BI 836845 Plus Enzalutamide in Castrate Resistant Prostate Cancer (CRPC)

The overall aim of the trial is to investigate the safety and anti-tumour activity of an experimental drug BI 836845 taken together with the prostate cancer drug, enzalutamide, compared to enzalutamide given alone, in castrate resistant prostate cancer (CRPC) patients that have previously been treated and failed on docetaxel and abiraterone treatments. Initially, a tolerability and safety phase (phase Ib escalation) will be performed to confirm the maximum tolerated dose (MTD), or recommended doses of both BI 836845 and enzalutamide that can be taken together.

Once the MTD, or recommended doses, have been determined an expansion cohort will also be explored (phase Ib expansion) in CRPC patients already taking enzalutamide and that are failing on this treatment as shown by a rise in prostate serum antigen (PSA) levels. Patients may, or may not, have received prior docetaxel in any setting, but must not have received abiraterone. Patients in this cohort will receive the MTD, or recommended doses, of BI 836845 and enzalutamide determined in the phase Ib escalation phase.

The randomised trial (phase II) will be an open label, parallel group study design in a 1:1 ratio to which patients will receive either BI 836845 plus enzalutamide (Arm A) at the MTD/recommended doses, or enzalutamide alone (Arm B).

In all parts of the trial safety, anti-tumour activity will be assessed, in addition to circulating tumour cells (CTC), prostate serum antigen (PSA) response and progression, pain score by Brief Pain Inventory - Short Form (BPI-SF), skeletal related events, pharmacokinetics (PK), pharmacogenomics (PGx) and biomarkers in blood and tumour tissue.