Confidentiality restrictions around clinical trials and prior public use (T 0670/20)

The recent Board of Appeal decision in T 0670/20 considered whether patients in a clinical trial were under conditions of confidentiality. The patent was for a tablet formulation that had been given to patients in a clinical trial conducted before the patent had been filed. The question became whether the patients could be considered members of the public, and whether their participation in the clinical trial therefore constituted prior public use of the formulation. 

Case background

The patent (EP 2140867) in T 0670/20 related to a tablet form of the anti-blood clot drug edoxaban (Lixiana, also known as DU-176b). The patent was opposed on the ground of, inter alia, lack of novelty in view of prior public use cited as the distribution of the tablets to patients in the phase IIa and IIb clinical trials for edoxaban (NCT00107900 and NCT00398216).

Critically, to satisfy the prior use test, it is not necessary to show that a disclosure has in fact taken place. It is a principle of novelty destroying prior art that it is only necessary for there to have been a potential disclosure to the public, the classic example of this being the unread thesis on the library shelf (IPKat). 

edoxaban tablets
The Opponent submitted that the skilled person, using common general knowledge, would have been able to determine the ingredients of the tablets used in the clinical trials for edoxaban. The Opponent further argued that the tablet, and therefore its ingredients, had been made available to the public during the course of the clinical trial. This was because the patients had been able to take the tablets home and, according to the Opponent, could not be considered under conditions of confidentiality for ethical reasons. As such, it was argued, the potential existed for the public to analyse and determine the formulation of the tablets. 

Confidentiality in clinical trials. 

The key question before the Board of Appeal was whether the patients were or were not under conditions of confidentiality. The Opponent argued that it would be unethical to prevent patients discussing the trial with their doctor and family. It was also pointed out that the clinical trial summaries themselves included guidance that, as a patient, you should "[t]alk with your doctor and family members or friends about deciding to join a study". 

The Board of Appeal, on the other hand, saw a distinction between confidentiality around the trial itself, and the tablets used in the trial. As such, a patient may have discussed the trial without disclosing information about the tablet itself. 

The Opponent had further argued that, whilst the patients were under an obligation to return unused tablets, not all unused tablets were in fact returned. For the Opponent, this demonstrated that the company had lost control of the product. Furthermore, it was argued that the lack of any legal sanction for not returning the tablets, meant that this requirement could not be considered legally equivalent to a confidentiality agreement. However, the Board of Appeal was not convinced by this argument. Instead, the Board of Appeal found that the patients could not be equated to members of the public free from conditions of confidentiality:

"the patients' agreement to use the provided medication according to instruction or to return the unused medication obliges the patient irrespectively [sic] of any sanction on non-compliance and therefore disqualifies the patients as members of the public with respect to the medication provided to them. The possibility of non-compliance to the instructed use and return of the tablets by participating patients does not affect the essence of this agreement" (r. 4.5)

The formulation was therefore found novel in view of the clinical trial summaries. The Board of Appeal also noted the difference in facts with the present case and that of T007/07. In T007/07 the patentee was found to have lost control of the drug product during the course of the clinical trial, as the tablets were handed out to members of the public not bound by confidentiality. 

Final thoughts

When running a clinical trial, preventing the accidental disclosure of confidential information can be an uphill battle. Clinical trial summaries, investor reports, and company announcements must all be reviewed and scrutinised to ensure there is no accidental disclosure of sensitive information before a patent application has been filed. The disclosure requirements stipulated by regulatory authorities are also increasing, most notably in Europe. All of this puts considerable pressure on companies to file patent applications for clinical inventions (such as dose and formulation), before clinical data can be obtained. In this context, the decision of the Board of Appeal at least provides some reassurance that patients in a clinical trial can be considered to be under conditions of confidentiality in a clinical trial. According to T 0670/20, the direct distribution of an investigative drug formulation to patients in a clinical trial thus does not necessarily constitute a public disclosure of the formulation. 

It is unclear from this decision, however, whether information about the drug product other than the formulation, such as the dose, would have been considered similarly confidential. If the patients were told the dose of the product, which they may then have discussed with their doctor and family (and which may also be observable), would this be considered a public disclosure? It is also worth noting that the decision rested very much on the facts of the case, and that, in contrast with T007/07, the patients could be considered under conditions of confidentiality in view of the way the trial itself was conducted. Trial design and patient communication is therefore another aspect to consider when ensuring details of a clinical invention are not prematurely and inadvertently disclosed. 

