Ex Parte Wang et al

Board of Patent Appeals and Interferences

Jun 11, 2012

11799354 (B.P.A.I. Jun. 11, 2012)

UNITED STATES PATENT AND TRADEMARK OFFICE
__________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
__________

Ex parte YUNBING WANG, DAVID C. GALE, and
VINCENT J. GUERIGUIAN
__________

Appeal 2011-003605
Application 11/799,354
Technology Center 3700
__________

Before ERIC GRIMES, FRANCISCO C. PRATS, and JACQUELINE
WRIGHT BONILLA, Administrative Patent Judges.

GRIMES, Administrative Patent Judge.

DECISION ON APPEAL
This is an appeal under 35 U.S.C. § 134 involving claims to a medical
device made from a polymer blend, which the Examiner has rejected as
obvious. We have jurisdiction under 35 U.S.C. § 6(b). We affirm.
STATEMENT OF THE CASE
The Specification states that some polymers that may be suitable for
implantable medical devices, such as stents, have potential shortcomings in
some important characteristics, especially fracture toughness and
Appeal 2011-003605
Application 11/799,354

2
degradation rate (Spec. 6: 21 to 7:2). “For example, polymers such as PLLA
are stiff and strong, but tend to be brittle under physiological conditions” (id.
at 7: 6-7). “Additionally, polymers generally do not possess sufficient
radiographic density to be easily imaged by fluoroscopy” (id. at 7: 19-20).
The Specification discloses that “[o]ne way to form a tougher
polymeric material from a brittle polymer is to form a polymer blend
including the brittle polymer and another polymer that has a higher fracture
toughness than the brittle polymer” (id. at 10: 11-13) and “radiopaque
functional groups [can be] chemically bonded to at least some of [the]
polymers of the polymer material” (id. at 8: 9-10).
Claims 10-23 are on appeal. Claim 10 is representative and reads as
follows:
10. An implantable medical device comprising structural elements
fabricated at least in part from a polymer blend comprising:
a biodegradable matrix polymer blended with biodegradable linear
block copolymers, the linear block copolymers having a discrete phase
segment and a continuous phase segment, wherein the discrete phase
segment is immiscible with the matrix polymer such that discrete phase
segments form a discrete phase within the matrix polymer, wherein the
continuous phase segment is miscible with the matrix polymer, wherein
radiopaque functional groups are chemically bonded to the discrete phase
segments, the continuous phase segments, or both.

Appeal 2011-003605
Application 11/799,354

3
The Examiner has rejected all of the claims on appeal under 35 U.S.C.
§ 103(a) based on Nottelet1 and Wang,2 by themselves or combined with one
of Jackson,3 Zhao,4 Arnold5 or Li6 (see Answer 4-11). The same issue is
dispositive for all of the rejections.
The Examiner finds that “Nottelet discloses a biodegradable matrix
polymer and radiopaque functional groups chemically bonded to the
polymers” but does not disclose the blend of matrix polymer and linear
block copolymers required by claim 10 (Answer 4). The Examiner finds
that Wang discloses the linear block copolymers required by claim 10,
blended with a polymer matrix “for the purpose of altering the strength of
the matrix” (id. at 5). The Examiner concludes that it would have been
obvious “to modify the stent matrix of Nottelet with the discrete and
continuous phase segments of Wang to increase the strength of the stent as
described in Wang” (id.).
We agree with the Examiner that the product of claim 10 would have
been obvious based on Nottelet and Wang. Nottelet discloses that “it is

