Tanya Dorff, MD, and Elisabeth Heath, MD, FACP, share perspective on the challenges inherent in delivering novel therapy to patients diagnosed with metastatic CRPC.
Tanya Dorff, MD: A big issue I still have, unfortunately, in the California landscape is getting the PSMA [prostate-specific membrane antigen] PET [positron emission tomography] scans. For instance, I ordered one recently, to see if a patient could qualify for lutetium PSMA, but their insurance denied it. They got an MRI [magnetic resonance imaging] of their pelvis because that’s what their insurance would allow, but how is that going to tell me if they qualify for or would benefit from a radiopharmaceutical? It’s maddening. I don’t know how these issues will play out across the country in different insurance marketplaces. With Medicare, we can order a PSMA PET scan, and [usually it will be approved], but with private insurance, there’s a lot of peer-to-peer. I worry about some decisions and practices because it can be so burdensome to fight to get the PET scan and try to [make the determination]: Is this positive enough to qualify? Then [the patient must be sent to the right] center because not everyone has the capability to administer radiopharmaceuticals, so it presents a lot of barriers. Thankfully, at least the therapy trial tells us survival rates are similar whether we’re using cabazi [cabazitaxel] or lutetium-177, so when access is a problem, at least we have an active treatment that we can use in the meantime.
Elisabeth Heath, MD, FACP: Absolutely. I think the access is one issue, but also [determining suitability for a] drug by doing the imaging is still a big deal. The number of prior authorizations and peer-to-peer is astonishing. It keeps growing, and I like to remind everyone that in the state of Michigan, we still struggle with oral chemotherapy parity. We’re still 1 of 7 states that sometimes has to fight to get oral drugs, as chemotherapy is easier to give. Depending on your practice and your staff’s bandwidth—and in health care we’re all strapped and stressed to the nth degree—it’s hard to see the big picture because you’re [ostensibly] flying treatment by treatment. That is an unmet need for all of us. Now that we have some real, active tools, we’re looking for these markers to tell us what to do. What I’m worried about in my practice is, at some point, your bone marrow conks out. Maybe it’s because there are so many more bone mets [metastases] over time. It could be years in the making, but we want to keep going; patients are otherwise OK and it’s a struggle, whether it’s given on a trial or patients are given it as an FDA- [US Food and Drug Administration] approved indication; regardless, their bone marrow is not strong. It makes the whole sequencing difficult—I think we have to be thoughtful about how to design the next generation of trials because patients won’t have any blood counts or platelets or red blood cells left to get treated.
Tanya Dorff, MD: This is a great place for real-world data or longer follow-up from prospective trials, to really fill in those gaps and say, “OK, for the patients that sequenced this way, how much of their subsequent treatment were they able to get vs the reverse sequence?” That happened when Radium-223 first came out. We asked the question: Is it better to do chemotherapy first or Radium, in terms of preserving marrow function and being able to get the next line of treatment? But now there’s this new radiopharmaceutical, and we have to ask those questions again. The other unmet need is knowing whether a treatment is working in the bone. We struggle to interpret when the PSA [prostate-specific antigen] has gone down, but alk phos [alkaline phosphatase] is up, or [the patient has] more pain and we look at the bone scan and maybe it’s the same, or maybe it’s better, or perhaps worse. We don’t have reliable information about what’s happening to bone metastases unless it’s obvious and everything is concordant. But there are a fair number of patients for whom the different parameters we look at are going in different directions and are more uncertain. With the lutetium PSMA and the PSMA PET scans, we still have some room to learn whether those will help us evaluate for response or whether in some of the experiences, there’s an improvement on the PSMA PET, but if you do an FDG [fluorodeoxyglucose] PET, you will see that there is active disease that hasn’t been treated. We’ve already struggled with assessment and response, particularly in bone, and we will have to do some relearning about how to evaluate for a response or knowing what else to investigate or in which direction to go when things just don’t make sense.
Elisabeth Heath, MD, FACP: And progression is always such a heterogeneous process, to boot. So [I’m giving] a shout-out to the AIQ Solutions folks from the University of Wisconsin; they’re asking that question. In one of the trials with enzalutamide in which we participated, we could see their heterogeneity—maybe 80% is still great, 20% is worse; 90% is still great, and 5% is worse. That’s so difficult when you’re thinking, “Everything is working and the pain [level] is tolerable, but oh, no, there are 2 new regions.” With PET scans, even if the patient’s insurance allows them, there’s more exposure for the patient, whereas a CAT scan or an X-ray doesn’t lend itself [to that level of exposure]. We need better parameters because I don’t see us [referring patients for repeated PET scans], not that I think insurance is ever going to let that happen; regardless, [undergoing] PET scans every 3 months for endless years is probably not a wise decision. A lot work needs to be done [in this area].
Transcript edited for clarity.