Radiation Safety and the Integration of Pluvicto™ (177Lu-PSMA-617) in Treatment of mCRPC- Kendra Harris

April 7, 2022

Chair of Radiation Oncology at Tulane University Cancer Center, Kendra Harris joins Phillip Koo to discuss radiation safety in regards to the recent approval of Pluvicto™, the first targeted radioligand therapy for the treatment of metastatic castration-resistant prostate cancer.

Biographies:

Kendra Harris, MD, MSc, Chair, Radiation Oncology, Associate Professor, Tulane Cancer Center, Tulane University School of Medicine

Phillip J. Koo, MD, FACS Division Chief of Diagnostic Imaging at the Banner MD Anderson Cancer Center in Arizona.


Read the Full Video Transcript

Phillip J. Koo: We're here today with Dr. Kendra Harris, Chair of Radiation Oncology at Tulane University Cancer Center. Obviously, everyone's very excited about the approval of Pluvicto. With that excitement comes a lot of questions about radiation safety. Radiation safety for employees and staff and obviously for patients, as well. 

Help us play Myth Busters here and walk us through that we need to be thinking about. 

Kendra Harris: Yeah. So one of the things I was most excited about when I saw the approval was the package insert for this. Contains an enormous amount of very specific information that should be thought of like a road map for new practices or institutions that want to offer this therapeutic. There is a very careful description of multiple approaches that a provider could use in terms of administration. There's also a significant amount of information related to the risk of exposure that can be put right into your institutional and state radiation safety applications. 

And then finally, there are precautions that are very specific that can be given to patients and their families with respect to how patients who have received this therapeutic should behave. Those precautions include things like obviously following the ALARA, as low as reasonably achievable, principles after being dosed. Things like emptying the bladder frequently and precautions related to the urine itself which is really how much of the, or essentially all of the unbound radioisotope is cleared from the body. There are additional specific instructions related to how close a person can be to other persons, approaches for clothing management, and the special precautions that come with protecting pregnant women and children from really receiving any dose. 

And now that we have those specific instructions as opposed to each institutional standard operating procedure, I think it provides a gold standard that anyone, anywhere, can use, both to get the approval needed to administer the drug but then importantly, to provide the counseling to patients because this is often viewed with trepidation about gosh, am I putting my loved ones at risk? And it's nice to have that really, FDA stamp of these are the guidelines that we can use. 

There is also really good information about the need to adhere to joint commission standards for sterile administration. So those two together help provide all the instructions that are needed to anyone who would like to add this to their armamentarium. 

Phillip J. Koo: Yeah. I think that's wonderful and I think it really will change how we handle radiation safety. Because even from my experience, it's amazing how much varying information is out there, how various practices across ... Within a state and even between states, just are different. 

Kendra Harris:  And we have the old school radiation safety guidance from the AAPM that helped us understand how to think about, say, radioactive iodine. But in an era of molecularly targeted radioisotopes, how do you think about that dose of entry? You have this gap where that dosimetry is going to depend on the amount of expression, the strength of the binding, the volume of disease, and the location of that disease within an individual person's body. And how do we close the gap between acknowledging that that is going to be different for everyone and meeting the regulatory requirements of all the radiation safety committees who just want what is the best estimate of an organ tolerance dose? And I would love to see new national guidelines because these therapeutics are here to stay. There's expansion into other disease sites, new radial ligans that are being conjugated, and really providing high-level guidance will help protect both individual physicians and our patients and provide guidance and across centers with a varying level of experience with this type of therapeutic. 

Phillip J. Koo: You know, it's interesting you brought up dosimetry. I think there's a lot of opportunity there for radiation safety, keeping patients safe but also maximizing treatment and efficacy which is a whole other discussion. But going back to radiation safety, you and the team here at Tulane have had a lot of experience treating patients with this, especially through the VISION Trial. Just overall, how have patients taken to the instructions and what should people out there expect from reactions from patients moving forward? 

Kendra Harris: Yeah. So I would actually divide that into two pieces. So one piece is giving a lot of injections in a clinic full of staff. And having education sessions to help the nurses and other persons in the clinic understand what the safety precautions are was really important. I think by now, I've given almost 300 injections just myself. And so coming up with a protocol that helps everybody feel comfortable if you're going to be doing a high volume of injections is important and that's why we're in this room, actually. So we've been using the CT simulation room for these injections. We're building a shielded room that we'll use in clinic. 

With respect to patients and their families, so very important that you are able to provide written instructions that have time limits. And that's, as I mentioned, what I love about the package insert. You can give those to patients in advance of the first dose so they and their loved ones can review them. But then you have to be available for questions. What does it mean? Hey, I've got a wedding I want to go to eight days after I'm dosed. None of these precautions apply but I'm really worried. How do I think about that? A big part of why we want patients to be able to get this therapy close to home is that we had patients flying into town to get this therapy. And how to think about what the precautions ought to be moving through an airport or sitting next to somebody on a plane. We came up with a card that we give everybody that delineates the dose, what they received, and then provides my cell phone numbers so that if they get stopped. And then just making sure that all the team members are well-informed about what is the truth so far as we know about the safety guidelines so that patients receive the same message from all members of the team. 

Generally, this therapy, in my experience is very well-tolerated. In 300 injections, we haven't had a single injection reaction. No one discontinued the therapy due to toxicity that they could feel. The hematologic toxicity is a thing that has caused a couple of patients to not be able to finish their full series. But this is very well-tolerated and in fact, our practice for patients receiving this therapy in the era of it being the standard of care, is really to give the injection, observe for 15 minutes, take an additional set of vital signs, and have them leave the clinic. 

Phillip J. Koo: That's great. Lots of messages to take home here but the one take-home message that I think everyone needs to heed is go read the package insert. It's your friend. Don't throw it away. So good. Thank you very much for sharing your expertise. 

Kendra Harris: Yes, indeed. 

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