Radiopharm Theranostics announced it has completed a Phase 1 study investigating the safety, dosimetry and efficacy of RAD201 in HER2 positive breast cancer subjects, in concert with its collaborators at Shanghai General Hospital in China and NanoMab in London, UK and Hong Kong, China. The single domain antibody RAD201 is a novel single domain antibody, engineered to bind the imaging isotope Tc-99m which targets a protein called human epidermal growth factor receptor 2 (HER2) often associated with breast cancer. HER2 overexpression in breast cancer is often associated with aggressive disease and consequently, poor prognosis. The study, conducted at Shanghai General Hospital under the direction of Dr Jinhua Zhao, imaged 40 histopathologically-proven breast cancer subjects. The procedure involved injecting the subject with RAD201, allowing time for the single domain antibody to localize at the HER2 positive cancer and clear from non-target organs, then imaging the subject two hours post-injection using a Single Photon Emission Computed Tomography (SPECT) camera. This procedure yielded uniformly excellent, easy to interpret images. The images demonstrated outstanding target-to-background, making quantification straightforward and RAD201 SPECT imaging a potentially fast and non-invasive way of gaining insight to HER2 overexpression in breast cancer primary and metastatic lesions. No concerning safety signal was observed, with only a minor grade 1 adverse event reported as unrelated to RAD201. Based on these encouraging results, RAD plans to accelerate development of RAD201 and to initiate a Phase 1 therapy study for RAD202 as a Company-sponsored Investigational New Drug (IND) recognized by the US Food and Drug Administration (FDA) in H1 CY22. RAD202 will be composed of the same single domain antibody construct as RAD201, but will incorporate the therapeutic, beta particle-emitting isotope, Re-188 that has the potential to kill cancer cells. This approach of demonstrating efficacy with imaging followed by targeted internal radiotherapy is consistent with RAD's vision for improving cancer therapy and the lives of patients living with oncological diseases.