Case Name: Takeda Pharma. Co. Ltd. v. Zydus Pharmas. USA, Inc., No. 2013-1406, 2014 U.S. App. LEXIS 3072 (Fed. Cir. Feb. 20, 2014) (Circuit Judges Prost, Plager, and Chen presiding; Opinion by Prost, J.) (appeal from D.N.J., Pisano, J.)
Drug Product and Patent(s)-in-Suit: Prevacid® SoluTab™ (lansoprazole); U.S. Patent No. 6,328,994 (“the ’994 patent”)
Nature of the Case and Issue(s) Presented: The invention of the ’994 patent is that its formulation contains granules small enough to avoid a feeling of roughness in the patent’s mouth upon disintegration. In response to Zydus’s ANDA, Takeda filed suit alleging patent infringement. Zydus counterclaimed, alleging that claim 1 was invalid for failure to comply with Section 112 of the Patent Act. The district court construed the claim term “fine granules having an average particle diameter of µm or less” in line with Takeda’s proposed construction, “fine granules up to and including the enteric coating layer having an average particle diameter of 400 µm (+ 10%) or less.”
The issue of infringement turned on how particle size was measured. Takeda argued that the average particle diameter should be determined by measuring each individual core, regardless of whether they had fused together into a hard agglomerate. Zydus argued that because the specification describes measuring particle size after the coating process and says nothing about de-agglomeration, it by definition includes hard agglomerates in the measurement of average particle diameter. The district court agreed with Takeda. The Federal Circuit reversed the district court’s finding of infringement, but affirmed its ruling on invalidity.
Why Zydus Prevailed: The Federal Circuit agreed with Zydus that the district court erred in reading a margin of error into the disputed claim term. Nothing in the claim language indicates that 400 µm was intended to mean anything other than exactly 400 µm. Moreover, the specification contrasts the “fine granules” of the claimed invention with larger “conventional” granules, which it defines as “400 µm or more of average particle diameter.” Such a distinction disappears if the “fine granules” of the invention are construed as incorporating a 10% deviation. Nowhere does the specification suggest that an average particle size greater than 400 um could achieve the inventive result. The prosecution history also supports Zydus’s construction. The inventors distinguished the claimed invention over a prior-art reference because the reference failed to disclose an average particle diameter of 400 µm or less. The inventors have consistently relied on 400 µm as the dividing line between granules that would avoid roughness in the mouth, and thus within the scope of the invention, and those that would not, a particle size not contemplated by the invention. Because Zydus’s ANDA product had an average particle diameter of 412.28 µm, outside the new construction, the Federal Circuit reversed the lower court’s finding of infringement.
The Federal Circuit next dispensed with Zydus’s three Section 112 challenges: that the asserted claim was indefinite, not enabled, and lacking sufficient written description. Zydus argued that the claim was indefinite because it did not specify the method of measurement that should be used to determine average particle diameter. The Federal Circuit held that while there are at least two ways of measuring the average particle diameter—laser diffraction and optical microscopy—both methods of measurement accurately report average particle diameter and there is no evidence that the differences between the techniques are in fact significant. Next, Zydus argued that the claim addresses average particle size in the finished tablet while the specification only teaches how to measure particle size pre-tableting, and as a result, the inventors were not in possession of the claimed invention: tablets with particles of 400 µm or less post-tableting. The Federal Circuit did not agree because actual testing conducted by Takeda’s expert showed no effect from compression forces on the granules in Zydus’s ANDA product. Finally, Zydus argued that the patent is not enabled because a skilled artisan would not be able to determine the average particle diameter using the coulter counter method of measurement without undue experimentation. Enablement is accomplished if the specification enables any mode of making and using the invention. Because the patent identifies laser diffraction as a viable measurement, and a skilled artisan would know how to use laser diffraction to measure particle diameter, there was no valid non-enablement argument.