Ex Parte Johnson

Board of Patent Appeals and Interferences

Oct 17, 2007

09880615 (B.P.A.I. Oct. 17, 2007)

UNITED STATES PATENT AND TRADEMARK OFFICE
__________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
__________

Ex parte MICHAEL W. JOHNSON
__________

Appeal 2007-2766
Application 09/880,615
Technology Center 3700
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Decided: October 17, 2007
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Before DEMETRA J. MILLS, LORA M. GREEN, and
RICHARD M. LEBOVITZ, Administrative Patent Judges.

LEBOVITZ, Administrative Patent Judge.

DECISION ON APPEAL
This is a decision on appeal from the Examiner’s final rejection of
claims 23, 24, 26-30, 32, 33, and 35-40. We have jurisdiction under 35
U.S.C. § 6(b). We affirm.
STATEMENT OF THE CASE
The claims are directed to methods of manufacturing a porous stent.
The stent is described as useful to deliver drugs to a desired body location by
loading stent pores with drug (Specification 1: 28-29; 3: 4-20).
Appeal 2007-2766
Application 09/880,615

Claims 23, 24, 26-33, and 35-41 are pending (Supp. Appeal Br. 3).
Claims 31 and 41 are withdrawn; claims 23, 24, 26-30, 32, 33, and 35-40
stand rejected (Supp. Appeal Br. 3). Two grounds of rejection are appealed:
1) Claims 23, 26-30, 32, 35-37, and 39 stand rejected under 35 U.S.C.
§ 103(a) as obvious over Yan (U.S. Pat. No. 5,843,172, Dec. 1, 1998) in
view of Solovay (U.S. Pat. No. 5,769,884, Jun. 23, 1998) (Answer 3); and
2) Claims 24, 33, 38, and 40 stand rejected under 35 U.S.C. § 103(a)
as obvious over Yan in view of Solovay, further in view of Richter (U.S.
Pat. No. 5,807,404, Sep. 15, 1998) (Answer 5).
We select claims 23, 24, and 32 as representative of the appealed
claims. Claims 23, 24, and 32 read as follows:
23. A method of manufacturing a stent comprising the steps of:
providing a tube, the tube characterized by a longitudinal
axis, having at least two different longitudinally spaced regions
of different predetermined porosities and each region having
substantially the same porosity about its circumference, and
subsequently cutting a stent from the tube.

24. The method of claim 23 wherein a first portion of the tube
is made from a first metal and a second portion of the tube,
axially spaced from the first portion of the tube is made from a
second metal different from the first metal.

32. A method of manufacturing a stent comprising the steps of:
providing a tube having at least two different
longitudinally spaced regions of different predetermined
porosities; and
subsequently, cutting a plurality of openings in the tube
to form a stent having multiple serpentine bands such that a first
band has a different porosity than a second band.

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The manufacturing process recited in independent claims 23 and 32
involve two steps: 1) providing a tube; and 2) cutting a stent from the tube.
In claim 32, the stent is cut into a serpentine pattern. The tube in both
claims 23 and 32 is characterized by having at least two different pores sizes
along the longitudinal axis.

FINDINGS OF FACT
The level of skill in the art
1. Stents are commonly used to treat medical conditions (see Solovay, at
col. 1, ll. 9-12; Yan, at col. 1, ll. 12-20; Richter, at col. 1, ll. 16-23).
2. The manufacture of stents using different designs and different materials
was known and routine in the art prior to the application filing date (see Yan,
at col. 4, ll. 32-40; at col. 9, ll. 15-40; Solovay, at col. 7, ll. 4-23; Richter, at
col. 1, ll. 43-48).
3. Different methods of manufacturing stents were also known and routine
to persons of ordinary skill in the art (see Yan, at col. 2, ll. 38-46; at col. 7,
ll. 45-50; Solovay, at col. 7, ll. 45-47; Richter, at col. 1, ll. 50-54).

