Zusammenfassung von Article 087 EPC für die Entscheidung T1555/23 vom 14.11.2025

In T 1555/23 the patent related to the medical use of chimeric antigen receptor-modified T cell (CAR T cell) products for cancer therapy in combination with IL-6 inhibitors for toxicity management. The appellants argued that the subject-matter of claims 1 and 5 was not entitled to the priority of the first priority document (P1). The board recalled that assessing the requirement of the "same invention" within the meaning of Art. 87 EPC was based on the determination whether the subject-matter claimed could be derived by the skilled person directly and unambiguously, explicitly or implicitly, using common general knowledge, from the previous application as a whole (G 2/98). For the subject-matter of further medical use claims, this entailed assessing whether the priority (or previous) application at the date of its filing rendered it credible that the known therapeutic agent was suitable for the claimed therapeutic application (see e.g. T 843/03). This was consistent with the general teaching in G 1/03 that the process of making the invention has to be completed when an application for a patent is filed. Appellants II and III argued that the subject-matter of claim 1 was not directly and unambiguously derivable from P1. Their reasoning was essentially based on an interpretation of current claim 1 in which no causal link between the monitoring step and the second-line therapy existed. Such a method without a causal link was not disclosed in P1. Appellant II further argued that P1 did not disclose the general use of a single cytokine inhibitory therapy for managing toxicity resulting from CAR T cell infusion. The board disagreed. Claim 1 did not refer to the general use of a (or any) single cytokine inhibitory therapy but rather to IL-6 as the cytokine to be monitored and inhibited when its level was increased. Claim 1 also included a causal link between the result of the monitoring, i.e. increased IL-6 levels, and the administration of an IL-6 inhibitor as a second-line therapy. As also pointed out by the respondents and acknowledged by the opposition division, a basis for IL-6 as the cytokine to be monitored and inhibited when its level is elevated could be found in several passages in P1. A further basis for this subject-matter could be found in claims 1 to 4 of P1. P1 further disclosed: "(CAR) in combination with toxicity management, where a profile of soluble factors from a post T cell infusion patient is generated and a therapy directed against the elevated soluble factor is carried out in order to treat the cancer" and "second-line of therapy appropriate to treat the patient as a consequence of the first-line of therapy". Thus, according to the board, the subject-matter of claim 1 was directly and unambiguously derivable from the disclosure of P1. Claim 5 required the second-line therapy to be tocilizumab. Appellants II and III also argued that this subject-matter was not directly and unambiguously derivable from P1. The board concluded that the skilled person would have derived directly and unambiguously that the IL-6 inhibitory compound tocilizumab was a preferred embodiment of the cytokine inhibitory therapy disclosed in claims 1 to 5 of P1, i.e. the same invention as in current claim 5. The appellants further contended that the invention as claimed was not enabled in P1 over its whole breadth, raising several objections, none of which were found convincing by the board. For example, the appellants argued that P1 did not disclose that a single agent, i.e. an IL-6 inhibitory compound, was capable of managing the toxicity arising from CAR T cell treatment and that the document only contained assertions to this effect, while the experimental evidence in Figure 9 was not conclusive. The board noted that, in this context, the relevant question was whether P1 made it credible that tocilizumab was effective in managing toxicity of CAR T cells. The board disagreed with the appellant’s contention that the document only contained assertions to that effect which, in accordance with T 609/02, might not represent sufficient evidence for a therapeutic effect. In the current case, a clinical trial had been conducted, albeit with only one or two patients, and the inventors drew conclusions from it. The board therefore considered the teaching of P1 sufficient to make it credible that the toxicity of CAR T cell therapy could be managed with a single agent. The board concluded that the invention to which claims 1 and 5 related was disclosed in an enabling manner in P1 and, therefore, the claims enjoyed priority from P1.