By Dennis Crouch
Santarus and the University of Missouri v. Par Pharma (Fed. Cir. 2012)
My employer (University of Missouri) owns several patents covering formulations of omeprazole proton pump inhibitors (PPIs). The patents are exclusively licensed to Santarus who markets the drugs under the brand Zegerid®. Par filed its request to make a generic version which prompted this infringement litigation.
The inventor, Dr. Jeff Phillips is a pharmacist at MU had the simple idea of combining omeprazole with baking soda (sodium bicarbonate). The baking soda helps the drug resist stomach acids long enough to be absorbed in the stomach wall. Although not a blockbuster drug, the approach has been successful for many patients with GERD and Santarus sales are about $40 million per year. (The reported deal is that MU receives about 5% of sales. As the inventor, Phillips receives a small cut from that.)
During litigation the patents were successfully attacked as obvious based upon a preliminary written description challenge.
Written Description Killing Priority and thus Nonobviousness: We know that patent applicants are allowed to narrow patent claims during the prosecution process. The vast majority of issued patent claims are not found in the originally filed patent application but instead are amended during prosecution. This is typically done by adding limitations into the claims as MU did here. The primary constraint on adding limitations is that the newly amended claim must be supported by the original application specification. Thus, a patentee cannot create limitations from thin-air, but must instead identify limitations found in the specification to be added into the claims. In the simple case, newly added claim limitations that are not supported by the specification are rejected for new matter at the USPTO and, once issued, can be invalidated for lacking written description under 35 U.S.C. § 112. The situation is a bit more confusing when the application claims priority to a prior patent filing. Of course, most issued patents do claim priority to a prior patent filing so the family member situation is quite important. In the patent family context, a child application might fully comply with the written description requirement if considered on its own. The child application can also be valid if new matter was added to the specification or claims at the time of filing. However, that new matter (if included within the claims) will mean that the patentee cannot claim priority to the parent application's filing date. Where the parent case is published more than one year before the patent filing, that parent application can also serve as a prior art against the child application under 35 U.S.C. §102(b) unless priority can be established. (Query how this will works under the AIA?)
In this case, the generic challenger argued that one of the claimed limitations was not supported by the parent patent and, as a consequence, that parent patent serves as a critical piece of prior art that invalidates the claims.
One set of asserted claims were amended from the priority filing to included an exclusionary wherein limitation. In particular, the claims stated that "the composition contains no sucralfate." The original specification had noted several reasons why omeprazole was preferable to sucralfate. In the same sentence, the specification also indicated that omeprazole is also preferable to sodium bicarbonate for those same reasons. Since sodium bicarbonate is actually an element of the invention, the district court held that the same sentence could not be used to particularly exclude sucralfate without further evidence that sucralfate is contraindicated. On appeal, the Federal Circuit rejected this reasoning – holding that preference statement in the specification was sufficient to justify addition of the exclusionary limitation and that the sodium bicarbonate inclusion (as a buffer) was justified by other portions of the specification.
Higher Bar for Negative Limitations?: The exclusionary limitation here is a negative limitation because it defines what the invention does not contain. Here, the invention does not contain sucralfate. The tradition in patent law has been to avoid negative limitations and, certainly, an invention cannot be wholly defined by negative limitations. However, negative limitations are allowed and are useful at times. It appears that the court sets a higher bar for the inclusion of negative limitations than it does positive elements of a claim. This is done by requiring that the specification include a reason for the exclusion in order to satisfy the written description requirement. The court writes here: "Negative claim limitations are adequately supported when the specification describes a reason to exclude the relevant limitation." Ordinarily, such justification is not required for positive claim elements - although justifying explanations can be helpful in justifying greater claim breadth.
Although some reasoning is required, the patentee need not disclaim the element in the specification in order to add the exclusionary limitation in the claims. "Such written description support need not rise to the level of disclaimer. In fact, it is possible for the patentee to support both the inclusion and exclusion of the same material."
With these notions in mind, the court held that the statements in the specification were sufficient to support the exclusionary limitation in this case. "The claim limitation that the Phillips formulations contain no sucralfate is adequately supported by statements in the specification expressly listing the disadvantages of using sucralfate." And, as a consequence, the parent patent is not a proper prior art reference against those claims supported by the original specification.
Patent with Multiple Priority: In cases with a complex family structure, patent priority is actually determined on a claim-by-claim basis. As discussed above, the Federal Circuit held that some of MU's claims properly claim priority to the original specification filed with the USPTO. On appeal, the patentee implicitly agreed that some of the other patent claims are not supported by the original specification. For those cases, the original filing qualifies as prior art against the no-priority claims under section 102(b). The question then is whether the newly added material is sufficiently different to avoid invalidation on obviousness.
Without going into detail, the Federal Circuit found that some of the patent claims that qualified for priority were also nonobvious and thus should be treated as valid and enforceable.
Need one to win: In the end, this appears to be a win for Mizzou since a patentee only need a court to find one of its claims is infringed and enforceable.
Notes:
- Although I am employed by the University of Missouri, the university is not my client and I have not spoken with any of the university counsel about this case.
- Par also appealed the district court's finding of no inequitable conduct. The Federal Circuit affirmed that holding based upon a lack of clear and convincing evidence of intent deceive the USPTO.
