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
1269 - One-year follow-up results of eribulin for soft-tissue sarcoma including rare subtypes in a real-world observational study in Japan
Presenter: Shunji Takahashi
Session: Poster Display session 1
Resources:
Abstract
2868 - Prevalence of chemotherapy use and its impact on overall survival in patients with bone- and soft tissue sarcomas -A population-based analysis of 3746 patients
Presenter: Herbert Loong
Session: Poster Display session 1
Resources:
Abstract
3042 - Clinical course and therapeutic management of classical and endemic Kaposi’s Sarcoma (C/E KS)
Presenter: Lina Benajiba
Session: Poster Display session 1
Resources:
Abstract
3141 - The final outcomes of study on combined therapy of adult patients with localized synovial sarcoma
Presenter: Katarzyna Kozak
Session: Poster Display session 1
Resources:
Abstract
5449 - Real-world Outcomes of Patients with Locally Advanced or Metastatic Epithelioid Sarcoma
Presenter: Mrinal Gounder
Session: Poster Display session 1
Resources:
Abstract
4465 - SAKK 57/16 Nab-Paclitaxel And Gemcitabine in soft tissue sarcoma (NAPAGE): results from the phase I part of a phase I/II trial
Presenter: Antonia Digklia
Session: Poster Display session 1
Resources:
Abstract
5013 - Outcome of 98 patients with epithelioid sarcoma treated in curative intent: a retrospective study from the French Sarcoma Group (GSF-GETO)
Presenter: Maud Pedrono
Session: Poster Display session 1
Resources:
Abstract
5614 - Comparison of filgrastim and pegfilgrastim prophylaxis in sarcoma patients receiving highly myelosuppressive chemotherapy.
Presenter: Paolo Tarantino
Session: Poster Display session 1
Resources:
Abstract
1033 - Access to clinical trials for soft tissue sarcoma patients in Western and Eastern Europe
Presenter: Vasilii Ostafiichuk
Session: Poster Display session 1
Resources:
Abstract
4094 - Treatment outcomes for adult patients with localized osteosarcoma treated with chemotherapy without methotrexate
Presenter: Marília Silva
Session: Poster Display session 1
Resources:
Abstract