Discovery of Cycloalkyl[c]thiophenes as Novel Scaffolds for Hypoxia-Inducible Factor-2α Inhibitors

Hypoxia-inducible factors (HIFs) are heterodimeric transcription factors induced in diverse pathophysiological settings. Inhibition of HIF-2α has become a strategy for cancer treatment since the discovery that small molecules, upon binding into a small cavity of the HIF-2α PAS B domain, can alter its conformation and disturb the activity of the HIF dimer complex. Herein, the design, synthesis, and systematic SAR exploration of cycloalkyl[c]thiophenes as novel HIF-2α inhibitors are described, providing the first chemotype featuring an alkoxy-aryl scaffold. X-ray data confirmed the ability of these inhibitors to induce perturbation of key amino acids by appropriately presenting key pharmacophoric elements in the hydrophobic cavity. Selected compounds showed inhibition of VEGF-A secretion in cancer cells and prevention of Arg1 expression and activity in IL4-stimulated macrophages. Moreover, in vivo target gene modulation was demonstrated with compound 35r. Thus, the disclosed HIF-2α inhibitors represent valuable tools for investigating selective HIF-2α inhibition and its effect on tumor biology.

Optimization of a Screening Hit toward M2912, an Oral Tankyrase Inhibitor with Antitumor Activity in Colorectal Cancer Models

Constitutive activation of the canonical Wnt signaling pathway, in most cases driven by inactivation of the tumor suppressor APC, is a hallmark of colorectal cancer. Tankyrases are druggable key regulators in these malignancies and are considered as attractive targets for therapeutic interventions, although no inhibitor has been progressed to clinical development yet. We continued our efforts to develop tankyrase inhibitors targeting the nicotinamide pocket with suitable drug-like properties for investigating effects of Wnt pathway inhibition on tumor growth. Herein, the identification of a screening hit series and its optimization through scaffold hopping and SAR exploration is described. The systematic assessment delivered M2912, a compound with an optimal balance between excellent TNKS potency, exquisite PARP selectivity, and a predicted human PK compatible with once daily oral dosing. Modulation of cellular Wnt pathway activity and significant tumor growth inhibition was demonstrated with this compound in colorectal xenograft models in vivo.