Appeal No. 2001-1580 Page 5
Application No. 08/955,090
The examiner concluded that
[i]t would have been obvious to the person of ordinary skill in the art
at the time the invention was made to modify the fusion proteins of
Pastan et al. . . . by substituting for the cytokines disclosed therein
the soluble flt3 ligand disclosed by Lyman et al. One of ordinary
skill in the art would have been motivated to make circularly
permuted forms of the soluble flt3 ligand disclosed by Lyman et al.
by the disclosure of Pastan et al. that such circularly permuted
proteins are expected to retain or have improved binding properties
to the receptor to which they bind, as compared to the non-
permuted forms. The particular termini recited in claim 1 are
considered to be obvious in view of Hannum et al., which discloses
. . . that such sites occur in regions between alpha helices, given
that Pastan et al. teach that regions that do not show a highly
regular three-dimensional structure are desirable for introducing the
new termini to the circularly permuted protein.
Id., page 6.
Appellants argue that the examiner has not shown prima facie
obviousness, because, inter alia, the cited references at best would have made
the claimed invention “obvious to try.” See the Appeal Brief, pages 12-17.
Appellants argue that the cited references would not have led those of skill in the
art to reasonably expect that a circularly permuted flt3 ligand would retain the
binding activity of the native ligand, much less have improved binding properties,
because the record shows that circular permutation produces unpredictable
effects. In support, Appellants refer to the prior art cited in the present
specification (pages 3-7), which lists sixteen proteins which have been circularly
permuted, and which concludes that
[t]he results of these studies have been highly variable. In many
cases substantially lower activity, solubility or thermodynamic
stability were observed [listing seven proteins]. . . . In other cases,
the sequence rearranged protein appeared to have many nearly
identical properties as its natural counterpart [listing eight
Page: Previous 1 2 3 4 5 6 7 8 9 10 11 Next
Last modified: November 3, 2007