BARCELONA, Spain (Reuters) - Testing of a new breast cancer (news - web sites) vaccine has begun in Britain and Denmark, the vaccine's maker, Danish biotechnology company Pharmexa, announced Wednesday.

Dr. Dana Leach, the company's manager of clinical development and immunopharmacology, told the 3rd European Breast Cancer Conference that the Auto-Vac vaccine targets a protein called HER-2 that is overexpressed in many tumors.

It is designed to boost the woman's immune response to produce killer T cells to attack the tumour and to make HER-2 antibodies.

"Our first objective is to test the safety of the vaccine, but we also want to make a preliminary evaluation of the vaccine's ability to raise an immune response," Leach told the conference.

HER-2 is also found in normal tissue so the body's immune system does not always respond to it. Auto-Vac is aimed at making the immune system recognize the HER-2 in cancer cells and destroy them while ignoring normal tissue.

"It is clear immunotherapy can work," Leach said, adding that it was within the realm of possibility to destroy tumors with this type of therapy.

The company will test the safety and immune response of 27 women with advanced cancer at four centers in Denmark and two in Britain.

The women will be given three injections of the vaccine and results are expected by the end of the year.

Leach hopes the vaccine will reduce the size of the tumor. If effective, he believes it could be used alongside other cancer treatments.

Animal studies of the vaccine have shown it produces an immune response without any toxic side effects.

"Although it is early days yet, anytime that you can successfully take a new cancer vaccine into the clinic it is an important and exciting event," Leach said.

An estimated 4,000 scientists, doctors and patient advocates are attending the five-day conference.