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)

The purpose of this study is to assess the efficacy and safety of iza-bren, a bi-specific antibody-drug conjugate against EGFR and HER3 with a topoisomerase inhibitor payload versus treatment of physician's choice (TPC) (paclitaxel, nab-paclitaxel, carboplatin plus gemcitabine, and capecitabine) for the treatment of first-line metastatic triple-negative breast cancer (TNBC) or estrogen receptor (ER)-low, human epidermal growth factor receptor 2 (HER2)-negative BC patients who are not candidates for anti-PD(L)1 therapy and endocrine therapies.

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.