Abstract 6264: NUV-868, a novel BD2-selective BET inhibitor, in combination with enzalutamide or olaparib, inhibits growth of solid tumor xenografts

Abstract

The bromodomain and extraterminal domain (BET) family of proteins play a vital role in gene transcription, making it an attractive therapeutic target for cancer. BET inhibitors can also combine with many anticancer agents to enhance activity. The bromodomains of the BET protein, BD1 and BD2, have unique functions and inhibiting either domain can result in differential responses. To date, non-selective BET inhibitors have failed during early clinical development due to significant on-target toxicity and limited benefit; however, selectively targeting specific bromodomains may result in a more favorable benefit/risk profile. NUV-868 is a novel and highly selective BD2 inhibitor of the BET protein family with ~1500-fold selectivity for BRD4-BD2 relative to BRD4-BD1. Herein, we describe NUV-868 and its activity in multiple in vitro and in vivo solid tumor models. Target engagement, selectivity of bromodomain inhibition, and regulation of BET-mediated gene expression were examined. Additionally, the antitumor activity of NUV-868 in combination with enzalutamide or olaparib was studied in tumor xenograft models of prostate, breast, and pancreatic cancer. NUV-868 demonstrated high selectivity for BD2 and regulated expression of several BET target genes. NUV-868 in combination with enzalutamide inhibited growth of several prostate cancer cell line- and patient-derived xenografts. NUV-868 in combination with olaparib inhibited tumor growth in models of breast, ovarian and pancreatic cancer. Our preclinical data demonstrate that NUV-868, a BD2-selective BET inhibitor, inhibits growth of tumor xenografts in combination with enzalutamide or olaparib and provides rationale for examination of these combinations in the clinic. An ongoing, phase 1 clinical study (NCT05252390) is evaluating NUV-868 as a monotherapy and in combination with olaparib or enzalutamide in patients with advanced solid tumors. Citation Format: Hitisha Patel, Jennifer Hertzog, Laura Heller, Spandana Vootukuri, Yan Zhang, Chris Miller, Gary Hattersley. NUV-868, a novel BD2-selective BET inhibitor, in combination with enzalutamide or olaparib, inhibits growth of solid tumor xenografts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6264.