Abstract LB433: RW-108, a first-in-class adenosine A2 receptor inverse agonist for treating late-stage triple negative breast cancer

Abstract Triple negative breast cancer (TNBC) is an aggressive breast cancer subtype that disproportionately affects younger patients (<40 years old) and Black and Hispanic communities. It is associated with high recurrence and mortality rates (usually recurring ≤5 years). Approximately 45% of patients progress to Stage IV, where the 5-year chance of survival drops drastically from 90% to 12%. The pro-tumor role of adenosine A2 receptor (A2AR and A2BR) signaling in TNBC cell growth and metastasis is well-documented. Inhibiting these receptors suppresses both TNBC growth and metastasis through A2BR and simultaneously promotes anti-tumor immunity through both A2AR and A2BR. Notably, A2BR overexpression correlates strongly with poor clinical prognoses in TNBC patients. In this study, we report the robust efficacy of RW-108, a novel drug candidate, in inhibiting metastatic TNBC progression and stimulating the anti-tumor immune system through a unique inverse agonist mechanism. We demonstrate the significant therapeutic potential of RW-108 in treating metastatic TNBC. RW-108 acts as a dual A2AR/A2BR receptor inverse agonist with potent inhibition of A2BR (Ki = 6.8 nM) and A2AR (Ki = 29 nM). This unique mechanism of action (MOA) provides stronger inhibition of A2AR and A2BR by locking the receptors in an inactive state, thus blocking both basal-level and adenosine-induced signaling. Structural modeling analysis revealed that RW-108 binds to the inverse agonist conformation, offering optimal binding energy compared to neutral antagonists. In vitro cAMP functional assays confirmed that RW-108 inhibits A2AR activity approximately 20% below baseline, supporting its role as an inverse agonist. Similarly, in an in vitro migration assay with human MDA-MB-231 cells, RW-108 inhibited both adenosine-induced migration and constitutive migration. This distinct MOA supports the strong efficacy observed in a variety of in vitro and in vivo models of metastatic TNBC. In vitro, RW-108 significantly inhibits TNBC cell migration and anchorage growth in human TNBC cells. In in vivo studies, RW-108 demonstrates orally bioavailability and significantly inhibits primary tumor growth (70%), metastatic bone growth (98%), and circulating TNBC cells in the blood (79%) and bone marrow (98%). Additionally, RW-108 enhances survival in metastatic models (53%) and anti-tumor T cells infiltration in the tumor microenvironment (70%). These compelling preclinical results support the continued development of RW-108 as a promising therapeutic for metastatic TNBC and other advanced cancers characterized by A2BR overexpression correlated with poor patient outcomes. Citation Format: Jean Jiang, Manuel Riquelme, Johanna Webb. RW-108, a first-in-class adenosine A2 receptor inverse agonist for treating late-stage triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr LB433.