ISPO

EWS-FLI1 targeted vectorized antisense oligonucleotides inhibit a model of Ewing sarcoma in mice

A. Maksimenko phD bc, G. Lambert phD a, J.R. Bertrand phD b, E. Fattal phD a, F. Subra phD b, H. Pinto-Alphandary phD a, C. Malvy phD b, C. Auclair phD b, P. Couvreur phD a

aLaboratoire de physico-chimie, pharmacotechnie et biopharmacie, UMR CNRS 8612, Faculté de Pharmacie, Chatenay Malabry, France b Laboratoire de physico-chimie et pharmacologie des macromolécules biologiques, UMR CNRS 8532, Institut G. Roussy, 94800 Villejuif, France cBioalliance Pharma SA, 59, Boulevard du Général Martial Valin, 75015, Paris

Aim : It is to block in a very specific way in mice the growth of tumors generated by EWS-Fli1. Vectorized antisense oligonucleotides (ODNs) complementary of the junction of both genes at the mRNA level allow this inhibition because the target is only present in the cancer cells. Methods : We have used two types of vectors for ODNs : poly-isobutylcyanoacrylate nanocapsules and transdrug® (Bioalliance Pharma). One million EWS-Fli1 transformed NIH 3T3 cells were injected subcuteanously to irradiated nude mice where a tumor appears after two weeks. Several injections of vectorized ODNs at non toxic doses were then performed in the tumor within a period of two weeks. The protection of ODNs by the vectors was measured using denaturing polyacrylamide gel electrophoresis after incubation of radioactively labeled ODNs in various serums. Results : We have used two antisense ODNs : Firstly a full phosphorothioate ODN vectorized by nanocapsules, secondly a structured chimeric phosphodiester phosphorothioate ODN vectorized by transdrug®. Both vectors improve the resistance of ODNs to degradation. Both antisense vectorized ODNs significantly inhibit the tumor growth in mice at a total dose ranging between 10 and 15 nanomoles whereas either the non vectorized antisense ODNs or the vectorized control ODNs have no effect. Conclusions : Thanks to the use of vectors associated with antisense ODNs we show that it is possible to inhibit the growth of a tumor in a very specific way. Tanaka et al (J.Clin Invest. 99, 239-247) have obtained a similar result with a 35 to 50 times higher dose of non vectorized phosphorothioate ODN targeted against the EWS part of EWS-FLI1, therefore much less specific than our junction targeted ODN. Our result shows that it should be possible to treat with specificicity tumors caused by chromosomic translocations without any major toxicity.

For more information, contact cmalvy@igr.fr

Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Paris, France; February 9 - 12, 2002; in the section on Novel Therapies, Part 1.

http://www.cancerprev.org/Journal/Issues/26/101/1195/4632