American Home Products Corp & Anor v Novartis Pharmaceuticals UK Ltd & Anor

A patent claim must be construed according to its language, specification and the Protocol, not by expanding its scope to protect research which the patent does not enable. A claim to a known compound for a second medical use does not ordinarily extend to derivatives merely because some may have the same therapeutic effect. If a claim covers a class of products, the specification must disclose an enabling method across the breadth of that class. Requiring skilled persons to undertake extensive research to discover which products work is not the same as requiring ordinary skill and trial and error to perform the invention. On that basis, the claim covered rapamycin itself, not the derivative SDZ RAD.

American Home Products Corporation and Professor Sir Roy Calne, the patentee and exclusive licensees, brought patent infringement proceedings against Novartis concerning European Patent (UK) 0401747. The patent claimed the use of rapamycin to prepare a medicament for inhibiting transplant rejection.

Laddie J held that SDZ RAD, a derivative of rapamycin, fell within claim 1 and rejected an insufficiency challenge: [2000] RPC 547. Novartis appealed. The central issues were whether “rapamycin” included derivatives and, if so, whether the specification sufficiently disclosed the alleged invention.

1. The appeal was allowed, the respondents’ notice was dismissed, the order of Laddie J was set aside, and the infringement claim was dismissed. It was declared that dealing in SDZ RAD in the United Kingdom did not infringe the patent.

2. Per Aldous LJ, the word “rapamycin” denoted the known molecule throughout the specification. The specification disclosed the second medical use of rapamycin itself. Its references to derivatives did not identify any derivative shown to possess the relevant activity. The claim therefore did not extend to all derivatives or to derivatives selected by an uncodified requirement of rapamycin-like activity.

3. Applying the Protocol questions, SDZ RAD could be assumed not to have a material effect on the way the invention worked. However, it was not obvious to the skilled person that the variant would have no material effect. Whether a particular derivative worked required manufacture and testing. The third question would, in any event, be answered in favour of strict compliance with the primary meaning because the specification consistently distinguished rapamycin from derivatives.

4. If the claim were construed to include working derivatives, it would be insufficient under Patents Act 1977, section 72(1)(c). The patent enabled rapamycin, but did not disclose a unifying characteristic or method enabling the vast and uncertain class of derivatives. The skilled person would have to conduct a research programme to discover which derivatives worked and whether they had defects. That exceeded the permissible use of skill, application and ordinary trial and error.

5. The word “medicament” in the Swiss-type claim had to be construed in context as referring to rapamycin, the product described as possessing the discovered therapeutic properties. It did not include a derivative, a product retaining only part of rapamycin, or a product containing rapamycin merely as an impurity. Claim 11 was likewise not infringed.

• Court of Appeal (Civil Division): Appeal from Laddie J allowed. The judgment and order made on 6 December 1999 were set aside, the infringement claim was dismissed, and a declaration of non-infringement was made.
• Chancery Division: Laddie J held the patent infringed and rejected the insufficiency allegation: [2000] RPC 547.