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In its decision X ZR 165/23 (Fampridin-SR), the German Federal Court of Justice (FCJ) further clarified the requirements for novelty and inventive step in the context of second medical use claims.

The case concerned EP 1 732 548, which relates to a sustained-release formulation of 4-aminopyridine (fampridine) for increasing walking speed in patients with multiple sclerosis. The claimed treatment involved a stable dosage of 10 mg administered twice daily.

The prior art already disclosed the use of fampridine in multiple sclerosis patients, sustained-release formulations, and clinical studies investigating similar dosages. It also referred to an ongoing clinical study evaluating walking speed as a primary endpoint. The Federal Patent Court had declared the patent invalid, holding that the claimed dosage regimen was disclosed in the prior art and that the therapeutic effect would inevitably result from its administration.

The FCJ disagreed and dismissed the nullity action. Regarding novelty, the Court reaffirmed that a therapeutic effect is novelty-destroying only if it is directly and unambiguously derivable from the prior art. Mere expectations, assumptions, or indications that a therapeutic effect may occur are insufficient. Although the prior art described a promising clinical study, it did not disclose results demonstrating the claimed improvement in walking speed.

The Court also provided important guidance on inventive step. According to the Court, a research path is obvious only if the skilled person would have pursued it with a reasonable expectation of success. This assessment must take into account the specific circumstances of the case, including the incentive to follow a particular approach, the required effort, and available alternatives. Importantly, the Court held that this assessment may also consider obstacles that would have emerged had the skilled person actually pursued the proposed path. In the present case, the referenced clinical study ultimately failed to achieve statistically significant results under its original study design, indicating that the route suggested by the prior art did not, in fact, provide a reliable path to the claimed invention.

The decision confirms that neither novelty nor inventive step can be denied merely because the prior art creates an expectation that a therapeutic effect may exist. Rather, the effect must either be clearly disclosed or obtainable through a path that the skilled person would have pursued with a reasonable expectation of success.