The Federal Circuit in Takeda v. Zydus (Fed. Cir. Feb. 20, 2014) resolved issues in relation to claim construction, infringement and invalidity. The patent was directed to an orally ingestable tablet that disintegrated in your mouth where the formulation contains granules small enough (i.e., 400 µm or less) to avoid a feeling of roughness in the patient’s mouth upon disintegration.
A significant portion of the opinion dealt with how to measure the size of the granules, including the measurement technique and whether two cores that are joined together should be counted as one granule, or whether the cores should be measured separately as two separate cores. In preparing a patent application, one might consider the pros and cons of including multiple measurement techniques in the patent application as well as the actual measurement process and also reciting the preferred technique in a dependent claim. But that was not done here.
I. Claim construction
In determining infringement, the court must first construe the meaning of the words used in the patent claims. In the instant case, the claims of the patent required “fine granules having an average particle diameter of 400 µm or less.” The patent owner (Takeda) argued that the phrase included a ±10% range from the 400 µm mark. The defendant (Zydus) argued that the claim term should be construed so that the average particle diameter is precisely 400 µm or less as literally stated with no variation on the upper end of the range.
In construing the claim terms, the Federal Circuit started with the language of the claims themselves and also reviewed the specification to come to the conclusion that the 400 µm limitation does not contemplate a ±10% range but meant what it literally said: “400 µm or less.” The specification supported this meaning. For example, the specification stated that the maximum particle size of the granule was 425 µm. If the claims were construed to include a +10% upper limit to the 400 µm size (i.e., 440 µm), then the claims would encompass a dimension larger than the stated maximum size mentioned in the specification.
Since the claims are construed as requiring the granule size to have an average particle size of 400 µm or less and the accused product has an average particle size of 412.28 µm, the Federal Circuit found no literal infringement. The District Court had used the ±10% variation and found infringement, so the District Court ruling was reversed.
The District Court had found the patent was not shown to be invalid. In reviewing the invalidity arguments, the Federal Circuit reviewed three different aspects that could invalidate Takeda’s patent, namely, indefiniteness, written description and enablement.
Zydus argued that the claims were indefinite because the claims did not specify the measurement technique for measuring the average granule size. There were several possible ways to make the measurement but experts from both parties agreed that the different techniques were merely expressing the same terms in different ways. Also, there was no evidence that the differences between the techniques were significant as the dimensions differed by only a few micrometers.
The Federal Circuit distinguished the instant case with the situation in Amgen v. Hoechst, 314 F.3d 1313 (Fed. Cir. 2003). In Amgen, the claims were directed to a glycosylation which differed from that of human urinary erythropoietin. However, “two uEPO preparations produced form the same batch of starting materials could nevertheless have different glycosylation patterns.” Thus, the claim itself was described as a moving target. In the instant case, the claim plainly required an average particle diameter of 400 µm or less. The fact that there is more than one way to make the measurement did not render the claim indefinite.
B. Written Description
Zydus argued that the written description requirement was not satisfied because the specification only taught how to measure particle size before tablets were formed (i.e., pre-tableting). It did not discuss particle sizing with post-tableting. However, the court found that the tableting procedure did not have any effect on the particle size. The particle size remained unchanged when they were combined to form tablets. As such, the Federal Circuit distinguished the instant case from Eli Lilly & co. v. Teva Pharmaceuticals USA, Inc., 619 F.3d 1329 (Fed. Cir. 2010) where the particle size was affected by the formulation process. Thus, the written description requirement was met here.
Zydus argued that the patent is invalid for lack of enablement because a skilled artisan would not be able to determine the average particle diameter using the coulter counter method of measurement without undue experimentation. It is well established that the enablement requirement is met if the description enables any mode of making and using the invention. In this case, the patent specification identified laser diffraction which was a viable method of measurement. Hence, there was no lack of enablement.
The Federal Circuit indicated that had measurement required the splitting of joined cores (agglomerated granules) then the specification would have failed to enable one of ordinary skill in the art. The reason was that the laser diffraction method, the sole measurement technique described in the patent, cannot virtually dissect or account for the joined cores. Laser diffraction cannot measure or virtually measure the size of cores that are joined. Optical microscopy had to be used to measure co-joined, agglomerated particles, but the specification did not mention use of optical microscopy. But since the claims required the size of the whole, agglomerated particle there was no need to try and measure the separate cores in such agglomerated particles.