LAUSR

Using the iOTarg genetic screening platform, salt-inducible kinase 3 (SIK3), a serine/threonine kinase of the AMP-activated protein kinase (AMPK) family was recently identified as a novel cell signaling modulator in cancer biology. OMX-0407, an orally available, single-digit nanomolar inhibitor of SIK3 was shown to inhibit tumor growth in a distinct panel of tumor models in vitro as well as in vivo by decreasing downstream pro-survival signaling of SIK3, enhancing caspase-mediated apoptosis and repolarizing the tumor microenvironment by decreasing regulatory T cells. In a comprehensive viability screening, more than 200 murine and human cancer cell lines and patient derived tumor models of different indications were used to identify a distinct subset of cancers highly sensitive towards OMX-0407. Representative for these tumors, OMX-0407 demonstrated dose-dependent anti-tumor efficacy in the renal cell carcinoma model RENCA, the squamous non-small cell lung cancer model (sqNSCLC) KLN205 and the murine colorectal tumor model MC38. With significantly prolonged overall survival of more than 60% tumor growth inhibition in all tumor models, OMX-0407 demonstrated equivalent or superior efficacy compared to anti-PD-1 monotherapy. In addition, OMX-0407 enhances the therapeutic potential of the standard of care chemotherapy in a broad range of human cancer cells and murine tumor models of sqNSCLC. Using comprehensive transcriptomics and proteomics analyses the selective activity profile of OMX-0407 on individual cancer cell lines and PDX models was used to identify and validate a predictive biomarker signature. With this gene signature, 84% of the selected cancer cells lines are correctly classified and would benefit from OMX-0407 therapy. The predictive biomarker will be evaluated in the clinical Phase I trial of OMX-0407 scheduled to start enrollment shortly. In summary, OMX-0407, a first-in-class oral SIK3 inhibitor, demonstrates potent monotherapy efficacy in tumor indications with high unmet medical need equal or superior to anti-PD-1 checkpoint blockade. By screening sensitive and non-sensitive tumor cell lines and PDX models, we identified a response-prediction biomarker signature. In upcoming clinical studies, this predictive biomarker signature will be evaluated for it’s potential to enrich for patients highly responsive to OMX-0407 therapy. Citation Format: Ilona-Petra Maser, Sonja Lacher, Vincent Piras, Barbara Kracher, Kai Zanziger, Murray Yule, Hannes Loferer, Stefan Bissinger. Development of a predictive biomarker signature for the highly potent SIK3 inhibitor OMX-0407 [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 953.