Paris, March 5, 2007 - Cytheris, a product-oriented biopharmaceutical company focused on the research and development of new and critical agents for immune modulation, announced today promising results from two phase I clinical studies of Cytheris Interleukin-7. The announcement follows presentation of the results by the AIDS Clinical Trial Group (ACTG) and French clinical investigators at the Conference on Retroviruses and Opportunistic Infections held February 25-28th in Los Angeles.

The studies both showed extremely good tolerance and an impressive increase in the patient's CD4 T cells, the count of which is frequently used by HIV patients to gauge their own health. This is the first product to demonstrate such an impressive increase of CD4 T cells and CD8 T cells together with a good clinical tolerance.

At the Los Angeles meeting, the ACTG communicated the results of an IL-7 phase I single dose study performed in US and a team of leading French clinical investigators communicated on a phase I/II repeated dose study performed in Paris, France.

Both studies performed in HIV infected patients were designed to assess product safety and activity by measuring cellular immune recovery. HIV infected patients' main immune deficit shows up in a severe loss of CD4 T cells, the pivotal cells in charge of orchestrating immune responses. Interleukin-7 is a recombinant human protein whose critical role for T cell maintenance and recovery is broadly documented in pre-clinical models.

In both studies and more specifically in the repeated dose study, Cytheris IL-7 treatment was extremely well tolerated and led to an impressive and prolonged increase of patient's CD4 T cells. This increase was systematically observed in all patients. It involved CD4 and CD8 T cells and both naïve and memory T cells. This broad spectrum of immune activities suggests a very promising outlook in terms of reaching clinical significance and preventing opportunistic diseases or secondary fatal malignancies.

"In addition, new results from large clinical studies presented at this CROI meeting are extremely positive for Cytheris, and give us confidence as we line up further clinical trials in France, Canada and the US" said Michel Morre, Cytheris CEO. "This new data now demonstrates how critical patients' CD4 numbers are in protecting them not only from opportunistic infections but also from AIDS-related or non-related diseases.

"So we are highly encouraged by the fact that our most recent IL-7 results demonstrate the impressive ability of this product to restore protective CD4 T cell counts. The rapidly growing amount of research data showing the link between HIV patients' CD4 counts and their long term outcome will also provide a favorable environment for the clinical development of IL-7 which is looking like a key product for CD4 cell recovery. These IL-7 effects are very consistent with the results already obtained in two other studies in the field of oncology."

About Cytheris:
Cytheris, Paris, is a product-oriented biopharmaceutical company focused on the research and development of new and critical agents for immune modulation. These drugs aim at reconstituting, enhancing or modulating the immune system activity of patients suffering from life-threatening diseases. The company's lead compound is a recombinant Interleukin-7 (rIL-7) a critical growth factor for immune T Cells. It has a second family of products based on NKT ligands in-licensed from New York University, the Aaron Diamond AIDS Research Center and the City University of New York. Cytheris has a strong network of collaborations with world-leading academic and clinical teams as well as pharmaceutical companies. The company was founded in 1999 and today employs around 20 experienced people in Europe and in the USA. The company, based in Issy les Moulineaux, Paris, has a subsidiary in Rockville (MD-USA). Website: www.cytheris.com
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