Comparison of the in vivo efficiency of photofrin II-, mTHPC-, mTHPC-PEG- and mTHPCnPEG-mediated PDT in a human xenografted head and neck carcinoma.
OBJECTIVE
One of the approaches to enhance the selectivity and efficiency of photodynamic therapy (PDT) was the conjugation of the photosensitizer meta-tetrahydroxyphenylchlorin (mTHPC) to the water-soluble polymer polyethylene glycol (PEG). Several studies have demonstrated that mTHPC-PEG has a higher selectivity and a longer circulating half-life than free mTHPC, whereas no in vivo effect of this benefit could be seen.


METHODS
In a model of RAG-2-mice bearing a human oral squamous cell carcinoma xenograft (XF 354), the in vivo efficiency assessed as growth retardation or remission caused by Photofrin II and free mTHPC was compared with mTHPC coupled in two different ways to polyethylene glycol (PEG). One hundred and fourty-nine female RAG-2-mice were randomised into one control group and 13 therapy groups. Treatment parameters were adapted from those routinely applied in animal studies.


RESULTS
Photofrin II-mediated PDT and mTHPC-mediated PDT were both in vivo highly effective, whereas mTHPC induced less scars. The in vivo results after mTHPC-PEG-mediated PDT were disappointing, whereas the effectiveness of mTHPCnPEG-mediated PDT, a newly coupled macromolecular photosensitizer, were promising.


CONCLUSIONS
These results demonstrated the impact of the method of linkage between the photoactive agent mTHPC and polyethylene glycol (PEG) upon the in vivo effectiveness. mTHPC and mTHPCnPEG are promising photosensitizers for the future, especially for the cosmetic treatment needs of head and neck surgery.
Reuther
T
T
Department of Oral and Maxillofacial Surgery, University of Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany.
Kübler
A C
AC
Zillmann
U
U
Flechtenmacher
C
C
Sinn
H
H
D000818:Animals; D000970:Antineoplastic Agents / Q000009:adverse effects / Q000627:therapeutic use*; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy*; D017484:Dermatitis, Phototoxic / Q000209:etiology; D017323:Dihematoporphyrin Ether / Q000009:adverse effects / Q000627:therapeutic use*; D004195:Disease Models, Animal; D005079:Excipients / Q000009:adverse effects / Q000627:therapeutic use*; D005260:Female; D006258:Head and Neck Neoplasms / Q000188:drug therapy*; D006801:Humans; D008652:Mesoporphyrins / Q000009:adverse effects / Q000627:therapeutic use*; D051379:Mice; D008875:Middle Aged; D010778:Photochemotherapy / Q000009:adverse effects*; D011092:Polyethylene Glycols / Q000009:adverse effects / Q000627:therapeutic use*; D011838:Radiation-Sensitizing Agents / Q000009:adverse effects / Q000627:therapeutic use*; D011897:Random Allocation; D014183:Transplantation, Heterologous; D016896:Treatment Outcome; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000528:radiation effects
D000970:Antineoplastic Agents; D005079:Excipients; D008652:Mesoporphyrins; D011838:Radiation-Sensitizing Agents; D011092:Polyethylene Glycols; D017323:Dihematoporphyrin Ether; C072269:temoporfin