Immunotherapy Targeting PD-1/PD-L1 in Early-Stage Triple-Negative Breast Cancer

The advent of immunotherapy, especially immune checkpoint inhibitors (ICIs), has revolutionized antitumor therapy. Programmed cell death receptor 1 (PD-1) and programmed cell death ligand 1 (PD-L1) are among the most promising targets for encouraging the immune system to eliminate cancer cells. PD-1/PD-L1 have made clinical remission for numerous solid tumors, including metastatic triple-negative breast cancer (TNBC). In recent years, integrating PD-1/PD-L1 inhibitors into existing treatments in early-stage TNBC has attracted wide attention. Herein, we summarize the clinical benefit of PD-1/PD-L1 inhibitors plus neoadjuvant chemotherapy, adjuvant chemotherapy, and targeted therapy in early-stage TNBC. Possible immunotherapy biomarkers, immune-related adverse events (irAEs), and the key challenges faced in TNBC anti-PD-1/PD-L1 therapy are also concluded. Numerous studies on immunotherapy are ongoing, and PD-1/PD-L1 inhibitors have demonstrated great clinical prospects in early-stage TNBC. To maximize the efficacy of anti-PD-1/PD-L1 therapy, further research into the challenges which still exist is necessary.

Modification of Breast Cancer Milieu with Chemotherapy plus Dendritic Cell Vaccine: An Approach to Select Best Therapeutic Strategies

BACKGROUND

The addition of dendritic cell vaccines (DCV) to NAC could induce immune responses in those patients with residual disease (RD) by transforming the tumor microenvironment.

METHODS

Core diagnostic biopsies and surgical specimens from 80 patients (38 in the vaccinated group plus NAC (VG) and 42 in the control group (CG, treated only with NAC) were selected. We quantify TILs (CD8, CD4 and CD45RO) using immunohistochemistry and the automated cellular imaging system (ACIS III) in paired samples.

RESULTS

A CD8 rise in TNBC samples was observed after NAC plus DCV, changing from 4.48% in the biopsy to 6.70% in the surgical specimen, not reaching statistically significant differences (p = 0.11). This enrichment was seen in up to 67% of TNBC patients in the experimental arm as compared with the CG (20%). An association between CD8 TILs before NAC (4% cut-off point) and pathological complete response in the VG was found in the univariate and multivariate analysis (OR = 1.41, IC95% 1.05-1.90; p = 0.02, and OR = 2.0, IC95% 1.05-3.9; p = 0.03, respectively).

CONCLUSION

Our findings suggest that patients with TNBC could benefit from the stimulation of the antitumor immune system by using DCV together with NAC.

A review of immune checkpoint blockade in breast cancer

In the recent years characterized by the cancer immunotherapy revolution, attention has turned to how to potentially boost and/or generate an efficient anti-tumor immune response in breast cancer (BC). Clinical activity of immune checkpoint blockade (ICB) targeting PD-1 or PD-L1 in BC has been more evident in the triple negative subtype and in earlier lines of the treatment. Remarkably, some responders to single agent ICB have achieved durable responses with metastatic disease, possibly as a result of treatment-induced immunological memory. However, most BC are immunologically quiescent and current research efforts developing ICB combinations are attempting to convert "cold" into "hot" tumors by manipulating the tumor microenvironment, expanding anti-tumor T cells improving efficient antigen presentation, and suppressing pro-tumor inhibitory cells. The aim of this review is to summarize existing data on the efficacy of immune checkpoint blockers as single agents and combination strategies in all BC subtypes, highlighting the BC subgroups that benefit most from ICB.

Progress and challenges of immunotherapy in triple-negative breast cancer

Triple-negative breast cancer (TNBC), a subtype of breast cancer, is defined as lacking estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER2) expression. Compared with other subtypes in breast cancer, TNBC is more likely to recur and metastasize, with a lower survival rate. Due to the absence of definitive targets, there was limited novel therapeutic interventions and chemotherapy remained the primary treatment in the past decades. Following the development of immune checkpoint inhibition (ICI) in solid tumors and validation of the immunogenicity in TNBC, immunotherapy has attracted more and more attentions. On basis of accumulating clinical studies, we reviewed the current progress targeting different immune checkpoints in several-lines treatment for TNBC, including programmed death-1 (PD-1)/programmed death ligand-1 (PD-L1) inhibitors, cytotoxic T-lymphocyte associated antigen-4 (CTLA-4) inhibitor, and other novel immunotherapeutic approaches (e.g., individualized peptide vaccine, cancer-testis antigen (CTA), new antigen vaccine, RNA vaccine and chimeric antigen receptor modified T cells (CAR-T)). In order to improve the survival outcome of TNBC populations, we further discussed potential predictive biomarkers for immunotherapy (e.g., PD-L1 expression, tumor mutational burden (TMB), tumor-infiltrating lymphocytes (TILs), microsatellite instability (MSI)/mismatch repair (MMR) deficiency) and challenges in the future treatment of TNBC.