Wyeth v. Abbott Labs – Application Drafting Lessons

by Ryan Alley on July 12, 2013

in -, CAFC District Court appeals

Case Nos. 2012-1223 et al. (Moore, Bryson, Wallach)

Breadth is, unfortunately, the primary currency for measuring a claim’s value (as well as its drafter’s worth). A narrower but more valid claim takes a back seat in many applicants’ minds. Add to this the fact that an overly narrow claim can give rise to a malpractice suit, and patent attorneys have plenty of incentive to draft and assert claims as broadly as possible. The prior art can be a check – and is often the only enforced check – on broad claiming in prosecution and litigation, but enablement is becoming a solid weapon against delusionally grand claim scope. Two recent cases, Wyeth v. Abbott Labs. and Convolve v. Compaq Computer, illustrate the often unrecognized danger in broad claim language. This first post looks at Wyeth, the gentler of the two cases.

Wyeth involved a fact-pattern more common in written description cases: assertion of a genus pharmaceutical claim supported by only a single species against third-party species undisclosed by the specification. Wyeth (now Pfizer) and Cordis sued Abbott, Medtronic, and Boston Scientific for infringement of US Patents 5,516,781 and 5,563,146. The ‘781 and ‘146 patents were parent and child applications directed to methods of preventing restenosis with rapamycin, now known as sirolimus, which was naturally produced from bacteria. The ‘781 and ‘148 patents disclosed only the naturally-occurring sirolimus. The defendants, however, were using sirolimus derivatives, everolimus and zotarolimus. Upon securing a broad claim construction for “administering an antirestenosis effective amount of rapamycin” that covered all structural analogs of sirolimus that had antirestenosis activity, the district court found the claims invalid for lack of enablement on summary judgment. An appeal to the Federal Circuit ensued. . .

The court on appeal reviewed the record for any disputed fact as to whether undue experimentation was required to practice the broadly-asserted genus. On the one hand, sirolimus was a well-known compound as of the ‘781 and ‘146 priority date, and the methods required to assay for antirestenosis activity among its analogs were routine. A person skilled in the art would further be able to screen for qualifying compounds using cell permeability and molecular weight characteristics. Thus, according to Wyeth, there may have been some time-consuming lab work to identify all species that fell within the asserted claim scope, but the work would be routine and yield predictably successful results, such that undue experimentation would not be required.

On the other hand, the number of sirolimus structural analogs was huge – millions of potential compounds – and tens of thousands of those compounds further exhibited antirestenosis-effectiveness and thus fell within the claims. The state of the art at the priority date further included no information about which structural analogs or modifications to sirolimus would preserve the antirestenosis activity; each candidate compound would have to be tested. Abbott argued that this lack of direction and laborious, iterative testing requirement amounted to undue experimentation.

The Federal Circuit agreed that undue experimentation was required by the claim construction, that there was no material dispute as to this status, and that the claims were thus properly invalidated as non-enabled on summary judgment. The court’s reasoning rested mostly on the undisputed large amounts of testing required to identify all species compounds within the construed claim:

The remaining question is whether having to synthesize and screen each of at least tens of thousands of candidate compounds constitutes undue experimentation. We hold that it does. Undue experimentation is a matter of degree. Chiron Corp. v. Genentech, Inc., 363 F.3d 1247, 1253 (Fed. Cir. 2004) (internal quotation omitted). Even “a considerable amount of experimentation is permissible,” as long as it is “merely routine” or the specification “provides a reasonable amount of guidance” regarding the direction of experimentation. Johns Hopkins Univ. v. CellPro, Inc., 152 F.3d 1342, 1360–61 (Fed. Cir. 1998) (internal quotation omitted). Yet, routine experimentation is “not without bounds.” Cephalon, Inc. v. Watson Pharm., Inc., 707 F.3d 1330, 1339 (Fed. Cir. 2013).

