ASCO Education Emerging Treatment Paradigms in Genitourinary Cancers
Dr. Pedro Barata and Dr. Rana McKay discuss the integration of innovative advances in molecular imaging and therapeutics to personalize treatment for patients with renal cell and urothelial carcinomas.
TRANSCRIPT
Dr. Pedro Barata: Hello, I'm Dr. Pedro Barata, your guest host of By the Book, a podcast series featuring insightful conversations between authors and editors of the ASCO Educational Book. I'm a medical oncologist at University Hospitals Seidman Cancer Center and an associate professor of medicine at Case Western Reserve University in Cleveland, Ohio. I'm also an associate editor of the ASCO Educational Book.
Now, we all know the field of genitourinary cancers (GU) is evolving quite rapidly, and we have new innovations in molecular imaging as well as targeted therapeutics. Today's episode will be exploring novel approaches that are transforming the management of renal cell and urothelial carcinomas and also their potential to offer a more personalized treatment to patients.
For that, joining for today's discussion is Dr. Rana McKay, a GU medical oncologist and professor at University of California San Diego. Dr. McKay will discuss her recently published article titled, “Emerging Paradigms in Genitourinary Cancers: Integrating Molecular Imaging, Hypoxia-Inducible Factor-Targeted Therapies, and Antibody-Drug Conjugates in Renal Cell and Urothelial Carcinomas.”
Our full disclosures are available in the transcript of this episode.
And with that, Rana McKay, great to have you on the podcast today.
Dr. Rana McKay: Oh, thank you so much, Dr. Barata. It's really wonderful to be here with you. So, thanks for hosting.
Dr. Pedro Barata: No, thanks for taking the time, and I'm looking forward to this conversation. And by the way, let me start by saying congrats on a great article in the Educational Book. Really super helpful paper. I'm recommending it to a lot of the residents and fellows at my own institution.
I would like to first ask you to kind of give our listeners some context of how novel approaches in the molecular imaging as well as targeted therapeutics are actually changing the way we're managing patients with GU, but specifically with renal cell carcinoma and urothelial carcinoma. So, what are the areas you would call out as like being big areas for innovation in this context, and why are they important?
Dr. Rana McKay: Very good question. And I think this is really what this article highlights. It highlights where are we going from an imaging diagnostics standpoint? Where are we going from a therapeutic standpoint? And I think if we have to step back, from the standpoint of diagnostics, we've seen PET imaging really transform diagnostics in prostate cancer with the advent of PSMA PET imaging, and now PSMA PET imaging is used as a biomarker for selection for theranostics therapy.
And so, we're starting to see that enter into the RCC landscape, enter into the urothelial cancer landscape to a lesser extent. And I think it's going to potentially be transformative as these tools get more refined. I think when we think about therapeutics, what's been transformative most recently in the renal cell carcinoma landscape has been the advent of HIF2α inhibition to improve outcomes for patients. And we have seen the approval of belzutifan most recently that has reshaped the landscape. And now there's other HIF2α inhibitors that are being developed that are going to be further important as they get refined.
And lastly, I think when we think about urothelial carcinoma, the greatest transformation to treatment in that context has been the displacement of cisplatin and platinum-based chemotherapy as a frontline standard with the combination of enfortumab vedotin plus pembrolizumab. And we've seen antibody-drug conjugates really reshape treatment and tremendously improve outcomes for patients. So, I think those are the three key areas of interest.
Dr. Pedro Barata: So with that, let's focus first on the imaging and then we’ll get to the therapeutic area. So, we know there's been a paradigm shift, really, when prostate-specific targets emerged as tracers for PET scanning. And so, we now commonly use prostate-specific membrane antigen, or PSMA-based PET scanning, and really transform how we manage prostate cancer. Now, it appears that we're kind of seeing a similar wave in renal cell carcinoma with the new radiotracer against the target carbonic anhydrase IX. What can you tell us about this? And is this going to be available to us anytime soon? And how do you think that might potentially change the way we're managing patients with RCC today?
