Appeal No. 1997-2139
Application No. 08/114,595
gene, the AAV terminal repeats appear to be transcriptionally neutral. However, (a) the
procedures for growing recombinant virus stocks are awkward, although not technically
insurmountable, (b) the mechanism for AAV integration is not known, and (c) relatively
little is known about the effect of AAV infection or integration on primary cells. (§ 6, pp.
122-123).
Drumm used a retrovirus vector to transduce CFTR cDNA into a cell line that
stably expresses the chloride transport abnormalities characteristic of cystic fibrosis
(CF) and found that expression of the normal CFTR gene conferred cAMP-dependent
Cl channel regulation on CF epithelial cells (summary, p. 1227).
According to the examiner,
claim 49 differs from Muzyczka's recombinant AAV virions solely by
specifying the inclusion of DNA encoding CFTR. ... It would have been
obvious to insert Drumm's CFTR cDNA into Muzyczka's AAV vector in
order to take advantage of the desirable characteristics of AAV vectors in
providing gene therapy for cystic fibrosis. [Answer, p. 4, para. 1.]
Appellants argue there is no motivation to combine Muzyczka and Drumm because
Muzyczka fails to provide a reasonable expectation of success of producing
recombinant AAV viral stocks given the problems of contamination, spontaneous
deletion of heterologous sequences, low viral titers and instability described by
Muzyczka at p. 115 et seq. (brief, pp. 7-10).
"Obviousness does not require absolute predictability of success.... For
obviousness under § 103, all that is required is a reasonable expectation of success."
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