177Lu-FAP-2286 Treatment in Urethelial Neoplasms: Utility and Safety as a Novel Treatment.

Ga-68-FAPI has recently been proven to be superior to F-18-FDG in various cancers. These results have also raised hope in using FAP radiopharmaceuticals with theranostic approach. Lu-177 bound FAPI molecules have been started to be used in some cancers in clinical trials following its efficacy proven by case reports. Similarly,as a pilot study, this project aims to investigate safety and efficacy of Lu-177- FAP-2286 in metastatic urothelial carcinomas of bladder.

A total of 10 histopathologically proven urothelial bladder cancer patients \>18y of age will be included in the study. After taking informed consent, all patients will undergo both 18F-FDG PET/CT and 68Ga-FAPI PET/CT for restaging before initiation of Lu-177-FAP-2286. Patients who show progression despite advanced therapies and high Ga-68 FAPI uptake will be enrolled. Patients with histopathologically proven advanced stage urothelial bladder cancer refractory to all standard therapies and no standard treatments are available or are contraindicated. Radiopharmaceutical will be administered 150mCi fixed dose, 3 cycles, 8 weeks interval. Posttherapy whole body SPECT/CT imaging will be obtained 4.,24.,96,120Hours of treatment for dosimetric calculations. All patients will be monitored for safety issues and possible long term side effects. Hematological tests, renal and liver function tests will be performed every 2 weeks, radiological imaging for tumor response assessment will be performed every 6 weeks. Symptoms will be taken under consideration for symptomatic response QoL questioner. In case of objective progression, therapy will be stopped. Otherwise, will be completed to 4 cycles.

Administration of Lu-177 FAPİ treatment will be performed by 1st partner from Turkey. Posttreatment SPECT/CT images will be obtained and collected for dosimetric calculations. Heatly organ doses and tumor doses will be calculated bt 2nd partner form Italy in collaboration with 1st partner. In consideration of the advances in radionuclide treatments to achieve objective response within safety margins to healthy organs, dosimetric approaches are mandatory. As a novel treatment dosimetric data for Lu-177 FAPİ treatment is limited. Despite to being a reference center for radionuclide treatments 1st partner has no experience on dosimetric calculations for systemic radionuclide treatments. As an experienced center for dosimetric studies, 2nd partner will be a milestone for analysis of dose response and toxicity analyses for this pilot study of novel treatment.