DR LOVE: Oliver, if radium-223 is approved, what do you think the conditions of approval or indications are going to be, and how do you see it being integrated into the increasingly complex algorithm for prostate cancer? I’m going to ask the group about that.
DR SARTOR: Yes. Great question. And, of course, I don’t know how the FDA will write the package insert. But I think we’ve explored this a little bit on the hormonal front — that the biology of the disease is not a pre- and postdocetaxel space. It’s really about bone metastatic, castrate-resistant prostate cancer. And I would hope that the FDA would allow this to have a relatively broad label, even if it were similar to what was used in the ALSYMPCA trial for the inclusion criteria, either after docetaxel or unfit for docetaxel or refusing docetaxel. But what that really does is it sort of opens up the space a little bit.
And I regard this as probably being used in integration with other therapies, particularly the hormonal therapies and, potentially, the immunotherapies as well.
DR LOVE: In combination?
DR SARTOR: Oh, absolutely. In the ALSYMPCA trial it was best supportive care, which basically mean a variety of hormones could be utilized. I regard something like enzalutamide/radium as being ideal. Abiraterone/prednisone/radium ideal. Sipuleucel-T/radium, very provocative. There are a variety of ways that you can have positive interaction. And I think Matthew’s point was well taken. If you want to be able to benefit patients by disease control, and this idea of sequential therapy is where we are today, I’m looking at the future being in combination, particularly since we have drugs with different mechanisms of action.
DR LOVE: And how much or how many bone mets would it take to get you wanting to use this?
DR SARTOR: Really good question. And I think with a higher burden of disease you’d probably have a little better indication. If you just have a single spot, then I’m not sure that this is what you want to do. On the other hand, the vast majority of the patients in the trial had more than 6 bone mets. That becomes very reasonable.
DR LOVE: So the FDA sometimes moves faster than you think. They’ve certainly been moving pretty fast recently, seems like. I’m just kind of curious, Tom. Again, this agent is approved. How are you thinking you might use it?
DR BEER: I think Oliver was outlining some very interesting ideas for future research. I think with the data that we have in hand today I’d be focusing on the types of patients that were studied, patients with bone metastases who either have been through chemotherapy or are not appropriate candidates for chemotherapy. We do have to remember this is a bone-targeted drug. So for those patients who have significant issues with visceral metastases, this would not be a good choice.
For me, the question really is, where does it fit into the sequence of — maybe oversimplify things a little bit — hormonal therapy, chemotherapy, other agents? And I think at the beginning it’s going to be hormonal therapy, chemotherapy, radium-223 chloride until I learn more about it. I would be interested in moving it earlier. I’ll be looking for more data to help me do that.
DR LOVE: How would you feel about using it in combination with, for example, hormonal therapy?
DR BEER: I think it hasn’t been prospectively studied in that way. Additional hormonal agents were allowed on the trial, but they were not systematically and prospectively tested with or without and so forth. So I think it’s feasible. I think that what we’ve learned from the study is that it’s safe and feasible to do so. Which combinations and how to do them we don’t really know a lot about. So I think I’d like to see those studies move forward.