GU Cancers 2019 | News from the STREAM trial: salvage radiation with enzalutamide and ADT

Right so, where is the best setting for these potent AR therapies? Is it to delay metastasis and improve survival, or is it to actually increase the cure rate? And I actually believe men are more interested in being cured than palliated. And so, the goal of Stream is to use it potent AR inhibitor as a radio sensitizer, to improve the salvagability of men whose PSAs are going up after surgery.

So this PSA rise hormone sensitive non metastatic disease that’s relapsed after radical prostatectomy. Many men do not have success with radiation alone. We know that hormone therapy does add to the survival of radiation in the salvage radiation setting, and our clinical trial called Stream tested whether enzalutamide at a very potent AR inhibitor could further improve their outcomes, improve their cure rates.

And cure is a difficult word. You need about 10, 15 years to really know the answer to that. Stream is a single arm phase II study. It’s a relatively small number of patients, but it is a multicenter study using a historic benchmark from previous studies showing about 50% of men with radiation alone will relapse by two to three years. Our data suggests that enzalutamide will bump that to 65% success.

So, an incremental advance, we’re still not there. We’re not curing 100% of men in this setting, but showing that you can improve that efficacy in this setting is really important. And we did so with great safety, so enzalutamide as a pretty well established safety profile in the stream regimen of six months ADT, six months ends a salvage radiation, men got through it really well.