A prostate cancer expert considers clinical implications from the phase 3 VISION study, including the potential role of 177Lu-PSMA-617 therapy for patients with mCRPC.
Scott T. Tagawa, MD, FACP: I believe that the VISION results, particularly in the context of all of the other studies—particular prospective studies that might’ve been single arm, plus the TheraP study, which was a patient population highly selected by imaging head-to-head against cabazitaxel—lutetium-PSMA [prostate-specific membrane antigen]-617 improved outcomes. In that context for patients with metastatic castration-resistant prostate cancer [CRPC], arguably for at least those who have some PSMA positivity, this represents a new standard of care.
That new standard of care isn’t yet available, at least not in the United States, outside of clinical trials. But I believe that this is coming. I’m guessing sometime in 2022, this is going to be an agent that will be implemented across the board. Centers will learn to have to use PSMA-PET [positron emission tomography] imaging as well as handle radionuclide therapy. Because different types of PET have been incorporated across oncology, including prostate cancer, and PSMA-PET is starting to come across the country, particularly for those with high-risk localized disease, or even more so with biochemically recurrent disease, this will be more embedded into what our practices have. Most centers will have access to this. This is certainly not going to be all.
There are some logistical issues. This is for treatment, too, as these are all radionuclides. They all have half-lives. For instance, the half-life of F-18 [fluorine-18] is approximately 110 minutes. We can make a lot and ship it, but we can’t have it sitting on a shelf and use it in a couple days. There are some practicalities. That’s also true of the therapy, with lutetium-177 having a half-life of approximately a week. As long as there are adequate safety protocols in place with a radiation safety officer, we can receive it one day and use it the next day or the following day. These are generally stable for 4 days. We have to calculate that a seventh of it is being decayed each day, so if we’re not going to use it the day of receipt, we need to receive more than we intend to use.
There are a number of practicalities there. One additional practicality is that even though this has been at least somewhat incorporated into the recent NCCN [National Comprehensive Cancer Network] guidelines, the FDA-approved labels for PSMA-PET at this point don’t include treatment selection for metastatic CRPC. I suspect that it’s going to be part of the label for lutetium-PSMA-617. Novartis may have their own companion diagnostic. If there’s a bundled type of scenario where there’s a PSMA-PET built into the cost of lutetium-PSMA-617, and it’s paid for even if it’s negative, that’s one way until we can get more ubiquitous use of PSMA-PET. That will be a logistical issue at the beginning.
Transcript Edited for Clarity