Introduction
In proving a patent invalid (or infringed), all claim limitations must be considered. A recent case illustrates this maxim for both derivation under 35 U.S.C. § 102(f) and obviousness under 35 U.S.C. § 103.

Background
Cumberland’s patent covers Acetadote®, a stable pharmaceutical composition of acetylcysteine free of chelating agents, which is used to treat overdoses of acetaminophen. Id. at 2. The prior art taught that acetylcysteine in aqueous solution had stability issues that were overcome by inclusion of sodium edetate (“EDTA” or “Edetate”), a chelating agent that was well known to bind heavy metal ions. Id. at 2-3. The prior art also taught that acetylcysteine compositions containing EDTA were safe, although they had potential negative side effects in patients. Id. at 3.

In 2002, Cumberland sought FDA approval for a formulation of acetylcysteine that contained EDTA. Id. at 3. During this approval process, the FDA requested that Cumberland “[p]rovide scientific and regulatory justification for the inclusion of Edetate as a component in the drug product.” Id. In a subsequent telephone call, the FDA reiterated that Cumberland was required to provide data supporting the inclusion of Edetate in the formulation. Id. at 3-4. After sending a letter to the FDA noting that EDTA was needed to stabilize the formulation, the inventor devised the idea to test the stability of a formulation that did not contain EDTA. Id. at 4. The inventor notified FDA of his idea, and FDA asked that Cumberland put the proposal for testing in writing. Id. at 4-5. Cumberland’s proposal stated that the future studies would investigate how decreasing and removing Edetate from the formulation would impact the stability of the drug product. After obtaining promising stability data, the inventor applied for the patent at issue. Id. at 5-6.

The Invention was Not Invalid as Derived from Another
Mylan argued that Cumberland’s patent was invalid as the claimed invention had been derived from someone at the FDA based on the FDA’s questioning of the need for Edetate. Id. at 7. An applicant is not entitled to a patent if “he did not himself invent the subject matter sought to be patented.” 35 U.S.C. § 102(f) (2006). Proving that an inventor derived the claimed invention from another requires proof of “prior conception of the claimed subject matter and communication of the conception” to the named inventor. Cumberland, slip op. at 8 (citing Price v. v. Symsek, 988 F.2d 1187, 1190 (Fed. Cir. 1993)). The Court further noted that conception must cover all limitations of the claimed invention. Id.

The Federal Circuit affirmed the district court’s holding that there was no prior conception by the FDA, and therefore no derivation. As the relevant claims require a “stable” composition that is “free of chelating agents,” conception of the claimed subject matter required “the specific idea to remove EDTA from Acetadote® (or a similar product that met all the other ‘445 claim elements) and not add another chelating agent” to achieve stability. Id. at 8-9. The Court stated that the FDA communications regarding its “request for justification of the inclusion of EDTA, supported by data, is not the same as a suggestion to remove it, let alone to remove it and not replace it with another chelating agent.” Id. at 10. In addition, the Court rejected Mylan’s argument that the FDA communications inevitably led to the relevant invention, noting that “derivation is not proved by showing conception and communication of an idea different from the claimed invention even where that idea would make the claimed idea obvious. Id. at 10-11. “The kind of general research suggestion at issue here, whatever its role in an obviousness analysis, does not establish the conception required for derivation.” Id. at 11. Thus, the Court approved the district court’s reasoning that there was no derivation because the idea of an aqueous acetylcysteine formulation containing a chelating agent other than EDTA—which would satisfy the FDA’s requirement for reducing or removing EDTA—did not satisfy the free-of-chelating-agents claim element, which each patent claim requires. Id. at 13.

The Invention was Not Invalid as Obvious
Mylan also argued that Cumberland’s patent was invalid as obvious based on, inter alia, two communications from the FDA, which Mylan alleged “motivates removal of EDTA by stating Cumberland’s commitment to study EDTA’s role.” Id. at 14-15. To prove obviousness, a party must demonstrate that “a skilled artisan would have been motivated to combine the teachings of the prior art references to achieve the claimed invention, and that the skilled artisan would have had a reasonable expectation of success in doing so.” Id. at 15 (citing Kinetic Concepts, Inc. v. Smith & Nephew, Inc., 688 F.3d 1342, 1360 (Fed. Cir. 2012)). The Court affirmed the district court’s reasoning that “the prior art taught that EDTA or another chelating agent was necessary to stabilize the [acetylcysteine] formulation,” such that a person or ordinary skill in the art “would not have reasonably expected a chelating-agent-free intravenous acetylcysteine formulation to succeed in being stable, a claim requirement.” Id. at 16 (internal citations omitted). The Court noted that persons of skill in the relevant art (and Mylan’s own scientists) believed that even if EDTA was suggested as unnecessary, another chelating agent was still needed to ensure the formulation’s stability, as required by the claims. Id. at 16-17.

Conclusion
When determining whether a patent claim is valid or invalid, the Cumberland case makes clear that one must consider all claim limitations recited in the subject claims.