Keywords :
B7-H1 Antigen; Immune Checkpoint Inhibitors; Nuclear Proteins; Transcription Factors; Paclitaxel; Humans; Animals; Mice; B7-H1 Antigen/metabolism; Immune Checkpoint Inhibitors/therapeutic use; Paclitaxel/pharmacology; Paclitaxel/therapeutic use; Immunotherapy/methods; Triple Negative Breast Neoplasms/pathology; Immunotherapy; Triple Negative Breast Neoplasms; Oncology; Cancer Research
Abstract :
[en] Immune checkpoint inhibition combined with chemotherapy is currently approved as first-line treatment for patients with advanced PD-L1-positive triple-negative breast cancer (TNBC). However, a significant proportion of metastatic TNBC is PD-L1-negative and, in this population, chemotherapy alone largely remains the standard-of-care and novel therapeutic strategies are needed to improve clinical outcomes. Here, we describe a triple combination of anti-PD-L1 immune checkpoint blockade, epigenetic modulation thorough bromodomain and extra-terminal (BET) bromodomain inhibition (BBDI), and chemotherapy with paclitaxel that effectively inhibits both primary and metastatic tumor growth in two different syngeneic murine models of TNBC. Detailed cellular and molecular profiling of tumors from single and combination treatment arms revealed increased T- and B-cell infiltration and macrophage reprogramming from MHCIIlow to a MHCIIhigh phenotype in mice treated with triple combination. Triple combination also had a major impact on gene expression and chromatin profiles shifting cells to a more immunogenic and senescent state. Our results provide strong preclinical evidence to justify clinical testing of BBDI, paclitaxel, and immune checkpoint blockade combination.
Funding text :
We thank members of the Polyak laboratory for their critical reading of the article and useful advice. Financial support: Funded by the NCI R35 CA197623 (K. Polyak), P50 CA168504 (J.L. Guerriero, K. Polyak), P01CA250959 (K. Polyak, H.W. Long), the Ludwig Center at Harvard (K. Polyak), and the Susan G. Komen Foundation PDF14302777 (S. Shu).
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