EP4 Antagonism by E7046 diminishes Myeloid immunosuppression and synergizes with Treg-reducing IL-2-Diphtheria toxin fusion protein in restoring anti-tumor immunity

Autor: Diana I. Albu, Zichun Wang, Kuan-Chun Huang, Jiayi Wu, Natalie Twine, Sarah Leacu, Christy Ingersoll, Lana Parent, Winnie Lee, Diana Liu, Renee Wright-Michaud, Namita Kumar, Galina Kuznetsov, Qian Chen, Wanjun Zheng, Kenichi Nomoto, Mary Woodall-Jappe, Xingfeng Bao
Jazyk: angličtina
Rok vydání: 2017
Předmět:
Zdroj: OncoImmunology, Vol 6, Iss 8 (2017)
Druh dokumentu: article
ISSN: 2162-402X
2162402X
DOI: 10.1080/2162402X.2017.1338239
Popis: Reprogramming of immunosuppressive tumor microenvironment (TME) by targeting alternatively activated tumor associated macrophages (M2TAM), myeloid-derived suppressor cells (MDSC), and regulatory T cells (Tregs), represents a promising strategy for developing novel cancer immunotherapy. Prostaglandin E2 (PGE2), an arachidonic acid pathway metabolite and mediator of chronic inflammation, has emerged as a powerful immunosuppressor in the TME through engagement with one or more of its 4 receptors (EP1-EP4). We have developed E7046, an orally bioavailable EP4-specific antagonist and show here that E7046 has specific and potent inhibitory activity on PGE2-mediated pro-tumor myeloid cell differentiation and activation. E7046 treatment reduced the growth or even rejected established tumors in vivo in a manner dependent on both myeloid and CD8+ T cells. Furthermore, co-administration of E7046 and E7777, an IL-2-diphtheria toxin fusion protein that preferentially kills Tregs, synergistically disrupted the myeloid and Treg immunosuppressive networks, resulting in effective and durable anti-tumor immune responses in mouse tumor models. In the TME, E7046 and E7777 markedly increased ratios of CD8+granzymeB+ cytotoxic T cells (CTLs)/live Tregs and of M1-like/M2TAM, and converted a chronic inflammation phenotype into acute inflammation, shown by substantial induction of STAT1/IRF-1 and IFNγ-controlled genes. Notably, E7046 also showed synergistic anti-tumor activity when combined with anti-CTLA-4 antibodies, which have been reported to diminish intratumoral Tregs. Our studies thus reveal a specific myeloid cell differentiation-modifying activity by EP4 blockade and a novel combination of E7046 and E7777 as a means to synergistically mitigate both myeloid and Treg-derived immunosuppression for cancer treatment in preclinical models.
Databáze: Directory of Open Access Journals
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