Grant: DRA : Canada Graduate Research Scholarship - Doctoral Program (CGRS D)

Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer that progresses rapidly and does not respond well to many standard treatments, including some of the newest immunotherapies. This leaves patients with few effective options and highlights a pressing need for innovative approaches. Our research has discovered that telmisartan, a widely prescribed blood pressure medication, can be repurposed to help the body's immune system fight TNBC. In preclinical models of TNBC, we found that telmisartan activates specialized immune cells called CD8+ T cells, which are capable of recognizing and killing cancer cells. Treatment with telmisartan alone reduced tumour growth in immune-competent models, but had no effect in immune-deficient models, showing that its benefit relies on the body's immune system. When telmisartan was combined with existing immunotherapy, the combination led to much stronger tumour control than either treatment alone. This suggests that telmisartan can enhance the effectiveness of current immunotherapies, offering a potential new combination treatment for cancers that are otherwise difficult to treat. Because telmisartan is already widely available, safe, and inexpensive, this research has the potential to be translated rapidly into clinical trials. If successful, it could improve health outcomes for individual patients, expand treatment options for populations with aggressive breast cancer, and provide a cost-effective strategy for the healthcare system. Beyond breast cancer, this work may also inform new therapies for other tumours that do not respond well to existing immunotherapies, helping more patients benefit from the immune system's natural ability to fight cancer.