Hartland,
The main goals of the Phase 1 trials are to determine the incidence of dose limiting toxicities and adverse events, to measure several pharmacokinetic parameters of the drug, and to perform a dose escalation to determine the maximally tolerated dose (MTD). The MTD was only recently determined. This means that most prior patients and most of the duration of the trial were under treatment conditions using the less than optimal dose. If I understand correctly, they now enter into the expansion phase of the trial in which they now expand the patient population at the optimal dose.
The "bonus" secondary outcome measures of the Phase 1 trials are to evaluate prostate-specific antigen (PSA) response, evaluate radiographic response, evaluate median progression-free survival and evaluate circulating tumor cell (CTC) response rate. The latter metric is only during the dose confirmation/expansion phase. The investigators and members of Resverlogix very likely have seen data for the PSA response, radiographic response and median progression-free survival during the coure of the trials first 6 months. However, they realistically just haven't had enough patients or enough time at the optimal dose to be able to say too much about controlling the cancer.
Regarding the start of the enzalutamide/ZEN-3694 combo trial, my understanding is that determining the MTD in the single-agent trial was what triggered the start of the combo trial. So showing efficacy/controlling the cancer was not a requirement of the single-agent trial in order to start the combo trial.
BDAZ
