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Patent Owner Loses Everything at PTAB
Wednesday, December 1, 2021


In Mati Therapeutics, Inc. v. Ocular Therapeutix, Inc., the Federal Circuit issued a Rule 36 opinion affirming the Patent Trial and Appeal Board’s (“PTAB’s”) Final Written Decision (“FWD”) holding all challenged claims unpatentable. Ocular Therapeutix, Inc. v. Mati Therapeutics, Inc., IPR2019-00448, Paper 56 (P.T.A.B. June 18, 2020), aff’d (Fed. Cir. Nov. 8, 2021).


Ocular Therapeutix petitioned for IPR of certain claims of Mati Therapeutics’ patent. Independent claim 1 reads:

  1. A drug delivery system for insertion into a lacrimal canaliculus of a patient, comprising:

a therapeutic agent, a distinguishing color to show placement of the system in the lacrimal canaliculus of the patient and a body of material to hold the therapeutic agent wherein the body of material comprises hydrogel polymers and wherein the body of material is a cylindrical rod.

Independent claim 11 further requires that the body of material “swells when placed in the lacrimal canaliculus.” IPR2019-00448 at *9. Additionally, independent claim 18 requires that the “therapeutic agent [is] selected from an anti-glaucoma agent, a corticosteroid[,] an anti-microbial agent, and anti-allergy agent[,] or a non-steroidal anti-inflammatory agent.” Id.

Claim Construction

The PTAB construed several claim limitations under the Phillips standard of “ordinary and customary meaning” to a person of ordinary skill in the art (“POSITA”) at the time of the invention. Id. at *25.

Regarding the limitation “distinguishing color to show,” the following statement is the only mention of color in the specification:

In many embodiments, the sheath body and/or retention structure may have a distinguishing feature, for example a distinguishing color, to show placement such that the placement of the sheath body and/or retention structure in the canaliculus or other body tissue structure can be readily detected by the patient.

Id. at *9 (emphasis removed). The PTAB agreed with the Patent Owner’s proposed construction that “the color must show the system as it sits in the lacrimal canaliculus of the patient.” Id. at *29. This construction was based on the specification describing “placement” as “the position of the implant in the eye, not the act of placing it there, as the only viewer described as needing to see the implant placement is a patient, who would not be a person actively implanting the device, but would only view it once it was placed in the eye.” Id. at *28−29.

Patent Owner Mati also argued other limitations were required by the claims, namely:

  1. “intracanalicular placement” of the claimed system (meaning the device is implanted subpunctally, with no outwardly exposed surface once placed; applies to all claims),

  2. “sustained release of the drug at the desired therapeutic level for an extended period of time” (applies to all claims),

  3. the claimed distinguishing color be “retained” or “lasting” (applies to all claims), and

  4. that the recited functional groups (applies to claims 9 and 22) “provide the desired solubility of the therapeutic agent in the matrix.”

Id. at *30. According to the PTAB, however, these proposed constructions were not supported and would impermissibly read limitations from the specification into the claims. Id. at *34−37.   


The PTAB agreed with Petitioner Ocular that several of the challenged claims were obvious over the combination of two references, Pritchard and Gillespie. Id. at *40. The PTAB found that a POSITA would have been motivated to pigment Pritchard’s punctal plugs per Gillespie’s teachings to make them easier to see. Id. at *39−40. Further, a POSITA would also have had a reasonable expectation that such a modification would succeed because it was within the state of the art of punctal plugs and colorings therein as of the time of the invention:

[I]rrefutable evidence . . . shows that a person of ordinary skill in the art had at least dozens of coloring agents that were generally regarded as safe to choose from when pigmenting a punctal plug, as taught by Gillespie, that included a therapeutic agent, as taught by Pritchard.

Id. at *47. The PTAB continued:

Patent Owner expressly agrees with our reading of Pritchard as the reference was discussed in the Institution Decision, that is, that Pritchard provides a “‘menu’ embrac[ing] a vast number of possible permutations and combinations of elements, including different punctal plug designs/shapes, different modes of administration, numerous classes of therapeutic agents, unknown and unknowable number of swellable materials defined by function, and other possible characteristics.” PO Resp. 29. Even, assuming arguendo, that such a menu of choices was more picking and choosing than appropriate under an anticipation analysis, it provides both express disclosure of claim elements and a reason to combine them when analyzing obviousness.

Id. at *55 (emphases removed).

The PTAB further agreed with Ocular that an additional set of claims were obvious in light of Pritchard, Gillespie, and a third reference, Hellberg. These claims required travoprost as the therapeutic agent. Id. at *66. The PTAB found that “Hellberg teaches travoprost was a known anti-glaucoma drug,” and that “Pritchard discloses that anti-glaucoma therapeutic agents are used with its gellan-based punctal plugs.” Id. at *67.

The PTAB found that the Petitioner’s remaining anticipation and obviousness grounds were not sufficiently supported by the evidence. Specifically, Petitioner’s anticipation ground failed because the “distinguishing color” limitation, as construed by the PTAB, was missing from the prior art, since Pritchard’s light straw color was not distinguishable from the surrounding tissue. Id. at *71. The other obviousness grounds failed because not all the recited claim limitations were taught or suggested by the asserted prior art. Id. at *72−73.


This case provides practitioners with an example of just how important claim construction is at the PTAB.  In fact, claim construction may be outcome-determinative. In both a district court and before the PTAB, the Phillips standard places the specification at the center of the claim construction analysis as “the single best guide to the meaning of a disputed term.” Phillips v. AWH Corp., 415 F.3d 1303, 1327 (Fed. Cir. 2005) (en banc). If the Patent Owner has not made its proposed construction clear in the specification and claims, it may not be possible to later persuade the court or the PTAB to apply that construction.

This case also reminds practitioners that subject matter disclosed in the specification but not recited in the claims may later be found to be dedicated to the public, and may not be read into the claims as a limitation for purposes of establishing infringement or validity/patentability. See Pfizer, Inc. v. Teva Pharms. USA, Inc., 429 F.3d 1364, 1378 (Fed. Cir. 2005); PSC Comput. Prods. Inc. v. Foxconn Int’l Inc., 355 F.3d 1353 (Fed. Cir. 2004); Toro Co. v. White Consol. Indus., Inc., 383 F.3d 1326 (Fed. Cir. 2004); Johnson & Johnston Assocs., Inc. v. R.E. Serv. Co., Inc., 285 F.3d 1046 (Fed. Cir. 2002) (en banc). Therefore, practitioners should take care while drafting the claims and specification to establish the best position to support valid and enforceable claims.

Stacy Lewis, a Law Clerk at Finnegan, and Brooke M. Wilner, a former associate, contributed to this article.

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