ROSETTA Breast-01: The Effects and Safety of Pumitamig in Patients With Triple-Negative Breast Cancer

Inclusion Criteria: * Are considered ineligible for combination treatment with a monospecific PD(L)1 targeting immunotherapy plus chemotherapy as per their tumor PD-L1 expression status. * Have confirmed locally recurrent inoperable or metastatic TNBC, or estrogen receptor (ER)-low, human epidermal growth factor receptor 2 (HER2)-negative breast cancer (ER and/or progesterone receptor \[PgR\]) 1% to 10%, HER2 immunohistochemistry \[IHC\] 0, 1+, or 2+ with fluorescence in situ hybridization \[FISH\] negative for HER2 gene amplification) documented prior to trial screening as part of standard of care. * Have at least one measurable lesion as the targeted lesion based on RECIST v1.1. * Have provided a tissue sample, archival or fresh, during the screening period (bone biopsies, fine needle aspiration biopsies, and samples from pleural or peritoneal fluid are not acceptable; participants with only one target lesion are not eligible to participate in the trial). * Eastern cooperative oncology group (ECOG) performance status of 0 or 1. Exclusion Criteria: * Have received any of the following therapies or drugs prior to the initiation of trial: * Have received prior systemic anticancer therapy for advanced disease. * Have received prior treatment with a PD(L)-1/vascular endothelial growth factor (VEGF) bispecific antibody. * Have received systemic corticosteroids (at a dosage greater than 10 milligrams \[mg\]/day of prednisone or an equivalent dose of other corticosteroids…