Cancer Vaccine CVac™ by Dendritic Cell Therapy involves the manipulation of a patient's own dendritic cells to create, in the case of cancer, tumour-protein expressing dendritic cells that can then be injected back into the patient to, directly or indirectly, trigger cytotoxic immune response to the protein leading to tumour regression.

Dendritic cells are a subset of white blood cells whose primary role is to educate the immune system to recognise infection and cancer. When the dendritic cell encounters foreign material it generates a recognition signal and triggers the immune system to respond by activating another subset of blood cells called cytotoxic or killer T cells. These cells then respond by killing the foreign material.

Manipulating the dendritic cells outside of the patient's own body allows the cells to overcome the evasive mechanisms of the tumour and the immune system is educated to recognise and fight the tumour.

At Prima BioMed the tumour antigen being targeted is called mucin-1. This is a molecule expressed by a variety of tumours including breast, ovarian, prostate, lung and colon cancers. Mucin-1 is expressed by normal tissue in the body but changes conformation on tumour cells so the immune response will be specific to the tumour tissue and will not damage normal tissue. We also use a proprietary immune adjuvant called mannan (oxidised mannose). Mannan assists in activating the immune system and ensures preferential expression of the production of killer T cells that will target mucin-1.

Dendritic Cell Therapy offers a number of advantages over other practised and experimental treatments for cancer. Firstly, by targeting a protein that sits on tumour cells in a form not on normal cells, the side effects are minimal which is in stark contrast to cytotoxic agents which kill cells indiscriminately. Secondly, the process activates the immune system to recognise the tumour and once the immune system is activated it will continue to fight the tumour, unlike antibody based therapies that need to be administered at frequent intervals to have their effect on tumours. 

Dendritic cells can be isolated from a cancer patient and manipulated to trigger recognition of a cancer by T cells. Isolation of the dendritic cells from the blood takes place via a process not dissimilar to donating blood, called called leukopheresis. Once the dendritic cells have been removed from the patient they are then manipulated in the laboratory to express a tumour associated protein or antigen. These cells are then injected back into the cancer patient where they activate the killer T cells to fight the tumour. Tumours have sophisticated mechanisms of avoiding the cells and thus evades the immune system and this evasion allows the tumour to grow.

Dendritic cell therapy is currently being utilised in Prima's CVac™ program, a completed Phase II clinical trial in ovarian cancer.