PD-L1-negative triple-negative breast cancer exhibited a remarkable response to cadonilimab: a case report.

Breast cancer, a prevalent malignancy among women, is primarily categorized into four subtypes based on immunohistochemistry: luminal A breast cancer, luminal B breast cancer, HER2-enriched breast cancer, and triple-negative breast cancer (TNBC). Molecular targets for TNBC therapy are lacking, and TNBC is characterized by a high risk of recurrence and a poor prognosis. The advent of immune checkpoint inhibitors (ICIs), including PD-1, PD-L1, and CTLA-4 inhibitors, has led to therapeutic advances in the management of TNBC. The combination of chemotherapy and immunotherapy has been shown to improve patient outcomes and survival rates. This case primarily discusses immunotherapy combination treatments for PD-L1-negative TNBC patients, for which research remains relatively scarce. This case report focuses on a 48-year-old female patient with PD-L1-negative stage IV TNBC who exhibited a significant therapeutic response to cadonilimab, a tetravalent PD-1/CTLA-4 bispecific antibody, in combination with chemotherapy, achieving a partial response (PR), as assessed by clinical evaluation. The tumor volume was reduced by more than 75%. The patient experienced grade 3 neutropenia, grade 2 thrombocytopenia, grade 2 nausea, and grade 2 immune-related adverse events, including pruritus and hyperthyroidism. Furthermore, this report reviews the current principal treatment modalities for TNBC. Particular emphasis was placed on discussing immunotherapy combination treatments for TNBC. Additional studies with larger cohorts are warranted for comprehensive translational research on PD-L1-negative TNBC, aiming to validate the efficacy and elucidate the mechanisms of action of various ICIs. This case highlights that dual-targeted therapy may provide a promising therapeutic option for patients with PD-L1-negative TNBC.