Abstract PR010: First-in-class TRPV6 inhibitors for the treatment of prostate cancer

Abstract TRPV6, a calcium channel, is an oncochannel that is overexpressed in epithelial cancers including prostate cancer. We have developed a novel series of first-in-class small molecule TRPV6 inhibitors for the treatment of advanced prostate cancer. Our preclinical candidate QED-203 has been shown to inhibit calcium influx at low nM potency in TRPV6 cellular assays (FLIPR, electrophysiology), and has low nM potency in a TRPV6-driven NFAT assay (NFAT luciferase reporter). Inhibition of TRPV6 with our TRPV6 inhibitors or by siRNA knockdown causes changes in genes related to NFAT and WNT signalling, ER stress and the cell cycle (RNAseq and qPCR analysis), and causes cell cycle arrest, decreased proliferation and apoptosis in prostate cancer cells (demonstrated via imaging and FACS analysis). Importantly, QED-203 demonstrates potency in enzalutamide resistant cell lines (in vitro proliferation inhibition) and has superior potency over enzalutamide and darolutamide [androgen receptor targeting agents (ARTA)] in prostate cancer cell lines with clinically relevant AR mutations or the ARV7 splice variant. The ARV7 variant in particular is represented in a significant portion of patients no longer responding to ARTA SoC interventions. QED-203 has high bioavailability with a pharmacokinetic profile amenable to once-a-day oral dosing. QED-203 is well tolerated in rodents and has similar in vivo efficacy (tumour growth and PSA inhibition) to enzalutamide in a castrated LNCaP mouse model of prostate cancer. We have also shown QED-203 target engagement in rodents by demonstrating a change in calcium levels in the urine, and have observed changes in genes consistent with a TRPV6-specific mode of action in xenograft tumours (demonstrated via qPCR). QED-203 targets a novel, non-hormonal mechanism in prostate cancer, and could be used to treat prostate cancer patients who have developed resistance to AR therapies, where there is a large unmet need. Citation Format: Kimberley Beaumont, Rebecca Pouwer, Raphael Rahmani, Matthew McLachlan, Claire Levrier, Rebecca Farrow, Mei Yeh, Therese Johnson, Malika Kumarasiri, Hasanthi Wijesekera, Grant Stuchbury, Terrie-Anne Cock, Andrew Harvey, Gregory Monteith, Brian Dymock. First-in-class TRPV6 inhibitors for the treatment of prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr PR010.