PTAB Finds Non-Obviousness for Missing Element

February 15, 2024

The Patent Trial and Appeal Board (PTAB) recently reversed the novelty, obviousness, and obviousness-type double patenting (ODP) rejections of the examining corps in a Track One case (USSN 17/342,945; Appeal 2023-004168; TC 1600). Led by Administrative Patent Judge (APJ) Richard Lebovitz, the PTAB panel further including APJs John E. Scheider and Eric B. Grimes reversed the rejections of Examiner Jake M. Vu, whose position was supported by Supervisory Patent Examiner (SPE) Michael G. Hartley, quality control SPE Scarlett Goon, and SPE Frederick F. Krass.

The initial claim rejected by the examining corps recited

[a] kit for forming crosslinkable compositions, said kit comprising:

   (a) a first fluid composition comprising a first polysiloxane having two or more unsaturated groups and a first imaging agent,

   (b) a second fluid composition that comprises a first hydride material having two or more hydride groups and a second imaging agent which is the same or different from the first imaging agent,

   (c) a dry composition comprising a first silica filler and optionally a second silica filler which is the same or different from the first silica filler, and

   wherein the first fluid composition, second fluid composition, and dry composition are stable, and when mixed, form a crosslinkable composition having the first and second imaging agents substantially evenly dispersed in the crosslinkable composition.

In the first office action, the examiner rejected the above claim for ODP over the claims of co-pending applications USSN 17/181,890 and 17/111,878, although the reference claims did not describe silica filler in a separate component. The examiner argued that it may be desirable to avoid over-bulking the composition for embolization with the filler, to adjust the amount of fillers, or to separately story the ingredients, if desired. The examiner asserted that the modification would have been reasonably expected to succeed because the filler does not appear necessary to make the invention work [presumably referring to the ODP reference claims].

The examiner further rejected the claims as anticipated and/or obvious over WO 2018/081837 A1 (Saber), optionally combined with US 6,251, 135 (Stinson). While the examiner acknowledged that Saber lacked an example (specific disclosure) of a silica filler, the examiner noted that intended uses recited in the claims are not distinguishing for articles or compositions of matter at the USPTO, and argued essentially identically to the ODP rejections. The examiner argued that the secondary reference, Stinson, supported his contention that it would be obvious to substitute bismuth trioxide for zirconium oxide because these are allegedly functional equivalents of radio opaque material, based on Stinson’s disclosure of these as alternative options using Markush language[1].

The appellant responded by adding the intended use, “for vascular embolization,” to the preamble of the active base claim, modifying the kit, and to add a clause at the end of the claim reciting that “the crosslinkable composition cures into a solid when injected into a target vessel and occludes the target vessel.” The appellant argued that no cited art describes maintaining the silica component as a dry composition of a kit for vascular embolization or the effects obtained thereby, pointing to a concurrently filed declaration under 37 CFR § 1.132. The appellant argued that Saber describes admixing silica filler in a fluid component composition(s) or eliminating silica entirely from Saber’s formulation in two-component systems, while the claimed kits contain three separate phases - a dry silica filler phase, and two fluid polymer phases that each include an imaging agent. The appellant argued, as supported by statements in the declaration, that the inventors had found that separating the fluid polymer phases from the silica filler prior to forming the crosslinkable compositions has significant impact on the rheological properties of the resulting compositions, and that including the imaging agent in the two fluid polymer phases (i.e., prewetting the imaging agent) has significant effect on the performance of the crosslinkable compositions in vivo.  The declaration stated that the claimed arrangement provided unexpectedly good results over Saber, i.e., that:

  • different compositions for vascular embolization prepared from the same components but with components stored in different phases surprisingly exhibit significantly different rheological and structural properties, significantly impacting in vivo performance, and providing good storage stability;
  • removing the silica filler from the formulations, described as equivalent in Saber, leads to liquid compositions that wash through the vessels after injection and do not provide occlusion of the vessel;
  • including the imaging agent in the fluid polymer phases of the composition (i.e., pre-wetting the imaging agent) provides another unexpected benefit not obtained when the imaging agent is added to the crosslinking compositions as a dry component; and
  • dry imaging agent results in immediate vessel constriction, reflux of the material to non-target locations, and eventual opening of the vessel to blood flow (no occlusion of the vessel) — only when the imaging agent is in the fluid polymer phases is the vessel occluded without vessel constriction and material reflux.
The amended claims and declaration were met with a final rejection with essentially the same assertions as the first office action. The examiner argued that the data in the declaration “shows that these examples are very similar, such as a gel time difference of only 4 minutes, and oscillation stress within 1 kPa,” indicating that the examiner “expected similar test values, but not exactly the same test values, and this is what Applicant's Declaration showed.”  The examiner posited whether “[i]f these data are unexpected, then what data were Applicant’s expecting?”  The examiner argued that the “main issue is if these examples are able to embolize or not, which is purpose of these compositions.”  The examiner impermissibly used knowledge from the appellants co-pending application, USSN 17/342,960, to characterize the data on pre-wetting imaging agents to be strange given the claims to non-pre-wetted coloring agents in the applicants own work, not available to the public on filing.

