Extracellular adenosine in the tumor microenvironment generates an immunosuppressive niche that promotes tumor growth and metastasis by signaling through the A2A receptor (A2AR) on immune cells. CPI-444 is a, selective A2AR antagonist that has demonstrated anti-tumor activity as a monotherapy and in combination with atezolizumab in an ongoing phase 1/1b trial in patients with advanced cancers. Here we analyzed gene expression profiles (GEPs) associated with A2AR agonism to characterize a “signature” of adenosine exposure in human immune cells and correlated this with GEPs in tumor biopsies from patients with renal cell cancer (RCC) treated with CPI-444.
Human PBMCs were stimulated with NECA (a stable adenosine analog) or an A2AR specific agonist (CGS21680). Purified RNA was analyzed using the NanoString PanCancer Immune Panel in conjunction with RNASeq. Select analytes were validated in culture supernatant by ELISA. RCC tumor biopsies collected from 64 pts treated with CPI-444 (100 mg BID) either as a single agent (n = 32) or in combination with atezolizumab (n = 32) were analyzed using NanoString.
In vitro A2AR stimulation resulted in dose-dependent increases in CXCR2 ligands (CXCL1,2,3,5,8) and key mediators of neutrophil/MDSC biology (CSF3, IL-23). Increases in monocyte/macrophage inflammatory mediators such as IL-1b and CCL2,3,7,8, 20 were also observed, as were increases in SERPINB2, S100A8, PTGS2, THBS1. Expression of CXCL10 and GZMB were decreased, consistent with a suppressed IFNg response. CPI-444 inhibited these changes at the transcript and protein level. Preliminary biomarker analysis suggests CPI-444 anti-tumor activity in RCC was associated with increased expression of these adenosine responsive genes in pretreatment biopsies. A second module of genes, which included CX3CL1 and complement inhibition, was associated with tumor progression.
A2AR agonists induce a specific gene signature dominated by immunosuppressive mediators of MDSC and monocyte/macrophage biology. Inhibition of these GEPs by CPI-444 are observed in vitro and in vivo in tumor biopsies from treated patients. These gene signatures may be used as biomarkers for patient selection.
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Legal entity responsible for the study
S. Willingham, A.N. Hotson, G. Laport, L. Kwei, R. Miller: Employee and shareholder: Corvus Pharmaceuticals. L. Fong: Grants: Merck, Dendreon, Bristol Myers Squibb, Roche-Genentech, Abbvie, Amgen. M. Sznol: Consultant: BMS, Genentech-Roche, AstraZeneca-Medimmune, Anaeropharma, Merus, Symphogen, Nektar, Amgen, Kyowa-Kirin, Astellas-Agensys, Lion Biotech, Neostem, Seattle Genetics, Pfizer, TRM Oncology, Physicians Education Resource, Imedex, Research to Practice. J. Powderly: Employment and leadership: BioCytics, Carolina BioOncology Institute; Stock and other ownership interests: BioCytics, Bluebird Bio, Carolina BioOncology Institute, Juno Therapeutics, Kite Pharma, Lion Biotechnologies, ZIOPHARM Oncology; Consulting or advisory role: AstraZeneca/MedImmune, Bristol-Myers Squibb, Curis, Genentech/Roche, TopAlliance BioSciences Inc; Speakers' bureau: Bristol-Myers Squibb, Dendreon, Genentech/Roche, Merck; Research funding: AstraZeneca/MedImmune, Bristol-Myers Squibb, EMD Serono, Genentech/Roche, Incyte, Lilly/ImClone; Macrogenics patents, royalties, other intellectual property: BioCytics is developing intellectual property for cellular immunotherapy.
All authors have declared no conflicts of interest.