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The next‐generation BET inhibitor, PLX51107, delays melanoma growth in a CD8‐mediated manner
Author(s) -
Erkes Dan A.,
Field Conroy O.,
Capparelli Claudia,
Tiago Manoela,
Purwin Timothy J.,
Chervoneva Inna,
Berger Adam C.,
Hartsough Edward J.,
Villanueva Jessie,
Aplin Andrew E.
Publication year - 2019
Publication title -
pigment cell and melanoma research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.618
H-Index - 105
eISSN - 1755-148X
pISSN - 1755-1471
DOI - 10.1111/pcmr.12788
Subject(s) - cancer research , cd8 , melanoma , tumor microenvironment , cytotoxic t cell , immune system , bromodomain , immunotherapy , immunology , medicine , biology , epigenetics , in vitro , genetics , gene
Epigenetic agents such as bromodomain and extra‐terminal region inhibitors (BETi) slow tumor growth via tumor intrinsic alterations; however, their effects on antitumor immunity remain unclear. A recent advance is the development of next‐generation BETi that are potent and display a favorable half‐life. Here, we tested the BETi, PLX51107, for immune‐based effects on tumor growth in BRAF V600E melanoma syngeneic models. PLX51107 delayed melanoma tumor growth and increased activated, proliferating, and functional CD8+ T cells in tumors leading to CD8+ T‐cell‐mediated tumor growth delay. PLX51107 decreased Cox2 expression, increased dendritic cells, and lowered PD‐L1, FasL, and IDO‐1 expression in the tumor microenvironment. Importantly, PLX51107 delayed the growth of tumors that progressed on anti‐PD‐1 therapy; a response associated with decreased Cox2 levels, decreased PD‐L1 expression on non‐immune cells, and increased intratumoral CD8+ T cells. Thus, next‐generation BETi represent a potential first‐line and secondary treatment strategy for metastatic melanoma by eliciting effects, at least in part, on antitumor CD8+ T cells.