Appeal No. 2004-2035
Application 09/978,763
Appellants further contend that “[t]he present specification teaches that the use of
patterned stents as opposed to non-patterned stents leads to surprisingly superior results,”
pointing to the disclosure at page 29, ll. 1-8, of the specification (brief, pages 7-8), which
statement is not specific with respect to the coating of “a polymer/paclitaxel matrix” used or the
construction of the patterned and coil stents on which the allegation of unexpected results are
based. The examiner takes the position that the alleged difference between patterned and coil
stents is not surprising because of the difference in the exterior surface area of the two stents, as
seen from a comparison of the patterned stent of Palmaz and the coil stent of Wiktor, and the
corresponding difference in available coating area (answer, pages 6-7).
In support of their position, appellants point to the results obtained with patterned stents
in specification Examples 11-13 compared with the results obtained with a coil stent in
specification Comparative Example 14 with “the same amount of the same drug” (reply brief,
pages 5-6; emphasis supplied). Appellants further characterize this comparison as “these
examples compare use of a patterned stent and coiled stent using substantially the same drug
(200 µg of paclitaxel used for the patterned stents and 175-200µg of Taxol used for the coiled
stent. See Example 11 and Comparative Example 14)” (reply brief, page 7; emphasis provided).
Appellant thus argues that “notwithstanding the differences in uncovered surface area of the two
types of stents, the stents can be prepared to carry the same amount of drugs (i.e. the coiled stent
can be covered with any number of layers of polymers to increase the surface area over which
the drug is deposited)” (id.). Appellants further points to specification Example 15 but not in the
context of a comparison (reply brief, page 6).
We find that specification Examples 11-13 all use “a stent prepared as set forth in
Example 10” wherein a “9 mm long balloon-expandable stainless steel NIR® stent” is coated
with a polylactic acid/polycaprolactone (PLA/PCL) copolymer/paclitaxel matrix containing
200 µg of paclitaxel, wherein paclitaxel “comprised approximately 30% by weight of the matrix”
(specification, pages 41-42). No other description of the stent is provided. The stents were
implanted in porcine coronary arteries in Example 11 and in a rabbit iliac in Examples 12 and
13, and the results stated in comparison to the same stent having no coating (id., pages 42-43).
In Examples 11 and 12, the results after 2-3 µg/day of paclitaxel over 28 days was 50% and
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