It is now a month and a half since WIPO ST.26 was adopted as the standard for sequence listings disclosed in a patent application. While the new standard brings a number of advantages, it has already led to concerns, particularly regarding divisional applications.

Aims of ST.26

Many patent applications in the biotech sector disclose nucleotide and/or amino acid sequences. Some of these applications include hundreds or even thousands of such sequences – each of which can be very long.

On 1 July 2022 (after considerable delays), the World Intellectual Property Office (WIPO) Standard ST.26 replaced ST.25 for sequence listings, and all IP offices of WIPO member states implemented it immediately for new patent applications. According to WIPO, the new standard aimed to harmonise sequence listing practices across offices, reflect advances in biotechnology and meet international sequence database requirements.

Notably, ST.25 did not capture sequence types such as branched sequences, D-amino acids and nucleotide analogues. There was also a concern that data could be lost when transferred from ST.25 to sequence databases.

A fundamental change in the new standard is that the file format is now required to be XML, rather than the more universally accessible TXT formats of the ST.25 standard. Due to this, and the considerable differences which can arise between the representation of the same sequences in the two formats, the conversion of an ST.25 sequence listing to one conforming to ST.26 can be a very considerable task.

To support applicants, WIPO released a new tool called WIPO Sequence to generate ST.26 sequence listings, to help transform ST.25 into ST.26 and to allow reading of the new file format. WIPO also published an FAQ on the implementation, including lengthy discussions on how to convert between the two formats without adding or losing content. Following problems reported with the software, it released a new version with a fix on 5 August.

However, questions have arisen regarding divisional applications. While WIPO required the use of ST.26 for new applications, it was left to individual patent offices to decide whether to require the ST.26 format for divisional applications filed after 1 July 2022, where the parent had a ST.25 sequence listing.

At least in Europe, divisional applications arise from the subject-matter included in a 'parent' application. The addition of subject-matter not present in the parent application is not permitted. Divisional applications inherit the filing date, and where applicable the priority dates of the parent, such that they are generally compared against the same state-of-the-art as the parent application before them.

The EPO regime

The EPO has taken a strict approach, requiring ST.26 to be used for all divisional applications filed after 1 July 2022, regardless of the standard used in the parent application. This contrasts with the UK IPO approach, which requires that the sequence listing in a divisional application should be in the same format as that in the parent application, and the sequence listing must not add matter.

The European Patent Institute (epi), which represents patent attorneys in Europe, has criticised the EPO policy (discussed on the IPKat blog here). It argued that a divisional application is not independent from its parent in relevant respects; that the EPO approach increased the burden on applicants to no clear advantage; and that it could lead to problems of possible added matter (or conversely, loss of subject-matter present in the parent application due to the removal of the previous ST.25 listing) that will be impossible to remedy: "By requiring more information, the danger is that filing an ST.26 listing will, inherently, add matter. That is an immediate and obvious consequence of ST.26 demanding more information."

The epi published data showing that about 9% of published sequence listings contained more than 50 SEQ IDs. Transforming these from ST.25 to ST.26 would take many hours of extra work, without necessarily avoiding the problems of loss or addition of subject-matter. Potential 'stopgap' solutions, such as including the previous ST.25 listing as part of the divisional description, have the potential to lead to thousands of euros of excess page fees.

In response to the epi concerns, the EPO said it would not change the rules on divisional applications – at least for the time being (a review of the regime is planned for the first half of next year).

In a letter to epi, EPO Principal Director Mihály Ficsor said the regime "allows benefits of the new standard to materialize sooner while reducing the necessary IT support for the old standard as far as possible" and corresponds to the approach taken in the US, Japan, Germany and other countries. He added that "a divisional application is an independent application, subject to the procedural requirements applicable on the date of its submission".

Don't get caught out!

The EPO's response makes it clear that it will not change its policy, despite pressure from users, and that it considers that placing of the burden of transitioning between the two systems on applicants is justified by the benefits of immediate exclusive use of the new standards.

Patent applicants in this sector, especially those with an interest in filing divisional applications, therefore need to plan ahead to make sure they comply and do not introduce added matter problems. Those with both European and UK filings also need to pay careful attention to the different approaches taken by the offices.

It is worth noting that International (PCT) Applications filed before 1 July 2022 will not require an updated ST.26 sequence listing to be filed on entry into the European Regional Phase, even if entry is after the implementation date.

Keltie attorneys are very experienced in working on patent applications including sequence listings and we continually monitor the latest developments. We can advise on using ST.26, as well as how to minimise any problems or risks that may arise. Please contact one of our team if you have any questions.

Image from National Cancer Institute

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