Appeal No. 1995-4572
Application 08/035,443
believed that the first rejection under 35 U.S.C. § 103 is subsumed by the second
rejection. For these reasons, both rejections will be discussed together.
The references relied upon by the examiner can be divided into two categories:
those that teach the use of liposomes for delivering drugs into the bloodstream and those
that teach the conjugation of a polymer to polymyxin B or another polypeptide. Woodle and
Hawrot both disclose the use of liposomes for delivering drugs to the bloodstream of a
human. Handley discloses the conjugation of polymyxin B to a carrier such as polyethylene
glycol (PEG), while Davis discloses the conjugation of a polypeptide to PEG without any
loss of biological activity.
In the first category of references relied upon by the examiner, Woodle teaches that
the problem with the use of liposomes for delivering drugs into the bloodstream is the rapid
uptake of the liposomes by the reticuloendothelial system (RES). Liposomes are normally
removed from the blood circulation by the RES with a half life on the order of minutes. In
order to solve this problem, Woodle derivatized polyethylene glycol (PEG) to the
phosphatidylethanolamine on the outside of a liposome. In so doing, the blood circulation
time of the liposome is significantly enhanced by up to tenfold or more. The liposomes
taught by Woodle contain a drug to be delivered entrapped within the interior of the
liposomes. The liposomes can also contain a surface-bound ligand molecule which is
used to bind specifically with high affinity to a ligand-binding molecule on the surface of a
specific target tissue or cell. The surface-bound ligand is
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