Originally posted on IPKat.
Sometimes patent law is about procedures and not inventions. The appeal in T 1168/24 related to the lipid nanoparticle (LNP) technology behind the COVID-19 vaccines, opposed by Merck and Moderna. After two rounds of opposition and two appeals, the patent was revoked for added matter. Whilst the global litigation surrounding LNPs is interesting in its own right, this case also raises some interesting legal issues surrounding the principle by which an appellant should not be put in a worse position by their own appeal (reformatio in peius). The Board of Appeal found that this principle continues to bind a Patentee who withdraws their appeal, even in cases where an opposition division (OD) decision is set aside for a violation of the right to be heard. The Patentee was left defending a narrow claim with an added matter problem which it could not then fix with a broadening amendment.
The commercial stakes were high in this case. The patent (EP 2279254) was one of the patents Arbutus and its exclusive licensee Genevant Sciences were asserting against Moderna over the LNP delivery technology in Spikevax. The Board of Appeal’s oral revocation on 15 January 2026 sent Arbutus’s shares down by as much as 22%, their steepest intraday fall since 2020. Arbutus said at the time that it disagreed with the outcome and would petition the EBA once the written decision issued. Arbutus also accepted that the revocation was likely to affect its Swiss action against Moderna and one of its two UPC actions (UPC_CFI_191/2025), whilst maintaining that the EPO’s added matter standard had no counterpart in the United States, Japan or Canada.
Legal background: The prohibition of reformatio in peius
The prohibition of reformatio in peius (PRP) is not found anywhere in the EPC. It was established by the Enlarged Board of Appeal in G 9/92 and G 4/93, and refined in G 1/99. In opposition appeals it means that if the Opponent is the sole appellant against a decision maintaining the patent in amended form, the Patentee is primarily restricted to defending the patent in the form maintained. Broader claims are therefore not permitted.
Exceptions to PRP
G 1/99 recognised a narrow exception to PRP which applies when the claims as maintained by the Opposition Division contain an amendment that turns out, on appeal, to be inadmissible (for example because it adds matter). Without an exception, the Patentee would be trapped. It could not defend the claims as maintained, because they are inadmissible, and it could not broaden them, because the Opponent is the sole appellant. The patent would be revoked as a direct consequence of the Opposition Division’s own error. In G 1/99, EBA thus considered it inequitable for a non-appealing Patentee to lose its patent in this way.
The exception of G 1/99 can therefore offer an escape route to PRP, but a very strict one. The Patentee must first try to overcome the objection with an originally disclosed feature that narrows the claim. Only if narrowing is impossible may it introduce a feature that broadens the claim relative to the version maintained, and even then only within the limit of Article 123(3) EPC. Deletion of the inadmissible amendment is the last resort.
Subsequent decisions have considered how this framework operates when a case is remitted and comes back on a second appeal. T 1843/09 held that PRP continues to apply after a remittal, but that any change in the factual or legal basis of the case could justify an exception. By contrast, T 0727/19 declined to apply PRP at all after a remittal where the first Opposition Division had been found to be partial.
This brings us to T 1168/24, in which the question was whether a violation of the right to be heard also displaces PRP after a remittal, as the finding of partiality did in T 0727/19.
Case background
The Arbutus patent (EP 2279254) related to nucleic acid-lipid particles for the in vivo delivery of nucleic acid, comprising a cationic lipid, a non-cationic lipid and a conjugated lipid in defined molar ratios. This is just one of the patent families in the great LNP litigation landscape. The granted claims were not limited to any particular nucleic acid payload, ionizable lipids or pegylated lipids.
As might be expected for a PRP case, the procedural history is rather involved. The Opposition Division first maintained the patent in amended form. All parties appealed, but importantly the Patentee then withdrew its appeal and became respondent. In T 505/20, the Board of Appeal found that the Opposition Division had decided on a differently worded claim 1 of auxiliary request 1, having read the word “systemically” into the “for use” clause when the claim as actually filed contained no such limitation. That error proved fatal three times over. The decision was not based on the text submitted by the Patentee (Article 113(2) EPC), the reasons given did not relate to the claim actually maintained and so the decision was not reasoned (Rule 111(2) EPC), and the Opponents’ right to be heard was violated because the patent had been maintained for reasons “that the appellants were not given the opportunity to comment on” (r. 14). The case was remitted and all three appeal fees were reimbursed. Back before the OD, the Patentee filed a main request and auxiliary requests 1 to 12 that were (importantly) broader than the claims it had defended as respondent, together with auxiliary requests 13 to 19 that were not. The OD refused to admit these claims under PRP and maintained the patent on the basis of auxiliary request 13. All three parties appealed again.
Does a violation of the right to be heard wipe the slate clean?
The Patentee first argued that PRP is a problematic concept with no basis in the EPC and should not be applied at all. The Board of Appeal was not impressed with this argument. PRP, it noted, is a settled principle binding on the Boards of Appeal (r. 18).
