( Bcl-2 Antagonist shown to be therapeut...)Santaris Pharma presents positive preclinical data on SPC2996 at,the American Association for Cancer Research,Health

Bcl-2 Antagonist shown to be therapeutically effective in a mouse model of Chronic Lymphocytic Leukaemia

COPENHAGEN, 18 April 2007 - Santaris Pharma, the Danish biopharmaceutical company developing RNAi drugs, yesterday presented encouraging data at the American Association for Cancer Research Annual Meeting in Los Angeles, showing that SPC2996, the Company's RNA Antagonist of Bcl-2, is therapeutically active in a preclinical model of human Chronic Lymphocytic Leukaemia (CLL).

In collaboration with scientists at the University of Duisberg-Essen in Germany, Santaris researchers reported that white blood cells obtained from CLL patient peripheral blood can be transplanted into immunodeficient mice and reliable engraftment of human CLL cells achieved in the spleen, resulting in focal aggregates of B-lymphocytes carrying surface markers characteristic of CLL cancer cells.

SPC2996 was tested for anti-leukaemic activity over two weeks in this model starting two weeks after transplantation and compared for efficacy with multiple doses of fludarabine, a standard chemotherapy for CLL, as well as a negative control oligonucleotide drug similar to but of different sequence from SPC2996. Therapy with SPC2996 resulted in a 54% reduction (p=0.043) in the number of CLL cells which could be recovered from the spleens of the treated transplanted animals compared to animals not receiving therapy. Fludarabine was also effective in the model whereas the negative control drug was not.

This is the first time that primary CLL cells taken from patient blood have been successfully transplanted and shown long term splenic engraftment in an animal model. The model appears to be validated by the efficacy of the fludarabine in clearing engrafted human CLL cells. The demonstration that single agent therapy with SPC2996, a non-chemotoxic agent inhibiting Bcl-2 expression, also clears CLL cells from splenic engraft
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