UK: Deciding When To File A Patent Application In Europe

Last Updated: 1 November 2007
Article by Nina White

Originally published in Nature Biotechnology , Vol. 25 No. 6, June 2007.

Guidelines for would-be patent applicants in Europe's 'first-to-file' system

Deciding on the right time to file a patent application can be a difficult decision in any technical field, but it is particularly difficult in competitive and rapidly developing areas of biotech. Would-be patentees must make a decision whether to delay filing until a substantial amount of data have been accumulated to support the invention and risk being 'scooped' by a competitor, or alternatively file early to secure a filing date ahead of the competition and risk the patent application being rejected as lacking adequate experimental support. Choosing the right time to file is particularly difficult in jurisdictions such as Europe, which operate a 'first-to-file' rather than a 'first-to-invent' system.

Patent applicants have tried to circumvent this problem by filing early on the basis of limited experimental data to establish a filing date ahead of potential competitors, on the understanding that it may be possible to submit further experimental data at a later date to show that the invention did in fact meet all the requirements for patentability as of the filing date.

Various recent decisions of the European Patent Office (EPO; Munich) have cast doubt on the ability to rely on late-filed experimental data (that is, data submitted to the EPO after the filing date of the patent application) to support patentability. This article summarizes the effects of these decisions, and identifies the circumstances in which applicants should not expect to rely on late-filed experimental evidence to support patentability before the EPO.

Sufficient disclosure requirement

Biotech inventions must satisfy the basic patentability requirements common to all technical fields: that is, the invention must be novel and nonobvious in comparison to the prior art. The invention must also be supported by sufficient technical disclosure to enable one skilled in the art to practice the invention over the full scope claimed without undue burden.

It is well established in the case law of the EPO Boards of Appeal that in order to meet the requirement for sufficient disclosure (Art.83 EPC) the application as filed must disclose at least one way of carrying out the invention. If the claims are particularly broad, then it may be necessary to provide more than one example to ensure that the technical disclosure of the application is sufficient to enable a skilled reader to carry out the claimed invention over the whole range claimed.

If the technical content of the application is judged fundamentally insufficient as of the filing date, it is not possible to remedy the situation by submitting late-filed experimental evidence. This principle is illustrated in an EPO Technical Board of Appeal decision concerning a claim to use of a peptide having insulinotropic activity for the treatment of diabetes mellitus1. In this case, the peptide was defined as consisting of a 31-amino acid sequence (GLP1(7-37)) but lacking one amino acid. The application as filed lacked any data to show that any of the claimed peptides were effective in the treatment of diabetes, but described an assay that could be used to test whether particular peptides would be effective. The applicant maintained that it was well within the capabilities of the skilled reader to make any one of the 31 peptides falling within the claim and test it for the required activity using the disclosed assay. Several postpublished documents had confirmed that at least one of the claimed peptides (GLP-1(7-36)) had the claimed biological activity.

The Board came to the conclusion that the technical disclosure in the application as filed was fundamentally insufficient, because it placed an undue burden on the skilled reader to make and test all of the 31 peptides falling within the claim to find a peptide with the required activity. The postfiled evidence confirming that at least one of the claimed peptides did, in fact, have the required activity could not remedy the lack of sufficiency present at the filing date.

The requirement for sufficient disclosure at the filing date does not mean that it is always necessary to include actual experimental results to demonstrate that the invention works as claimed. In certain situations, it may be sufficient to include a hypothetical example, provided that the skilled reader can follow this example and arrive at the claimed invention without undue burden or exercise of inventive skill. Nevertheless, applicants should be aware that use of 'paper examples' alone can lead to a reversal of the burden of proof in establishing that the disclosure of a patent is sufficient, specifically in European Opposition proceedings, as illustrated by a Board of Appeal decision2 concerning the display of proteinaceous binding domains on the surface of filamentous phage. In this case, the application as filed contained only a hypothetical experimental example and did not include any experimental data to confirm that the invention would work. Postfiling data submitted by the patentee was based on an experimental protocol that deviated from the hypothetical protocol in the application. The Appeal Board confirmed that, although use of hypothetical examples is not prohibited, if the only example is explicitly described as a hypothetical example that has clearly not been carried out, the burden of proof is on the patentee to show that what is described actually works.

