When a product which has a medical use has been patented, the European Patent Convention allows the patenting of a second medical use to which that product is put. This encourages further research into existing products with beneficial applications, research that might appear unattractive if its results were unprotectable since the cost of investment in the further research would be borne by one but its fruits would be enjoyed by all. What constitutes patentable second medical use is occasionally a subject of dispute, a neat example being Actavis UK Ltd v Merck & Co Inc  EWHC 1311 (Ch), an English Patents Court decision from Mr Justice Warren yesterday, available here on BAILII. This case turns on the Patents Act 1977, s.2(6), which is derived from Article 54(5) of the European Patent Convention, Art.54(5). Under s.2(6):
"In the case of an invention consisting of a substance or composition for use in a method of treatment of the human or animal body by surgery or therapy or of diagnosis practised on the human or animal body, the fact that the substance or composition forms part of the state of the art shall not prevent the invention from being taken to be new if the use of the substance or composition in any such method does not form part of the state of the art".Merck was the owner of the patent for anti-baldness drug finasteride, which Actavis wanted to revoke. At the patent's priority date, way back in 1993, Merck sold finasteride tablets as PROSCAR for the treatment of benign prostatic hyperplasia (prostate enlargement), the conventional dose being 5mg a day, this patent apparently dating back to 1978. The disputed patent claimed the use of a low dose of finasteride for the treatment of androgenic alopecia (a condition which included both male and female pattern baldness). Merck sold finasteride tablets for male baldness as PROPECIA, the dosage being just 1mg a day. Merck also filed a patent application ('382) in 1988 for methods of treating baldness with certain compounds that included finasteride.
When Actavis applied to revoke Merck's patent it argued that, for a second medical use claim to be valid, its novelty had to be in the new therapeutic application: novelty could not, it maintained, reside in nothing more novel than a dosage scheme for treatment of the same disorder as previously treated. According to Actavis, '382 disclosed the therapeutic application - the treatment of androgenic alopecia.
Warren J agreed with Actavis and revoked the patent. In his view it was well established that second medical use claims had to have a specified therapeutic application or purpose that was not only non-obvious but which was also new. That novelty had to reside in the second or subsequent therapeutic use. He added that, having regard to the description of the underlying chemistry of '382 and its specification, there was no novelty in the use of finasteride as a possible treatment for male pattern baldness. Even if a small dosage which it was now apparent could result in successful treatment, rather than the much larger doses mentioned in '382, that was just a different dosing regime.
This decision looks right to the IPKat and appears to fall within the rule articulated by the Court of Appeal in the Taxol case, Bristol-Myers Squibb v Baker Norton here. Merpel says, this is the time for patent owners to devise effective branding and marketing strategies for their unpatentable second medical uses, since there's not much else on offer.
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