Résumé de EPC2000 Art 056 pour la décision T1126/19 du 21.07.2023

In T 1126/19 the patent was directed to new polymorphic forms of rucaparib salts. Rucaparib is used in cancer therapy to potentiate the effect of radiotherapy or cytotoxic drugs which cause DNA damage. The invention was based on the finding that crystalline rucaparib camsylate was particularly suitable for the preparation of solid dosage forms due to its physical stability and low hygroscopicity. The closest prior art was D1, which disclosed a list of about 60 pharmaceutically acceptable salts of rucaparib that could be used in therapy, including camsylate, although the preferred salts were phosphate and gluconate. Starting from the list of pharmaceutically acceptable salts in paragraph of D1, the subject-matter of claim 1 differed in the selection of camsylate as the rucaparib salt and the additional requirements that the salt be crystalline and show three specific PXRD peaks. The board stated that the starting point should be the whole list rather than the specific option of the camsylate salt. As explained in decision T 970/00, the disclosure of the closest prior art had to be considered on the basis of its technical information, without distorting or misrepresenting it by the knowledge of the invention. D1 neither illustrated the camsylate salt of rucaparib nor presented it as a standalone embodiment; camsylate was one among a long list of possible options, but not among the preferred ones. The board held that the isolation of one of the non- preferred options would distort the teaching of D1, putting an inappropriate weight on that option. The board found the objective technical problem to be the provision of a solid form of rucaparib having a suitable combination of properties for development into a solid dosage form. The board was satisfied that the subject-matter of claim 1 solved this problem. On the issue of obviousness, D1 did not deal with the formulation of solid forms of rucaparib. It contained no teaching on whether any of the salts in the long list therein might possibly be suitable for preparing an oral solid formulation. The skilled person would have needed to study each of the salts for assessing: first, whether they were solid; second, how many solid forms they could adopt; and third, whether there were forms with properties suitable for a solid formulation. The board noted it was common general knowledge that finding a salt of an active compound which has a balance of properties making it suitable for an oral solid formulation was generally a difficult semi-empirical task which required non-routine experimentation and had an uncertain outcome. The board did not find a pointer to the salt of claim 1 in any of the combination documents cited by the appellant-opponent either. The board accepted the argument that D3 and D35 showed it was common general knowledge that crystalline forms were less hygroscopic and more stable than amorphous forms, and that searching for stable solid forms was part of the development of solid oral dosage forms. However, starting from the list of salts in D1, it went beyond routine work to find whether any of the listed salts, if at all, exhibit the set of properties required for solid oral dosage forms. The board distinguished T 777/08, in which the skilled person started from the amorphous form a drug, and T 41/17, in which the skilled person started from a known crystalline form of sorafenib tosylate. These situations were not comparable with the one at hand, in which the skilled person had to start from a long list of possible salts. Thus the board found the salt of claim 1 involved an inventive step and claim 1 met the requirements of Art. 56 EPC.