Immuno-Gene Therapy for HIV Infection

D. von Laer, G. Brandenburg, M. Egelhofer, C. Baum, H. Martinius, K. Kuehlcke, A. Schilz, G. Koopman, A. Alexandrov, J. van Lunzen, Georg-Speyer-Haus, Applied Virology and Gene Therapy, Paul-Ehrlich-Strasse 42-44, 60596 Frankfurt a.M.

e-mail: laer@em.uni-frankfurt.de

Background: HAART has significantly improved the survival of HIV-infected patients. However, treatment limitations such as the development of drug-resistant HIV variants and long-term toxicities have become obvious. Thus, innovative strategies to treat HIV infection are needed.

Objective: To develop an effective gene therapy for HIV infection involving the ex vivo transfer of an antiviral gene into autologous CD4+ T-lymphocytes.

Methods: Mathematical modelling predicted that only genes inhibiting early steps of virus replication will allow in vivo accumulation of gene-modified T cells and lead to an overall reduction of viral load. Thus, we cloned a novel antiviral gene (M87o) into a retroviral vector backbone which inhibits virus entry by expressing a membrane-anchored peptide derived from the second heptad repeat of HIV-1 gp41.

Results: M87o inhibited virus entry in cell lines and primary T cells for all HIV isolates tested with 99-100% efficiency. Gene-modified T cells enriched in mixed lymphocyte cultures due to a selective advantage. No toxicity was observed in mice or rhesus macaques. A GMP-protocol for large scale production of gene-modified T cells from HIV-infected donors was established. Up to 10E10 CD4+ T cells were obtained with a transduction efficiency of 20-30%. Viral replication in culture was inhibited by antiretroviral drugs.

Conclusion: The preclinical development of this first gene therapeutic approach for HIV infection based on entry inhibition has been completed and shows promising results. Transduced CD4+ T cells have been manufactured and will go into clinical phase I. First data will be available.