Potential applicants should therefore be aware that although it is possible to file on the basis of a hypothetical example only, and adduce technical evidence after the filing date to show that the example works, problems will arise if the hypothetical example does not in fact work as it is written, or if substantial variation from the protocol as written, amounting to 'undue burden' or 'exercise of inventive skill', is required to make it work. Moreover, it appears from later EPO decisions that there are some technical fields in which hypothetical examples can never be enough to satisfy the requirements of the European Patent Convention (EPC). There are some situations where experiments will absolutely be required to show that an invention has been made. Falling into this category are inventions relating to therapeutic treatment, claimed in Europe as new medical uses.

In one key case3, the EPO Technical Board of Appeal considered the patentability of a claim to the use of a steroid hormone or steroid hormone analogue, which fails to promote transcriptional activation of glucocorticoid receptor or retinoic acid receptor genes, for the preparation of a pharmaceutical for the treatment of AP-1 stimulated tumour formation, arthritis, asthma, allergies and rashes. The application had been refused by the Examining Division for a lack of sufficient disclosure in relation to this medical use claim. Although the application disclosed a screening method for finding steroid molecules with the required properties, no such molecule was identified or disclosed and no data of any kind were presented indicating that such a hormone could have an impact on any of the diseases is was claimed to treat.

The applicant provided postpublished evidence that steroid hormones having the mechanism of action required for the medical uses claimed had indeed been identified using screening methods identified in the patent application, and argued therefore that by carrying out the teaching in the parent application, one would necessarily obtain pharmaceutical compositions that would have the claimed medical utility. The Appeal Board did not agree with this approach, stating that sufficiency of disclosure must be satisfied at the effective date of the patent. In the case of a claim to a medical use of a pharmaceutical composition, attaining the therapeutic effect was a functional feature of the claim. Unless this was already known to the skilled person at the priority date, the application must disclose the suitability of the product for the claimed therapeutic application to satisfy the requirement for sufficient disclosure. This did not mean that human clinical trials, or even animal data, were necessarily required, but there must be some evidence that the claimed molecules actually have an effect on the metabolic mechanism involved in the disease. The presence of a cause-and-effect relationship must be made 'plausible'. Even showing a pharmaceutical effect in vitro may be sufficient, if for the skilled person this observed effect directly and unambiguously reflects a therapeutic application. Such rudimentary evidence may be backed up with further evidence produced later.

This case established that although it is not always necessary to have clinical trial data, or even animal data, to support a claim to a new medical use of a known substance, it is not sufficient merely to state that "substance X can be used to treat disease Y". Such statements must be backed up by some form of experimental data, whether animal data or data from an accepted in vitro model, which backs up the claim to medical utility. The supporting data must be present in the application as filed to provide acceptable disclosure of 'the invention' as claimed. Thus, although it may be possible to file on the basis of animal data, or even in vitro data, and back this up during prosecution with in vivo data if and when required, it is not possible to submit data generated after the filing date to back up a simple statement of medical utility.

The implication of the EPO case law is that even if the specification as filed provides 'sufficient' technical teaching to enable a skilled person to make and use "substance X" in the treatment of disease Y, and it could be later shown that by following this teaching the claimed treatment would indeed be successful, the requirements for patentability would not be met if the specification as filed lacked the necessary experimental evidence to convince a skilled reader that the treatment could reasonably be expected to work.

Showing the inventive step

Going beyond the requirements of sufficiency, a more recent Technical Board of Appeal decision4 has cast doubt on the ability of applicants to adduce post-filing date evidence in support of inventive step, even if the basic disclosure is sufficient. The case in question concerned a patent application in the name of Johns Hopkins University (Baltimore) with claims directed to polynucleotides encoding polypeptides having the activity of growth differentiation factor (GDF)-9, a putative further member of the transforming growth factor (TGF)-˛ superfamily of growth differentiation factors.

