Immunex' Flt3; First Clinical Data

Immunex has presented the results of its first clinical trial of itsrecombinant Flt3 ligand, showing that the cytokine safely increases immune cells and may improve patients' defenses against cancer and infections.

The data, from a Phase I/II study involving 20 healthy volunteers, show that escalating doses of Flt3 ligand increased the levels of stem cells and dendritic cells. Daily injections of between 10 and 100mcg of the drug over 14 days resulted in up to 30-fold increases in dendritic cells and CD34 cells in the peripheral blood compared to placebo. The drug was well-tolerated and there was no evidence of mast cell stimulation, which could lead to allergic reactions.

Immunex is now planning to test Flt3 ligand in combination with other cytokines with the aim of reducing the number of blood collections required for stem cell transplants. The company has also initiated studies in patients with cancer. An article in the June issue of Nature Medicine has shown that Flt3 ligand can induce tumor regression in mice.