Abstract 5965
Background
The androgen receptor (AR) pathway drives most metastatic castration-resistant prostate cancers (mCRPC) even in late stages of the disease. Anti-androgen resistance mechanisms include AR gene amplification, C-terminal ligand-binding domain (LBD) mutations and expression of constitutively-active truncated AR splice variants lacking the LBD (eg. AR-V7). Selective inhibition of the N-terminal domain (NTD) of the AR can inhibit its’ transcriptional activity even in the presence of LBD-driven resistance. A Phase I clinical trial of the first-generation AR NTD inhibitor, EPI-506, demonstrated minor PSA declines in mCRPC patients. EPI-7386 is a more potent and stable NTD inhibitor (Anitens) that is advancing to clinical trials. The compounds’ characteristics and the initial clinical study plans including potential biomarkers will be reviewed.
Methods
Chemical structure activity relationships were developed to increase molecule potency using a wide variety of CRPC models in vivo and in vitro. Similarly, the stability and selectivity of the molecule were characterized with screening and functional assays. Biomarkers were also explored.
Results
EPI-7386 demonstrated a 20 fold improvement in AR-driven cellular potency compared to EPI-002, while being highly stable in human and animal hepatocytes. In vitro proliferation assays demonstrated on-target activity across a panel of prostante cancer cell lines, with activity in AR-V7-driven cellular models. EPI-7386 was able to control tumor growth and induce tumor regressions in several CRPC xenografts, including enzalutamide resistant models. In addition, the combination of enzalutamide with EPI-7386 demonstrated a more robust and more homogeneuous antitumor response. Pharmacodynamic markers specific to NTD inhibitors will be presented.
Conclusions
The next generation aniten compound EPI-7386 is more active and more metabolically stable than EPI-002. It demonstrated potential as single agent in overcoming anti-androgen clinical resistance as well as in combination therapy in earlier stages of the disease. The clinical strategy supporting the development of this new generation of Aniten will be discussed.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
ESSA Pharmaceuticals.
Funding
ESSA Pharmaceuticals.
Disclosure
R. Le Moigne: Full / Part-time employment: ESSA pharma. C.A. Banuelos: Shareholder / Stockholder / Stock options: ESSA pharma. N.R. Mawji: Shareholder / Stockholder / Stock options: ESSA pharma. R.J. Andersen: Research grant / Funding (institution), Shareholder / Stockholder / Stock options, Officer / Board of Directors: ESSA pharma. A. Cesano: Advisory / Consultancy: ESSA pharma; Full / Part-time employment: Nanostring. M.D. Sadar: Speaker Bureau / Expert testimony, Leadership role, Research grant / Funding (institution), Travel / Accommodation / Expenses, Shareholder / Stockholder / Stock options, Officer / Board of Directors: ESSA pharma; Speaker Bureau / Expert testimony: Pfizer. H. Zhou: Shareholder / Stockholder / Stock options, Full / Part-time employment: ESSA pharma. P. Virsik: Shareholder / Stockholder / Stock options, Full / Part-time employment: ESSA pharma. All other authors have declared no conflicts of interest.
Resources from the same session
1271 - A large scale prospective concordance study of oncogene driver detection between plasma- and tissue-based NGS analysis in advanced non-small cell lung cancer (NSCLC).
Presenter: Ryo Itotani
Session: Poster Display session 1
Resources:
Abstract
1132 - Biomarker status as a mediator of age-related overall survival (OS) in advanced non-small cell lung cancer (aNSCLC)
Presenter: Aaron Cohen
Session: Poster Display session 1
Resources:
Abstract
1502 - An exploratory analysis of on-treatment ctDNA measurement as a potential surrogate for overall survival for atezolizumab benefit in the OAK Study
Presenter: David Gandara
Session: Poster Display session 1
Resources:
Abstract
3912 - Disease monitoring of EGFR mutation-positive NSCLC patients via circulating tumor DNA
Presenter: Wei Fang Hsu
Session: Poster Display session 1
Resources:
Abstract
3856 - Incidence of T790M in NSCLC patients progressed to gefitinib, erlotinib, and afatinib: a study on circulating tumor DNA
Presenter: Romano Danesi
Session: Poster Display session 1
Resources:
Abstract
1330 - Folate receptor-positive circulating tumor cells as a predictive biomarker for the efficacy of first-line pemetrexed-based therapy in patients with non-squamous non-small cell lung cancer
Presenter: Xiaoxia Chen
Session: Poster Display session 1
Resources:
Abstract
3512 - Carcinoembryonic Antigen of Cerebrospinal Fluid Predict Prognosis of Leptomeningeal Metastasis from Non-Small Cell Lung Cancer
Presenter: Junjie Zhen
Session: Poster Display session 1
Resources:
Abstract
3852 - Liquid biopsy in clinical pratice of Non-Small-Cell-Lung Cancer (NSCLC): a multi-institutional experience
Presenter: Giovanna De Maglio
Session: Poster Display session 1
Resources:
Abstract
1205 - A Phase III Study Comparing SB8, a Proposed Bevacizumab Biosimilar, and Reference Bevacizumab in Patients with Metastatic or Recurrent Non-squamous NSCLC
Presenter: Martin Reck
Session: Poster Display session 1
Resources:
Abstract
2432 - Retrospective comparative study of the efficacy and safety in docetaxel and ramucirumab combination chemotherapy with or without previous immune checkpoint inhibitor treatment.
Presenter: Daijiro Harada
Session: Poster Display session 1
Resources:
Abstract