Targeted chemotherapy in combination with external beam radiation therapy (radiotherapy) is a promising approach to significantly improve the therapeutic outcome for cancer patients. To achieve this, it is essential to develop drug delivery technology that specifically delivers the chemotherapeutic drugs to cancerous tissue. Radiotherapy is an indispensable part of modern cancer treatment; however, despite efforts in improving planning and execution of treatment, the unbalance between therapeutic benefit and side effects limits cure rates, and new approaches are needed to bring to fruition the full potential of radiotherapy. Today, there is considerable focus on systemically administered radiosensitizers for enhancing the effect of radiotherapy and clinical investigations have shown promising results; however, radiosensitizer use is hampered by considerable side effects due to lack of drug targeting to the cancerous tissue.In the first phase of this project, the aim is to develop tumor targeted nanocarrier delivery systems of radiosensitizers to enhance their therapeutic potential and provide a more efficient and site-directed effect of radiotherapy. In the second phase of the project, nanocarriers for tumor specific delivery of checkpoint inhibitors of cancer cell repair mechanisms will be investigated as an additional targeting strategy for sensitizing cancer cells to radiotherapy. The idea is to circumvent cell cycle checkpoints of DNA damage induced by tumor radiation and thereby enhance mitotic catastrophe. This approach will in combination with the delivery of conventional radiosensitizer drugs, further lower the radiation dose needed to induce irreversible damage to cancer cells.Thus, the project aims to develop targeted nanocarriers for high precision delivery of radiosensitizing drugs to cancerous tissue for enhancing the effect of radiotherapy. We aim to demonstrate the applicability and clinical potential of this new approach within the project period