On November 14, 2018, the Patent Trial and Appeal Board (PTAB) rendered a final written decision in PGR2017-00022 holding pharmaceutical dosage form claims of U.S. Patent No. 9,404,862 unpatentable for lack of enablement. In particular, the PTAB concluded that the ’862 patent did not enable one skilled in the art to make the full scope of the claimed dosage forms. Although the petitioner Grünenthal GMBH also successfully challenged certain claims of the ‘862 patent as anticipated or obvious, the decision illustrates how post-grant review (PGR) may serve as a vehicle to attack a patent for inadequate disclosure, a statutory basis unavailable through inter partes review (IPR).

The ‘862 patent relates to therapeutic compositions of the osteoporosis drug zoledronic acid and their use for treating knee pain. Zoledronic acid was known to have poor bioavailability (≤1%). The claims of the ‘862 patent functionally limit the compositions to dosage forms providing improved bioavailability of zoledronic acid. For example, Claims 2 and 17 recite dosage forms with a bioavailability of about 1.1% to about 4%. The specification of the ‘862 patent discloses the types and amounts of various excipients that the dosage forms may include, but the specification does not include any working example or description of a specific dosage form having a bioavailability within a claimed range.

Nonetheless, the patent owner Antecip Bioventures II LLC argued the disclosures in the patent “explained how to prepare the zoledronic acid-containing compositions,” including how to improve zoledronic acid bioavailability. The patent owner also pointed to prior art methods of improving zoledronic acid bioavailability as enabling how to make the claimed dosage forms. The patent owner thus contended that, guided by these disclosures, the skilled artisan need only perform routine bioavailability tests to identify dosage forms with the claimed bioavailability.

The PTAB agreed with the petitioner, however, that the patent specification did not provide sufficient disclosure that would enable a skilled artisan, without undue experimentation, to make dosage forms having the full scope of claimed bioavailability. The PTAB emphasized that the ‘862 patent did not describe any examples or particular ingredients that provide dosage forms with the claimed bioavailability ranges. Likewise, the prior art disclosure of techniques to enhance zoledronic acid bioavailability, in amounts overlapping with the claims, failed to remedy the absence in the ‘862 patent of the specific disclosures needed to enable the full scope of the claims. Quoting from the Federal Circuit’s decision in Genentech, Inc. v. Novo Nordisk A/S, 108 F.3d 1361 (Fed. Cir. 1997), the PTAB stated “when there is no disclosure of specific starting material or conditions under which the process can be carried out, undue experimentation is required; there is a failure to meet the enablement requirement that cannot be rectified by asserting that all the disclosure related to the process is within the skill of the art. It is the specification, not the knowledge of one skilled in the art, that must supply the novel aspects of the invention in order to constitute enablement.” PGR2017-00022 at p. 29.

In an attempt to salvage some patent protection, the patentee filed a motion to amend the claims to narrow the bioavailability range to 1.1% to 2.3%. In the PTAB’s view, however, the absence of working examples or description of specific dosage forms meeting the bioavailability requirement also doomed the proposed substitute claims for lack of enablement. The specification of the ‘862 patent still failed to enable a skilled artisan to make a dosage form with the full bioavailability range of the claims.

In a twist, prior art that failed to provide the required enablement nonetheless sufficed to render the claimed bioavailability ranges obvious. The PTAB reached this result by relying on established case law that applies a general presumption of obviousness where a claimed range overlaps with that in the prior art. For example, the PTAB found that one reference rendered obvious a bioavailability range of 1.1% to 5%.

A concurring opinion questioned how the prior art could render subject matter obvious, but not enable the same subject matter when considered together with the specification. Indeed, this somewhat incongruous result appears at odds with the general presumption of enablement of the prior art. The PTAB decision did not address how a 1.1-5% range enabled in the prior art would not enable a 1.1-2.3% or 1.1-4% range in the claims of the ‘862 patent.

This decision highlights the enablement risks that patents in the unpredictable arts can face in a PGR where the specification fails to include a specific description of how to make an operable embodiment of the claimed invention. Moreover, relying on the prior art to supply enablement leaves a patent more vulnerable to attack for obviousness or anticipation. Prior art enabling a particular claim limitation could also very well render that limitation obvious or anticipated.

More generally, the PGR process created under the America Invents Act provides both potential challenges and opportunities for innovators in the life sciences. Compared to IPR, PGR provides additional statutory bases (35 U.S.C. §§101 and 112) upon which to challenge recently granted patents, thereby opening new fronts for a patentee to defend. On the other hand, innovators can also potentially leverage the §112 grounds available with a PGR to clear out a thicket of overly broad patent claims that stymie innovation in newly developing or unpredictable art fields.