Article by Dr. Frederick Chen
A recent decision of the Patents Court highlights what appears to be an important gap between European Patent Office (EPO) jurisprudence on second medical use and the approach of the English courts.
Merck & Co., Inc. (Merck) is the proprietor of a number of patents related to a drug called finasteride. Finasteride is the active pharmaceutical ingredient in a product called PROPECIA, a 1 mg/day tablet of finasteride for the treatment of male pattern balding. Male pattern balding is believed to be caused by dihydrotestosterone, which is produced from testosterone by the activity of the enzyme 5α-reductase. Finasteride blocks the activity of this enzyme.
Actavis UK Limited (Actavis) sought to revoke the patent under which PROPECIA is sold (Actavis UK Limited v Merck & Co., Inc. [2007] EWHC 1311 Ch). This disputed patent claimed, in the so-called “Swiss-type” form, the use of low dose (0.05 to 1 mg/day) finasteride for the preparation of a medicament for oral administration useful for the treatment of androgenic alopecia (a condition including both male and female pattern baldness).
At the priority date of the disputed patent, October 1993, Merck was already marketing a product called PROSCAR, a 5 mg/day tablet of finasteride for the treatment of a condition known as benign prostatic hyperplasia (prostate enlargement) under an earlier patent. The specification of the earlier patent disclosed the treatment of androgenic alopecia with finasteride, but at a much higher dosage than claimed in the disputed patent.
Actavis’ grounds of invalidity were that the claims in the patent in suit were (1) a method of treatment; and (2) obvious in light of the prior art and common general knowledge. In relation to the first ground, Actavis argued that for a “Swiss-type” (or second medical use) claim to be valid, it needed to be directed to the use of a substance for the manufacture of a medicament for a specified new and inventive therapeutic application. In particular, following Bristol Myers Squibb v Baker Norton (2000) ENPR 230, a new dosing regimen for the treatment of a previously disclosed disorder would not confer novelty.
Mr Justice Warren agreed with Actavis’ submission that Merck’s earlier patent had disclosed the therapeutic application, i.e. treatment of androgenic alopecia, and that there had been no novelty in the use of finasteride as treatment for androgenic alopecia, only in its reduced dosing regimen. The judge held that although it may be novel to use finasteride in the small dosage which it was apparent could result in successful treatment (rather than the much larger doses mentioned in Merck’s previous patent), that was simply a different dosing regime and thus precisely the same as the situation disclosed in Bristol-Myers. The judge was bound by Bristol-Myers and revoked the patent on that basis. Actavis, however, failed in its case on inventive step: the judge found that the invention was not obvious.
The Bristol-Myers case purports to follow EISAI/Second Medical Indication [1985] OJEPO, 64, in which it was held by the Enlarged Board of Appeal that European patents could be granted containing claims in the Swiss style and that such claims would not fall foul of Article 52(4) of the European Patent Convention. In the more recent EPO case of T1020/03 Method of administration of IGF-1/Genetech Inc. (29 October 2004), however, the Technical Board decided that cases that purported to follow EISAI, but which placed limits on the circumstances in which Swiss style claims could be obtained, and in particular which held that Swiss style claims to dosing regimens were contrary to Article 52(4), wrongly interpreted EISAI. At least six EPO cases have since cited T1020/03, none with disapproval. Since both Merck and Actavis have leave to appeal, it will be interesting to see whether the English courts will now address the question of what is patentable second medical use.
This article is intended merely to highlight issues and not to be comprehensive, nor to provide legal advice. Should you have any questions on issues reported here or on other areas of law, please contact one of your regular contacts at Linklaters.