Ex Parte Lye et al

Board of Patent Appeals and Interferences

Jun 4, 2012

11200655 (B.P.A.I. Jun. 4, 2012)

UNITED STATES PATENT AND TRADEMARK OFFICE
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
11/200,655 08/10/2005 Whye-Kei Lye P31019.01 2676
28390 7590 06/04/2012
MEDTRONIC VASCULAR, INC.
IP LEGAL DEPARTMENT
3576 UNOCAL PLACE
SANTA ROSA, CA 95403
EXAMINER
PELLEGRINO, BRIAN E
ART UNIT PAPER NUMBER
3738
MAIL DATE DELIVERY MODE
06/04/2012 PAPER
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
__________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
__________

Ex parte WHYE-KEI LYE, GARY K. OWENS,
MATTHEW S. HUDSON, JOSHUA SPRADLIN,
BRIAN R. WAMHOFF, MICHAEL REED, and KAREEN LOOI
__________

Appeal 2011-003617
Application 11/200,655
Technology Center 3700
__________

Before TONI R. SCHEINER, MELANIE L. McCOLLUM, and ERICA A.
FRANKLIN, Administrative Patent Judges.

McCOLLUM, Administrative Patent Judge.

DECISION ON APPEAL
This is an appeal under 35 U.S.C. § 134 involving claims to a stent.
The Examiner has rejected the claims as obvious. We have jurisdiction
under 35 U.S.C. § 6(b). We affirm.
STATEMENT OF THE CASE
Claims 1-10 and 13-23 are on appeal (App. Br. 2). The claims subject
to each rejection have not been argued separately and therefore stand or fall
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together. 37 C.F.R. § 41.37(c)(1)(vii). Claim 1 is representative and reads
as follows:
1. A stent for insertion into a body structure, comprising:
a tubular member comprising:
a first end and a second end,
a lumen extending along a longitudinal axis between the first end and
the second end,
an ablumenal surface,
a lumenal surface;
a first porous metal layer, the first porous layer comprising a first
surface, a first interstitial structure and a first interstitial space;
wherein the first porous layer has a tortuosity factor of greater than
about 1.1, an average thickness of less than 10 microns and a peak-valley
surface roughness of less than about 2 microns,
wherein the first porous layer further comprises at least one
therapeutic agent within at least a portion of the interstitial space.
Claims 1-9, 13-16, and 20-23 stand rejected under 35 U.S.C. § 103(a)
as obvious over Brandau et al. (WO 00/25841 A1, May 11, 2000) in view of
Michaels (US 3,788,322, Jan. 29, 1974) (Ans. 4).
Claim 10 stands rejected under 35 U.S.C. § 103(a) as obvious over
Brandau in view of Michaels and Stinson (US 2004/0000046 A1, Jan. 1,
2004) (Ans. 6).
Claims 17-19 stand rejected under 35 U.S.C. § 103(a) as obvious over
Brandau in view of Michaels and Rathenow et al. (US 2005/0079200 A1,
Apr. 14, 2005) (Ans. 6).
The Examiner relies on Brandau for disclosing “an implantable device
(stent structure) . . . ha[ving] a first porous layer 6 with an outer surface,
[and] an interstitial space to provide a structure for releasing therapeutic
agents when the device is implanted into a location in the body” (Ans. 4).
The Examiner finds that “Brandau discloses the porous layer contains a
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metal, . . . the surface thickness is less than 10 microns, . . . the drug is in the
interstitial space or pores, . . . [and] a peak-valley surface roughness less
than the thickness of the porous layer, but not explicitly less than about
2 microns” (id.). The Examiner concludes that it would have been obvious
“to optimize the depth or peak-valley roughness of the cavities of the porous
layer such that it provides the optimal depth for therapeutic agents for the
desired treatment protocol” (id.).
The Examiner also finds that “Brandau does not explicitly state the
tortuosity factor is greater than about 1.1” (id.). However, the Examiner
finds that “Michaels teaches implants for drug delivery placed in liquid
conveying lumens” and that “the implantable structure includes a porous
surface utilizing a tortuosity factor that is greater than about 1.1” (id. at 4-5).
The Examiner concludes:
It would have been obvious to one of ordinary skill in the art to
utilize a tortuosity greater than 1.1 for the porous layer as
taught by Michaels on the stent of Brandau et al. such that the
drug release is not too fast being released into the liquid flow of
the lumen it is placed in from the porous layer since it is known
that tortuosity is a factor . . . affecting release rate.
Optimization of the release rate only involves routine skill in
the art.
(Id. at 5.)
ISSUE
With regard to each ground of rejection, the only issue raised by
Appellants is: Do Brandau and Michaels suggest a stent having a porous
layer having a tortuosity factor of greater than about 1.1?
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FINDINGS OF FACT
1. Brandau states:
A stent is already known . . . which forms the starting
point of the present invention; a stent which comprises a
nonporous support with a porous covering layer. . . . The porous
covering layer is formed of sintered metal particles. A drug or
a therapeutic agent is absorbed in the pores of the porous
covering layer. . . .
In the known stent, it is detrimental that the sintered
metal particles of the porous covering layer form very irregular,
indefinite pores. Accordingly, in the case of a drug to be
released, only a relatively indefinite release behavior is
achieved.
(Brandau, col. 2, ll. 11-26.)
1

