Tokai Pharmaceuticals has started its Phase III clinical trial (ARMOR3-SV) of galeterone in patients with AR-V7 positive metastatic castration-resistant prostate cancer (mCRPC).
The trial is designed for mCRPC patients whose tumours express the AR-V7 splice variant, which is a truncated form of the androgen receptor (AR) that has been associated with non-responsiveness to commonly-used oral therapies for mCRPC.
The company also noted that the components of the AR-V7 clinical trial assay have been finalised by its collaborator, Qiagen, and that global deployment of the assay is now underway.
Tokai president and chief executive officer Jodie Morrison said: "ARMOR3-SV represents an important step forward in bringing precision medicine to patients with prostate cancer, and we are pleased with the progress made by our valued collaborator Qiagen in readying the AR-V7 clinical assay for global implementation.
"With worldwide commercial rights to galeterone, our pivotal clinical trial on track to read out by the end of 2016, and a strong financial position, Tokai is well positioned to realise its mission of bringing new therapeutic treatment options to patients with prostate cancer."
The Phase III ARMOR3-SV trial is designed to compare galeterone to Xtandi (enzalutamide) in 148 mCRPC treatment-naïve patients whose prostate tumours express the AR-V7 splice variant.
The company said that these truncated ARs are missing the C-terminal end of the AR that contains the ligand-binding domain, which is known as C-terminal loss.
The trial will employ a precision medicine approach for selection of patients with the AR-V7 splice variant by using an AR-V7 clinical trial assay optimised by Qiagen for global use.
The primary endpoint of the trial is radiographic progression-free survival (PFS) assessed by blinded independent central review.
The design of the Phase III ARMOR3-SV trial is aligned with feedback obtained from the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA).
The trial has been started at more than 15 sites in the US, with site initiations in Canada and the UK expected later this month, while additional study centres across North America, Western Europe and Australia are expected to join in the coming months.
Additionally, with recent finalisation of the components of the AR-V7 clinical trial assay, technology transfer activities and training of the global central laboratories are underway, and screening of eligible patients for the splice variant is expected to begin next month.
Top-line data from the Phase III ARMOR3-SV trial is expected to be available by the end of 2016.