Jordan is a second-year law student at the University of Missouri and a registered patent agent. He has an extensive background in chemistry and food science.
Amgen markets apremilast, a phosphodiesterase-4 (“PDE4”) inhibitor, which is used for treating psoriasis and related conditions, under the brand name Otezla® which is covered by three patents, U.S. Patents 7,427,638, 7,893,101, and 10,092,541. Sandoz submitted an Abbreviated New Drug Application (“ANDA”) seeking approval market a generic version of apremilast. Celgene, the original plaintiff, brought this Hatch-Waxman suit, asserting that Sandoz’s generic product would infringe the ’638 and ’101 patents. The Federal Circuit affirms the district court’s findings on all issues raised.
Sandoz asserts that U.S. Patent 6,020,358 renders the Amgen patents obvious. The ’358 patent is the first U.S. patent describing a racemic mixture containing apremilast. Enantiomers detail the orientation of the molecule around a chiral center and can have vastly different therapeutic outcomes and clinical results between the (+) and (-) enantiomers, particularly thalidomide analogues. The critical difference between the ‘358 and ‘638 patents is the composition of the mixture:
The ’358 patent is a racemic mixture comprised of 50% of the (+) enantiomer of 2-[1-(3-ethoxy-4-methoxyphenyl)-2-methylsulfonylethyl]-4acetylaminoisoindoline-1,3-dione and 50% of the (-) enantiomer.
Compare to an excerpt of Amgen’s language in claim three of ‘638:
A pharmaceutical composition comprising stereomerically pure (+)–2-[1-(3- ethoxy-4-methoxyphenyl)-2- methylsulfonylethyl]-4- acetylaminoisoindoline-1,3-dione, or a pharmaceutically acceptable salt, …
The ’638 Patent: Sandoz failed to provide clear and convincing evidence at the district court to show that a skilled artisan would have reasonably expected a benefit from separating the enantiomers or that the (+) enantiomer was the cause of the desirable properties of the ‘358 formulation. Sandoz’s appeal asserts that the district court erred in its findings.
At the Federal Circuit, Judge Lourie, writing for a unanimous panel of Judges Cunningham and Stark, focuses on the unexpected potency of apremilast discovered relative to the apremilast-containing racemic mixture during testing and experimentation. At the district court, the named inventor, Dr. Schafer, testified that the stereomerically pure apremilast reduces the production of tumor necrosis factor alpha (“TNFα”), the factor that is linked to psoriasis, 20 times more effectively than the previous patent.
Dr. Schafer also says that a skilled artisan would expect a twofold improvement in efficiency. The district court finds that the 20-fold difference, when an otherwise two-fold difference would have been expected by the skilled artisan was sufficient to support a finding of an unexpected result and subsequent nonobviousness. A 20-fold difference from the steromerically isolated formulation goes well beyond a difference in degree into a difference in kind.
It strikes me as interesting that the characteristics of apremilast were largely left undiscussed. Apremilast is a thalidomide analogue and safety concerns about the infamously teratogenic effects related to thalidomide were sufficient skepticism for a skilled artisan and the industry at large regarding stereomerically pure formulations. However, it would seem that this teratogenicity could cut both ways as a skilled artisan would have ample incentives to investigate the enantiomers separately for safety concerns in light of the thalidomide paradox.
The thalidomide paradox provides that racemic mixtures and pure enantiomers have different characteristics, despite in vivo racemization. If the molecule is sufficiently analogous to thalidomide, it seems that a skilled artisan would be inclined to be taught towards separating the enantiomers. Regardless, the unexpected result was found to be dispositive on appeal and the objective indicia weren’t necessary but the other findings of the objective indicia of long-felt need, others had tried and failed, industry skepticism, and commercial success were also affirmed.
The ’101 Patent: Sandoz also alleges that the ’101 patent should have been found to be obvious. Sandoz says the ‘101 patent should not be entitled to the priority date of March 2002 because the ’515 provisional application did not inherently disclose crystalline Form B of apremilast and therefore did not satisfy the written description requirements of 35 U.S.C. § 112. The district court relies on a finding that ‘515 application did inherently disclose the crystalline form.
The Federal Circuit did not find it necessary to delve into inherent disclosure because a review of the trial record shows Amgen provided multiple experiments, and expert testimony, showing that there was actual disclosure of the crystalline Form B. Absent any contrary evidence by Sandoz, the priority date and subsequent finding of nonobviousness were affirmed. Another win chalked up to Amgen’s excellent expert testimony.
The ’541 Patent: On cross-appeal, Amgen asserts that the district court finding that the patent is obvious in light of prior art is erroneous. The district court found that the ’541 patent would have been obvious over the prior art or in crediting expert testimony stating that dose-titration modification would have been routine to a skilled artisan. Specifically, dose titration would be something that is regularly done in the treatment of psoriasis.