PSMA Imaging: Radiopharmaceutical-Based Therapeutics

In this final part of GU Oncology Now’s Round the Wire series on PSMA Imaging, moderator Dr. Neeraj Agarwal, Dr. Jeremie Calais, and Dr. Jonathan D. Tward wrap up the series by discussing the emergence of radiopharmaceutical-based therapeutics in the setting of prostate cancer.

 

Dr. Agarwal:

Dr. Calais Jeremie, any final takeaway on how radiopharmaceuticals-based therapeutics are emerging, how they’re going to be used in the treatment of our patients with local asset advanced prostate cancer.

Dr. Calais:

I think the positive results of the vision trials were a huge and milestone for the whole radiopharmaceutical field, but that’s just the first step. There is much more work to do in terms of patient selection, individualized dosimetry, new targets using new radionuclide to go towards other disease. So I think that’s just one of the first trials in such a deep population, but I would expect, and I’m expecting, many more new approaches using similar radiopharmaceuticals in the next decade for many other applications.

Dr. Agarwal:

Like thorium, actinium, would you have any comment on them?

Dr. Calais:

Indeed, you can change the radionuclide that we use to not deliver beta and deliver alpha. That’s one thing you can do; you can change the target. There are multiple other very relevant and interesting targets with also maybe even better therapeutic index with lower expression in normal organs. That’s another thing you can do. You can play with the amount of how much drugs you administer, the time interval between the cycles, how much cycles you can give, what is the best stage to administer it, how do you monitor and select and use imaging to refine the use? I think we are all at the beginning now, but all these questions I hope will be answered the next year, which will lead to an even better outcome of using such radiopharmaceuticals.

Dr. Agarwal:

Thank you very much. That’s fantastic. Dr. Tward, how do you think radiopharmaceutical-based therapeutics are going to change the landscape in the setting of localized prostate cancer?

Dr. Tward:

Needless to say, there’s going to be a high degree of an enthusiasm of testing this in earlier and earlier stages. The general trend in, I will say, high-risk localized prostate cancer or node-positive is sort of therapeutic escalation. We’re looking at androgen receptor inhibitors with radiation. We’re looking at other combinations, and it’s just a natural progression to take these radiopharmaceuticals and test them in these settings. Tumors are a very complex microenvironment and one thing we learned on the VISION Trial, which again was a very heavily pretreated advanced population. There were still about 13% of people that screening didn’t meet criteria to get the drug, because they had lesions maybe that weren’t PSMA avid or there was perhaps some kind of heterogeneity there. So, I still think there’s going to be an important role for localized therapies along with these agents, and that’s how I see the future. One other thing I wanted to comment on is actually access to the therapy. So this is, I believe, going to be a very popular treatment, one that many people are going to want to rapidly adopt across the country.

And it’s my understanding that there might be some challenges with access to nuclear medicine departments around the country, and that might be where radiation oncology facilities can also help. So in both nuclear medicine departments as well as radiation oncology departments are qualified to deliver unsealed sources like this, and so it’ll be interesting to see how access issues do play out with this important new therapy and just sort of touching on maybe one last element, which is the multidisciplinary care team. I agree it’s absolutely critical to have multidisciplinary care teams who know how to care for these patients because with new radiopharmaceuticals come new side effect profiles and, and new ways of having to address those and assess for them and radiation oncologists, of course as well as nuclear medicine doctors as part of their training. This is an important part of their training on how you evaluate and mitigate those kinds of things.

Dr. Agarwal:

Thank you. So, I will summarize for the sake of our audience what we learned from Dr. Tagawa today about the data behind the upcoming approval of lutetium PSMA treatment and how it may move or how it has already moved to upfront setting in the context of metastatic castration-sensitive prostate cancer. We learned from Dr. Calais how various type of radiopharmaceuticals are going to be emerging and how they are going to be changing the way we treat patients with prostate cancer, and from Dr. Tward, who sees definitely a role of these radiopharmaceuticals in the management of localized prostate cancer, maybe localized high-risk prostate cancer. I think we can summarize by saying that this is an unprecedented time as far as treatment of metastatic or localized prostate cancer is concerned. We never had so many options available for our patients. And future is even more exciting as far as treatment of our patients with prostate cancer is concerned. With that, I’d like to thank you for listening and thank you to the panel members for sharing their wisdom with us. Thank you.