controversial issue of the patentability of so-called "intermediate chemical products". The decision followed the general approach taken by the Italian courts to prevent the patentability of such intermediates. It is hoped that the appeals court will reverse the Turin court's decision, thereby aligning Italy with many other jurisdictions throughout the world.

Technical background
Most chemical reactions take place in a series of steps in order to produce the desired product. An “intermediate” refers to the reaction product formed by each step up to the last one, which forms the final product. In short, an intermediate is used in a chemical reaction process in order to prepare another product which ultimately leads to the end product. In addition, an intermediate may be isolated from the reaction medium through separation techniques such as extraction or precipitation.

Additives, solvents and catalysts, although involved in the chemical process, are excluded from this definition, since they do not undergo structural changes connected with the formation of the desired compound.

Pharmaceutically active ingredients are often obtained via the step process and typically result in a number of intermediates. In many cases a particular intermediate may be obtained only when a specific route is taken, so that such intermediate is a truly characterising feature of the process. In other cases, however, a specific intermediate structure is the pivotal point through which several processes - whether to obtain the intermediate or to make the intermediate react to provide an end product - must necessarily pass. In such case, it is evident that the intermediate product is of particular importance.

As a consequence, in addition to pursuing patent protection for the new chemical process, obtaining protection for intermediate compounds may be of particular relevance. Successfully patenting an important intermediate prevents third parties from performing any process leading to its preparation or from using it to prepare a desired compound.

Legal background
The patent law of some countries (eg, the United States and Germany) contains specific provisions permitting the protection of intermediates, at least in certain circumstances. European Patent Office decisions accord with this view.

In contrast, the Italian courts have usually denied patent protection to intermediates. In a 1990 milestone decision (11094/1990) the Court of Cassation argued that conceptually, an intermediate could not be separated from the process as it represents a mandatory step through the synthesis. Thus, it was unable to satisfy any needs beyond the process. Accordingly, it could not be patented separately and even if it was disclosed and claimed as such, it enjoyed protection only by process claims (the so-called “relative protection approach”).

Notwithstanding this precedent, in 1993 the Milan Court of Appeal issued a judgment supporting the patentability of an intermediate (16th November 1993). However, a subsequent decision of the Court of Cassation (8324/1997) confirmed the earlier 1990 approach.

More recent legal developments
A more recent decision of the Court of Turin (14th January 2011) continued the trend to deny patent protection to intermediate products.

The decision was rendered in a case between Industriale Chimica Srl and Bayer Schering Pharma Aktiengesellschaft concerning the alleged partial invalidity of an Italian patent deriving from the validation of European Patent EP0918791 owned by Bayer and its infringement by Industriale Chimica.

European Patent EP0918791 relates to a process for the preparation of the active pharmaceutical ingredient drospirenon (DRSP), which is a known steroid. The synthesis of DRSP includes a first step of reducing a precursor (ZK34506) which results in the compound ZK92836. This is followed by an oxidising step to provide the compound ZK90965.

With respect to the prior art, the above-described process is easier, avoids the use of toxic chromium salts and results in a final product with a lower impurity content.

The description of the invention stated explicitly that the invention related both to the process for preparing DRSP and to the intermediate ZK90965. Thus, both were objects of the invention.

Claim 1 recited the process for preparing DRSP through the reduction of ZK34506 to ZK92836 and the subsequent oxidation step up to ZK90695. Claim 2 recited the intermediate ZK90965 itself. Other claims related, among other things, to process claims for obtaining DRSP and product-by-process claims for DRSP.

With respect to the infringement issue, Bayer asserted that Industriale Chimica had infringed Claim 2 by performing a process which involved the preparation of ZK90965 in stable form.

Consistent with the precedent set by the Court of Cassation, the Turin court, although recognising the novelty of ZK90695, found that it had no independent use outside the patented process and therefore was not patentable. As a consequence, the court did not need to address the question of infringement.

This decision is under appeal, and it is hoped that the decision will be reversed so that the Italian courts will begin applying the same standards for the patentability of intermediates as are used by the European Patent Office and many other countries.

This is an Insight article, written by a selected partner as part of IAM's co-published content. Read more on Insight

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