Dr. Rana McKay: First, I'll step back and say that in the context of PSMA PET imaging, we have actually been able to better understand RCC as well. So, we know that PSMA is expressed in the neovasculature of tumors, and it can actually be used to detect renal cell carcinoma tumors. It has a detection rate of about 84% when used for detection. And so, you know, I don't think it's just restricted to carbonic anhydrase IX, but we will talk about that. So, PSMA expressed in the neovasculature has a detection rate of around 84%, particularly if we're looking at clear cell RCC.
CAlX is overexpressed in clear cell RCC, and it's actually used in diagnosing renal cell carcinoma when we think of CAlX IHC for diagnosing clear cell RCC. And now there are CAlX PET tracers. The first foray was with the ZIRCON study that was actually an interestingly designed study because it was designed to detect the likelihood of PET imaging to identify clear cell RCC. So, it was actually used in the early diagnostics setting when somebody presents with a renal mass to discriminate that renal mass from a clear cell versus a non-clear cell, and it was a positive study.
But when I think about the potential application for these agents, you know, I think about the entire landscape of renal cell carcinoma. This is a disease that we do treat with metastasis-directed therapy. We have certainly seen patients who've undergone metastasectomy have long, durable remissions from such an approach. And I think if we can detect very early onset oligometastatic disease where a metastasis-directed therapy or SABR could be introduced - obviously tested in a trial to demonstrate its efficacy - I think it could potentially be transformative.
Dr. Pedro Barata: Wonderful. It's a great summary, and I should highlight you are involved in some of those ongoing studies testing the performance of this specific PET scanning for RCC against conventional imaging, right? And to remind the listeners, thus far, for the most part, we don't really do FDG-PET for RCC. There are some specific cases we do, but in general, they're not a standard scanning. But maybe that will change in the future. Maybe RCC will have their own PSMA-PET. And to your point, there's also emerging data about the role of PSMA-PET scanning in RCC as well, as you very elegantly summarized. Wonderful.
So, let me shift gears a little bit because you did, in your introduction, you did highlight a novel MOA that we have in renal cell carcinoma, approved for use, initially for VHL disease, and after that for sporadic clear cell renal cell carcinoma. We're talking about hypoxia-inducible factor 2-alpha inhibitors, or HIF2α inhibitors, such as belzutifan. But there's also others coming up.
So, as a way to kind of summarize that, what can you tell us about this breakthrough in terms of therapeutic class, this MOA that got to our toolbox of options for patients with advanced RCC? Tell us a little bit what is being utilized currently in the management of advanced RCC. And where do you see the future going, as far as, is it moving early on? Is it getting monotherapy versus combinations? Maybe other therapies? What are your thoughts about that? What can you tell us about it?
Dr. Rana McKay: Belzutifan is a first-in-class HIF2α inhibitor that really established clinical validation for HIF2α as a therapeutic target. When we think about the activity of this agent, the pivotal LITESPARK-005 trial really led to the approval of belzutifan in patients who were really heavily pretreated. It was patients who had received prior IO therapy, patients who had received prior VEGF-targeted therapy. And in the context of this study, we saw a median PFS of 5.6 months, and there did seem to be a tail on the curve when you looked at the 12-month PFS rate with belzutifan. It was 33.7% compared to 17.6% with everolimus. And then when we look at the response rate, it was higher with belzutifan on the order of 22-23%, and very low with everolimus, as we've previously seen.
I think one of the Achilles heels of this regimen is the primary PD rate, which was 34% when used in later line. There are multiple studies that are testing belzutifan in combination across the treatment landscape. So, we have LITESPARK-011, which is looking at the combination of belzutifan plus lenvatinib in the second-line setting. We've got the MK-012 [LITESPARK-012] study, which is looking at belzutifan in various combinations in the frontline setting. So there is a combination with IO plus belzutifan. And so this is also being looked at in that context. And then we also have the LITESPARK-022 study, which is looking at pembrolizumab with belzutifan in the adjuvant setting. So there's a series of studies that will be exploring belzutifan really across the treatment landscape. Many of these studies in combination.
Additionally, there are other HIF2α inhibitors that are being developed. We have casdatifan, which is another very potent HIF2α inhibitor. You know, I think pharmacologically, these are different agents. There's a different half-life, different dosing. What is going to be the recommended phase 3 dose for both agents, the EPO suppression levels, the degree of EPO suppression, and sustainability of EPO suppression is very different. So, I think we've seen data from casdatifan from the ARC-20 trial from monotherapy with a respectable response rate, over 30%, primary PD rate hovering just around 10%.
