Selecting Among Novel Imaging Options in Metastatic CRPC

Transcript:

Alicia Morgans, MD, MPH: To that point, speaking of technetium, there are other forms of imaging that we certainly use, and there are other PET [positron emission tomography] tracers that we’ve used. Evan, what are your thoughts on the array of PET tracers that we have available? Are we still thinking about using them, and how do we think about them in terms of PSMA [prostate-specific membrane antigen] tracers? There are actually multiple PSMA tracers as well. How do you sort through all of that?

Evan Y. Yu, MD: You’re right. We have a lot of different tracers that are available, but most of which aren’t commonly used. I’ll say that fluciclovine is something that can be used still for detection of disease in a PSA [prostate-specific antigen]-recurrent situation. But I think we know from the literature that PSMA PET is probably more sensitive now, so there will probably be less and less use of fluciclovine. In the older days, we were using choline and acetate to measure lipid metabolism, and those are sensitive modalities as well but not as sensitive as PSMA PET either. There may be unique situations for certain therapeutics where they might be a reasonable pharmacodynamic biomarker. Fluoride has been used, which is very sensitive for bone metastases detection, but again, with the exception of rare circumstances, it probably won’t be very commonly used.

What I will say is that we need to be careful with PSMA PET imaging and not extrapolate its use to every single situation. I’ll give one example that incorporates FDG [fluorodeoxyglucose]. When you take patients who maybe have been through a few lines of therapy for metastatic castration-resistant prostate cancer, it’s not clear to me that PSMA PET will be a good imaging biomarker of treatment response for progression. We need to be careful to not insert it into every single situation. It might be good for identification of who should receive a PSMA-targeted therapy. But for that sort of treatment response, especially for later stages of disease, especially for disease that can be transforming, or aggressive variants, neuroendocrine disease, I think FDG might be a better biomarker. So, FDG PET may actually, somewhere down the road, have an increasing role for this disease. And it can be obtained, 3D FDG PET scans for metastatic prostate cancer, for subsequent treatment strategy. It can be done and paid for by the payers.

Alicia Morgans, MD, MPH: That’s very important to know. Thank you for sharing that and for walking us through the different approaches. It can get confusing, especially as we’re trying to sort through all the different tracers to understand, are we trying to identify, are we trying to monitor progression, and where are we in the disease setting. Thank you for that.

Transcript edited for clarity.