Merck triumphs as new and inventive dosing regimen held patentable

Actavis sued to revoke Merck's patent with a second medical use claim (in the so-called 'Swiss form') for the use of finasteride in the preparation for a drug to treat androgenic alopecia with a lower dosage than disclosed in the prior art.

The Court of Appeal reversed the High Court's decision and held the patent valid. In so doing, it effectively overturned a previous Court of Appeal precedent in relation to second medical use claims and fell into line with European Patent Office (EPO) practice.

It found that a second medical use claim need not disclose a different disease/medical condition to be regarded as novel. Swiss form claims are allowable where the novelty is conferred by a new dosage regime or other form of administration of a substance.

Background

The relevant provisions of the European Patent Convention (EPC) (which are those prior to amendment by EPC 2000) are summarised below:

Art 52(4): This states that methods of treatment or diagnosis are not patentable. However, this does not apply to products for use in any such methods.

Art 54(5): This is an exception to the usual rules in relation to novelty and states that a known substance may still be novel if it is for use in a method referred to in Art 52(4) provided that its use for any such method is novel, i.e. the first medical use of a known compound.

Actavis applied to revoke Merck's European patent in the English High Court. This concerned the use of finasteride for the preparation of a medicament for the treatment of androgenic alopecia (a type of baldness in men) wherein the dosage amount is about 0.05-1mg. Merck held a patent for finasteride itself for benign prostatic hyperplasia. The closest prior art was Merck's patent which proposed to treat androgenic alopecia with finasteride at a dosage of 5-2000mg.

The High Court had ruled that the invention was not novel and not patentable as it concerned a method of treatment. The invention was not new because the prior art disclosed the use of finasteride to treat androgenic alopecia at a higher dosage. The only new aspect was the lower dosage regimen.

The judge had held that the lower dosing regimen itself was inventive. Evidence showed that at the priority date, a skilled person would have considered finasteride to be ineffective for the treatment of androgenic alopecia, and so would not have made further investigations into better dosing regimens.

However, he felt himself bound by a previous Court of Appeal authority - the Bristol Myers Squibb case (BMS) - which appeared to say that a new dosing regimen could not render a patent novel and that the treatment of a new disease had to be disclosed for a second medical use claim to be valid. Furthermore, the BMS case held that a claim concerning a new dosing regimen was a method of treatment and thereby excluded from patentability. Merck appealed and Actavis cross appealed on obviousness.

Outcome

The crucial question in Merck's appeal was whether a new dosing regime could render a Swiss form claim novel, and if so, whether such an invention would be unpatentable because it was a method for treatment.

EPO case-law on second medical use – Eisai and Genentech

In the EPO case of Eisai (G5/83), the Enlarged Board of Appeal held that "the use of a known compound X in the manufacture of a medicament for a specified new and inventive therapeutic application Y" is patentable. These types of claims are called 'Swiss form' claims. Such a claim will not fall foul of either Article of the EPC cited above. It qualifies as being new from the new therapeutic application, and it is not a method of treatment as the claim goes to the manufacture of the substance.

In the EPO case of Genentech T1020/03, the Enlarged Board interpreted Eisai as holding that "any specified new and inventive therapeutic application" could extend to new dosage regimes, even for treating the same disease using the same substance at a different dosage.

UK case-law on second medical use – BMS

The English courts have allowed Swiss form claims since 1985. However, they have diverged from the EPO's position (or at least prior to the Merck case it was thought that they had diverged) by only allowing Swiss form claims if the specified new and inventive therapeutic application is a different medical indication to that already known.

They have disallowed claims to new dosage regimes for the same disease. The authority for this is the BMS case, the patent in which concerned a claim for the use of taxol for making a medicament to be used in a particular dosing regime for treating cancer whereby the dosing regime reduced a side effect of the drug. The prior art disclosed the use of taxol for treating cancer.

In Actavis v Merck, the Court of Appeal analysed the BMS case. It held that the court in BMS had decided that the taxol claim was a method of treatment because (unlike the claim for finasteride) it covered a patient specific dosage, usually formulated by doctors. However, the court noted that the EPO would, in any event, disagree with the reasoning in the BMS case as it considered that any Swiss form claim by its nature stops short at claiming a method of treatment [our emphasis].

Importantly, the court held that rather than follow its own BMS case, it should follow the interpretation of Eisai as set out in Genentech and allow Swiss form claims to dosing regimes. This was justifiable as new and better dosing regimes are desirable and should be patentable if they are inventive.

Although in this case, the court upheld the High Court's finding that the dosing regime was inventive, it commented that a claim for a new dosing regime would be usually invalid for obviousness as investigations into the best dosing regimes would be standard practice.

Comment

This decision has been long awaited by the patent practitioners and innovator pharmaceutical companies as it finally brings the UK's practice in relation to Swiss form claims in line with the EPO. If work has been done leading to a new and inventive dosing formulation/regimen, it should be patentable.

However, under EPC 2000 which came into force at the end of last year, Swiss form claims are no longer necessary. Claims in the form of "substance X for the treatment of disease Y" are now allowed for second medical uses. Nevertheless Swiss form claims can still be applied for under EPC 2000 and are also the subject of pending applications. The interpretation of Swiss type claims under EPC 2000 has now been referred to the Enlarged Board of Appeal in the case of Kos Life Sciences T1319/04, so the saga continues.

Finally, the Merck case raised an interesting question as to whether the Court of Appeal was bound by its previous BMS decision, even if it ran contrary to the settled position in the EPO. Find out more by reading Wragge & Co's analysis of this important point of law.

This analysis was co-written by Seiko Hidaka and Dr Luke Kempton.