And then we've also seen data of the combination of casdatifan with cabozantinib as well that were recently presented this year. And that agent is also being tested across the spectrum of RCC. It's being looked at in combination with cabozantinib in the PEAK-1 study, and actually just at the KCRS (Kidney Cancer Research Summit), we saw the unveiling of the eVOLVE-RCC trial, which is going to be looking at a volrustomig, which is a PD-1/CTLA-4 inhibitor plus casdatifan compared to nivo-ipi in the frontline setting.
So, we're going to see some competition in this space of the HIF2α inhibitors. I think when we think of mechanism of action in that these are very potent, not a lot of off-target activity, and they target a driver mutation in the disease. And that driver mutation happens very early in the pathogenesis. These are going to be positioned much earlier in the treatment landscape.
Dr. Pedro Barata: All these studies, as you're saying, look really promising. And when we talk about them, you mentioned a lot of combinations. And to me, when I think of these agents, it makes a lot of sense to combine because there's not a lot of overlapping toxicities, if you will. But perhaps for some of our listeners, who have not used HIF2α inhibitors in practice yet, and they might be thinking about that, what can you tell us about the safety profile? How do you present it to your patients, and how do you handle things like hypoxia or anemia? How do you walk through the safety profile and tolerability profile of those agents like belzutifan?
Dr. Rana McKay: I think these drugs are very different than your traditional TKIs, and they don't cause the classic symptoms that are associated with traditional TKIs that many of us are very familiar with like the rash, hand-foot syndrome, hypertension, diarrhea. And honestly, these are very nuanced symptoms that patients really struggle with the chronicity of being on a chronic daily TKI. The three key side effects that I warn patients about with HIF2α inhibitors are: (1) fatigue; (2) anemia; and (3) hypoxia and dysregulation in the ability to sense oxygen levels.
And so, many of these side effects - actually, all of them - are very dose-dependent. They can be very well-managed. So, we can start off with the anemia. I think it's critically important before you even start somebody on belzutifan that you are optimizing their hemoglobin and bone marrow function. Make sure they don't have an underlying iron deficiency anemia. Make sure they don't have B12 or folate deficiency. Check for these parameters. Many patients who have kidney cancer may have some hematuria, other things where there could be some low-level blood loss. So, make sure that those are resolved or you're at least addressing them and supplementing people appropriately.
I monitor anemia very closely every 3 to 4 weeks, at least, when people start on these medications. And I do initiate EPO, erythropoietin, should the anemia start to worsen. And I typically use a threshold of around 10g/dL for implementing utilization of an EPO agent, and that's been done very safely in the context of the early studies and phase 3 studies as well.
Now, with regards to the hypoxia, I think it's also important to make sure that you're selecting the appropriate individual for this treatment. People who have underlying COPD, or even those individuals who have just a very high burden of disease in their lung, lymphangitic spread, pleural effusions, maybe they're already on oxygen - that's not an ideal candidate for belzutifan. Something that very easily can be done in the clinic before you think about initiating somebody on this treatment, and has certainly been integrated into some of the trials, is just a 6-minute walk test. You know, have the patient walk around the clinic with one of the MAs, one of the nurses, put the O2 sat on [measuring oxygen saturation], make sure they're doing okay. But these side effects, like I said, are very dose-dependent. Typically, if a patient requires, if the symptoms are severe, the therapy can be discontinued and dose reduced. The standing dose is 120 mg daily, and there's two dose reductions to 80 mg and 40 mg should somebody warrant that dose modification.
Dr. Pedro Barata: This is relatively new, right? Like, it was not that we're used to checking oxygen levels, right? In general, we're treating these patients, so I certainly think there's a learning curve there, and some of the points that you highlight are truly critical. And I do share many of those as well in our practice.