2. Brandau discloses a stent having a covering layer comprising “a
plurality of defined cavities with separate openings to the surface of the
covering layer for absorbing at least one therapeutic agent” (id. at col. 2,
l. 61, to col. 3, l. 6).
3. In particular, Brandau discloses “an essentially tube-shaped
insert for vessels,” wherein the “implant 1 or the stent comprises a
preferably metal or metallized support 2” (id. at col. 7, ll. 15-20).
4. Brandau also discloses that “the covering layer 6 is applied
preferably on the whole surface 7 of the support 2,” the “covering layer 6
compris[ing] a plurality of distributed openings 9 spaced from one another
and attached cavities 10 on its surface 8 facing away from the support 2.

1
The point citations to Brandau are to its US counterpart, US 6,709,379 B1,
issued Mar. 23, 2004, which was relied on by the Examiner as an
“equivalent English version” (Ans. 4).
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The therapeutic agent 5 . . . is absorbed and optionally chemically fixed in
the cavities 10.” (Id. at col. 7, ll. 38-49.)
5. In addition, Brandau discloses: “Here, the cavities 10 are
formed essentially tube-like and each is closed on its ends. They extend
from the surface 8 of the covering layer 6, essentially perpendicularly to the
support 2.” (Id. at col. 7, ll. 51-55.)
6. Brandau also discloses: “Here, the cavities 10 extend
essentially parallel to one another and are separated from each other without
having the cavities 10 linked to one another. However, this is not absolutely
necessary; possibly, links may also exist between the cavities 10 in the
covering layer 6.” (Id. at col. 7, l. 65, to col. 8, l. 3.)
7. Michaels discloses a “drug delivery device for releasing drug
internally to a drug receptor such as a cavity in an animal, human or avian at
a controlled rate for a prolonged period of time” (Michaels, col. 1, ll. 9-12).
8. In particular, Michaels discloses:
Device 14 of FIG. 3 is comprised of a shell or wall 15 with an
internal space for containing a drug reservoir 17. . . . Drug
reservoir 17 is formed of a polymeric elastomeric material . . .
and it is equipped with a flow control means 19 that acts both as
a passageway between reservoir 17 and the exterior of
device 14 and as a means for metering drug from reservoir 17 to
the exterior of the device 14. Flow control means 19 is suitably
made of a porous inert material, a calibrated aperture, a needle
valve, or the like to act as a meter for releasing a drug, for
example according to the Hagen-Poiseuille equation, at a
constant rate over a prolonged period of time.
(Id. at col. 5, l. 60, to col. 6, l. 9.)
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9. Michaels also discloses:
The rate of flow through the resistive means is governed by the
Hagen-Poisseuille equation wherein Q = ¶ D
4
ΔP/128L, where
Q equals flow in ml/sec, D equals diameter in cm,  equals
viscosity in poise, ΔP equals pressure in dynes/cm
2
, and L
equals length of the means. The use of this equation allows the
flow rate to be easily predicted and readily adjusted by
changing the length and diameter parameters of the flow
resistive means.
(Id. at col. 13, ll. 12-20.)
10. In addition, Michaels discloses:
The elastic member is closed at one end and is equipped with a
flow control means consisting of a porous polyethylene plug
. . . which has a porosity of 20 percent, an average pore size of
1 micron, and a tortuosity factor of about 2; for example, the
effective length is about twice the actual length.
(Id. at col. 13, ll. 47-54.)
11. Michaels also states: “Another approach for administering a
drug to drug receptor sites . . . has been to enclose the drug within a single
drug delivery capsule having a wall permeable to the drug through which it
can pass, for example, by diffusion. . . . [H]owever, these too have inherent
difficulties. . . .” (Id. at col. 2, ll. 4-11.)
ANALYSIS
Brandau discloses a stent comprising a tubular member comprising a
porous covering layer having interstitial space and a therapeutic agent within
the interstitial space (Findings of Fact (FF) 2-4). In particular, Brandau
discloses that cavities “extend from the surface 8 of the covering layer 6,
essentially perpendicularly to the support 2” (FF 5). Michaels discloses that
length is a factor in determining flow rate and that tortuosity is a way to
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affect length (FF 9-10). Based on the teachings in Michaels, we agree with
the Examiner that it would have been obvious to provide Brandau’s covering
