Parenteral Delivery of Peptides and Proteins - Challenges in Delivery of Therapeutic Genomics and Proteomics - page 557

acid, and phosphatidylglycerol) are cleared more rapidly than neutral liposomes
of similar composition [239] . During the last decade, immunoliposomes (antibody-
directed liposomes) have been studied to establish their potential in cancer therapy
as a tool for efficient site-specific drug delivery using antibodies such as antibody to
HER-2/neuroreceptor [240] , which can be exemplified by diphtheria toxin containing
immunoliposomes for ovarian carcinoma having a low-toxicity profile. In one study
on immunoliposomes, it was found that antibody mobility and molar ratio of antibody
cluster play a key role in increasing receptor-mediated cell targeting [241,242] .
Some examples of proteins and peptides encapsulated in liposomes for therapeu-
tic use are given in Table 11.6 .

Table 11.6 Examples of Liposomally Encapsulated/Surface Conjugated P/P Used as Either
Therapeutic P/P or for Targeting

Peptide/Protein
Encapsulated

Characteristics of the System Reference

Interleukin-2;
interferon-

External association of proteins to the surface of liposomes
may yield a prolonged biological effect with retained
structural activity

[243-245]

RGD-motif-
containing
peptide bound
liposomes

Peptide coupled to the phospholipid-1, 2-dioleoyl-
sn-glycero-3-phosphatidylethanolamine- N -[3-(2-
pyridyldithio) propionate] (PDP-DOPE) of the liposomes
by a thiol-disulfide exchange to achieve target specificity
by coupling with tetrapeptide Arg-Gly-Asp-Cys.
Chemically stable coupling. Potential to be explored as a
liposomal target carrier for P/P drugs

[246]

VDAC and Bak VDAC (regulates cytochrome c release from mitochondria)

and Bak (modulates mitochondrial membrane
permeability upon activation) integrated in natural
liposomes can represent an excellent candidate for
cancer protein therapy

[247]

Vasopressin PEG conjugated to the phospholipid distearoyl

phosphatidyl ethanolamine (PEG-DSPE), prolonged
circulation as compared to phosphatidyl serine

[248,249]

tPA Plasminogen-bearing liposomes for targeted delivery of tPA [250,251]

muMab4D5;
rhuMAbHER2

Sterically stabilized immunoliposomes for breast cancer
therapy

[240,252]

IGFI-R
antagonistic
antibody (1H7)

Antibody coupled to the surface of sterically stabilized
liposomes loaded with anticancer moiety

[253]

Epirubicin-
glucuronide

“Immunoenzymosomes,” enzyme fl-glucuronidase capable
of activating the prodrug epirubicin-glucuronide has been
coupled to the external surface of immunoliposomes
directed toward ovarian carcinoma cells

[254]

Leridistim, a
protein from the
Myelopoietins
(MPO) family

Multivesicular liposomes, sustained-release profile [233]