Appeal No. 2004-1259
Application No. 09/832,355
3. Lack of Written Description and Enablement of fusion proteins with specified
half-life
The examiner argues there is no written description of fusion proteins with a half-
life of at least twice as long as either the first or second peptide portion or both as in
claim 6. The examiner argues that “the specification, as filed, does not disclose the
half lives of various proteins, nor does it provide any data or working example of the
half-life of any of the claimed fusion proteins”, and that the art of increasing half-lives of
proteins is unpredictable. Answer, page 11.
Appellants respond arguing that (Brief, page 7)
methods for determining protein half-life having long been known to those
of ordinary skill in the art, and include for example, pulse chase
experiments as described in Dandri... and Distelhorst... Moreover the
specification discloses specific structural features of the claimed fusion
protein, the absence or presence of which enhances protein stability. For
example the specification discloses that removal of the Ang-1 coiled-coil
domain imparts an increased half-life to a fusion protein comprising Ang-1
as the non-VEGF peptide portion (see, e.g. paragraph [0108], lines 10-
14.) The specification also indicates that the inclusion of cysteine
residues in either or both of the VEGF and non-VEGF peptide portions of
the claimed fusion protein renders the fusion protein more resistant to
extracellular degradation... thereby enhancing protein stability. Fusion
protein half-life can also be extended when the non-VEGF peptide portion
comprises an IgG domain as described in the specification at paragraph
[0108], lines 18-22.
The examiner returns, that “it is well known in the art that adding cysteine
residues may adversely effect protein folding and activity, and there is no guidance as
to where, in any particularly disclosed protein, such cysteine residues could be added.”
Answer, page 21. We find no evidence of record cited by the examiner to support this
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