1 Benjamin Nottelet et al., Synthesis of an X-ray opaque biodegradable
copolyester by chemical modification of poly (ε -caprolactone), 27
BIOMATERIALS 4948-4954 (2006).
2 Yunbing Wang et al., Polyethylene-Poly(L-lactide) Diblock Copolymers:
Synthesis and Compatibilization of Poly(L-lactide)/Polyethylene Blends, 39
J. OF POLYMER SCIENCE: PART A: POLYMER CHEMISTRY 2755-2766 (2001).
3 Jackson et al., Patent Application Publication US 2003/0004563 A1, Jan. 2,
2003.
4 Zhao, Patent Application Publication US 2006/0292077 A1, Dec. 28, 2006.
5 Arnold et al., Patent Application Publication US 2003/0086958 A1, May 8,
2003.
6 Li et al., Patent Application Publication US 2003/0224033 A1, Dec. 4,
2003.
Appeal 2011-003605
Application 11/799,354

4
highly desirable to visualize an implant or an embolization device via
routine X-rays radioscoscopy [sic]” (Nottelet 4948, left col.). Nottelet
discloses that one “approach to make a polymer radio-opaque is to
covalently link a radiocontrast dye, typically containing an iodine moiety, to
the polymeric backbone” (id. at 4948, right col.). Nottelet discloses a
method of modifying poly (ε-caprolactone) to contain iodine on the polymer
backbone (id. at 4948, right col. to 4949, left col.).
Wang discloses that polylactide is biocompatible and biodegradable
and “has been used for biomedical applications” (Wang 2755, left col.), but
poly(L-lactide) (PLLA) is inherently brittle and thus has been modified by
preparing copolymers and blends (id. at 2755, right col.). Wang discloses
that blends of PLLA and polyethylene (PE) “are attractive materials for
toughened composites” (id. at 2756, left col.) but PLLA and PE (including
low-density PE, or LDPE) are immiscible (id.), and that in a mixture of 80%
PLLA and 20% LDPE, the LDPE forms discrete spherical particles (id. at
2760, left col.).
Wang discloses that “[w]hen a block copolymer containing segments
equivalent to the blend constituents is added to the immiscible binary blend,
. . . [t]he segments of the copolymer mix with the respective homopolymer
phases,” which “can cause dramatic improvement of the final mechanical
properties of the blends” (id. at 2763, right col.). Wang discloses adding a
copolymer consisting of separate blocks of PLLA and PE, referred to as PE-
b-PLLA (see 2758, Fig. 2), to a PLLA/LDPE blend, and found that “after
adding block copolymer, the LDPE was still dispersed in the PLLA matrix
as spheres but the particle size had significantly decreased” (id. at 2760, left
Appeal 2011-003605
Application 11/799,354

5
col.), and addition of more copolymer decreased particle size further (id. at
2760, right col.). Wang also discloses that addition of the PE-b-PLLA
copolymer to the PLLA/LDPE mixture resulted in “dramatic improvements
in the mechanical properties” (id. at 2763, right col.).
We agree with the Examiner that it would have been obvious to
substitute Wang’s PLLA/LDPE/PE-b-PLLA for Nottelet’s poly(ε-
caprolactone), because doing so would result in an iodine-containing (and
therefore radiopaque) polymer with the beneficial mechanical properties of
Wang’s polymer blend. Wang teaches that polylactide has been used for
biomedical applications, and Nottelet teaches that radiopacity is desirable for
implanted medical devices, and therefore it would have been obvious to use
the polymer blend suggested by the references to make an implantable
medical device.
Appellants argue that the claims do not read on Wang’s polymer
blend, because in Wang’s blend “the PLLA block [of the block copolymer]
forms a continuous phase with the PLLA of the matrix and the PE block [of
the block copolymer] forms a continuous phase with the LDPE” (Appeal Br.
7). Appellants argue that “[t]his is very different from the current invention
where only one block of the block copolymer is miscible and can form a
continuous phase with the matrix, while the other block remains a discrete
phase” (id. at 8). Appellants have provided diagrams illustrating what they
view as the difference between the claimed polymer blend (Reply Br. 4) and
Wang’s polymer blend (id. at 5).
We agree with the Examiner (Answer 12), however, that claim 10
reads on the polymer blend disclosed by Wang. Claim 10 is directed to a
Appeal 2011-003605
Application 11/799,354

