3 March 2023
by Dr Michael Ford MIMMM

Substance, composition or medical device?

Dr Michael Ford MIMMM at Haseltine Lake Kempner reviews legal challenges surrounding materials-related biomedical inventions.

© National Cancer Institute / unsplash

Patents in Europe (including the UK) cannot protect surgical or therapeutic methods for treating, or diagnostic methods carried out on, human or animal bodies. Such methods are excluded from protection to maintain the freedom of doctors and vets in treating their patients. However, this restriction does not apply to products known as 'substances or compositions' for use in such methods.

There are also differences in the way novelty is assessed for medical inventions as compared to other technologies. For most purposes, an invention is new if it is different from everything that has already been disclosed publicly in any way, anywhere in the world. A patent claim to a known 'substance or composition', however, can be rendered novel in Europe by specifying its use in a method of medical treatment or diagnosis, as long as that medical use is not known.

For example, a public disclosure of the structure of compound X and its use as an additive in an engine oil would not prevent X being patented for use as a medicament generally, nor would it prevent further patenting of X for use more specifically in the treatment of dementia or pain.

The meaning of the terms 'substance' and 'composition' is therefore an important question in European case law for determining the patentability of medical inventions.

The principal driving force for legal exceptions for 'substances' and 'compositions' is to provide protection for pharmaceuticals, and it is reasonably clear that these carve-outs are not intended to cover medical devices. For example, according to an early decision of the European Patent Office (EPO), a 'substance or composition' should relate to an 'active ingredient' of a medicinal product with pharmaceutical, physiological or immunological effects.

Distinguishing between an active ingredient (e.g. an antibiotic drug) or a device (e.g. a pacemaker) is easy in many situations. However, the line can become blurred where the product is a device with chemically or biologically active components, or where the innovation lies in a materials aspect of the product. Different approaches to this problem have arisen in the EPO case law.

For instance, EPO Board of Appeal case T 2003/08 concerned an immunoapheresis column for removing immunoglobulin from a patient’s plasma to treat dilated cardiomyopathy. The column contained a specific ligand for human immunoglobulin.

The Board had to decide whether the invention made use of a substance or composition and considered the key issue to be whether the means of achieving the therapeutic effect constituted a 'chemical entity'. The Board determined that the specific ligand, rather than the column per se, was the therapeutic means in this case. This was undisputedly a chemical entity and thus also a substance within the meaning of the law.

In contrast, in case T 0773/10, the Board found that the use of a known polymeric membrane for a new treatment of multiple myeloma by dialysis lacked novelty because the membrane was not a 'substance or composition' – it lacked an active ingredient or chemical entity comparable to the ligand. Two more recent cases concern injectable materials that form 3D structures in the body.

In T 1758/15, the material was a biocompatible, biodegradable filler (such as collagen or hyaluronic acid) for injection between body tissues to form a radiation shield. In T 2136/15, it was a self-gelling alginate for injection into a heart ventricle to treat cardiomyopathy. Both cases turned on whether these materials were substances or compositions – in both cases, the Boards of Appeal decided in the negative.

In T 1758/15, the therapeutic effect was achieved by an accumulated mass of filler material mechanically displacing radiation-sensitive tissue from target tissue. The nature of the material used only had an indirect influence on the characteristics of the resulting structure. In T 2136/15, physical structures, formed by injecting alginate in specific patterns, cinched a baggy globe-shaped ventricle into a more effective conical shape. In each case, the 3D macrostructures formed did not qualify as chemical entities and the injectable materials were characterised as initially viscous devices rather than substances or compositions.

A different approach, however, was taken in T 0264/17, which concerned a synthetic lubricant containing a known perfluoropolyether for use as a synovial fluid replacement in diseased joints. The lubricant was inert in the sense that it was not pharmacologically, metabolically or immunologically active. Nevertheless, the Board determined that the mode of operation was different from the inert injectable materials of T 1758/15 and T 2136/15. The perfluoropolyethers were liquids with no fixed form before or after introduction to the body. The therapeutic effect also did not depend on the formation of a 3D macrostructure, but on the characteristics (particularly omniphobicity) of the substances themselves, which arose from the perfluoropolyether chemical structures. The physiological effect of the lubricant was achieved by (a lack of) interaction with body tissues. The lubricant was therefore classed as a substance or composition. It did not matter whether the interaction with the body was itself physical or chemical.

It is likely that case law in this area will continue to develop as more applicants seek to protect materials-based biomedical innovations.

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Dr Michael Ford MIMMM

Haseltine Lake Kempner