Dual Prognostic Classification of Triple-Negative Breast Cancer by DNA Damage Immune Response and Homologous Recombination Deficiency

PURPOSE

Triple-negative breast cancer (TNBC) is a heterogeneous disease. We previously showed that homologous recombination deficiency (HRD) and the DNA damage immune response (DDIR) signature are prognostic in TNBC. We hypothesized that these biomarkers reflect related but not completely interdependent biological processes, that their combined use would be prognostic, and that simultaneous assessment of the immunologic microenvironment and susceptibility to DNA damaging therapies might be able to identify subgroups with distinct therapeutic vulnerabilities.

METHODS

We analyzed the dual DDIR/HRD classification in 341 patients with TNBC treated with adjuvant anthracycline-based chemotherapy on the SWOG S9313 trial and corroborated our findings in The Cancer Genome Atlas breast cancer data set.

RESULTS

DDIR/HRD classification is highly prognostic in TNBC and identifies biologically and immunologically distinct subgroups. Immune-enriched DDIR+/HRD+ TNBCs have the most favorable prognosis, and DDIR+/HRD- and DDIR-/HRD+ TNBCs have favorable intermediate prognosis, despite the latter being immune-depleted. DDIR-/HRD- TNBCs have the worst prognosis and represent an internally heterogeneous group of immune-depleted chemoresistant tumors.

CONCLUSION

Our findings propose DDIR/HRD classification as a potentially clinically relevant approach to categorize tumors on the basis of therapeutic vulnerabilities.

TIME Is a Great Healer-Targeting Myeloid Cells in the Tumor Immune Microenvironment to Improve Triple-Negative Breast Cancer Outcomes

The word myeloid is derived from the Greek word muelós which means "marrow". Therefore, myeloid cells are described as cells that arise in the bone marrow. They can be distinguished from lymphoid cells based on their different differentiation trajectories-Lymphoid cells (B and T cells) are usually born in the bone marrow, but they need to migrate to lymphoid organs to mature and differentiate usually in response to antigens produced due to infections and diseases like cancer. On the other hand, myeloid cells do not follow this differentiation trajectory. They arise from the bone marrow, and do not need an encounter with antigens to gain their functionality. Thus, while lymphoid cells are a part of the adaptive immune system, myeloid cells are a part of the innate immune system. Hematopoiesis gives rise to two progenitor cells-the common myeloid progenitor (CMP) and the common lymphoid progenitor (CLP). The CMP can give rise to megakaryocytes, erythrocytes, mast cells and myeloblasts. Myeloblasts in turn lead to the formation of basophils, neutrophils, eosinophils and monocytes that can further differentiate into macrophages. This review will focus on macrophages as well as the phenotypes they acquire with the tumor immune microenvironment (TIME) in triple-negative breast cancer (TNBC). It will address how cancer cells in the tumor microenvironment (TME) recruit macrophages and may switch to recruiting neutrophils upon depletion of these tumor-associated macrophages (TAMs). Finally, it will also shed light on past and current treatment options that specifically target these cells and how those affect patient outcomes in TNBC.

Neoadjuvant Treatment for Triple Negative Breast Cancer: Recent Progresses and Challenges

Triple negative breast cancer (TNBC) is an aggressive breast cancer with historically poor outcomes, primarily due to the lack of effective targeted therapies. The tumor molecular heterogeneity of TNBC has been well recognized, yet molecular subtype driven therapy remains lacking. While neoadjuvant anthracycline and taxane-based chemotherapy remains the standard of care for early stage TNBC, the optimal chemotherapy regimen is debatable. The addition of carboplatin to anthracycline, cyclophosphamide, and taxane (ACT) regimen is associated with improved complete pathologic response (pCR). Immune checkpoint inhibitor (ICI) combinations significantly increase pCR in TNBC. Increased tumor infiltrating lymphocyte (TILs) or the presence of DNA repair deficiency (DRD) mutation is associated with increased pCR. Other targets, such as poly-ADP-ribosyl polymerase inhibitors (PARPi) and Phosphatidylinositol-3-kinase/Protein Kinase B/mammalian target of rapamycin (PI3K-AKT-mTOR) pathway inhibitors, are being evaluated in the neoadjuvant setting. This review examines recent progress in neoadjuvant therapy of TNBC, including platinum, ICI, PARPi, phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) pathway targeted therapies, and novel tumor microenvironment (TME) targeted therapy, in addition to biomarkers for the prediction of pCR.