layer with a tortuosity factor greater than about 1.1 in order optimize the
flow rate of therapeutic agent from its cavities (Ans. 5).
Appellants argue, however, that “one of ordinary skill in the art of
stents would not look to a reference regarding capsules to be ingested into
the stomach for drug elution parameters” (App. Br. 4). We are not
persuaded.
Although Michaels does not relate to stents, we agree with the
Examiner that “it is clearly within the field of endeavor that one of ordinary
skill in the art [would] look to [for] the designs of drug release into the body
and ways to control the elution or release into the body in which it is
delivered” (Ans. 7). Thus, we agree with the Examiner that Michaels is
analogous art (id. at 8).
Appellants also argue that “both Brandau and Michaels teach away
from the combination proposed by the Examiner” (App. Br. 4). We are not
persuaded.
A reference may be said to teach away when a person of
ordinary skill, upon reading the reference, would be
discouraged from following the path set out in the reference, or
would be led in a direction divergent from the path that was
taken by the applicant. The degree of teaching away will of
course depend on the particular facts; in general, a reference
will teach away if it suggests that the line of development
flowing from the reference’s disclosure is unlikely to be
productive of the result sought by the applicant.
In re Gurley, 27 F.3d 551, 553 (Fed. Cir. 1994).
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Brandau discloses cavities that “extend from the surface 8 of the
covering layer 6, essentially perpendicularly to the support 2” and
“essentially parallel to one another” (FF 5-6). However, we do not agree
that Brandau teaches away from cavities that are not perpendicular to the
support and parallel to each other. Brandau does state that “it is detrimental
that the sintered metal particles of the porous covering layer form very
irregular, indefinite pores” (FF 1). However, the Examiner’s combination
does not require very irregular, indefinite pores, merely that the cavities are
tortuous enough to provide the claimed tortuosity factor of greater than
about 1.1.
In addition, Michaels discloses that there are “inherent difficulties”
with enclosing a “drug within a single drug delivery capsule having a wall
permeable to the drug through which it can pass, for example, by diffusion”
(FF 11) and instead utilizes a different approach (FF 8). However,
Appellants have not pointed to anything in Michaels that suggests that the
use of permeable walls is “unlikely to be productive.” In re Gurley, supra.
Thus, we do not agree that Michaels teaches away from permeable walls.
Appellants also argue that “the resultant combination would not have
been the device recited in claim 1” (App. Br. 7). In particular, Appellants
argue:
If one of ordinary skill in the art would have relied on th[e]
“teaching” of Michaels, . . . such a person of ordinary skill
would not have increased the tortuosity factor of cavities 10 of
Brandau. Instead, because cavities 10 of Brandau are, at best,
similar to reservoir 17 of Michaels, one of ordinary skill in the
art would have, at best, added a flow control means to Brandau,
as taught by Michaels.
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(Id. at 8.) We are not persuaded.
First, Appellants have not explained why the Examiner is incorrect in
his position that adding a flow control means having a tortuosity factor of
about 2, as described in Michaels (FF 10), would not provide a porous layer
having a tortuosity factor of greater than about 1.1 (Ans. 8-9). Moreover,
obviousness analysis “need not seek out precise teachings directed to the
specific subject matter of the challenged claim.” KSR Int’l Co. v. Teleflex
Inc., 550 U.S. 398, 418 (2007). Instead, it proper to “take account of the
inferences and creative steps that a person of ordinary skill in the art would
employ.” Id. In this case, we agree with the Examiner that it would have
been obvious to apply the principles disclosed in Michaels to Brandau’s
cavities, and thus increase the tortuosity of Brandau’s cavities to greater than
about 1.1, in order decrease the flow rate of therapeutic agent from the
cavities (Ans. 5).
CONCLUSION
We conclude that Brandau and Michaels suggest a stent having a
porous layer having a tortuosity factor of greater than about 1.1. We
therefore affirm the obviousness rejections.
TIME PERIOD FOR RESPONSE
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a).

AFFIRMED

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