Neurotech patents in Europe: Part 2 - Novelty, Inventive Step, and Device-Specific Pitfalls

Building on my previous article relating neurotech to European patentability exclusions, I will discuss how the novelty of medical devices is assessed differently from pharmaceuticals. At first this may seem illogical, especially if both the device and the medicament are directed to treat the same condition, albeit in different ways. 

Product claims are typically framed as a product for a particular purpose. A common example used in EPC guidance is a mould for molten steel. The mould must be suitable for use with molten steel and may not, for example, be made with a plastic which would melt on contact with molten steel. It would not be possible to patent an identical mould simply by drafting the claim as “a mould for molten gold.” That identical product would infringe the original patent. On one hand, the intended purpose does not limit the invention, which is beneficial for protecting against infringement. On the other, the intended purpose does not lend any novelty to the invention, with one notable exception.

Medicaments are unique in that, in accordance with Article 54(4) and (5) EPC, a known substance or composition may be patented for a new use in a surgical, therapeutic or diagnostic method. This has been reaffirmed in case law several times throughout the decades. However, a medical device is distinct from a substance or composition and the exclusion does not apply. Unlike a medicament, a medical device is not expended or consumed during use. For example, the same non-invasive Transcranial Magnetic Stimulation (TMS) device may be used on multiple patients. 

Bioresorbable implants are of particular interest, since it is arguable that they are in fact expended during use. If an implant comprises magnesium electrodes and a poly(lactic-co-glycolic acid) (PLGA) substrate, but stimulates neurons by applying electrical pulses, its use is unrelated to its bioresorbable properties. T 1252/20 indicates that the mode of action (mechanical or chemical) cannot be the deciding factor in whether an invention is a substance or device. This should be determined on a case-by-case basis.

If the same medical device may be used for several different purposes, then the supposed new use may overlap with existing uses. For example, the same neural electrode may be used to stimulate neurons to treat Parkinson’s Disease, epilepsy, or depression. Neuromodulation parameters are commonly tuned to the individual patient by a clinician or a closed-loop system. It is possible that the parameters used for a Parkinson’s patient could overlap with those for an epilepsy patient. If the neural electrode was patented “for” both treatments, which of these electrodes would be the infringing article?

A medical device may be novel if it has been modified from a known medical device to be suitable for a new surgical, therapeutic or diagnostic method. The important distinction is that the structural features of the invention are modified. Considering the example of the neural electrode, an electrode designed for epilepsy treatment may be sufficiently long to stimulate deep brain regions, or rigid enough to be implanted through centimetres of brain tissue without buckling or fracturing. An electrode designed to stimulate the motor cortex could take the form of a flexible surface electrode.

It is important to caveat that if a piece of prior art is not suitable for the same purpose as the claimed invention, then the claimed invention is arguably novel. For example, a surface electrode would be unlikely to destroy the novelty of an electrode for deep brain stimulation, as it is not suitable for that purpose.

The assessment of inventive step is not unique for medical devices. However, as neuroscientists refine their understanding of the brain, our ability to modulate neural signals and treat neurological disorders also improves. Where an invention involves an unexpected effect, it may not be possible to precisely describe how or why the invention works, even when experimental and clinical data confirm the efficacy of the treatment. For that unexpected effect to impart an inventive step, it must be possible for the skilled person, considering the common general knowledge, to deduce the claimed inventive step from the application as filed. Where possible, applicants should ensure their inventive concepts are underpinned by a theoretical explanation which would be understood by a skilled person in their field.

As with any other engineering invention, a medical device with a structural feature which is clearly novel and distinct over the prior art is more likely to proceed swiftly to grant. The challenge lies in persuading an Examiner when the differences are subtle, but important, or perhaps where the Examiner refuses to consider how a particular feature contributes to inventive step. As I will discuss further in the third and final article of this series, one of the best approaches to avoid novelty, inventive step, or sufficiency objections, is to disclose the invention as clearly and completely as possible.