A Study of Izalontamab Brengitecan Versus Chemotherapy in Participants With Previously Untreated, Locally Advanced, Recurrent Inoperable, or Metastatic Triple-negative Breast Cancer Ineligible for Anti-PD(L)1 Drugs (IZABRIGHT-Breast01)

Inclusion Criteria

• Histologically or cytologically confirmed and documented locally-advanced, recurrent inoperable, or metastatic TNBC (ER < 1%, PgR < 1%, HER2 IHC 0, 1+, or 2+ with ISH negative for HER2 gene amplification) or ER-low, HER2-negative BC (ER and / or PgR 1% to 10%, HER2 IHC 0, 1+, or 2+ with ISH negative for HER2 gene amplification) per ASCO/CAP criteria, based on the most recently analyzed biopsy or other pathology specimen.

• Patients with recurrent disease must have experienced disease relapse at least 6 months after finishing their last therapy with curative intent.

• Patients with TNBC must be considered ineligible for 1L chemotherapy combination treatment with an anti-PD-1 or an anti-PD-L1 due to either one of the following criteria:

i) Investigator-determined ineligibility based on PD-L1 negative disease determined and documented prior to trial screening as part of SoC; ii) Has experienced disease relapse between 6 to 12 months after the completion of (neo)adjuvant therapy with an anti-PD(L)1; iii) Has a severe auto-immune disease or other contraindication.

• Patients with ER-low, HER2-negative BC must be ineligible, in the opinion of the Investigator, for endocrine therapy-based treatments.

• No previous systemic therapy in the locally advanced, recurrent inoperable or metastatic setting (ie incurable setting).

• Measurable disease by CT or MRI as per RECIST v1.1.

• Other protocol-defined Inclusion/Exclusion criteria apply.