The applicant had isolated a novel polynucleotide molecule encoding the GDF-9 polypeptide. It was not contested that the polynucleotide and encoded polypeptide represented novel molecules. The applicant claimed that the GDF-9 molecule represented a further member of the TGF-˛ superfamily, although its sequence was only very weakly conserved, exhibiting no more than 34% homology with known members of the TGF-˛ family, and the protein contained only six cysteine residues instead of the seven cysteine residues that were a key characterizing feature shared by all members of the TGF-˛ family. The application as filed did not contain any functional data characterizing GDF-9 as a growth differentiation factor of the TGF-˛ family.

The EPO assesses inventive step in terms of a solution to a technical problem arising in the closest prior art. In the Johns Hopkins case, the closest prior art described the identification of a different novel member of the TGF-˛ superfamily, GDF-1. The problem allegedly solved by the invention was therefore defined as providing a new growth differentiation factor of the TGF-˛ family. The applicant maintained that inventive step should be acknowledged on the basis of the unexpected structural properties of GDF-9, namely the weak homology with known members of the TGF-˛ family, the fact that it contained only six cysteine residues instead of seven and the limited expression restricted to ovarian tissues. The applicant also filed numerous postpublished documents as further evidence of the role of GDF-9 as a growth differentiation factor. This evidence claimed to support the description in the application as filed of the presumed functions of the GDF-9.

The Board of Appeal considered that on the basis of the information presented in the application as filed, GDF-9 could not be clearly and unambiguously identified as a member of the TGF-˛ superfamily because of the low sequence homology with known members of the family and the presence of only six cysteine residues rather than the characteristic seven residues found in family members. The application as filed contained no experimental evidence to support the predicted function as a growth differentiation factor. The Board concluded that as structural features alone failed to allow GDF-9 to be identified as a member of the TGF-˛ family and the application as filed did not contain sufficient evidence to make it "at least plausible" that a solution had been found to the problem of identifying further members of the TGF-˛ family, then inventive step could not be recognized. The postpublished evidence establishing that GDF-9 was indeed a growth differentiation factor, as the applicant had claimed all along, could not be relied upon to establish inventive step. The Board distinguished the situation where supplementary postpublished evidence may in some circumstances be taken into consideration to support technical evidence given in the application as filed, from the situation where postpublished evidence provides the sole basis to establish that the application does indeed solve the problem it purports to solve.

The logical conclusion from the Johns Hopkins case is that applicants who are deemed to have "speculated" as to the function of a novel molecule but do not present technical evidence in the application as filed to support the claimed function may find their claims refused for lack of inventive step, even if it can be established by postfiled experimental evidence that the "speculative" function was correct all along. The problem with this approach is that it introduces a subjective test to determine whether it was "at least plausible" that the invention provided a solution to the problem that was purportedly solved based on the content of the application as filed.

Indications to date are that EPO Technical Boards of Appeal are following the decision issued in the Johns Hopkins case, based on a subjective assessment of the "quality" of the experimental evidence included in the application as filed. Several subsequent EPO Appeal Board decisions5-7 all refer to the Johns Hopkins case but are distinguished from it on the basis that the supporting data in the application as filed is of "better quality". The implications are that if the quality of supporting experimental data included at the filing date is judged inadequate to satisfy the "at least plausible" test, then experimental results submitted after the filing date are unlikely to be of assistance. This has been interpreted by many patent practitioners in the Biotech field as introducing a requirement for actual reduction to practice as of the filing date of a European patent application, a requirement that finds no explicit basis in the EPC.


The message to prospective applicants from the EPO case law is that supporting experimental evidence may be required (i) to enable others to perform the invention over the full scope claimed, and/or (ii) to show that an invention has been made, in comparison to the prior art.

It is not possible to submit late-filed data to remedy a fundamental lack of sufficiency in the application as filed. Nevertheless, the EPO case law does not preclude submission of experimental evidence generated after the filing date to show that a paper example works. It is also possible to submit experimental evidence generated after the filing date to show that the invention works across the whole range claimed, provided the specification as filed contains sufficient technical disclosure to satisfy the requirements of Art. 83 EPC (e.g., at least one way of performing the invention is adequately described in the application as filed). With certain inventions, notably inventions based on therapeutic treatment, the requirements for sufficient disclosure go beyond enabling skilled readers to "make and use" the invention. The application as filed must contain some evidence of therapeutic efficacy. Even if the requirements for sufficient disclosure are met, experimental evidence may still be required to show that an 'invention' has been made in comparison to the prior art. It is not possible to use post-filing date experiments to show that an 'invention' solves the technical problem it purports to solve in comparison with the prior art if this is not "at least plausible" based on the content of the application as filed.


