Takeda Prevacid SoluTab Patent Valid, But Not Infringed

24 February 2014 PharmaPatents Blog

In Takeda Pharmaceutical Company Ltd. v. Zydus Pharmaceuticals USA, Inc., the Federal Circuit reversed the district court’s finding that Zydus’s proposed generic product infringed Takeda’s Prevacid® SoluTab™ patent, but agreed with the district court that Zydus had failed to prove that the patent is invalid. However, the Federal Circuit also explained that it would have held the claim at issue invalid if Takeda had prevailed on all of its claim construction // infringement arguments. While this decision is not particularly remarkable, it highlights the scrutiny that the Federal Circuit will apply to claim construction and the risks of arguing for a broad claim construction.

The Patent at Issue

The patent at issue is Takeda’s U.S. Patent 6,328,994, which is listed in the Orange Book for Prevacid® SoluTab™, an orally disintegrating dosage form of lansoprazole used to treat acid reflux that can be taken without water. As noted in the Federal Circuit opinion, “the stated objective of the ’994 patent is that the formulation contains granules small enough to avoid a feeling of roughness in the patient’s mouth upon disintegration.”

Claim 1 was the only claim at issue on appeal:

1. An orally disintegrable tablet which comprises (i) fine granules having an average particle diameter of 400 μm or less, which fine granules comprise a composition coated by an enteric coating layer comprising a first component which is an enteric coating agent and a second component which is a sustained-release agent, said composition having 10 weight % or more of an acid-labile physiologically active substrate that is lansoprazole and (ii) an additive wherein said tablet having a hardness strength of about 1 to about 20 kg, is orally disintegrable.

While Zydus argued that the highlighted phrase should be construed precisely, the district court construed the highlighted phrase as including a 10% deviation, based on Takeda’s arguments that it was “‘universally accepted’ that there is a 10% standard of error for particle size measurements.”

The Federal Circuit Decision

The Federal Circuit decision was authored by Judge Prost and joined by Judge Plager and Judge Chen.

The Federal Circuit determined that the claim language, specification and prosecution history supported Zydus’s position on claim construction.

The Federal Circuit first noted that “the claim language [at issue] is not qualified by the word ‘about’ or any other indicator of imprecision,” even though the hardness strength is recited as “about 1 to about 20 kg.”

Turning to the specification, the Federal Circuit noted:

The specification explains that conventional granules of that size “produce a feeling of roughness in the mouth”—one of the very problems the claimed invention purports to solve. …. That clear dividing line between the “fine” granules of 400 μm or less (which avoid a feeling of roughness in the mouth) and “conventional” granules of 400 μm or more (which do not) disappears if the “fine granules” are construed as incorporating a 10% deviation. Thus, there can be little doubt that the narrower construction “most naturally aligns with the patent’s description of the invention.”

Takeda pointed to passages in the specification that refer to a particle size of “about 400 μm or less,” but the Federal Circuit found that those same passages indicate that a smaller particle size is desired.

In the present invention, “fine granules having an average particle diameter of 400 μm or less … have an average particle diameter of about 400 μm or less, in order that roughness is not felt in the mouth. Preferably, the average particle diameter of the fine granules is 300 to 400 μm.

[T]he average particle a [sic] diameter of the included granules must be about 400 μm or less, preferably about 350 μm.

The “fine granules” have an average particle diameter of about 400 μm or less, preferably 350 μm or less. Preferably; the average particle diameter of the fine granules is 300 to 400 μm.

Overall, the Federal Circuit found that “[n]owhere does the specification suggest that an average particle size greater than 400 μm (even within 10% of that figure) could achieve the inventive result of avoiding a feeling of roughness in the mouth.”

The court also found a similar line drawn in the prosecution history, where “the inventors distinguished the claimed invention over a potentially invalidating prior art reference because the reference failed to disclose an average particle diameter of …. ‘within 400 μm’ … [such that] the feeling of roughness in a mouth can be prevented.’”

Thus, the Federal Circuit concluded,

[T]he proper construction of the disputed claim term is “fine granules having an average particle diameter of precisely 400 μm or less.”

Although this claim construction meant that Zydus’s generic product would not literally infringe the patent, the Federal Circuit considered Zydus’s invalidity arguments, and agreed that Zydus had not established invalidity.

The Federal Circuit agreed with the district court that claim 1 was not invalid for indefiniteness for failing to specify the means by which particle size is determined, even if different methodologies would produce different results:

It is true … that there are several possible ways to measure average particle diameter …. [and] that different measurement techniques could indeed produce different results. …. [However,] there is no evidence that the differences between these techniques are in fact significant.” …. To the contrary, the measurements of Zydus’s ANDA product using laser diffraction and optical microscopy, though not exactly the same, were substantially similar.” …. Any theoretical minor differences between the two techniques are therefore insufficient to render the patent invalid.

The Federal Circuit agreed with the district court that claim 1 was not invalid for lack of written description for failing to disclose how to measure particle size post-tableting:

Zydus’s argument depends on there actually being an impact on particle size from the tableting process, and the evidence showed the opposite.

The Federal Circuit agreed with the district court that claim 1 was not invalid for lack of enablement for failing to disclose how to measure particle size “using the coulter counter method of measurement without undue experimentation.”

[B]ecause the patent identifies laser diffraction as a viable measurement technique, and there is no dispute that a skilled artisan would know how to use laser diffraction to measure particle diameter, Zydus has not established that the patent is invalid for lack of enablement on this basis.

The Federal Circuit also decided to discuss another enablement issue that depended on a claim construction/infringement argument that it only addresses in dicta. That is, the court explains that if Takeda had prevailed on its argument that hard agglomerates should be subjected to a virtual deagglomeration in the measurement process, then the claim would have been invalid for lack of enablement because “nothing in the written description directs a skilled artisan to evaluate whether a sample contains ‘more than nominal’ hard agglomerates … nor does it explain how one would make that determination. Similarly, it does not explain how to conduct virtual dissection of deagglomerates using optical microscopy.”

The Federal Circuit explained that the district court’s determination that the claim did require deagglomeration prior to measurement was incorrect:

The only method of measurement discussed in the specification is laser diffraction, which cannot account for hard agglomerates. …. We cannot conclude that the patent affirmatively requires a step that was entirely absent from (and even precluded by) the procedure described in the specification.

Thus, the Federal Circuit reversed the district court’s claim construction and finding of literal infringement, affirmed the judgment of no invalidity, and remanded for further proceedings.

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