After the second, final office action, the appellant submitted a Pre-Appeal Brief Request for Review, in which the examiner was sustained by his supervisors, then appealed to the PTAB. Largely the same arguments were exchanged in the appeal brief and the Examiner’s Answer.

Saber describes under “Summary of the Invention” on p. 2, ¶ 4, that “[s]ome preferred polymerizable compositions are silicone elastomer compositions comprising two or more separate components,” and that “[a] first component can include a catalyst and a second component can include a cross-linker such that when the two components are combined or mixed, a temporary or permanent seal quickly forms and adheres to the inner wall of the vessel.” Saber describes on p. 2, ¶ 5, that

[t]he polymerizable composition can have a work time sufficient such that the two or more components can be delivered simultaneously to the target site via a catheter without clogging.  Where desired or necessary, the two or more components of the polymerizable compositions can be delivered to the target site sequentially to further prevent unwanted and premature curing within the catheter.

Saber’s p. 8, ¶ 2, describes that “[w]here a filler is included in the polymerizable formulation, an exemplary filler includes amorphous fumed silica … . Other contemplated fillers include … precipitated silica, diatomaceous earth, titanium dioxide, zinc oxide, barium sulfate, colloidal silica, and boron nitride.” Saber further describes on p. 9, ¶ 2, that its filler can be present in 0 to 80 wt.%, 5 to 35 wt.%, or 10 to 23 wt.% “of the combined two part formulation where the catalyst and crosslinker are combined.” Saber’s p. 12, ¶ 1, describes that “[i]t is also contemplated that inert pigments can be suspended in the polymerizable formulations without leaching.” Saber’s Tables 1 to 12 show only two-component formulations with fumed silica (filler) in each component, while Tables 13 to 17 show two-component formulations without fumed silica or any other filler. Saber’s FIG. 1 shows a dual-chambered syringe, and Saber’s p. 5, ¶ 4, indicates that this structure is such that “crosslinking cannot occur until the two components are mixed together (e.g., delivered separately via a catheter to the target site, or delivered as a mixture).”

Many applicants may be familiar with the fact that post-KSR, MPEP § 2144(I) allows examiner’s to apply “common knowledge in the art” in asserting a rationale to modify or combine the prior art. That is, the examiner’s rationale “does not have to be expressly stated in the prior art; the rationale may be expressly or impliedly contained in the prior art or it may be reasoned from knowledge generally available to one of ordinary skill in the art, established scientific principles, or legal precedent established by prior case law,” as indicated in MPEP § 2144(I), citing a variety of CAFC and BPAI caselaw from 1985 to 2000.

In the case at hand, the examiner rejected the claims without citing to a dry silica filler component in the cited art, nor any particular basis to doubt the declaratory evidence stating and experimentally showing that the particular use of dry silica filler and pre-wetted coloring agents, separately as three components, provided unexpectedly superior results.

Regarding the novelty rejection, the PTAB argued that the examiner had not provided evidence that the filler is present in Saber as a “dry composition” as claimed. Accordingly, although the PTAB appeared to indicate that the three-component feature may have been anticipated by or obvious over Saber’s “two or more components” feature, the lack of a dry component made the claims novel. On obviousness, the PTAB embraced the Appellant’s argument that “there is no disclosure in Saber of providing a dry composition in its embolization procedure, let alone providing the filler as a dry component.” Accepting the examiner’s reasons for using a silica filler, the PTAB countered that the examiner did not identify a reason that one of ordinary skill in the art would have found it obvious to provide the filler as “a dry composition,” as claimed. Accordingly the PTAB reversed the obviousness rejection for failing to provide a reason to include a dry silica filler component. The ODP rejections were likewise reversed for a failure of the reference applications to recite a “dry” silica filler component or an imaging agent in the “wet” component.

The success on appeal in the present case and reversal of all rejections of the examining corps without a need to make the claims “commensurate” or to convince the examiner of what was expected, as the examiner demanded in the final office action, was based on the lack of a claimed element in the cited art. Although Saber disclosed “fumed silica” as a filler, Saber only showed this component mixed into the “wet” component and made no indication that dry silica should be separately used in Saber’s formulations. Such a facile process is a reminder to applicants to seek out missing features from the art, which, like modifications not expected to maintain the quality of the art or feared to be risky, is an attack on the prima facie obviousness finding. Were Saber to have shown dry silica filler, or were the examiner to have cited a further reference describing the use of dry silica in related applications, the applicant may have been in a situation requiring rebuttal of the prima facie obviousness finding, which invokes the need to make the claims commensurate in scope with any data the applicant provides either in the original application or by declaration(s) under 37 CFR § 1.132.

[1] Stinson’s col. 13, ll. 60 to 63, describes “[a] composite radiopaque marker 14 may be made from materials coated or compounded with a radiopaque substance such as iodine, zirconium oxide, barium sulfate, bismuth trioxide, or a related oxide or salt substance.”