6
device comprising elements made from a polymer blend comprising (a) a
matrix polymer and (b) linear block copolymers having a segment that is
miscible with the matrix polymer (i.e., a “continuous phase segment”) and a
segment that is immiscible with the matrix polymer (i.e., a “discrete phase
segment”). Wang discloses a polymer blend comprising a “PLLA matrix”
(Wang 2760, left col.) and a block copolymer having a PLLA (PLLA-
miscible, continuous phase) segment and a PE (PLLA-immiscible, discrete
phase) segment.
Appellants argue, however, that the claimed blend is distinguished
from Wang’s because it requires that “discrete phase segments form a
discrete phase within the matrix polymer” (claim 10), while in Wang’s blend
the PE (discrete phase) segments of the block copolymer form a continuous
phase with the LDPE spheres (see Appeal Br. 7-8).
We disagree. As the Examiner points out (Answer 9), the
“comprising” transitional language of claim 10 opens it up to other
components that are not expressly recited. Appellants have pointed to no
definition in the Specification of a “discrete phase” that requires it to be
composed solely of discrete phase segments of the linear block copolymer,
or otherwise precludes the additional presence in the discrete phase of a
polymer (such as LDPE) that is not part of the block copolymer. Read in
light of the claim language and the Specification, a “discrete phase” requires
only a phase that is discrete from the matrix. See In re Hyatt, 211 F.3d
1367, 1372 (Fed. Cir. 2000) (“[D]uring examination proceedings, claims are
given their broadest reasonable interpretation consistent with the
specification.”). A “discrete phase” therefore reads on the phase of Wang’s
Appeal 2011-003605
Application 11/799,354

7
polymer blend that is formed from LDPE and the PE blocks of its PE-b-
PLLA copolymer.
With regard to claim 14, Appellants additionally argue that the
Examiner has not shown that it would have been obvious to limit the
iodination only to the discrete phase of the block copolymer (Appeal Br. 8).
This argument is not persuasive. First, while claim 14 requires
radiopaque groups bonded to the discrete phase segments, it does not
exclude bonding radiopaque groups to the continuous phase segments as
well. Second, we agree with the Examiner that Nottelet would have made it
obvious to iodinate the polymer(s) of Wang’s blend, and a skilled worker
would have recognized that iodination would provide radiopacity whether
the iodine was attached to the matrix polymer, the discrete segment of the
block copolymer, or the continuous segment of the block copolymer.
Appellants have provided no persuasive reason to conclude that iodination
of, among other things, the discrete phase of Wang’s copolymer would not
have been among the “identified, predictable solutions,” KSR Int’l Co. v.
Teleflex Inc., 550 U.S. 398, 421 (2007), to the problem of iodinating Wang’s
polymer blend.
We therefore affirm the rejection of claims 10 and 14 as obvious in
view of Nottelet and Wang. Claims 12, 15-20, and 22 fall with claim 10
because they were not argued separately. 37 C.F.R. § 41.37(c)(1)(vii).
With regard to claim 11, Appellants argue that “[t]here would be no
earthly reason for the skilled artisan to consider combining Nottelet with
Jackson” (Appeal Br. 10).
Appeal 2011-003605
Application 11/799,354

8
This argument is also unpersuasive. The Examiner cites Jackson as
evidence that a stent would have been an obvious medical device to make
using the polymer blend made obvious by Nottelet and Wang (Answer 9).
We agree with the Examiner’s reasoning set out in the Answer (pages 9-10).
Appellants present no additional arguments based on Zhao, Arnold, or
Li (see Appeal Br. 10-11). We therefore affirm the rejections on appeal that
are based on Nottelet and Wang, further combined with one of Jackson,
Zhao, Arnold, or Li.
SUMMARY
We affirm all of the rejections on appeal.
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

lp