Further Reading

Proving the existence of confidentiality agreements and the celestial teapot - T 2037/18 (9 Dec 2019)

Mr Justice Nugee and the Superhose: The potentiality of disclosure (13 May 2019)

Hacon HHJ and the Seed Drill: Intentionality in prior use (Claydon v Mzuri, [2021] EWHC 1007) (27 April 2021)

Confidentiality restrictions around clinical trials and prior public use (T 0670/20) Confidentiality restrictions around clinical trials and prior public use (T 0670/20) Reviewed by Rose Hughes on Tuesday, January 31, 2023 Rating: 5


  1. This reminds me of the English case about tentative disclosure of a prototype product to a buyer working for a retail chain, where the buyer (quite understandably) was not willing to sign an NDA. I wonder, how does the opinion at the EPO compare with Robin Jacob's tests: objective (intelligent fly on the wall of the room where the disclosure took place) and subjective (what the buyer, the patient in the clinical trial and the patient's doctor and family members, actually understood to be the extent of their fair dibs, equitable understanding to refrain from disseminating the information further).

  2. Comment - Part 1

    It is manifest that running a clinical trial, preventing the accidental disclosure of confidential information is an uphill battle. The difficulties are numerous, but they apply to any potential applicant. They might simply be more strenuous, but not fundamentally different.

    There is a further decision which should also be taken into account.

    In T 239/16, the situation was similar to the present one. There was a clinical study in which patients participated without any obligation of confidentiality.

    From the information that can be gained from the file it was clear that the patients participating in the study were actively encouraged to discuss their participation to the tests with “anyone” including their family and family doctor.

    For the board in T 239/16, it was established case law that if a single member of the public who is not under an obligation to maintain secrecy has the possibility to access particular information, this information is considered as being available to the public within the meaning of Art 54(2). In other words G 1/92 applies.

    The board came to the conclusion that the contents of D 55 = “Information for the patient concerning the study 42446 02 041” have been made available to persons neither being bound by any confidentiality agreement nor being in a special relationship to the study sponsor who are thus to be classified as members of the public.

    In T 239/16, there was no apparent obligation to return unused medicaments. As soon as patients are allowed to discuss the study with anyone including their family members or their family doctor, they are members of the public.

  3. Comment - Part 2

    In T 670/20, it is an acquired fact that clinical tests of phase IIa (606 participants) and IIb (903 participants) have been carried out before the filing date as the priority was not valid.

    It happens that the proprietor is a Japanese Company and the clinical tests have been carried out in the US. See D19 and D20.

    It happens further that Japan and the USA have a grace period which is unknown in Europe.

    I see here an explanation as to why the proprietor felt secure to carry out not confidential tests as usual but went into clinical tests of phase IIa and IIb of its medicament before the priority or the filing date.

    The patients have never signed a NDA. That a NDA can be implicit is not at stake here.

    Requiring patients to sign a NDA when participating to large scale clinical test is not acceptable from an ethical point of view. If this would be the case, the reservoir of persons willing to participate to clinical homologation tests would dry out very quickly.

    With 1500 participants, simply discharging the proprietor from the proof that all medicines were consumed or returned is not really acceptable. For me, it is the fact that there is an absence of sanctions for not returning the unused medicine which is determining.

    In my opinion, a clear distinction should be made between clinical trials for the purpose of obtaining a marketing authorisation and clinical trials that follow in-vitro or animal model tests and are undertaken with a view to a subsequent filing.

    The purpose of this type of clinical trials is to demonstrate a therapeutic effect on a small scale which can later be claimed. This type of clinical trials on a very small number of patients is in no way comparable with clinical trials of phase II for the purpose of obtaining a marketing authorisation. It is manifest that these small scale trials are confidential.

    In the present case, I am thus more inclined to follow T 7/07 and T 236/19 than T 670/20.

    There is actually no need to carry out clinical tests for the purpose of obtaining a marketing authorisation before any filing. This is why there is Art 63(2,b) and SPCs.

    Doing such tests before any filing might bring about a commercial advantage, but it is risky. Divulgations by such tests cannot be fall under “non-opposable disclosures” under Art 55.

    As conclusion of his posting in Kluwer Patent Blog, Mr Bausch made the following comment: “it is unlikely that this decision will settle this question once and for all times”. One can only agree.


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