7.4. Factors contributing to a finding of undue burden

In T 187/93 there were experimental uncertainties in the patent application. The board found that the skilled person, when trying to obtain the same technical effect with a different glycoprotein would have experienced lack of predictability, which amounted to an undue burden.

In T 2006/08, although no experimental details were provided for factor IX in the patent-in-suit, the board considered that no undue experimentation would be required to carry out the method steps. It was plausible that the claimed process achieved an improvement of the in vivo function of factor IX. The requirements of Art. 83 EPC were fulfilled.

Similarly, in T 727/95, the board found that the invention relied too much on chance. The claimed subject-matter included a "microorganism designated Acetobacter and having the ability of microorganisms [...]". The board observed that by including the phrase "having the ability of", the claim covered not only Acetobacter microorganisms derived from the deposited strains, but also Acetobacter microorganisms which had the stated characteristics in common with the deposited strains. In the board's judgment, finding other stable, cellulose high-producing Acetobacter strains in nature was a chance event, and relying on chance for reproducibility amounted to an undue burden in the absence of evidence that such chance events occurred and could be identified frequently enough to guarantee success. The board concluded that the claim was not repeatable without undue burden over the entire breadth of the claim.

The claimed subject-matter in T 639/95 concerned a method for producing PHB biopolymers in a host transformed with genes encoding the enzymes ß-ketothiolase, acetoacetyl-CoA reductase and polyhydroxy butyrate (PHB) synthetase. The board found that the experimental plan for identifying and isolating the PHB gene was very general. Some references were missing and/or incomplete. There were no results and no details which could facilitate the repetition of the work. The board thus held that the total amount of experimental effort necessary amounted to an undue burden for the skilled person.

However, in T 412/93, where errors and omissions prejudiced the reproducibility of one of the examples in toto and of another example in part, the reproducibility of the invention was not affected, as the examples were alternatives to previous ones.

In T 612/92, further scientific research would have been necessary in order to carry out the invention in some of the areas claimed. The board held the requirements of Art. 83 EPC 1973 were not fulfilled because there were serious doubts as to whether such a method could be performed over the whole range that was claimed (see T 694/92, OJ 1997, 408).

However, in T 223/92 the disclosure enabled those skilled in the art to reproduce the invention, possibly in a time-consuming and cumbersome way, but, in the given circumstances, without undue burden of experimentation and without needing inventive skill (see also T 412/93).

T 1456/06 concerned the level of disclosure required for enablement of a claim directed to peptide vaccines. It was apparent from the prior art that the development of peptide-based vaccines to treat cancer – the sole specific type of vaccine mentioned in the application as filed – was not only extremely laborious, but also fraught with uncertainties. The application as filed did not disclose any telomerase peptide which might – plausibly – be regarded as a suitable candidate for a vaccine, nor did it contain either technical information as to how to identify possible candidate peptides, or instructions on how to proceed in case of failure. The board concluded that identifying immunogenic fragments of the telomerase protein suitable for the manufacture of a vaccine by a trial and error procedure constituted an undue burden to a person skilled in the art.

The application in T 1364/08 concerned viruses for the treatment of cellular proliferative disorders. It provided no experimental data proving that the claimed adenovirus was able to replicate in cells having an activated Ras-pathway but not in normal cells. No data was present demonstrating that such a virus could be useful for the treatment of Ras-mediated cell proliferative disorders. However, based on what was described in the application as filed and taking into account what was known in the prior art, it was credible that the modified adenovirus specified in the claim would have been effective for the treatment of Ras-mediated cell proliferative disorder. Post-published evidence could therefore be taken into account to back up this evidence (following T 609/02).

In T 1846/10 the invention under consideration related to the preparation of a live vaccine against L. intracellularis which relied on the use of attenuated L. intracellularis bacteria. L. intracellularis is the causative agent of proliferative enteropathy in pigs, also known as porcine proliferative enteropathy (PPE). To be suitable as a live vaccine strain, the attenuated bacteria must fulfil the following three criteria: (i) apathogenicity, which means that they do not cause the disease; (ii) be suitable and retain immunogenicity, which means that they induce protective immunity in the animal host, and (iii) genetic stability, which means that they do not revert to being pathogenic or conversely become too attenuated. This was undisputed among the parties.

The skilled person, wanting to carry out the claimed invention, could not rely on his common general knowledge or the prior art to obtain suitable attenuated L. intracellularis bacteria. The patent had to provide the necessary guidance for the successful implementation of the claimed invention. The board concluded that the guidance provided by the patent did not allow the skilled person to obtain an attenuated L. intracellularis strain without undue burden or inventive step.

The skilled person was taught by the patent that he had to test the passaged strain, but only to confirm attenuation. The L. intracellularis strain suitable to carry out the invention not only had to be less virulent than the corresponding wild type strain, but also had to fulfil the additional two criteria of appropriate immunogenicity and genetic stability. Relying on the guidance provided by the patent and not knowing why the strain used in example 5 did not protect the vaccinated animals he would have had no reason to assume that the number of passages had to be increased. The person skilled in the art would not be inclined to consider the intervals disclosed in the description of the patent as mere lower limits but would have understood these indications as concrete ranges. The board concluded that example 5 of the patent represented evidence that the skilled person, by following the guidance of the patent, would fail to obtain an attenuated strain of L. intracellularis suitable for the preparation of a live vaccine.

In T 1376/11 the board concluded that the only way disclosed in the application to arrive at the paprika plants of the invention started from parental Capsicum annuum NM varieties, such as Capsicum annuum NM 1441. The public availability of these parental plants at the priority date of the application was therefore a mandatory requirement for the skilled person to reproduce the invention. In the absence of evidence that Capsicum annuum NM 1441 was publicly available, the board concluded that the application did not disclose the subject-matter of claim 1 in a manner sufficiently clear and complete for it to be carried out by the skilled person.