1 T497/02 (27 May 2004)

2 T792/00 (2 February 2002)

3 T609/02 (27 October 2004)

4 T1329/04 (28 June 2005)

5 T293/04 (5 April 2006)

6 T604/04 (16 March 2006)

7 T1336/04 (9 March 2006)

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

To print this article, all you need is to be registered on

Click to Login as an existing user or Register so you can print this article.

In association with
Related Video
Up-coming Events Search
Font Size:
Mondaq on Twitter
Register for Access and our Free Biweekly Alert for
This service is completely free. Access 250,000 archived articles from 100+ countries and get a personalised email twice a week covering developments (and yes, our lawyers like to think you’ve read our Disclaimer).
Email Address
Company Name
Confirm Password
Mondaq Topics -- Select your Interests
 Law Performance
 Law Practice
 Media & IT
 Real Estate
 Wealth Mgt
Asia Pacific
European Union
Latin America
Middle East
United States
Worldwide Updates
Check to state you have read and
agree to our Terms and Conditions

Terms & Conditions and Privacy Statement (the Website) is owned and managed by Mondaq Ltd and as a user you are granted a non-exclusive, revocable license to access the Website under its terms and conditions of use. Your use of the Website constitutes your agreement to the following terms and conditions of use. Mondaq Ltd may terminate your use of the Website if you are in breach of these terms and conditions or if Mondaq Ltd decides to terminate your license of use for whatever reason.

Use of

You may use the Website but are required to register as a user if you wish to read the full text of the content and articles available (the Content). You may not modify, publish, transmit, transfer or sell, reproduce, create derivative works from, distribute, perform, link, display, or in any way exploit any of the Content, in whole or in part, except as expressly permitted in these terms & conditions or with the prior written consent of Mondaq Ltd. You may not use electronic or other means to extract details or information about’s content, users or contributors in order to offer them any services or products which compete directly or indirectly with Mondaq Ltd’s services and products.


Mondaq Ltd and/or its respective suppliers make no representations about the suitability of the information contained in the documents and related graphics published on this server for any purpose. All such documents and related graphics are provided "as is" without warranty of any kind. Mondaq Ltd and/or its respective suppliers hereby disclaim all warranties and conditions with regard to this information, including all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement. In no event shall Mondaq Ltd and/or its respective suppliers be liable for any special, indirect or consequential damages or any damages whatsoever resulting from loss of use, data or profits, whether in an action of contract, negligence or other tortious action, arising out of or in connection with the use or performance of information available from this server.

The documents and related graphics published on this server could include technical inaccuracies or typographical errors. Changes are periodically added to the information herein. Mondaq Ltd and/or its respective suppliers may make improvements and/or changes in the product(s) and/or the program(s) described herein at any time.


Mondaq Ltd requires you to register and provide information that personally identifies you, including what sort of information you are interested in, for three primary purposes:

  • To allow you to personalize the Mondaq websites you are visiting.
  • To enable features such as password reminder, newsletter alerts, email a colleague, and linking from Mondaq (and its affiliate sites) to your website.
  • To produce demographic feedback for our information providers who provide information free for your use.

Mondaq (and its affiliate sites) do not sell or provide your details to third parties other than information providers. The reason we provide our information providers with this information is so that they can measure the response their articles are receiving and provide you with information about their products and services.

If you do not want us to provide your name and email address you may opt out by clicking here .

If you do not wish to receive any future announcements of products and services offered by Mondaq by clicking here .

