Appeal 2007-1161
Application 09/954,166
this argument persuasive because the claims at issue are not limited to how
the claimed complex is utilized. Harris’s statement, at most, appears to
apply only when antibodies are used in a milieu where certain properties,
such as “complement binding,” would be unwanted (Harris, p. 2, ll. 5-8).
Appellants also contend that even if there were reason to modify Dal
Porto, “the modification would have been to substitute one of the TCR or
class II MHC extracellular domains for the MHC class I α chain in the
fusion protein, to express the other extracellular domain by itself, and to
permit the two extracellular domains to associate as the prior art taught they
would” (Br. 15). We do not agree.
In its normal configuration, each of the two TCR extracellular
domains of the T-cell receptor is linked to a unique transmembrane segment
which together form a heterodimer (Specification 4, 8, and Fig. 1A; Findings
of Fact 2). Chang’s soluble synthetic TCR heterodimer – where the TCR
extracellular domains are appended to peptides which themselves dimerize
together – mimics this normal T-cell receptor configuration. Thus, the most
logical and normal structure of a soluble synthetic TCR is one in which each
extracellular domain is fused to a separate peptide segment. The skilled
worker, in adopting Dal Porto’s strategy to enhance the binding affinity of
soluble TCR, would have been motivated to graft one extracellular domain
to the immunoglobulin heavy chain and the other to the light chain in order
to mimic the native TCR configuration.
Moreover, as argued by the Examiner, Chang’s disclosure that
dimerization between soluble TCR subunits can be improved by grafting
each subunit to proteins which themselves associate together would have led
the skilled worker to fuse the second T cell receptor subunit to the
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