The scope and contents of the prior art
The Yan Patent
4. Yan describes a stent having porous cavities which “can be formed by
sintering the stent material from metallic particles, filaments, fibers or other
materials” (Yan, at col. 2, ll. 7-9).
5. Drugs can be loaded into the pores (Yan, at col. 1, ll. 64-66).
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6. “The stent can be formed from a sintered cylindrical tube or sintered
metal sheet which can be laser cut or chemical etched into an expandable
stent structure” (Yan, at col. 2, ll. 11-14; at col. 2, ll. 39-46; Answer 4).
7. “A sheet or tube of sintered metal can be cut in the desired shape to form
the metal structural member with a laser, such as a continuous CO2 laser, a
pulsed YAG laser, or an excimer laser, for example, or alternatively, by
chemical etching or stamping” (Yan, at col. 7, ll. 44-49).
8. The stent described by Yan can comprise outer and inner core layers
comprising pores of different diameters, where the core’s pores have a larger
diameter than the pores of the outer layer to control the rate at which drugs
are released into the walls of the vessel (Yan, at col. 2, ll. 20-32; at col. 8, ll.
52-55; see Fig. 12. See also Answer 3).

The Solovay Patent
9. Solovay describes a stent covering which has different porosities along its
length (Answer 5). Typically, tissue ingrowth and re-endothelialization are
desired at the ends of the stent. To encourage ingrowth into this region, the
stent covering “is more porous, and in those regions w[h]ere it is desirable to
inhibit such ingrowth, the stent covering is substantially non-porous”
(Solovay, Abstract; see also at col. 2, ll. 2-9; at col. 3, ll. 35-41; Fig. 6).
10. Ingrowth can also be controlled by pore size and density, using smaller
diameter and/or less dense porosity to inhibit ingrowth, and larger diameter
and higher porosity to encourage it (Solovay, at col. 2, ll. 2-41; at col. 4, ll.
53-67; Fig. 6).
11. Each longitudinally spaced region of different porosity has the same
porosity around its circumference (see Solovay, Fig. 6; Answer 5).
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12. The stent covering can be disposed on a suitable expandable frame
(Solovay, at col. 7, ll. 25-44).
13. A “nonuniform porosity stent” can be prepared from any suitable
material; such as a polymer that consists of an extruded tube (Solovay, at
col. 7, ll. 4-14).
14. The stent’s pores “may be filled with a material, such as drug or protein”
(Solovay, at col. 6, ll. 47-55; Answer 5).
15. Solvay describes a preferred embodiment in which a braided porous
stent covering is produced on a mandrel and then cut to its desired length
(Solovay, at col. 8, ll. 19-30; see Fig. 7).
The Richter Patent
16. Richter teaches a stent comprised of C-shaped, U-shaped, and S-shaped
loops (Richter, at col. 3; at col. 6, ll. 42-60; Fig. 11; Answer 6).
17. The flexibility of the loops can vary from loop to loop. The different
flexibilities may be accomplished by using different materials in the
different loops, such as different metals (Richter, at col. 6, ll. 42-51; at col.
10, ll. 38-40; Answer 6).

