by Dennis Crouch
In this case the Federal Circuit shoots down two fairly silly arguments, but not without first giving them full credence and consideration. Although the patentee lost here, the Federal Circuit appears to agree with the patentee that its less-pure compound could have been patentable over a purer version identified in the prior art even though the added impurities provided no benefit, functionality, or synergy — PHOSITA simply would not have been motivated to make the less-pure version.
Background: The ANDA lawsuit here centers around Strathclyde’s patent (licensed to Spectrum) covering the the drug Fusilev aka l-leucovorin and Sandoz’s related generic drug application. The drug leucovorin was found to be effective at treating iron deficiency that can occur with 5-FU cancer treatment. Later, researchers discovered that it was actually one isomer of leucovorin (6S) that was effective and the other isomer (6R) was just along for the ride. The patentee here substantially purified the 6S isomer and attempted to patent it as part of a therapeutic composition. Claim 1 requires “a mixture of (6S) and (6R) diastereoisomers and consists of at least 92% by weight of the (6S) diastereoisomer, the balance of said compound consisting of the (6R) diastereoisomer.” It turns out that years earlier a researcher had manufactured a pure form of the 6S isomers and the 50/50 mixture of 6S/6R isomers was known as well. By the time of the invention in question here it was also known that the 6S isomer was the effective one. Later studies proved that the substantially pure form was clinically no better than the 50/50 mixture having the same effective amount of the 6S isomer.
A patent claim is invalid as obvious if an alleged infringer proves that the differences between the claims and the prior art are such that “the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art.” 35 U.S.C. § 103(a) (2006) (pre-AIA). Obviousness is ultimately a conclusion of law premised on underlying findings of fact, including the scope and content of the prior art, the differences between the claimed invention and the prior art, and the level of ordinary skill in the pertinent art. KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398 (2007); Graham v. John Deere Co., 383 U.S. 1 (1966). “The presence or absence of a motivation to combine references in an obviousness determination is a pure question of fact.” Alza Corp. v. Mylan Labs., 464 F.3d 1286 (Fed. Cir. 2006). In addition to common knowledge or teachings in the prior art itself, a “design need or market pressure or other motivation” may provide a suggestion or motivation to combine prior art elements in the manner claimed. Rolls Royce, PLC v. United Techs. Corp., 603 F.3d 1325 (Fed. Cir. 2010);
Here, the patented mixture could be made by simply mixing the known pure 6S isomer with the 50/50 mixture so as to reach the claimed 92% ratio. The patentee argued that there would have been no motivation to combine these references — going from a pure substance to a less-pure substance. The Federal Circuit sees merit in that argument:
[I]f the pure material is known, no reason has been shown why one would want to have an impure material. Although one may not be motivated to obtain an impure material and, in effect, it therefore can be argued to have been nonobvious—which is Spectrum’s position here, that the 92–95% pure material was nonobvious over the known pure material.
The Federal Circuit ultimately rejected that argument “despite its superficial appeal” by looking at the patent from the starting point of a 50/50 mixture – and finding that there would have been a motivation to improve its purity. The court also noted that the new mixture offered no “unexpected advantages over the prior art pure material, the less-than-pure material, and any others of similar concentration.” In essence, this case is can be seen as very much parallel to KSR – where a combination of two known elements, with each element being used as expected, is unlikely to be patentable absent some unexpected results or synergy.
Objective Post-Invention Evidence Showing Obviousness: Of interest, the Federal Circuit approved of two additional bits of evidence that occurred post-invention that helped prove obviousness. The first was evidence that several other researchers were able to obtain the 92% isomer concentration shortly after the patentee obtained its results — that appears have provided some evidence of obviousness. Secondly, the court relied upon post-invention studies showing no benefit of the pure drug to negate any synergy argument.
Infringement by Importation: A second set of claims included a limitation that the composition was provided in “a quantity at least sufficient to provide multiple doses of said mixture of (6S) and (6R) diastereoisomers in an amount of 2000 mg per dose.” Although Sandoz was planning to sell drug in single-use vials of ~200 mg per dose, the patentee argued that Sandoz did plan to import the drug in larger shipments and, at that importation would be infringing. The Federal Circuit rejected that argument – finding that the ANDA infringement inquiry under 271(e)(2) “focuses on a comparison of the asserted patent claims against the ANDA product that is likely to be sold following FDA approval.” Thus, the fact that Sandoz plans bulk-imports does not create liability.
On this front, it seems that the Federal Circuit may have left open the possibility that Sandoz imports may still infringe under 271(a) once the generic maker begins imports.
Doctrine of Equivalents: The patentee had argued for infringement under the DOE even though it had narrowed the very amount element during prosecution. Its argument was that the amendment should not count as narrowing because other claims in the patent were still broader. That argument fell on deaf ears:
[B]y claim amendments and distinguishing statements on the prior art during prosecution, Spectrum is now estopped from invoking the doctrine of equivalents to prove infringement. When submitting an amendment with the application claims that eventually issued as claims 5–9, the applicants asserted that the newly added claims “include specific limitations as to quantities of materials,” and distinguished the prior art by pointing to the “quantities of these specific mixtures specified in the claims.” Those claims were also added following an office action rejecting the previous original claims as obvious in view of Rees. The applicants again explicitly highlighted the significance of the dosage limitation during an appeal to the Board, their brief stating that the claims “require a minimum of four grams,” the “quantity limitations set forth in the claims” which “define an aspect of the invention that is of great practical significance.” The applicants unequivocally argued that Rees, which allegedly only produced experimental quantities, “do[es] not teach, suggest, or otherwise render obvious the claimed compositions in the quantity specified” in the application claims that became claims 5–9. Those statements are clear and unmistakable expressions of the applicants’ intent to surrender coverage of quantities of the compound in lower doses.
Thus, Sandoz wins here on all fronts.