[177Lu]Lu-NeoB in Combination With Ribociclib and Fulvestrant in Participants With ER+, HER2- and GRPR+ Advanced Breast Cancer

Inclusion criteria

• . relapsed with documented evidence of relapse on or within 12 months from completion of (neo)adjuvant endocrine therapy (+/- CDK4/6 inhibitor) with no treatment for advanced disease OR
• . relapsed with documented evidence of relapse more than 12 months from completion of (neo)adjuvant endocrine therapy and then subsequently progressed with documented evidence of progression after one line of endocrine therapy (except fulvestrant) (+/- CDK4/6 inhibitor) for advanced disease OR
• . advanced breast cancer at diagnosis that progressed with documented evidence of progression after one line of endocrine therapy (except fulvestrant) (+/- CDK4/6 inhibitor) Note: Participant who relapsed with documented evidence of relapse on/or within 12 months from completion of (neo)adjuvant endocrine therapy and then subsequently progressed with documented evidence of progression after one line of endocrine therapy (with either an antiestrogen or an aromatase inhibitor) for advanced disease will NOT be included in the study. At least one target lesion (i.e., a measurable lesion as per RECIST 1.1) in the baseline stand-alone CT or MRI, showing \[68Ga\]Ga-NeoB uptake on PET/CT or PET/MRI scoring 2 or higher, based on the Visual Scoring Scale.