Improved therapeutic activity of folate-targeted liposomal doxorubicin in folate receptor-expressing tumor models.
OBJECTIVE
The folate receptor (FR) is overexpressed in a broad spectrum of malignant tumors and represents an attractive target for selective delivery of anti-cancer agents to FR-expressing tumors. Targeting liposomes to the FR has been proposed as a way to enhance the effects of liposome-based chemotherapy.


METHODS
Folate-polyethylene glycol-distearoyl-phosphatidyl-ethanolamine conjugate was inserted into pegylated liposomal doxorubicin (PLD). The therapeutic activity of folate-targeted (FT-PLD) and non-targeted (PLD) pegylated liposomal doxorubicin was tested in two human tumor models (KB, KB-V) and in one mouse ascitic tumor model (FR-expressing J6456) by the i.v. systemic route in all models, and by the i.p. intracavitary route in the ascitic tumor model only.


RESULTS
Consistent with previous studies, PLD was clearly superior to free doxorubicin in all tumor models. When targeted and non-targeted liposome formulations were compared, FT-PLD was more effective than PLD in the KB and KB-V xenograft models, and in the J6456 intra-cavitary therapy model. The therapeutic effect was dose-dependent in the KB model and schedule-dependent in the J6456 intra-cavitary therapy model. In some experiments, toxic deaths aggravated by folate-depleted diet were a major confounding factor. In a non-FR expressing J6456 model, FT-PLD was as active as PLD indicating that its activity is not limited to FR-expressing tumors.


CONCLUSIONS
Folate-targeting confers a significant albeit modest therapeutic improvement to PLD in FR-expressing tumor models, which appears particularly valuable in intracavitary therapy. The potential clinical added value of this approach has yet to be determined.
Experimental Oncology Laboratory, Shaare Zedek Medical Center, 11 Shmuel Bayit Street, 7th Floor, PO Box 3235, Jerusalem 91031, Israel. alberto.gabizon@gmail.com
Alberto
A
Gabizon
Dina
D
Tzemach
Jenny
J
Gorin
Lidia
L
Mak
Yasmine
Y
Amitay
Hilary
H
Shmeeda
Samuel
S
Zalipsky
D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics; D002352:Carrier Proteins / Q000378:metabolism*; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004317:Doxorubicin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000737:chemistry / Q000493:pharmacokinetics; D016503:Drug Delivery Systems / Q000379:methods*; D005260:Female; D058973:Folate Receptors, GPI-Anchored; D005492:Folic Acid / Q000008:administration & dosage* / Q000737:chemistry; D006801:Humans; D007274:Injections, Intraperitoneal; D007275:Injections, Intravenous; D008081:Liposomes / Q000008:administration & dosage* / Q000138:chemical synthesis / Q000493:pharmacokinetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009369:Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D011092:Polyethylene Glycols / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics; D011956:Receptors, Cell Surface / Q000378:metabolism*; D023041:Xenograft Model Antitumor Assays
D000903:Antibiotics, Antineoplastic; D002352:Carrier Proteins; D058973:Folate Receptors, GPI-Anchored; D008081:Liposomes; D011956:Receptors, Cell Surface; C506643:liposomal doxorubicin; D011092:Polyethylene Glycols; D004317:Doxorubicin; D005492:Folic Acid