The Selective WEE1 Inhibitor Azenosertib Shows Synergistic Antitumor Activity with KRAS G12C Inhibitors in Preclinical Models

Kirsten rat sarcoma (KRAS) is a potent oncogenic driver that results in the downstream hyperactivation of MAPK signaling while simultaneously increasing replication stress (RS) and accumulation of DNA damage. KRASG12C mutations are common and targetable alterations. Therapeutic inhibition of KRASG12C and eventual resistance to these inhibitors are also known to drive RS and DNA damage through adaptive mechanisms that maintain addiction to high MAPK signaling. High levels of RS result in a stronger reliance on cell-cycle checkpoints, thereby introducing a vulnerability to inhibition of cell-cycle checkpoint regulators such as the WEE1 kinase. This provides a rationale for combining azenosertib, a novel, selective, and orally bioavailable WEE1 inhibitor, with KRASG12C inhibitors. An in vitro combination of azenosertib with multiple KRASG12C inhibitors demonstrated synergistic cell growth inhibition across a panel of KRASG12C cell lines in both 2D and 3D assays. In vivo studies demonstrated that azenosertib exhibited significant monotherapy activity as well as synergistic tumor growth inhibition (TGI) when combined with KRASG12C inhibitors, including tumor regression in cell-derived xenograft models of non–small cell lung cancer, colorectal cancer, and pancreatic ductal adenocarcinoma. Importantly, KRASG12C inhibitor–resistant cell-derived xenograft and patient-derived xenograft models demonstrated synergistic TGI in combination arms. Finally, analysis of biomarkers from in vitro and in vivo tumor samples displayed increases in protein markers of RS, DNA damage, and apoptosis after combination treatment. Taken together, our results suggest that the combination of azenosertib with KRASG12C inhibitors enhances TGI over single-agent therapy and may be an effective treatment strategy for patients with KRASG12C tumors. SIGNIFICANCE: Resistance to KRASG12C inhibitors is a growing clinical concern. The synergistic interaction observed between azenosertib and multiple KRASG12C inhibitors could result in deeper and more durable responses.