Track: Advances in Breast Cancer Immunotherapy

Advances in Breast Cancer Immunotherapy

Immunotherapy in Early-Stage Breast Cancer
Neoadjuvant and adjuvant immunotherapy is an emerging area of research. The KEYNOTE-522 trial combined pembrolizumab with chemotherapy in early-stage TNBC, showing improved pathological complete response (pCR) and event-free survival. These findings suggest immunotherapy could reduce recurrence and improve long-term outcomes when integrated earlier in treatment. However, further studies are needed to identify which early-stage patients will benefit most and how to manage potential immune-related adverse events in a curative-intent setting.
 
Combining Immunotherapy with Chemotherapy
Chemotherapy can enhance immunotherapy response by increasing tumor antigen presentation and immune activation. Studies like IMpassion130 and KEYNOTE-355 used taxane-based regimens with checkpoint inhibitors, improving survival in TNBC. Research is ongoing into optimal chemo-immunotherapy combinations and dosing schedules. Novel strategies include pairing immunotherapy with PARP inhibitors, radiotherapy, or angiogenesis inhibitors, which may further sensitize tumors and enhance outcomes, especially in immune-excluded or PD-L1-negative patients.
 
Cancer Vaccines in Breast Cancer
Therapeutic cancer vaccines are being investigated as a way to stimulate anti-tumor immunity in breast cancer. Unlike prophylactic vaccines, these target tumor-associated antigens (e.g., HER2, MUC1, CEA). Studies such as NeuVax (nelipepimut-S) have shown safety, but mixed efficacy. Newer vaccines use neoantigen targets and mRNA platforms (like COVID-19 vaccines), showing promise in preclinical models. Clinical trials are ongoing to evaluate vaccines as monotherapy or in combination with checkpoint inhibitors in early and metastatic settings.
 
CAR-T and Adoptive Cell Therapies
While CAR-T cell therapy is established in hematologic malignancies, its application in breast cancer is still in early-phase trials. Researchers are engineering T cells to target HER2, MUC1, or other breast-specific antigens. Challenges include tumor heterogeneity, safety concerns (e.g., cytokine release syndrome), and limited T-cell infiltration in solid tumors. Combination strategies and regional delivery methods are under investigation to overcome the immunosuppressive tumor microenvironment and improve cell therapy efficacy.
 
Role of the Tumor Microenvironment (TME)
The tumor microenvironment plays a significant role in immunotherapy resistance. Breast tumors often contain immunosuppressive cells like regulatory T cells (Tregs), M2 macrophages, and myeloid-derived suppressor cells (MDSCs) that inhibit T-cell activity. New approaches aim to “reprogram” the TME using agents that target CSF1R, IDO1, or VEGF pathways, making tumors more responsive to immunotherapy. Modulating the TME may enhance checkpoint inhibitor efficacy and convert immunologically “cold” tumors to “hot.”