The Emergence of Triplet Therapies in ccRCC in the Frontline Setting

Drs. Pedro Barata and Naomi Haas discuss the emergence of clinical trials investigating triplet combinations in advanced renal cell carcinoma, factors that influence treatment decisions, strategies to personalize therapies in the frontline setting, including response-adaptive treatment strategies, and the use of biomarkers such as gene expression analysis to guide initial therapy. TRANSCRIPT Dr. Pedro Barata: Hello, I'm Dr. Pedro Barata. I'm your guest host of the ASCO Daily News Podcast today. I'm an associate professor of medicine and also a GU medical oncologist at University Hospital Seidman Cancer Center, Case Western University in Cleveland, Ohio. I'm also an associate editor for the ASCO Educational Book. Today I'm really delighted to welcome Dr. Naomi Haas, the director of the Prostate and Kidney Cancer Program at the Abramson Cancer Center and professor of medicine at the University of Pennsylvania.  Welcome, Dr. Haas. Dr. Naomi Haas: Thank you, Dr. Barata. It's a pleasure to be interviewed. Dr. Pedro Barata: Thank you. As you know, we've seen significant strides in the frontline treatment for patients with advanced clear cell renal cell carcinoma (RCC), and there are multiple doublet regimens that are now the standard of care for those patients. The goal for us to chat today is to discuss the emergence of clinical trials that are really investigating triple combinations and the factors that influence treatment decisions around triplet combinations for patients with advanced renal cell carcinoma. I want to congratulate you for the great work that you did in a recently published article in the 2023 ASCO Educational Book. So thank you for your contributions. And just before we get started, I just want to highlight that our full disclosures are available in the transcript of this episode. So, Dr. Haas, again, it’s great to have you. Thank you for taking the time. Let me get started. So, we know that there are multiple standard of care doublet regimens, all of them immunotherapy-based combos, and they usually include 1 checkpoint inhibitor or 2, such as ipilimumab plus nivolumab or a combination of an immune checkpoint inhibitor with a VEGF TKI. And we have a number of examples like that. Can you tell us about the trials that have emerged exploring triplet therapies in the first-line setting for patients with advanced RCC? Dr. Naomi Haas: Sure, and I'm going to focus just on triplet therapies that are just about ready to go. But as you know, Pedro, there are probably many different combinations that we'll see in the future. Some of the combinations that have already been conducted as clinical trials include combinations of VEGF receptor tyrosine kinase inhibitors along with immune checkpoint inhibitors. I'll highlight one which was batiraxcept plus cabozantinib and nivolumab, and it's a combination of VEGF inhibitor, immune checkpoint inhibitor, and also an AXL inhibitor. So, most of these capitalize on other vulnerabilities with renal cell carcinoma.  So, as you said, they build on the tyrosine kinase inhibitor pathway or on the immune checkpoint inhibitor pathway. Some of them are combining drugs such as CDK inhibitors. There was axitinib plus nivolumab plus palbociclib trial that is getting ready to launch. Others are combining the use of belzutifan, which is a HIF inhibitor in combination with VEGF inhibitor and immune checkpoint inhibitor. There are a couple of those that are ongoing, one of them looking at combinations with lenvatinib. And I think there are also trials getting ready to launch that are using it in combination with cabozantinib and nivolumab.  Additionally, another very interesting direction is trying to affect the gut microbiome. And there was a clinical trial presented by Dr. Monty Pal at the gut microbiome session at ASCO, which combined CBM-588, which is a probiotic, in combination with cabozantinib and nivolumab. And that showed an improvement in progression-free survival compared to the combination of cabozantinib and nivolumab alone. And previously there was work published using CBM-588 in combination with ipilimumab and nivolumab. So that's an area of high interest to patients. But most of these combinations capitalize on either vulnerabilities, signs of resistance in pathways or in adding other pathways that have previously been unaddressed in renal cell carcinoma, and are combined with pathways that we know are effective. Dr. Pedro Barata: Wow, that's a fantastic overview of some of the approaches being considered in the frontline, so thank you for that. And actually to your point, some of them we've seen some data, others more later stages of development. So with that in mind, we also know that we have on one side of the story we have how much of these combos of triplets can actually be effective and help patients. From the other perspective is about tolerability, treatment options, and patient health. They're both very important considerations.  Can you tell us a little bit about the safety profile of these triplet combos? I know we're talking about many different things. The microbiome triplet has a different safety profile than perhaps a combination with a TKI and different checkpoints, for instance. Can you tell us a little bit about what we expect from the safety profile when we start to combine these therapies in the upfront setting?  Dr. