Continuing their segment on radioligand therapy in metastatic castration-resistant prostate cancer, panelists highlight data behind use of radium-223.
Rana McKay, MD:It’s very interesting to hear the discussion about radium. Where do you see that falling in the lutetium–PSMA [prostate-specific membrane antigen] world? We saw data from the RALU study, which looked at radium prior to lutetium. It was a retrospective analysis of patients who had received radium prior to lutetium, demonstrating that there was no compromise in AE [adverse effect] profiles after radium exposure. They broke it down by less than 6 months and greater than 6 months. How do you see radium playing into this space?
Ulka Vaishampayan MD:The VISION trial allowed patients with prior radium as long as it was 6 months or more from their previous radium. There is experience, at least of PSMA-lutetium after radium, and those patients didn’t seem to have excess adverse events or no change. Although if Pluvicto is moving to the earlier setting, which is likely based on the randomized trials, then radium will go to the castration-resistant bone-only disease after lutetium. That is where it will still be used in a limited indication.
Sumit K. Subudhi, MD, PhD:I agree. It’s nice to have another option as opposed to what we were talking about: 3 PARP inhibitors, 3 second-generation hormones. This is a different mechanism of action, so it’s good.
Arash Rezazadeh Kalebasty, MD:It’s interesting that they’re looking at combinations like PARP inhibitor and radium. To see how to make radium work better, we have the agent. Can we push it to do a little better?
Scott Tagawa, MD, MS, FACP:Or the opposite. There are 2 ongoing phase 3 trials with radium internal combination. I’m not sure about piece 3 because it’s a shifting ARPI landscape. We don’t have that much, but that will be interesting. But DORA could still be relevant. We need safety data on the docetaxel-radium combination following lutetium. We know that either is OK alone, but what about the combination? It could make radium even more relevant—you don’t have to worry about it being bone only or predominant because you have the docetaxel. For the audience, if you aren’t aware of that, enroll. There’s a randomized phase 2 led by Mike Morris that [showed that] docetaxel alone was worse than docetaxel plus radium in terms of progression and tolerability. That was no secret. It was a lower dose of docetaxel, and the radium was every 6 weeks to match up. It may be that there’s a survival benefit with less toxicity. That will be interesting to see.
Transcript edited for clarity.