Delivery vehicles lipoproteins, liposomes and antibodies

Several lipoprotein formulations have been tested for delivery of photosensitizers to tumor tissue [54-56] and it has been shown that LDL is a particularly suitable delivery vehicle for different porphyrins. Uptake of LDL complex is mainly mediated via an active endocytotic pathway, involving LDL receptors on both tumor cells and endothelial cells [57-60]. Depending on the time after administration, the LDL complexed photosensitizers can be found either in the vasculature [61], or in the tumor cells themselves [57,62]. Covalent linkage of LDL to chlorin e6 resulted in conjugates which were specifically taken up by LDL-receptor carrying fibroblasts, and a retinoblastoma cell line, indicating its potential use in ocular tumors [54]. 

Alternatively, liposomes have been used as delivery vehicles for photosensitizers. The mechanisms by which liposomes can specifically deliver photosensitizers to tumors are not clear, but it is suggested that the photosensitizer is transferred from liposomes to lipoproteins and delivered in this form [57]. 

ANNE C.E. MOOR, BERNHARD ORTEL AND TAYYABA HASAN 

Clinical applications of photoimmunotherapy have been sparse, probably because of the complexity of the approach. It was reported that photoimmuno-conjugates of Mabs recognizing CA125 on human ovarian cancer cells were used in humans [89,90]. In this study, selective photocytotoxicity to target cells in vitro and in vivo in a tumor bearing nude rat model was shown and 3 patients with advanced ovarian cancer were treated. The group (Hahn and co-workers) at the University of Pennsylvania continues to develop the treatment for cancer in the peritoneal cavity. 

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