Appeal No. 2006-0632 Παγε 2
Application No. 09/929,665
BACKGROUND
“PSMA is an integral membrane protein known to have a short intracellular tail
and a long extracellular domain.” Specification, page 9. Various researchers have
reported that “PSMA is prostate-specific and shows increased expression levels in
metastatic sites and in hormone-refractory states” (id.,page 8); that “PSMA is more
strongly expressed in prostate cancer cells relative to cells from the normal prostate or
from a prostate with benign hyperplasia” (id.); and that “PSMA is not found in serum”
(id.). According to appellant, PSMA is “an attractive target for antibody mediated . . .
imaging and therapy of prostate cancer” (id.). However, “antibody molecules do not,
under normal circumstances, cross the cell membrane unless they bind to the
extracellular portion of a molecule and become translocated intracellularly,” thus
antibodies that bind the intracellular portion of PSMA “do[ ] not have access to [the]
antigenic target site in . . . viable cell[s]” and will only bind cells that are already dead
(id., page 9).
The present invention is directed to “biological agents,” in this case, polyclonal or
monoclonal antibodies which bind the extracellular domain of PSMA. Appellant
describes four “particularly preferred” biological agents, monoclonal antibodies E99,
J415, J533 and J591, to be “used alone or as a component in a mixture with other
antibodies or other biological agents to treat or image prostate epithelial cells” (id., page
19). “In a particularly preferred embodiment . . . a first biological agent is conjugated
with a prodrug . . . [and] [t]he prodrug activator is conjugated with a second biological
agent . . . preferably one which binds to a non-competing site” on PSMA. “Whether two
biological agents bind to competing or non-competing binding sites can be determined
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