Secondary patents in chemistry and pharmaceutics

Secondary patents, as opposed to original or primary patents, are commonly understood as patents protecting not a novel chemical entity, but a polymorph, salt, derivative, pharmaceutical composition or a specific medical use thereof, among other things. In this context, ‘secondary’ does not mean ‘worse’ or ‘not meeting patentability conditions’, but only that the corresponding patent application was filed later than the ‘primary’ patent application and improves on it in some respect.

Secondary patents play a significant role in pharmaceutics. Considering that costs associated with bringing a novel drug to the market tend to be exceptionally high, innovators try to obtain protection for investments made at the later stages of the R&D pipeline or aimed at improvement and further development of existing drugs.

On the other hand, secondary patents in chemistry and pharmaceutics are sometimes associated with the issue of evergreen patents. ‘Evergreening’ is commonly understood as an extension of patent monopoly on an existing product by filing an additional patent application claiming a technical solution based on inherent properties or obvious modifications of the product. This practice is often perceived as unscrupulous and makes it difficult for generic manufacturers to enter the market with a generic drug after the original patent has expired.

Professionals around the world continually debate the questions of reasonable scope of protection for secondary patents and patentability standards that should be applied to such patents. In various jurisdictions, different approaches to secondary patents have been proposed, with some countries placing additional requirements on secondary patent applications and others rejecting them outright.

For a long time, Russian practice in the secondary patent field was mainly regulated by general patentability rules with no specific provisions targeting such types of subject matter as, for example, novel forms of known chemical compounds or compositions. However, this situation has changed considerably in recent years, as amendments were made to the Russian Patent Rules and Requirements (Rules for drafting, filing and examination of documents serving as the grounds for preforming legally significant actions on the state registration of patents for inventions, and the forms thereof, and requirements for documents contained in applications for the grant of a patent for invention as approved by the Order of the Ministry of Economic Development No 316, 25 May 2016) to specifically address issues closely linked to the question of secondary patents.

Novel compositions of known compounds

First, the Russian government addressed the problem of secondary composition claims that are construed by explicitly reciting some novel (ie, previously unknown and not necessarily inherent) measured property of a composition, special effective dosage and administration mode, among other things.

According to the Order of the Ministry of Economic Development No 527, 1 October 2018, the Patent Requirements were amended to state the following:

it is not allowed to characterise a composition by features reflecting information having no direct connection to said composition (for example, the conditions and modes for using the composition in a process/method), a quantitative (measured or calculated) parameter characterising one or more properties of the composition, where said parameter is used as a distinctive feature of the composition characterised in an independent claim (for example, parameters of lamination strength, stress cracking resistance, pharmacokinetic profile, and the like), the technical result exhibited during the manufacture or use of the composition. When characterising a pharmaceutical composition, it is not allowed to use features related to a method of treating or preventing a disease (for example, an indication to dosages, conditions or modes of administering the composition or a drug based thereon).

According to the same order, the Patent Rules were amended to explicitly recite that the above features should not be taken into account by examiners when analysing novelty and inventive step of a claimed composition.

This amendment effectively provided examiners with a robust and predictable tool for rejecting claims aimed at compositions distinguished by features other than actual ingredients and their amounts, such as a measured property, composition dosage, administration mode or any type of previously unknown technical effect exhibited by the composition.

In general, to avoid a formal rejection based on the new rule, patentability of a claim aimed at a novel composition should rely on a novel combination of ingredients or novel amounts thereof, with the selection of such ingredients and amounts allowing achievement of an unexpected technical effect.

Novel forms and derivatives of known compounds

Once the new rules on claims aimed at compositions of known compounds were established, the matter of secondary patents claiming novel forms of previously known compounds remained on the table.

On 31 March 2021, the question of novel forms and derivatives of previously known compounds was addressed in the Order of the Ministry of Economic Development No 155 (in force from 8 June 2021). According to Order 155, the Patent Rules added a specific rule stating that the invention does not involve an inventive step when it is based:

on the creation of a chemical compound, which is a form of a known chemical compound (in particular, an isomer, stereoisomer, enantiomer, amorphous or crystalline form) or a derivative thereof (in particular, a salt, solvate, hydrate, complex compound, an ether/ester), if such compound does not exhibit novel properties in qualitative or quantitative terms in comparison with the known compound that are non-obvious to a skilled person based on the prior art.

In addition, according to Order 155, the Patent Requirements were added with a requirement to submit reliable evidence on the novel non-obvious properties of the claimed form or derivative, when the claimed invention relates to a novel form or derivative of a known compound.

In contrast with the clear (although, limiting) wording of the rule about inadmissible features of compositions, the newly introduced rule about novel forms or derivatives of previously known compounds may seem somewhat confusing as it is not exactly clear in what manner and to what extent the new rule modifies the general inventive step requirement, according to which every invention must exhibit some non-obvious technical result (effect) to be patentable.