Next the Patentee argued that PRP should not apply where the first instance decision was set aside for a substantial procedural violation. Following such a remittal, the Patentee argued, the case had to be heard from the start. The Patentee relied on T 0727/19 and T 2086/13, and asked for a referral to the EBA. However, the Board of Appeal distinguished T 0727/19 on its facts. In that case, the Board found, there had been an objectively justified suspicion of partiality: “A finding of partiality undermines the legitimacy of the entire earlier decision making process and accordingly justifies an exceptional departure from PRP” (r. 20). A violation of the right to be heard in respect of a single auxiliary request, by contrast, “while serious, does not undermine the legitimacy of the entire earlier decision making process” (r. 20, emphasis added).
Instead, the Board of Appeal found that the exceptions to PRP are to be construed narrowly, and they thus saw “no reason to extend the exceptions to PRP to these circumstances” (r. 24). Nor was it writing on a blank sheet. The Board of Appeal noted that its conclusion was in line with T 974/21, in which another Board of Appeal had likewise held that a breach of a party’s right to be heard did not preclude the application of PRP (r. 25). The referral request was refused on the ground that G 9/92 and G 1/99 already provided clear guidance.
The Patentee’s fallback position was that the admission of an experimental report filed by Opponent 1 in the first appeal had changed the factual basis of the proceedings, in the sense of T 1843/09. The Board of Appeal was not convinced. The report merely confirmed conclusions the first Opposition Division had already reached (r. 27). Furthermore, the Board of Appeal added that, even if an exception had been available, the Patentee had not followed the G 1/99 sequence: “The proprietor has made no attempt to file such restricted claims, and the proprietor has not shown (nor is it apparent to the Board) that compliance was impossible by restriction” (r. 30). The broader requests were therefore not admitted.
Two arbitrary selections and no pointer
That left auxiliary request 13, which the Opponents attacked on the ground that the combination of the amended cationic lipid range with the newly defined non-cationic lipid mixture was not directly and unambiguously derivable from the application as filed. The Board of Appeal agreed, concluding that “at least two independent arbitrary selections are required to arrive at the claimed combination of features” (r. 111).
Once past the procedural issues, T 1168/24 is a canonical application of the EPO’s gold standard for selections from lists, and continues the line followed in T 2171/21, T 0868/23 and T 0422/23. As previously noted, the drafting style needed to satisfy the EPO on basis sits uncomfortably with the US aversion to patent profanity, and formulation cases, with their often long lists of overlapping ratio ranges and concentrations, can be particularly rich hunting ground for added matter attacks.
Procedural requests are amendments to the appeal case too
Having lost on added matter at the oral proceedings, the Patentee asked for a remittal so that it could consider which requests might now benefit from a G 1/99 exception, or alternatively for an interlocutory decision on added matter alone. The Patentee argued that these were procedural requests to which Article 13(2) RPBA (Amendment to a party’s appeal case) did not apply. The Board of Appeal acknowledged that the case law on this point is not uniform, but held that “the plain wording of Article 13 RPBA does not distinguish between a party’s procedural requests and non-procedural requests” (r. 119). The Board noted that the added matter objection had been on file from the outset and the preliminary opinion had signalled the likely outcome. As such, “The proprietor could and should have prepared fallback requests in advance” (r. 121). A Rule 106 EPC objection was dismissed, since a party has no absolute right to be heard on the substance of a request that is not admitted. The patent was revoked.
Analysis
For the EPO, it seems, a party which waives a right in full knowledge of the legal situation has little claim to equity. A Patentee whose patent has been maintained in amended form should think very carefully before withdrawing an appeal, however remote the prospect of the broader claims may seem.
Events, however, rather overtook the procedural drama of this case. In March 2026, two months after the oral revocation and well before the written decision appeared, Genevant and Arbutus settled globally with Moderna for $2.25 billion, $950 million payable upfront in July 2026 and a further $1.3 billion contingent on an appellate ruling that Section 1498 does not bar their US claims. The settlement resolved every pending dispute between the parties worldwide, including the Swiss action and UPC cases. Arbutus and Genevant have, however, since opened a new front at the Hague local division against Pfizer and BioNTech’s Comirnaty, on EP 4241767 and its divisional EP 4495237.
Nonetheless, for Patentees without a billion-dollar settlement to fall back on, T 1168/24 is a reminder that added matter remains the most reliable way to lose a European patent, as Moderna itself discovered in September 2026 when the Boards of Appeal revoked EP 3590949, the patent at the heart of its own campaign against Pfizer and BioNTech, on the very same ground.
Author: Rose Hughes
Rose is a biotech and pharmaceutical patent specialist with over a decade of experience in intellectual property. Rose is a patent attorney at Evolve, where she leverages our unique fractional in-house model to provide clients with deep patent law expertise combined with the strategic commercial oversight typically associated with senior in-house counsel.
With a PhD in Immunology from UCL, Rose applies her technical background to complex innovations in biologics, cell and gene therapies, and the rapidly emerging field of AI-assisted drug development. Previously, Rose held the role of Director, Patents at AstraZeneca, where she was responsible for global IP portfolios and IP strategy at every stage of the pharmaceutical pipeline, from platform development and on-market commercialization to SPCs and patent term extensions.
A recognized thought leader in the field, Rose has been a regular contributor to IPKat since 2018, offering practical insights into European patent law developments. She is also a frequent speaker on the epi podcast, a guest lecturer for the Brunel University IP law Postgrad Certificate, and a contributing author to published books A User’s Guide to Intellectual Property in Life Sciences (2021) and Developments and Directions in Intellectual Property Law (2023).
