177Lu-DOTA-EB-FAPI

A 29-year-old man with Ewing sarcoma in the right ankle underwent 68Ga-DOTA-IBA PET/CT and 18F-FDG PET/CT, both of which showed high radiotracer activity for the primary tumor. Interestingly, bone metastases were detected early using 68Ga-DOTA-IBA PET/CT for the sixth thoracic vertebrae and with 18F-FDG PET/CT for the bilateral humerus. Higher uptake of 68Ga-DOTA-IBA was found in both primary and metastatic sites of Ewing sarcoma. 177Lu-DOTA-IBA may be one of the possible therapies for metastatic or recurrent Ewing sarcoma.

Radioimmunotherapy (RIT) uses monoclonal antibodies to deliver radionuclides to cancer cells or the tumor microenvironment and has shown promise in treating localized and diffuse tumors. Although RIT agents have gained FDA/EMA approval for certain hematologic malignancies, effectiveness of RIT in treating solid tumors remains limited. In this study, we present PreTarg-it, a novel approach for pretargeted RIT, providing optimized delivery of payloads in a two-step regimen. The effectiveness of PreTarg-it is demonstrated by a powerful combination of ON105, a novel bispecific antibody against both oxidized macrophage migration inhibitory factor (oxMIF) and the histamine-succinyl-glycyl (HSG) hapten, as the first component and the radioactively labeled DOTA-di-HSG peptide as the second component in murine models of cancer. Mice bearing either subcutaneous mouse colorectal CT26 or human pancreatic CFPAC-1 tumors received an i.v. injection of ON105. After ON105 had accumulated in the tumor and cleared from circulation to approximately 1% to 3% of its peak concentration, 177Lu-DOTA-di-HSG peptide was administered. A single PreTarg-it treatment cycle resulted in tumor regression when mice bearing CT26 tumors were given the highest treatment dose with a pretargeting delay of 3 days. Administered with a 5-day interval, the highest dose arrested tumor growth in both CT26 syngrafts and CFPAC-1 xenografts. In all cases, the highest treatment dose resulted in 100% survival at the study endpoint, whereas the control cohorts showed 0% and 60% survival in the CT26 and CFPAC-1 models, respectively. Therefore, PreTarg-it holds potential as a novel and potent therapy for patients with hard-to-treat solid tumors, such as pancreatic cancer, as well as those with late-stage malignancies.