Catherine Christie1, Aftin Pomeroy1, Rohit Nair1, Kristian Berg2, Henry Hirschberg3. 1. Beckman Laser Institute and Medical Clinic, University of California, Irvine 1002 Health Sciences Rd Irvine, CA 92617, USA. 2. Dept. of Radiation Biology, The Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway. 3. Beckman Laser Institute and Medical Clinic, University of California, Irvine 1002 Health Sciences Rd Irvine, CA 92617, USA. Electronic address: hhirschb@uci.edu.
Abstract
INTRODUCTION: Gene-directed enzyme prodrug therapy (GDEPT) employing the cytosine deaminase (CD) gene, which encodes an enzyme that converts the nontoxic agent 5-fluorocytosine (5-FC) into the chemotherapeutic drug 5-fluorouracil (5-FU), has shown promise both in experimental animals and in clinical trials. Nevertheless, with the transfection systems available presently the percentage of tumor cells incorporating the desired gene is usually too low for successful therapy. We have examined the ability of photodynamic therapy (PDT) to enhance the efficacy of the metabolites, converted from 5-FC by CD gene transfected rat glioma cells. METHODS: Hybrid tumor cell spheroids consisting of CD poitive and CD negative F98 glioma cells in varying ratios were used as in vitro tumor models. PDT was performed with the photosensitizer AlPcS2a and λ=670nm laser irradiance, both before and after confrontation with 5-FC. RESULTS: PDT increased the toxicity of 5-FU either as pure drug or derived from monolayers of CD positive cells chalanged with 5-FC. PDT in combination with 5-FC resulted in a significantly enhanced inhibition of hybrid spheroid growth compared to non light treated controls. This was the case even at tumor to producer cell ratios as high as 40:1. CONCLUSION: The results of the present study show that GDEPT and PDT interact in a synergistic manner over a range of prodrug concentration and tumor to transfected cell ratios. The degree of synergy was significant regardless if PDT treatment was given before or after 5-FC administration. The highest degree of interaction was observed though, when PDT was delivered prior to prodrug exposure.
INTRODUCTION: Gene-directed enzyme prodrug therapy (GDEPT) employing the cytosine deaminase (CD) gene, which encodes an enzyme that converts the nontoxic agent 5-fluorocytosine (5-FC) into the chemotherapeutic drug 5-fluorouracil (5-FU), has shown promise both in experimental animals and in clinical trials. Nevertheless, with the transfection systems available presently the percentage of tumor cells incorporating the desired gene is usually too low for successful therapy. We have examined the ability of photodynamic therapy (PDT) to enhance the efficacy of the metabolites, converted from 5-FC by CD gene transfected ratglioma cells. METHODS: Hybrid tumor cell spheroids consisting of CD poitive and CD negative F98 glioma cells in varying ratios were used as in vitro tumor models. PDT was performed with the photosensitizer AlPcS2a and λ=670nm laser irradiance, both before and after confrontation with 5-FC. RESULTS: PDT increased the toxicity of 5-FU either as pure drug or derived from monolayers of CD positive cells chalanged with 5-FC. PDT in combination with 5-FC resulted in a significantly enhanced inhibition of hybrid spheroid growth compared to non light treated controls. This was the case even at tumor to producer cell ratios as high as 40:1. CONCLUSION: The results of the present study show that GDEPT and PDT interact in a synergistic manner over a range of prodrug concentration and tumor to transfected cell ratios. The degree of synergy was significant regardless if PDT treatment was given before or after 5-FC administration. The highest degree of interaction was observed though, when PDT was delivered prior to prodrug exposure.
Authors: Omar D Perez; Christopher R Logg; Kei Hiraoka; Oscar Diago; Ryan Burnett; Akihito Inagaki; Dawn Jolson; Karin Amundson; Taylor Buckley; Dan Lohse; Amy Lin; Cindy Burrascano; Carlos Ibanez; Noriyuki Kasahara; Harry E Gruber; Douglas J Jolly Journal: Mol Ther Date: 2012-05-01 Impact factor: 11.454
Authors: Roger Stupp; Monika E Hegi; Warren P Mason; Martin J van den Bent; Martin J B Taphoorn; Robert C Janzer; Samuel K Ludwin; Anouk Allgeier; Barbara Fisher; Karl Belanger; Peter Hau; Alba A Brandes; Johanna Gijtenbeek; Christine Marosi; Charles J Vecht; Karima Mokhtari; Pieter Wesseling; Salvador Villa; Elizabeth Eisenhauer; Thierry Gorlia; Michael Weller; Denis Lacombe; J Gregory Cairncross; René-Olivier Mirimanoff Journal: Lancet Oncol Date: 2009-03-09 Impact factor: 41.316