Since I have you, I want to make sure we touch base on antibody-drug conjugates as well. It's also been a hot area, a lot of developments there. When I think of urothelial carcinoma and renal cell carcinoma, I see it a little bit different. I think perhaps in urothelial carcinoma, antibody-drug conjugates, or ADCs, are somewhat established already. You already mentioned enfortumab vedotin. I might ask you to expand a little bit on that. And then in renal cell carcinoma, we have some ADCs as well that you include in your chapter, and that I would like you to tell us what's coming from that perspective. So, tell us a little bit about how do you see ADCs in general for GU tumors, particularly UC and RCC? Tell us a little bit about the complexity or perhaps the challenges you still see. At the same time, tell us about the successes.
Dr. Rana McKay: Stepping back, let's just talk about like the principles and design of ADCs. So, most ADCs have three components. There's a monoclonal antibody that typically targets a cell surface antigen, which is conjugated by a linker, which is the second component, to a payload drug. And typically, that payload drug has been chemotherapy, whether it be topoisomerase or whether it be MMAE or other chemotherapeutic.
We can start in the RCC space. There's been multiple antibody-drug conjugates that have been tested. There's antibody-drug conjugates to CD70, which is expressed on clear cell RCC. There's been antibody-drug conjugates to ENPP3, which is also expressed on RCC. There's antibody-drug conjugates to CDH6. And they have different payloads, like I said, whether it be topoisomerase I or other microtubule inhibitors.
Now, when we think about kidney cancer, we don't treat this disease with chemotherapy. This disease is treated with immunotherapy. It is treated with treatments that target the VEGF pathway and historically has not been sensitive to chemo. So, I think even though the targets have been very exciting, we've seen very underwhelming data regarding activity, and in some context, seen increased toxicity with the ADCs. So, I think we need to tread lightly in the context of the integration and the testing of ADCs in RCC.
We just came back from the KCRS meeting, and there was some very intriguing data about a c-Kit ADC that's being developed for chromophobe RCC, which is, you know, a huge unmet need, these variant tumors that really lack appropriate therapeutics. But I just caution us to tread lightly around how can we optimize the payload to make sure that the tumor that we're treating is actually sensitive to the agent that's targeting the cell kill. So, that's a little bit on the ADCs in RCC. I still think we have a long way to go and still in early testing.
Now, ADCs for UC are now the standard of care. I think the prototypical agent, enfortumab vedotin, is a nectin-4-directed ADC that's conjugated to an MMAE payload and was the first ADC approved for advanced urothelial, received accelerated approval following the EV-201 trial, which was basically a multicenter, single-arm study that was investigating EV in cisplatin-ineligible patients with advanced urothelial carcinoma, and then ultimately confirmed in the EV-301 study as well. And so, that study ended up demonstrating the support superiority of EV from an overall survival standpoint, even PFS standpoint. Building on that backbone is the EV-302 study, which tested EV in combination with pembrolizumab versus platinum-based chemotherapy in the frontline setting. And that was a pivotal, landmark study that, like I said, has displaced platinum therapy as a frontline treatment for people with advanced urothelial carcinoma. And when we think about that study and the median overall survival and just how far we've come in urothelial cancer, the median OS with EV-pembro from that trial was 31 and a half months. I mean, that's just incredible. The control arm survival was 16 and a half months. The hazard ratio for OS, 0.47. I mean this is why when this data was presented, it was literally a standing ovation that lasted for several minutes because we just haven't seen data that have looked that good.
And there are other antibody-drug conjugates that are being tested. We've all been involved in the saga with sacituzumab govitecan, which is a trophoblast cell surface antigen 2 (Trop-2) targeted ADC with a topoisomerase I payload. It was the second ADC to receive approval, but then that approval was subsequently withdrawn when the confirmatory phase 3 was negative, the TROPiCS-04 trial. So, approval was granted based off of the TROPHY-U-01, single-arm, phase 2 study, demonstrating a response rate of around 28% and a PFS of, you know, about 5 and a half months. But then failure to show any benefit from an OS standpoint. And I think there's a lot of controversy in the field around whether this agent still has a role in advanced urothelial carcinoma. And I think particularly for individuals who do not have molecular targets, like they're not HER2-amplified or have HER2-positivity or FGFR or other things like that.