Our cases have described limits on permissible experimentation in the context of enablement. For example, in ALZA Corp. v. Andrx Pharmaceuticals, LLC, we affirmed a judgment of nonenablement where the specification provided “only a starting point, a direction for further research.” 603 F.3d 935, 941 (Fed. Cir. 2010) (internal quotation omitted). We concluded that one of ordinary skill “would have been required to engage in an iterative, trial-and-error process to practice the claimed invention even with the help of the . . . specification.”

Looking at the undisputed facts, the court was swayed that the amount of time and effort required to synthesize and test each sirolimus derivative would be well beyond the degree permitted by routine experimentation in the above-quoted caselaw. In this instance, it would have taken years for even a corps of technicians to test every candidate:

Here, the specification similarly discloses only a starting point for further iterative research in an unpredictable and poorly understood field. Synthesizing candidate compounds derived from sirolimus could, itself, require a complicated and lengthy series of experiments in synthetic organic chemistry. Even putting the challenges of synthesis aside, one of ordinary skill would need to assay each of at least tens of thousands of candidates. Wyeth’s expert conceded that it would take technicians weeks to complete each of these assays. The specification offers no guidance or predictions about particular substitutions that might preserve the immunosuppressive and antirestenotic effects observed in sirolimus. The resulting need to engage in a systematic screening process for each of the many rapamycin candidate compounds is excessive experimentation. We thus hold that there is no genuine dispute that practicing the full scope of the claims, measured at the filing date, required undue experimentation.

Summary judgment of invalidity affirmed.

Lessons: The most prominent lesson here is a litigation one already taught by cases like Liebel-Flarsheim: ask only for a literal claim construction that clears the prior art and is proportional to the enabling support. Yes, seeking only narrower claim constructions may involve giving up some litigation targets or relying on the capricious doctrine of equivalents, but the alternative risks invalidation due to non-enablement, which gives up all litigation targets. In this case, I’m not sure Wyeth could have reasonably sought any narrower construction that would have still literally ensnared the everolimus and zotarolimus variants, but by seeking the entire genus of restenosis-reducing analogs, they now have nothing to enforce. Everolimus and zotarolimus appeared very structurally close to the native sirolimus, and they certainly performed the same function; Wyeth may have fared better proceeding under the doctrine of equivalents for these future-arising analogs.

The more subtle lesson, emphasized more in the next post on Convolve, is to give yourself as more breathing room in the specification from the outset. Demonstrate as much breadth as possible when using claim terms, or species/examples falling within claim terms, in the specification. Have inventors consider and offer different structures and implementations that fall within draft claim terms and include them in the disclosure. Sometimes inventors fixate on a best or simplest commercial implementation; part of the invention harvesting process should focus on alternative embodiments and fabrication/use methods, especially less straightforward design-arounds. Moreover, where an inventor can’t give any additional examples, this should be a clear sign that there may be enablement problems in anything more broadly drafted. At least a dependent claim should be confined to the limited species the inventor offers, in order to preserve a valid fallback option. The patents in Wyeth v. Abbott Labs described and claimed only rapamycin; this made non-enablement of the whole effective genus easy.

Comment: Although I an a little uneasy resolving what is clearly a question of “degree” on summary judgment with facts going both ways on the depth of effort required to practice the whole claim scope, I think the affirmance was correct. If you’ll indulge my love of enablement-obviousness comparison, I think the accused products, everolimus and zotarolimus, looked a lot like separately patentable, non-obvious compounds over sirolimus. This is to say that the prior sirolimus did not enable the accused products. Specifically, the everolimus and zotarolimus looked a lot like critical species within a nearly infinite universe that offered no suggestion as to how to arrive at the species from the prior sirolimus. This would probably have been enough to defeat any obvious to try or motivation to modify close structural analog argument.

I’ve also been a fan of relying more on enablement than written description to police claim scope. PatentDocs has some good discussion on the written description monster lurking in this case – I’m glad the court was able to resolve this one entirely on enablement without peeking under the bed.

6 July 17, 2013 at 6:46 pm

“A narrower but more valid claim takes a back seat in many applicants’ minds.”

Only the ones that are bad at inventing.

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