Appeal No. 2006-0656 Page 6
Application No. 10/086,637
Nor do we find anything in Goldenberg or Barbet which would have led one
skilled in the art to use a divalent fragment with a molecular weight of 85,000 daltons or
less. As appellant points out, Goldenberg “is concerned with . . . a method of reducing
background radiation so as to obtain an accurate reading of the radiation associated
with the primary antibody that binds the tumor antigen” (Appeal Brief, page 8), and “it
doesn’t really matter what type of antibody is used as the primary antibody” (id., page
9). Barbet, on the other hand, does suggest that dual specificity conjugates comprising
various combinations of antibody fragments are preferable to conjugates comprising
whole antibodies, but all of Barbet’s dual specificity conjugates are trivalent (at least),
with two or more binding sites for antigen, and one or more for hapten, and are
considerably larger than the divalent fragments required by the present claims (Barbet,
columns 4 and 5, and Example 1). Moreover, “clearance of [ ] excess dual specificity
conjugate” is not an issue in Barbet’s method because clearance “is not required prior
[to] injection of the [affinity enhancement probe]” (id., column 9, lines 4-6).
Much has been said on both sides about the propriety of combining Goldenberg
and Barbet, but the bottom line is, quite simply, neither reference describes or suggests
the use of an antibody fragment that has two binding sites and a molecular weight of
85,000 daltons or less. Horowitz, cited with respect to claim 190 as evidence that
brachytherapy via endoscope or catheter is conventional, does nothing to remedy this
deficiency.
“[T]he examiner bears the initial burden of presenting a prima facie case of
obviousness. Only if that burden is met, does the burden of coming forward with
evidence or argument shift to the applicant.” In re Rijckaert, 9 F.3d 1531, 1532, 28
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