PQ1565

**PQ1565** is a second-generation, highly potent small molecule inhibitor of glutaminyl cyclases (QC/QPCT and isoQC/QPCTL), developed by Vivoryon Therapeutics (formerly Probiodrug) primarily for oncology indications. It demonstrates superior potency, stability, bioavailability, and systemic exposure compared to first-generation inhibitors like PQ912, with favorable in vivo toxicology profiles in rodents and non-rodents, and efficacy in cellular cancer models and in vivo inflammatory models. By blocking QC and isoQC, PQ1565 prevents the formation of neurotoxic pyroglutamylated peptides and modulates immune checkpoints such as CD47-SIRPα, offering potential in cancers driven by inflammation and immune dysregulation.[1][3]