Immutep S.A. Reports that LAG-3 Enhances Activity of a Cellular Cancer Immunotherapy in Preclinical Studies

Orsay, June 25th, 2008 - Immutep S.A., a biopharmaceutical company specialized in immunostimulatory and immunomodulatory treatments of cancer and infectious or autoimmune disease, announced today the publication of research conducted by Cell Genesys, Inc. showing that a lymphocyte activation gene-3 fusion protein increases the potency of a granulocyte macrophage colony-stimulating factor (GM-CSF)-secreting tumor cell immunotherapy. These data were published in the June issue of Clinical Cancer Research.

The research team found that combining mLAG-3Ig with a murine GM-CSF-secreting tumor cell immunotherapy prolonged the survival of tumor-bearing animals compared to animals treated with either therapy alone. Prolonged survival correlated with increased numbers of systemic IFN gamma-secreting CD8+ T-cells and a significantly increased infiltration of activated effector CD8+ T-cells into the tumor.

"Combination therapies are being evaluated with the goal of enhancing overall antitumor activity, which could allow treatment of patients with a large tumor burden," said Frédéric Triebel, Immutep's Scientific and Medical Director. "Elevated levels of TNF alpha were detected in the supernatant of splenocytes isolated from animals treated with the combination therapy compared to splenocytes from animals injected with the immunotherapy alone. This increased proinflammatory cytokine production that correlated with an overall enhancement of in vivo CD8 T-cell activation clearly indicates that LAG-3 further increases anti-tumor activity in conditions where GM-CSF is already used as an immunostimulant."

The mLAG-3Ig fusion protein is a murine homologue of Immutep's lead product ImmuFact(R) IMP321, a potent natural human immunostimulatory factor designed to amplify the T cell immune response. IMP321 can be used either as an immunopotentiator in therapeutic vaccines or alone at higher doses as a monotherapy or in combination with chemotherapy. Six clinical trials have been initiated with ImmuFact IMP321 in the last three years.

For further information please visit the website www.immutep.com or e-mail John Hawken, CEO, at JBHawken@immutep.com.