Abstract 4466: New biomarkers to optimize preclinical development of the PDI inhibitor XCE853

Protein disulfide isomerase (PDI) is a chaperone protein that regulates oxidative protein folding as well as cell viability. Increased PDI levels have been documented in a variety of human cancers, including ovarian, prostate, and lung cancers. Inhibition of PDI activity leads to apoptosis in cancer, suggesting that PDI is a promising druggable target. XCE853 was originally identified within a family of synthetic compounds displaying a preferential antiproliferative activity on drug-resistant human cancer cells (Gutmann et al, AACR annual meeting, 2013). XCE853 inhibits in vitro recombinant PDI activity and blocks in vitro proliferation of human tumor cells with IC50s in the nanomolar range through an irreversible cytolysis (Prevost et al, AACR annual meeting, 2014). By contrast, XCE853 has no or limited antiproliferative activity on several human non-tumoral immortalized cells (MCF10, RPE1 or RWPE1) even at high concentrations. The ex-vivo approach using fresh human hepatocellular carcinoma explants incubated 48h with XCE853 (100nM) has shown the decrease of the proliferation (KI-67 labeling) with an apoptosis induction (Caspase-3 labeling). In addition, XCE853 which displayed an excellent oral bioavailability in mouse blocks growth of human ovarian cancer using the in vivo OVCAR-3 xenograft model leading to complete tumor growth arrest even after the cessation of treatment. To optimize the preclinical and clinical development, we are now characterizing new biomarkers to 1) stratify the tumors which are sensitive and non-sensitive to XCE853 and to 2) identify the optimal dose regimen. Altogether, these data support further efforts on XCE853 preclinical studies to prepare the Phase-I clinical study entry. Citation Format: Gregoire Pierre Prevost, Marine Garrido, Shili Xu, Celine Lefebvre, Anne Chauchereau, Denis Carniato, Jean Francois Briand, Mathieu Gutmann, Maria Serova, Annemilai Tijeras-Raballand, Armand De Grammont, Eric Raymond, Christian Gespach, Michele Sabbah, Nouri Neamati, Marc-Henry Pitty, Paul Foster. New biomarkers to optimize preclinical development of the PDI inhibitor XCE853. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4466. doi:10.1158/1538-7445.AM2015-4466