The Salk Institute for Biological Studies v Karo Bio and Astra (EPO, T 609/02, 2004)

Dhenne Avocats · 11 October 2026

Our analysis

Summary

Technical Board of Appeal 3.3.08 of the EPO held that a Swiss-type therapeutic use claim was insufficiently disclosed under Article 83 EPC where the patent offered no more than a vague indication of a possible medical use for a compound yet to be identified. Evidence published after the effective date cannot remedy such a fundamental insufficiency. The decision requires the application to make the claimed therapeutic effect plausible, through information such as tests showing a direct effect on a mechanism involved in the disease, and confines later evidence to backing up such data.

Facts and procedure

The Salk Institute for Biological Studies held European patent EP 0 552 202, “Methods mediated by the proto-oncogenic protein complex AP-1”. On oppositions by Karo Bio AB and Astra AB, the Opposition Division, by interlocutory decision of 12 April 2002, maintained the patent in amended form without the use claim it found insufficiently disclosed. The proprietor, sole appellant, filed at the hearing on 27 October 2004 a new claim 6 to the use of a steroid hormone or analogue, identified by the method of claims 1 to 5, for the preparation of a pharmaceutical for the treatment of AP-1 stimulated tumour formation, arthritis, asthma, allergies and rashes. The respondents did not attend.

The applicable law

Article 83 EPC requires the invention to be disclosed in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art. Where a therapeutic application is claimed in the form allowed by G 5/83, attaining the therapeutic effect is a functional technical feature of the claim, within the meaning of G 2/88 and G 6/88 (point 9).

Question

Is a therapeutic use claim sufficiently disclosed where the patent provides no data on the claimed effect and that effect is established only by publications after the effective date?

Decision

As the proprietor was the sole appellant, the claims maintained by the Opposition Division could not be challenged, under G 9/92; only claim 6 was open to review (point 1). It complied with Article 123(2) and (3) EPC (point 2), and the Board did not decide the so-called “reach-through” issue (point 3). The patent contained no evidence relating to claim 6: no steroid hormone was identified, and no data linked such a compound to the diseases listed, the only reference being a general passage in the description (point 5). The proprietor relied on documents OD19, OD22 and OD23, published in 1994 and 1995 (points 6 and 7).

The Board rejected the argument: sufficiency must exist at the effective date, on the basis of the application and common general knowledge, otherwise a patent would be granted for an invention made later (point 8). Although clinical or animal results are not always required, a mere verbal statement that a compound may treat a disease is not enough; the patent must provide some information, for example experimental tests, showing that the compound has a direct effect on a metabolic mechanism specifically involved in the disease, an in vitro effect sufficing if it directly and unambiguously reflects the therapeutic application (T 241/95, T 158/96); post-published evidence may only back up such findings (point 9). Such tests make the cause and effect relationship plausible (point 10). Absent any data at the effective date, claim 6 amounted to no more than an invitation to set up research programmes (point 11), and the years of later research, possibly involving inventive step, reflected an undue burden (point 12). The appeal was dismissed.

Key points for practice

• Sufficiency of a therapeutic use is assessed at the effective date, on the basis of the application and common general knowledge (points 8 and 13).
• A verbal statement of medical use is not enough: the application must make the effect plausible, for instance through tests on a mechanism involved in the disease (points 9 and 10).
• Post-published evidence may confirm data present in the application but cannot make up for their absence (points 9 and 13).
• Practical point: include at filing data, even in vitro, linking the compound to the mechanism of the target disease, failing which the medical use claim is exposed to an insufficiency objection.

Provisions applied

European Patent Convention

Art. 83, 123(2) and (3)

Case law cited

G 5/83; G 2/88; G 6/88; G 9/92; T 409/91; T 241/95; T 158/96

Related decisions

• Eisai, G 5/83, EPO Enlarged Board of Appeal, 5 December 1984, origin of the therapeutic use claim format examined.

Prepared by Dhenne Avocats from the text of the decision (epo.org, official English text), consulted on 11 October 2026. Only the official text is authoritative.