The U.S. Court of Appeals for the Federal Circuit affirmed the judgment of the district court regarding the five asserted patents. Cubist Pharmaceuticals, Inc. v. Hospira, Inc., 805 F.3d 1112, 1115 (Fed. Cir. 2015).

The asserted patents were follow-on patents directed to compositions, formulations and methods of treating bacterial infections with the antibiotic daptomycin (U.S. Patent No. RE 39,071, the ‘071 patent), dosage regimens for administering daptomycin (the dosing patents), and purification of daptomycin compositions (the purity patents).

The district court found the asserted claims of the ‘071 patent valid and infringed. The U.S. Patent and Trade Office (USPTO) issued a certificate of correction to the ‘071 patent that corrected an error in the chemical structure of daptomycin. When the original application and the reissue application for the ’071 patent were filed, it was universally believed that the asparagine amino acid in daptomycin was the L-isomer, as depicted in the ‘071 patent. Later, it was discovered that the asparagine was in fact the D-isomer. Cubist sought and obtained a certificate of correction, correcting the structural diagram of daptomycin found in the specification and claims.

Before the district court and on appeal, Hospira argued that the certificate of correction was invalid because it broadened the scope of the claims. Under Hospira’s proposed construction of the as-issued claim, Hospira would not infringe because the claim would not cover daptomycin.

The Federal Circuit rejected Hospira’s argument, noting that the specification did not rely exclusively on the erroneous structural diagram to describe daptomycin, but rather also identified the compound they were claiming in several ways, including a process to obtain daptomycin and an internal code name. Cubist established that the process necessarily resulted in, and the code name referred to daptomycin, not the L-isomer variant.

Hospira made two additional arguments that the claims as-corrected of the ‘071 patent are invalid: written description and the recapture rule. The Federal Circuit rejected both arguments. The recapture rule applies if the reissue claims are broader than the original patent claims, and the broader aspects of the reissued claims relate to subject matter surrendered in the prosecution of the original patent in order to overcome a prior art rejection. The court found the reissue claims did not violate the recapture rule because they are narrower than the original claims, and also the applicants did not surrender subject matter to avoid prior art during the prosecution of the original application.

Regarding written description, the court found the specification as a whole showed that that the inventors had possession of daptomycin, even though they may not have had an accurate picture of the entire chemical structure of that compound.

In a somewhat pyrrhic victory for Hospira, the Federal Circuit affirmed the district court’s decision that the remaining four asserted patents were invalid for obviousness. Confronted with a prior art reference that pointed to the claimed dosage regimen, Cubist relied heavily on secondary considerations evidence to support its non-obviousness arguments relating to the dosage regimen patents, but the Federal Circuit found no clear error in the district court’s analysis.

The specification and claims of the purity patents focused on two primary purification steps: micelle or aggregation filtration and anion exchange chromatography. The purity patents do not point to any additional techniques necessary to obtain the recited purity levels in the claims. The district court found, and the Federal Circuit affirmed, that it would have been obvious to use micelle filtration in view of two prior art references showing that: 1) micelle filtration could be used for the recovery and purification of most surfactants, and 2) daptomycin displays the properties of a surfactant. Anion exchange chromatography was well known in the industry as a purification technique. As it did for the dosage regimen patents, the Federal Circuit found no clear error in the district court’s analysis of secondary considerations. The court noted in particular that there was no long felt need because Lilly’s decision not to pursue its research into daptomycin was based on economic considerations, not on the absence of methods for obtaining sufficiently high purity levels.