HER-2 is overexpressed in about a quarter of all breast cancers and has become a key target for new treatments, such as the monoclonal antibody therapy Herceptin. But, the development of a vaccine by Danish pharmaceutical company Pharmexa represents an entirely novel treatment paradigm, according to Pharmexas manager of preclinical development and immunopharmacology, Dr Dana Leach.
He told a news briefing at the 3rd European Breast Cancer Conference in Barcelona on Wednesday (20 March0: "The objective of our vaccine is to stimulate the patients own immune system and to see whether we can induce it to launch specific killer cells as well as producing HER-2 specific antibodies. This is a phase I/II trial. Our first objective is to test the safety of the vaccine, but we also want to make a preliminary evaluation of the vaccines ability to raise an immune response. There are 27 patients with advanced breast cancer in the trial, which should be completed late this year."
HER-2 is a protein that is overexpressed in many tumours. But, because it is also expressed at low levels in some normal tissues, the immune system does not recognise it as foreign and the immune cells, especially helper T cells that initiate the immune response, are simply not around to launch an attack. So, the vaccine AutoVac has been designed to help kick-start the immune response by giving the T cells a foreign agent to recognise and react against. The aim is that the immune system then recognises the overexpressed HER-2 in the cancer cells and attacks them, but ignores the normal tissue because that contains only low levels.
Dr Leach said that animal tests had shown that the vaccine produced a specific immune response and there had been no adverse side effects.