Dr. Pedro Barata: Fantastic summary, Rana. You were talking about the EV, and it came to mind that it might not be over, right, for the number of ADCs we use in clinical practice in the near future. I mean, we've seen very promising data for ADC against the HER2, right, and over-expression. It also can create some challenges, right, in the clinics because we're asking to test for HER2 expression. It's almost like, it's not exactly the same to do it in breast cancer, but it looks one more time that we're a little bit behind the breast cancer field in a lot of angles. And also has vedotin as a payload. Of course, I'm referring to disitamab vedotin, and there's very elegant data described by you in your review chapter as well. And it's going to be very interesting to see how we sequence the different ADCs, to your point as well.
So, before we wrap it up, I just want to give you the opportunity to tell us if there's any area that we have not touched, any take-home points you'd like to bring up for our listeners before we call it a day.
Dr. Rana McKay: Thank you so much. I have to say, you know, I was so excited at ASCO this year looking at the GU program. It was fantastic to see the progress being made, novel therapeutics that really there's a tremendous excitement about, not just in RCC and in UC, but also in prostate cancer, thinking about the integration of therapies, not just for people with refractory disease that, even though our goal is to improve survival, our likelihood of cure is low, but also thinking about how do we integrate these therapies early in the treatment landscape to enhance cure rates for patients, which is just really spectacular. We're seeing many of these agents move into the perioperative setting or in combination with radiation for localized disease. And then the special symposium on biomarkers, I mean, we've really come a long, long way. And I think that we're going to continue to evolve over the next several years. I'm super excited about where the field is going in the treatment of genitourinary malignancies.
Dr. Pedro Barata: Oh, absolutely true. And I would say within the Annual Meeting, we have outstanding Educational Sessions. And just a reminder to the listeners that actually that's where the different teams or topics for the Educational Book chapters come from, from actually the educational sessions from ASCO. And your fantastic chapter is an example of that, right, focusing on advanced GU tumors. So, thank you so much, Rana, for taking the time, sharing your insights with us today on the podcast. It was a fantastic conversation as always.
Dr. Rana McKay: My pleasure. Thanks so much for having me, Dr. Barata.
Dr. Pedro Barata: Of course.
And thank you to our listeners for your time today. You will find the link to the article discussed today in the transcript of this episode. I also encourage you to check out the 2025 ASCO Educational Book. You'll find an incredible wealth of information there. It's free, available online, and you'll find, hopefully, super, super important information on the key science and issues that are shaping modern oncology, as we've heard from Dr. McKay and many other outstanding authors. So, thank you, everyone, and I hope to see you soon.
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The purpose of this podcast is to educate and to inform. This is not a substitute for professional medical care and is not intended for use in the diagnosis or treatment of individual conditions. Guests on this podcast express their own opinions, experience, and conclusions. Guest statements on the podcast do not express the opinions of ASCO. The mention of any product, service, organization, activity, or therapy should not be construed as an ASCO endorsement.
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Disclosures:
Dr. Pedro Barata:
Stock and Other Ownership Interests: Luminate Medical
Honoraria: UroToday
Consulting or Advisory Role: Bayer, BMS, Pfizer, EMD Serono, Eisai, Caris Life Sciences, AstraZeneca, Exelixis, AVEO, Merck, Ipson, Astellas Medivation, Novartis, Dendreon
Speakers’ Bureau: AstraZeneca, Merck, Caris Life Sciences, Bayer, Pfizer/Astellas
Research Funding (Inst.): Exelixis, Blue Earth, AVEO, Pfizer, Merck
Dr. Rana McKay:
Consulting or Advisory Role: Janssen, Novartis, Tempus, Pfizer, Astellas Medivation, Dendreon, Bayer, Sanofi, Vividion, Calithera, Caris Life Sciences, Sorrento Therapeutics, AVEO, Seattle Genetics, Telix, Eli Lilly, Blue Earth Diagnostics, Ambrx, Sumitomo Pharma Oncology, Esiai, NeoMorph, Arcus Biosciences, Daiichi Sankyo, Exelixis, Bristol Myers Squibb, Merck, Astrazeneca, Myovant
Research Funding (Inst.): Bayer, Tempus, AstraZeneca, Exelixis, Bristol Myers Squibb, Oncternal Therapeutics, Artera