Appeal 2007-1633
Application 09/480,236
that “one could not predict the effectiveness of a given PE-Tac immunotoxin
on a given cell population by knowing the activity of a given DT-Tac
immunotoxin on that cell population” (id.). In further support of this
assertion, Appellants direct attention to Batra3 to teach that the relative
activity of PE and DT based immunotoxins varies depending on the cell line
used to test the immunotoxin (Br. 11-12). According to Appellants “[a]s far
back as the seminal case of In re Papesch, 137 USPQ 43 (CCPA 1963), the
courts have recognized that it is an error of law to fail to take into
consideration the biological or pharmaceutical property of a claimed
composition of matter” (Br. 12). Therefore, Appellants assert that
“[b]ecause of the variability of immunotoxins as demonstrated in the cited
art, it would not be obvious that Appellants’ invention would be successful”
(Br. 12). We disagree.
Claim 35 is drawn to a recombinant immunotoxin polypeptide or a
pharmaceutically acceptable salt thereof that comprises a CD3-binding
domain and a Pseudomonas exotoxin (PE) mutant, said PE mutant having
ADP-ribosylating and translocation functions but substantially diminished
cell-binding ability. There can be no doubt that “a compound and all of its
properties are inseparable . . . .” In re Papesch, 315 F.2d 381, 391, 137
USPQ 43, 51 (CCPA 1963). On this record, the prior art recognizes that
both DT and PE based immunotoxins have immunotoxin properties. While
Appellants argue that the art illustrates that, under certain circumstances, the
activity of DT based immunotoxins and PE based immunotoxins may vary
3 Batra, et al., Single-Chain Immunotoxins Directed at the Human
Transferrin Receptor Containing Pseudomonas Exotoxin A or Diphteria
Toxin : Anti-TFR(Fv)-PE40 and DT388-Anti-TFR(Fv), 11(4) Mol. Cell.
Biol. 2200-2205 (1991).
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