Antibody claims: breaking the routine methods mindset

I reported last year on the three-part article series published in EPI Information by Tamaris Bucher, Principal Patent Attorney at Novartis, on the EPO’s approach to assessing inventive step for antibody inventions (posted on 9 January and 27 March 2025). Bucher had argued that Part G.II.6.2 of the EPO Guidelines created an artificial barrier to obtaining patent protection for antibody inventions, based on an unfounded prejudice that generating antibodies amounts to routine work.

The article series, accompanied by Bucher’s passionate advocacy on the topic, generated significant discussion amongst the patent community last year and appears to have prompted action by the EPO. The 2026 Guidelines, which will come into force on 1 April 2026, contain an amendment from “The subject-matter of a claim defining a novel antibody binding to a known antigen does not involve an inventive step unless…” to “…involves an inventive step if…”. However, although this softens the negative presumption of obviousness slightly, Bucher argues that it does not go far enough as the ‘routine methods mindset’ is still embedded in the guidance on inventive step.

Bucher’s latest article focuses on the interplay between Art. 56 EPC (inventive step) and Art. 83 EPC (sufficiency of disclosure) and the idea postulated in a 2020 paper by Ulrich Storz1that the EPO has historically justified granting broad, functionally defined antibody claims with minimal disclosure on the assumption that antibody generation is routine. She critically examines whether this ‘routine methods mindset’ is appropriate or necessary for functionally defined claims, and argues that characterising a constantly evolving field such as antibody engineering as inherently routine is a bold and inherently flawed position.

The article emphasises that the assessment of sufficiency under Art. 83 (which should ask whether the claimed antibody can be made without undue burden or inventive skill) should be fact-specific, based on the features of the claim, the disclosure in the specification and the common general knowledge. It does not require an automatic assumption that all functionally defined claims are sufficiently disclosed across their full scope based on abstract analysis and mindsets stemming from early case law relating to the development of murine monoclonal antibodies for in vitro use. Bucher warns against overapplying this mindset to antibody engineering for therapeutic antibodies for in vivo use. The development of such products is complex, often requiring optimisation of multiple characteristics via varied methods so the assumption that all antibodies are routine to make is technically inaccurate.

The role of functional features in antibody claims is scrutinised, with the article distinguishing between purely functionally defined claims, purely structurally defined claims, and mixed claims, and how such claims might be assessed under Art. 83 and Art. 56. According to Bucher’s analysis, the functional effect of the claimed antibody, and its role in defining which subset of antibodies is being claimed, is pivotal for both assessments. For functionally defined claims, the test should not be whether antibodies are routine to make in general, but whether there is an undue burden to make the subset of antibodies actually claimed.

Ultimately, the presumption of obviousness embedded in the Guidelines remains problematic, and a more nuanced approach is needed to support innovation in the biotechnology sector. Bucher therefore calls for the removal of the routine methods characterisation from the field of antibody technology and advocates for standards that genuinely reflect the realities of modern antibody engineering.

Tamaris Bucher’s article can be accessed at the following link:

epi Information | Antibody Claims: Routinely Sufficient?

• 1Storz, U “The nine lives of epitope-based antibody patents”; Human Antibodies; Vol. 28, Issue 2; May 2020; pages 89-110