Appeal No. 2006-0656 Page 2
Application No. 10/086,637
bispecific antibody fragment with a molecular weight of 85,000 daltons or less (such as
a divalent single chain (sFv)2 or (sFv’)2 fragment), which has a first binding site specific
for an antigen associated with the lesion, and a second binding site specific for a
bivalent labeled hapten. Id., page 26.
According to appellant, a bispecific antibody fragment with a molecular weight of
85,000 daltons or less is “critical” (Appeal Brief, page 10) to the claimed invention
because an antibody fragment of this size is small enough to be “cleared quickly and
naturally through the kidneys . . . so that targeting [and detection] can be effected within
48 hours” (Specification, pages 4-5) with minimal background interference (id., page 2).
Fab and Fab’ fragments (about 50,000 and 55,000 daltons, respectively) are small
enough to be cleared rapidly, but are unsuitable for the claimed method because they
are monovalent, and cannot bind both antigen and labeled hapten (id., page 26). On
the other hand, F(ab)2 or F(ab’)2 fragments (about 110,000 daltons for IgG), although
divalent, are “too large to be filtered through the glomerular basal membrane[,] . . . must
be catabolized elsewhere” first, and take much longer to clear, “unduly delay[ing] other
procedures” (id.).
The Claims
Claims 183-193, 196 and 197 are pending and the subject of appeal. Claims
99-182, 194, 195 and 198-201 are also pending, but have been withdrawn from
consideration. Claim 183 is representative of the subject matter on appeal:
183. A method of close-range detection of lesions during an operative,
endoscopic, laparoscopic, intravascular catheter, or surgical procedure, wherein the
method comprises:
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