The study will be done in two parts. The first part is called "escalation" and the second part is called "expansion". In both parts of the study, patients will be screened with a \[68Ga\]Ga-FF58 positron emission tomography (PET)/computed tomography (CT) or PET/magnetic resonance imaging (MRI) scan to assess eligibility for treatment with \[177Lu\]Lu-FF58. In the escalation part, different doses of \[177Lu\]Lu-FF58 will be tested to identify the recommended dose. The expansion part of the study will examine the safety and preliminary efficacy of \[177Lu\]Lu-FF58 at the recommended dose determined during the escalation part. The end of study will occur when at least 80% of the patients in the expansion part have completed the follow-up for disease progression or discontinued from the study for any reason, and all patients have completed treatment and the 36 month long term follow- up period, or the study is terminated early in which case all patients would also be followed up for safety.
