Abstract C007: Quemliclustat (CD73 Inhibitor) reduces adenosine-regulated NR4A gene expression and increases mPDAC inflammation in patients from the ARC-8 trial

Abstract Background: Metastatic pancreatic ductal adenocarcinomas (mPDACs) express high levels of the adenosine-generating enzyme CD73 and therapeutically represent a significant unmet medical need, with median patient overall survival (OS) of <1 year. The small-molecule quemliclustat (quemli; AB680) was designed to inhibit soluble and cell-bound CD73 enzymatic activity, thereby providing the capability of reversing adenosine-mediated anti-tumor immune suppression. Quemli, in combination with gemcitabine/nab-paclitaxel (G/nP) ± anti-PD-1 antibody zimberelimab (zim), demonstrated encouraging clinical activity in the first line (1L) mPDAC study ARC-8 (NCT04104672), with median OS ranging from 14.6-19.4 months. Methods and Results: We began by identifying surrogates for tumor adenosine levels, given that it is not possible to measure adenosine levels directly in clinical samples. Cell culture experiments indicated that the stable adenosine analogue NECA can drive upregulation of the NR4A family of transcription factors (NR4A1, NR4A2, and NR4A3) in cancer cells as well as cancer-associated stromal cells (fibroblasts). Treatment with quemli reversed NR4A gene family upregulation, supporting a model in which high baseline levels of NR4A expression in tumors may be reflective of tumors with higher levels of adenosine. Next, we investigated quemli’s mechanism of action (MoA) by transcriptomic assessment of 37 matched pairs of pre- compared to post-treated mPDACs from ARC-8 patients dosed with 100mg of quemli. Treatment with quemli-containing regimens led to a significant reduction in tumor expression levels of the NR4A gene family. Decreased NR4A family tumor expression after treatment was accompanied by a significant increase in tumor inflammation, as measured by a T-cell activation gene signature. Analysis of a published transcriptional dataset from the nivolumab + G/nP control arm of the PRINCE trial in front-line mPDAC (NCT03214250) indicated that high levels of tumor NR4A1, 2, and 3 expression portend significantly worse clinical outcomes in patients treated with this IO/chemotherapy regimen, highlighting a potential opportunity for quemli to provide clinical benefit by reversing adenosine-mediated immunosuppression in mPDAC. Conclusion:Quemli + G/nP treatment was associated with a reduction in tumor expression levels of adenosine-regulated NR4A gene family and was accompanied by an increase in tumor inflammation. Given the adenosine-modulating MoA, patients with mPDACs expressing high levels of NR4A in baseline tumor tissue, which portended poor prognosis in 1L mPDACs treated with G/np-containing regimen from the PRINCE study, may benefit from treatment with quemli. A phase 3 trial (PRISM-1) of G/nP +/- quemli in the 1L mPDAC setting is being planned. Citation Format: Ji Yun Kim, Ning Wang, Ben Weeder, Enzo Stagnaro, Karim Mrouj, Jose Aquino, Xian He, Eileen M O’Reilly, Shubham Pant, Gulam A Manji, Zev A Wainberg, Joon Rhee, Brandon Beagle, Daniel DiRenzo, Matthew J Walters, Angelo Kaplan, Sean Cho, Omar Kabbarah. Quemliclustat (CD73 Inhibitor) reduces adenosine-regulated NR4A gene expression and increases mPDAC inflammation in patients from the ARC-8 trial [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr C007.