T cells are white blood cells involved in a variety of our immune system responses, including detection and destruction of cancer cells. With T cell therapy, “tumour-reactive” T cells are isolated from a patient’s blood, and large numbers are grown outside the body. These T cells are then infused back into the patient to help the body recognize and destroy cancer cells, a method called adoptive immunotherapy. Michele Martin is studying the potential for using T cell therapy to treat breast cancer. Early results show about 19 per cent of tumours will regress or shrink with this treatment – unprecedented with other types of treatment – while the rest have partial or no regression. Michele is investigating how some of the tumours manage to exclude the T cells and also whether combining T cell therapy with low doses of chemotherapy can facilitate T cell infiltration into these tumours. If successful, this approach could improve breast cancer cure rates and reduce the side effects associated with current treatments.