Securing robust patent protection for cell-based therapeutics presents unique challenges, particularly before the European Patent Office (EPO). As the field of regenerative medicine and cell therapy continues to evolve, so too must the strategies employed to safeguard intellectual property in this domain.
Traditional paradigms of patent protection in drug development were shaped around small molecule therapeutics. However, as innovation progresses through biologics and into cell-based therapies, conventional approaches often prove inadequate. Cell products, by their nature, demand more nuanced and adaptable strategies to ensure meaningful exclusivity and commercial viability.
Patent claims generally fall into two broad categories: those directed to a product or apparatus (“thing” claims) and those directed to a method, use, or process (“activity” claims). Product claims are generally considered to provide the best protection for therapeutic assets, also manufacturing processes may also provide useful protection for cell-based products, whose properties may be significantly affected by the process by which they were made. Ideally, both the product and related processes are protected by patent claims.
The EPO requires that products be defined by their technical features—that is, their physical or structural characteristics. This requirement is relatively straightforward for conventional products, and in some cases, for cell products as well.
For example, when a cell product comprises a recombinant nucleic acid or protein, it may be defined by reference to that component. In such cases, the patentability of the cell product often depends on the features of the recombinant nucleic acid or protein. For example, a typical claim might read: “[a] host cell comprising the nucleic acid molecule of claim 3 or vector of claim 4…” (EP4269421). The host cell of this claim is made patentable by the features of the nucleic acid molecule or vector that are defined in other claims.
Alternatively, cell products may be defined by expression profiles of endogenous markers. While such marker panels can satisfy the EPO’s formal requirements, they often raise issues of clarity and novelty. Descriptors such as “+”, “−”, “high”, or “low” may be deemed ambiguous without quantified thresholds. Moreover, cells in the prior art may not be characterised by the same marker panels, which can make it difficult to establish novelty. For instance, a typical claim of this type might read: “[a] cell or cell population…, wherein >60%, … of the cells specifically express at least one or more of the following markers: …, preferably, the expression level of the marker is at least about 1.5 times, … higher than that of primary cells.” (EP4198122).
In some cases, a therapeutic cell product is intended to replicate the phenotype of an endogenous cell. In these circumstances, the features that distinguish the product from the endogenous cell may be subtle and difficult to articulate. Translating subtle differences revealed by transcriptomic analyses (e.g., heatmaps) into precise, claim language remains a significant hurdle for practitioners.
When it is not feasible to define a cell product by its technical features alone, product-by-process claims may offer an alternative. These are claims directed to a product, but the product is defined in terms of the process used to produce it. This use of process features to define a product is often contentious at the EPO.
The EPO generally interprets product by process claims as claims to the product per se, not to the process (EPO Guidelines for Examination, Part F-IV, 4.12). Accordingly, the patentability of a product-by-process claim depends on whether the process imparts distinctive technical features onto the product that render it novel and inventive over the prior art.
This distinction is critical: the process itself does not confer novelty unless it results in a product with identifiable, distinguishing features. Infringement—ultimately a matter for the UPC or national courts—will likely hinge on whether the allegedly infringing product exhibits the same imparted features, rather than whether it was made by the same process.
The EPO permits product-by-process claims only when it is impossible to define the product by other means. This high bar reflects the EPO’s general reluctance to allow such claims, particularly where the imparted features are difficult to characterise or verify. Ironically, if the imparted features are easily characterised, the EPO may argue that the product should be defined directly by those features. This may not be possible for other reasons, creating a Catch-22 situation in which neither the process nor its features can be used to define the product.
The protection conferred by a process claim is extended by Article 64(2) EPC to products directly obtained by that process. The EPO often cites this provision as a reason not to allow product-by-process claims. However, the scope of protection under Article 64(2) is limited to products of the specific claimed process, whereas a product-by-process claim may cover any product that exhibits the imparted features, regardless of how it was made. The product by process claim therefore has a broader scope which may reduce the evidentiary burden in infringement proceedings.
Product-by-process claims are particularly relevant for complex biological products, such as cell therapies, when the manufacturing process is well-defined, but the resulting product is complex and difficult to characterise by its structural features. In such cases, the process effectively defines the cell product. However, the applicant will need to show that process set out in the claims yields a product that is structurally or functionally distinct from known alternatives in order to establish patentability. This is likely to require convincing supporting evidence, either in the specification or filed subsequently. It may also require the process to be defined tightly enough that the product always displays the structurally or functionally distinct features.
As the field of cell and gene therapy continues to stretch the paradigms established for small molecule drugs, patent strategies need to evolve to meet the demands of next-generation therapies. Despite their challenges, product-by-process claims may be a valuable tool in protecting cell-based therapeutics. For patent attorneys operating in this space, a deep understanding of EPO practice and a strategic, flexible approach is likely to be needed to provide adequate protection for cell-based therapeutics in the future.
Mewburn Ellis LLP has extensive experience advising on patent strategies across the cell therapy landscape, including CAR-T, stem cell technologies, and regenerative medicine. We understand the scientific and regulatory complexities involved and can help you develop tailored IP approaches that align with your commercial goals. Contact the Mewburn team to discuss how we can help.