Information Collection and Use

We require site users to register with Mondaq (and its affiliate sites) to view the free information on the site. We also collect information from our users at several different points on the websites: this is so that we can customise the sites according to individual usage, provide 'session-aware' functionality, and ensure that content is acquired and developed appropriately. This gives us an overall picture of our user profiles, which in turn shows to our Editorial Contributors the type of person they are reaching by posting articles on Mondaq (and its affiliate sites) – meaning more free content for registered users.

We are only able to provide the material on the Mondaq (and its affiliate sites) site free to site visitors because we can pass on information about the pages that users are viewing and the personal information users provide to us (e.g. email addresses) to reputable contributing firms such as law firms who author those pages. We do not sell or rent information to anyone else other than the authors of those pages, who may change from time to time. Should you wish us not to disclose your details to any of these parties, please tick the box above or tick the box marked "Opt out of Registration Information Disclosure" on the Your Profile page. We and our author organisations may only contact you via email or other means if you allow us to do so. Users can opt out of contact when they register on the site, or send an email to with “no disclosure” in the subject heading

Mondaq News Alerts

In order to receive Mondaq News Alerts, users have to complete a separate registration form. This is a personalised service where users choose regions and topics of interest and we send it only to those users who have requested it. Users can stop receiving these Alerts by going to the Mondaq News Alerts page and deselecting all interest areas. In the same way users can amend their personal preferences to add or remove subject areas.


A cookie is a small text file written to a user’s hard drive that contains an identifying user number. The cookies do not contain any personal information about users. We use the cookie so users do not have to log in every time they use the service and the cookie will automatically expire if you do not visit the Mondaq website (or its affiliate sites) for 12 months. We also use the cookie to personalise a user's experience of the site (for example to show information specific to a user's region). As the Mondaq sites are fully personalised and cookies are essential to its core technology the site will function unpredictably with browsers that do not support cookies - or where cookies are disabled (in these circumstances we advise you to attempt to locate the information you require elsewhere on the web). However if you are concerned about the presence of a Mondaq cookie on your machine you can also choose to expire the cookie immediately (remove it) by selecting the 'Log Off' menu option as the last thing you do when you use the site.

Some of our business partners may use cookies on our site (for example, advertisers). However, we have no access to or control over these cookies and we are not aware of any at present that do so.

Log Files

We use IP addresses to analyse trends, administer the site, track movement, and gather broad demographic information for aggregate use. IP addresses are not linked to personally identifiable information.


This web site contains links to other sites. Please be aware that Mondaq (or its affiliate sites) are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of these third party sites. This privacy statement applies solely to information collected by this Web site.

Surveys & Contests

From time-to-time our site requests information from users via surveys or contests. Participation in these surveys or contests is completely voluntary and the user therefore has a choice whether or not to disclose any information requested. Information requested may include contact information (such as name and delivery address), and demographic information (such as postcode, age level). Contact information will be used to notify the winners and award prizes. Survey information will be used for purposes of monitoring or improving the functionality of the site.


If a user elects to use our referral service for informing a friend about our site, we ask them for the friend’s name and email address. Mondaq stores this information and may contact the friend to invite them to register with Mondaq, but they will not be contacted more than once. The friend may contact Mondaq to request the removal of this information from our database.


This website takes every reasonable precaution to protect our users’ information. When users submit sensitive information via the website, your information is protected using firewalls and other security technology. If you have any questions about the security at our website, you can send an email to

Correcting/Updating Personal Information

If a user’s personally identifiable information changes (such as postcode), or if a user no longer desires our service, we will endeavour to provide a way to correct, update or remove that user’s personal data provided to us. This can usually be done at the “Your Profile” page or by sending an email to

Notification of Changes

If we decide to change our Terms & Conditions or Privacy Policy, we will post those changes on our site so our users are always aware of what information we collect, how we use it, and under what circumstances, if any, we disclose it. If at any point we decide to use personally identifiable information in a manner different from that stated at the time it was collected, we will notify users by way of an email. Users will have a choice as to whether or not we use their information in this different manner. We will use information in accordance with the privacy policy under which the information was collected.

How to contact Mondaq

You can contact us with comments or queries at

If for some reason you believe Mondaq Ltd. has not adhered to these principles, please notify us by e-mail at and we will use commercially reasonable efforts to determine and correct the problem promptly.