REJECTION OVER YAN IN VIEW SOLOVAY
Claims 23, 26-30, 32, 35-37, and 39 stand rejected under 35 U.S.C. §
103(a) as obvious over Yan in view of Solovay.
Claims 23 and 32 are directed to a manufacturing process comprising:
1) providing a tube characterized by having at least two different pores sizes
along its longitudinal axis; and 2) cutting a stent from the tube. Claim 32 is
directed to a manufacturing process involving a tube of the same non-
uniform porosity characteristics recited in claim 23, but it further limits the
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cutting step to “cutting a plurality of openings in the tube to form a stent
having multiple serpentine bands such that a first band has a different
porosity than a second band.”
In making an obviousness determination over a combination of prior
art references, it is important to identify a reason why persons of ordinary
skill in the art would have attempted to make the claimed subject matter.
KSR Int’l Co. v. Teleflex Inc., 127 S. Ct. 1727, 1741, 82 USPQ2d 1385,
1396 (2007). When making such a determination, the scope of the prior art
and level of ordinary skill must be considered. Graham v. John Deere Co.,
383 U.S. 1, 17 (1966).
Both Yan (FF 6-7) and Solovay describes the same basic
manufacturing steps (FF 15) which are claimed, i.e., of providing a tube and
cutting it. The issue in this rejection is whether the skilled worker would
have had sufficient reason to have supplied the patterned stent of Yan “with
at least two different longitudinally spaced regions of different
predetermined porosities wherein each region has substantially the same
porosity about its circumference, . . . in light of the teachings of Solovay”
(Answer 5). If so, the burden shifts to Appellant to come forward with
rebuttal arguments or evidence. In re Oetiker, 977 F.2d 1443, 1445, 24
USPQ2d 1443, 1444 (Fed. Cir. 1992); Hyatt v. Dudas, 492 F.3d 1365, 1370,
83 USPQ2d 1373, 1375-76 (Fed. Cir. 2007).
In the instant Specification, it is stated that “cellular ingrowth [into the
porous stents of the present invention] is sometimes desirable”
(Specification 4: 5). The Specification also states that pore size determines
whether cellular infiltration will occur and states that “pore size of the stent
may be varied to foster or inhibit cellular infiltration and/or tissue ingrowth”
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(Specification 4: 6-14). Solovay’s stent covering is designed around these
same principles (FF 9-10); thus, the Specification’s statements about cell
ingrowth and infiltration had been known in the prior art.
Solovay places smaller diameter pores in middle regions to inhibit
ingrowth and larger diameter pores in end regions to encourage cell
ingrowth (FF 9-10). Thus, skilled workers at the time of the invention
would have known, based on Solovay’s teachings, that changing stent
porosity allows the ingrowth to be manipulated. Appellant admits in the
Specification that cellular ingrowth into a stent may be desirable (see supra;
Specification 4: 6-14). Therefore, the skilled worker would have had reason
at the time the invention was made to apply Solovay’s teaching about non-
uniform porosity in a covered stent to other stent designs – such as the
claimed stent – for the advantages described by Solovay. Persons of skill in
the art being familiar with stent use, design, and manufacture would have
considered the application of Solovay’s teaching about covered stents to the
particular class of stents described in Yan as a routine exercise of their skills
(FF 1-3), including stents with serpentine patterns as recited in claim 32.
Appellant contends that Solovay discloses a stent cover which is
“placed about a stent” (Appeal Br. 7). He asserts that a “skilled person in
the art will not look to the stent cover art to find a method for manufacturing
a stent having longitudinally spaced regions of different predetermined
porosities” (Appeal Br. 7).
We do not find this argument persuasive. As stated above, Appellant
admits in the Specification (Specification 4: 5) that it may be desired to have
ingrowth into the stent – the same event that is described by Solovay as
desirable for its stent covering (FF 9). Appellant even explains that this
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would be accomplished by varying the pore size of the stent material – the
same solution taught by Solovay (FF 10). In other words, Solovay’s
teaching about stent coverings is applicable to non-covered stents – which is
logical because the exterior of the stent covering would be exposed to the
body cavity as would be the exterior of the non-covered stent.
Solovay also teaches that it may be desirable to discourage growth in
certain regions of the stent covering, and suggests non-uniform porosity to
address this problem (FF 9-10). It is reasonable that such benefit would also
extend to non-covered stents, such as the stent described by Yan, because its
exterior is also exposed to the body cavity. Accordingly, the skilled worker
would have had reason to apply the teachings of Solovay to Yan’s non-
covered stent.
Appellant also argues “if one were to take the stent cover of Solovay
and then cuts [sic] it as one would in forming a stent, the very purpose of the
Solovay stent cover would be destroyed; the stent cover would at best now
sparsely and intermittently cover the stent and the struts of the stents and
would likely interfere with stent expansion as the serpentine portions of the
cut stent cover would become tangled with the serpentine bands of the
stent.” (Appeal Br. 8). As explained above, the rejection does not require
cutting Solovay’s stent into a serpentine pattern, but rather applying
Solovay’s teaching to patterned non-covered stents, such as Yan’s stent.
Appellant urges that
column 4 lines 58-64 of Yan which teaches uniform porosity
and the undesirability of areas of different porosity. As the
explicit language of the Yan reference teaches the undesirability
of areas of different porosity, it does not make sense that Yan
would teach longitudinally spaced regions of different
predetermined physical porosities. In fact, Yan teaches away
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from such a teaching; one would never predetermine to produce
the very thing that is undesirable (i.e. non-uniform porosity).
(Appeal Br. 6.)
We do not agree. Yan states that consistent pore size and consistent
distribution of pores ensures even distribution of drug within the stent and
even distribution of drug in contact with the stent (Yan, at col. 4, ll. 54-65).
Thus, the teaching of Yan cited by Appellants deals with the issue of drug
delivery, and not the separate problem of tissue ingrowth addressed by
Solovay. However, claims 23 and 32 do not recite that drug is present in the
stent; thus, even were this consideration relevant, it would only be relevant
to the extent that the stent in the claimed method loaded with drug.
Nevertheless, we are not convinced by Appellant’s argument because
Solovay also teaches that that its stent of non-uniform porosity may be
loaded with drug (FF 14). Thus, we do not find that persons of skilled in the
art would have been discouraged from applying Solovay’s teaching to Yan’s
stent since Solovay also teaches loading the stent pores with drug.
Appellant contends that the Examiner erred because of his repeated
assertions that “that Yan discloses providing a tube having at least two
different longitudinally spaced regions of different predetermined physical
characteristics” which is inconsistent with Yan’s teaching that the stent must
have uniform porosity (Appeal Br. 5-6).
The Examiner’s characterization of Yan is correct. Yan shows an
embodiment of a stent in Fig. 12 having a core layer of large diameter pores
surrounded by a top and bottom layers of smaller diameter pores (FF 8).
Thus, there are different porosities at different regions along the length of
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the stent, where each of the different porosities extends along the entire
length of the stent.
In sum, we conclude that there is sufficient evidence to establish
prima facie obviousness of claims 23 and 32. Claims 26-30, 35-37, and 39
fall with claims 23 and 32 because separate arguments for their patentability
were not provided. See 37 C.F.R. 41.37(c)(1)(vii) (2006).

