In Sun Pharmaceutical Industries v. Eli Lilly and Co., the Court of Appeals for the Federal Circuit (CAFC) ruled U.S. Patent No. 5,464,826 (US ‘826) invalid for obviousness-type double patenting over U.S. Patent No. 4,808,614 (US ‘614). US ‘826 would have expired two-and-a-half years after the expiration of US ‘614.
US ‘614 contains claims directed to products and methods of use for treating viral infections. This patent resulted from a continuation-in-part (CIP) application where the description regarding the uses for the treatment of cancer was added when the CIP was filed. The disclosure of the parent application of US ‘614 did not contain disclosure related to the treatment of cancer.
US ‘826 resulted from an application filed on the same day as the CIP from which U.S. ‘614 resulted. U.S. ‘826 discloses and claims a method for treating cancer.
The CAFC followed its precedents holding that a claim to a method of using a product in a patent is not patentably distinct from a claim to the product in another patent in which other patent the same use is disclosed. The obviousness-type double patenting analysis for a claimed product extends to any use that is disclosed in the specification for that product. The CAFC further held that the specification that must be considered is that of the issued patent, and not the earlier application that was modified when the CIP was filed.
As such, the addition of the disclosure of uses for the treatment of cancer in the CIP, which uses were not claimed in that application, led to the invalidity of the patent providing patent protection for the method of treatment of cancer.