CAAA603B12101 NeoB

Assess the safety and tolerability of [177Lu]LuNeob in combination with ribociclib and fulvestrant in patients with HR-positive, HER2-negative breast cancer experiencing early relapse following (neo)adjuvant endocrine therapy.;Determine the optimal dose of [177Lu]LuNeob in combination with ribociclib and fulvestrant for a future study.;Evaluate the preliminary efficacy of this combination by measuring tumor response (partial or complete response).;Assess progression-free survival (PFS), defined as the time until disease progression or death.;Monitor the pharmacokinetics of [177Lu]LuNeob to understand its behavior in the body.