While the new practice is yet to be established in view of Order 155, judging by the language of the new rule, public comments by representatives of Rospatent, and the fact that the new rule is evidently construed as an additional limitation, the non-obviousness bar may be set higher for novel forms or derivatives of the previously known compounds. In particular, taking hints from the latest official actions issued by Rospatent examiners, it is possible that examiners may start declaring that ‘usual’ technical effects (eg, increased stability of a polymorph, increased efficacy of one isomer or enantiomer in comparison with another, and advantageous pharmacokinetics of salts or hydrates) are properties that are obvious to a skilled person based on the prior art and, therefore, insufficient for acknowledging inventive step.

It remains to be seen whether it will become harder to argue inventive step of novel forms or derivatives of the previously known compounds in view of the new rules; however, there is a chance that additional effort may be required to show non-obviousness of novel forms or derivatives of known compounds.

Eurasian practice

Since there are two parallel patent systems in Russia (national and regional), it is always necessary to keep in mind that legislation and practice of the Russian and Eurasian patent offices may be different in such subtle matters as secondary patents.

For example, the Eurasian Patent Rules contain a provision very similar to the one included in the Russian Patent Rules in 2018:

It is not permissible to characterise a composition by features reflecting information having no direct connection to said composition (for example, the conditions and modes for using the composition in a process/method), a quantitative (measured or calculated) parameter characterising one or more properties of the composition, where said parameter is used as the only feature characterising the composition in an independent claim (for example, parameters of lamination strength, stress cracking resistance, pharmacokinetic profile, and the like), the technical result exhibited during carrying out or using the composition. When characterising a pharmaceutical composition, it is not allowed to use features related to a method of treating or preventing a disease (for example, an indication to dosages, conditions or modes of administering the composition or a drug based thereon).

However, despite the superficial similarity, the Eurasian Patent Rules do not allow for the use of quantitative parameters characterising properties of the composition in the claims only when such parameters are “used as the only feature characterising the composition in an independent claim”. Obviously, this requirement is significantly less strict than the approach used in the Russian Patent Rules.

Moreover, the Eurasian Patent Rules contain no special limitations on patentability of novel forms or derivatives of previously known compounds (eg, isomers, crystalline forms, salts and solvates), therefore, patentability of such novel forms or derivatives is analysed by examiners of the Eurasian Patent Office based on the general inventive-step principles.

Practical implications – amendments to the Russian Patent Rules

It is easy to see that the latest amendments to the Russian Patent Rules are aimed at making it more difficult to obtain secondary patents, particularly in chemistry and pharmaceutics. In recent years, specific provisions were added to the Russian Patent Rules and Requirements dealing with common types of secondary invention, such as compositions, polymorphs, isomers, enantiomers, salts, hydrates and solvates.

Additional care should be taken to avoid possible objections and obtain a solid patent that can withstand third-party attacks.

Compositions

When dealing with compositions characterised by any features other than ingredients and their amounts, it may be advisable to include in the Russian application a claim aimed at ‘use’ subject matter. The rule forbidding usage of quantitative parameters, technical results, features related to a specific mode of using the composition only applies to the ‘composition’ type of subject matter and does not apply to the ‘use’ type of subject matter.

At the same time, according to Article 1358 of the Civil Code, the use of a product type of subject matter protects not only the claimed use per se, but also the product, provided that it is intended for the claimed use.

For example, while the claim “composition for treating disease A, the composition comprising components X, Y, and Z and having a pharmacokinetics characterised by distinguishing feature M” will be rejected by Rospatent based on the Patent Rules as amended, the claim “use of a composition comprising components X, Y, and Z and having a pharmacokinetics characterised by distinguishing feature M for treating disease A” may not only be found patentable, but may actually protect the composition as defined in the claim, provided that the composition is intended for the claimed use.

In addition, when choosing a jurisdiction for filing or entering the national stage, the Eurasian Patent Office should be considered, as the Eurasian Patent Rules allow the use of quantitative parameters characterising properties of the composition as features in the claims, provided that the quantitative parameter is not the only feature characterising the composition.

Forms and derivatives of known compounds

When dealing with inventions based on novel forms and derivatives of known compounds, it may be reasonable to provide as much data on the unexpected technical result (effect) of the invention as possible. It may be advantageous to provide comparative data showing that alternative forms and derivatives do not allow the technical result to be achieved. When dealing with inventive step objections, it may be helpful to submit a detailed explanation as to why a skilled person could not be sure that the technical problem could actually be solved by the invention with the achievement of the technical result.

It is yet to be seen whether Rospatent will apply the new rules to novel forms and derivatives of known compounds per se or to all inventions involving such forms and derivatives. It may turn out that the statement “the invention is based on the creation of a chemical compound, which is a form of a known chemical compound or a derivative thereof” in the Patent Rules as amended applies to corresponding compositions, methods and uses as well. On the other hand, the statement introduced in the Patent Requirements (“when the invention relates to a novel form/derivative of a known compound”) implies that the new rules apply only the forms and derivatives claimed as chemical compounds, and other types of subject matter (eg, compositions) do not fall under the new requirements. If the latter is the case, a possible way to argue non-obviousness of novel forms or derivatives of known compounds may be to add the application with a claim aimed at a composition comprising such a form or derivative.

Once again, it is important to carefully choose the jurisdiction when filing or entering the national stage, as the Eurasian Patent Rules contain no special limitations on the patentability of novel forms and derivatives of previously known compounds.