REJECTION OVER YAN IN VIEW OF SOLOVAY AND RICHTER
Claims 24, 33, 38, and 40 stand rejected under 35 U.S.C. § 103(a) as
obvious over Yan in view of Solovay and Richter.
We select claim 24 as representative of the claims for the purpose of
deciding this rejection. Claim 24, which depends on claim 23, recites that “a
first portion of the tube is made from a first metal and a second portion of
the tube, axially spaced from the first portion of the tube is made from a
second metal different from the first metal.”
The Examiner contends that Richter discloses a stent comprising first
and second serpentine segments which are made of first and second metals,
respectively (FF 16, 17; Answer 6). The Examiner concludes that it would
have been obvious to a person of ordinary skill in the art to have modified
Yan’s stent with Richter’s teaching “in order to provide more flexibility at
the ends to allow the stent to accommodate the curvature of a vessel in
which the stent is implanted” (Answer 7). Appellant does not identity any
defect in the Examiner’s reasoning, and as we find none, we affirm the
Examiner’s rejection of claim 24. Claims 33, 38, and 40 fall with claim 24
because separate arguments for their patentability were not provided. See 37
C.F.R. 41.37(c)(1)(vii) (2006).
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CONCLUSION
The Examiner’s final rejection of all pending claims is affirmed.

TIME PERIOD
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a)(1)(iv) (2006).

AFFIRMED

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