On 27 March 2019, the Supreme Court handed down its judgement in Actavis v ICOS1, unanimously agreeing with the Court of Appeal that ICOS’ patent to a new dosage regime for tadalafil lacked inventive step.


The claims on which the judgement focussed were directed to a composition comprising 1 to 5mg tadalafil in a unit dosage form suitable for oral administration up to a maximum total dose of 5mg per day for use in treating a sexual dysfunction (and the Swiss-style equivalent).

The most relevant prior art, “Daugan”, taught the use of tadalafil for the treatment of erectile dysfunction. Daugan explained that doses will generally be in the range of 0.5mg to 800mg/day. Examples included a 50mg tablet.

At first instance, Mr.Justice Birss found the claims to be non-obvious, largely on the grounds that the 5mg dose would not have been tested with a reasonable expectation of success.

The Court of Appeal disagreed. Whilst the judges conceded that the skilled team would find the efficacy of the 5mg dose to be “rather surprising”, they found that this was not enough for the patent to be considered inventive, given routine nature of the research that resulted in the unexpected discovery.

A more detailed discussion of the Court of Appeal’s decision can be found here.

The decision

The Supreme Court unanimously agreed with the Court of Appeal that ICOS’ patent to a new dosage regime for tadalafil lacked inventive step.

In coming to their judgement, the Court acknowledged the so-called “patent bargain”, whereby an inventor obtains a monopoly in return for disclosing the invention and dedicating it to the public for use after the patent has expired. This principle was confirmed in Agrevo2, in which it was stated that the extent of the patent monopoly should correspond to, and be justified by, the technical contribution to the art.

The Court went on to compare the EPO and UK approach to inventive step and concluded that neither approach should be applied in a mechanistic way. Rather, a fact-specific approach should be taken. With all this in mind, the Court set out 10 factors which were held to be relevant considerations in the present case:

  1. whether something was “obvious to try”;

  2. whether the research was routine in nature;

  3. the burden and cost of the research programme;

  4. the necessity for and the nature of value judgements during a research programme;

  5. the existence of alternative or multiple paths of research;

  6. the motivation of the skilled person to undertake certain tasks;

  7. whether the results of the research were unexpected or surprising;

  8. the need to avoid hindsight;

  9. whether the feature of the claimed invention is an added benefit in the context in which the claimed invention is obvious for another purpose; and

  10. the fact that there is no blanket prohibition on dosage regime patents, but that there has been relaxation in the rules in relation to the assessment of the inventive step of these patents.

In this case, the Court conceded that the efficacy of the 5mg dose was unexpected and that a value judgement was required to characterise a minimum effective dose.

However, the Court considered that the relevance of these factors, in addition to the burden and cost of the research, was undermined by the routine nature of the research that resulted in the discovery. It was established that skilled team would consider investigating both on-demand dosing and daily dosing and that, in respect of the latter, the first dose ranging study would include 25mg, 50mg and 100mg doses. Given the results of these tests, which showed a therapeutic plateau, it was considered highly likely that a skilled team would investigate lower doses (including 5mg) to fully ascertain the dose response relationship. Without this, the purpose of the Phase IIb trials would not have been fulfilled. As a result, the decision to test the 5mg dose was, as one witness stated, a “no brainer”.

Furthermore, the fact that this dose had unexpectedly reduced side effects was considered an added benefit which does not prevent the identification of the 5mg dose as the appropriate dose from being obvious.

It is clear that dosage regimes are not excluded from patentability per se in the UK. Following this judgement, several different factors will be considered when determining whether a dosage regime is inventive, while the weight given to each factor will vary depending on the facts of the case.

While the list of factors to be considered appears lengthy, a closer look suggests that, in most cases, the question of whether a new dosage regime is inventive is likely to turn on just a few of them.

Factor 1 (“obvious to try”) would not appear to be a separate consideration, but rather one that is closely linked to several other factors (in particular factors 2, 5 and 7). Factor 3 (burden and cost) would appear to be more of a policy consideration behind allowing the patenting of dosage regimes in principle. It seems unlikely, if ever, that this will be a deciding factor in whether a dosage regime is inventive. Factor 6 (motivation) would always seem to be present for dosage regime patents, as the Court considered it standard practise to investigate appropriate dosage regimes for a known drug, which would normally include the minimum effective dose. Factor 8 (hindsight) relates to a mindset to be avoided when considering inventive step, rather than a specific factor to be assessed. Factor 10 simply confirms that there is no blanket prohibition to dosage regime patents.

The remaining factors would appear to be those around which most arguments for and against the inventive step of dosage regimes will turn. In order to be considered inventive, it would seem to be essential that the results are surprising or unexpected (factor 7) and that the feature of the claimed invention is not merely an added benefit in the context in which the claimed invention is obvious for another purpose (factor 9).

Assuming that these two requirements are met, discussion is then likely to turn to remaining factors; whether the research was routine (factor 2), the necessity for and the nature of value judgements during a research programme (factor 4) and the existence of alternative or multiple paths of research (factor 5). The Court’s comments imply that the weight each of these factors will be given will vary depending on the circumstances.

If the dosage regime was discovered using the routine experimentation, following the standard procedures used to establish a dose response curve, this judgement suggests it is unlikely ever to be considered inventive in the UK. The Court held that it would be obvious to make a product “if the step by step approach, without the benefit of hindsight, demonstrates that the skilled team would be very likely to pursue the tests to the point at which they would ascertain the product or process falling within the claims”.

However, if the dosage regime was not discovered in this way, or if there were alternative paths of research and significant value judgements had to be made to arrive at the invention, then the dosage regime may yet be considered inventive.

Aside from the question of obviousness, the Court also answered several further questions.

The Court confirmed that an appellate court has the power to overturn the first instance judgement only if there has been an error of principle, and that an appellate court ought not to interfere unless it is satisfied that the judge’s conclusion is outside the bounds within which reasonable disagreement is possible.

The Court also noted that judgements of foreign jurisdictions were not “particularly helpful” due to differences in evidence and the manner in which that evidence is tested.

Finally, the Court provided reassurance that the judgement of the Court of Appeal in this case should not be construed to mean that the result of any routine investigations cannot lead to a valid patent claim. In particular, they confirmed that this judgement does not mitigate against selection patents and improvement patents merely because their discovery involved well-known research tests. The Court stated that selection patents will still be considered inventive if the selection is not arbitrary and is justified by a hitherto unknown technical effect, while an “improvement” in the context of patent law is “in the most technical sense….an invention which comes within the claims of an earlier patent but contains a further inventive step”. It remains to be seen the extent to which parties will seek to apply the present decision to patents outside the realm of dosage regime patents.