Enhanced expression of galectin‐9 in triple negative breast cancer cells following radiotherapy: Implications for targeted therapy.

Optimizations are expected in the development of immunotherapy for the treatment of Triple‐negative breast cancer (TNBC). We studied the expression of galectin‐9 (Gal‐9) after irradiation and assessed the differential impacts of its targeting with or without radiotherapy. Tumor resections from TNBC patients who received neoadjuvant radiotherapy revealed higher levels of Gal‐9 in comparison to their baseline level, only in non‐responder patients. Gal‐9 expression was also found to be increased in TNBC tumor biopsies and cell lines after irradiation. We investigated the therapeutic advantage of targeting Gal‐9 after radiotherapy in mice. Irradiated 4T1 cells or control non‐irradiated 4T1 cells were injected into BALB/c mice. Anti‐Gal‐9 antibody treatment decreased tumor progression only in mice injected with irradiated 4T1 cells. This proof‐of‐concept study demonstrates that Gal‐9 could be considered as a dynamic biomarker after radiotherapy for TNBC and suggests that Gal‐9 induced‐overexpression could represent an opportunity to develop new therapeutic strategies for TNBC patients. [ABSTRACT FROM AUTHOR]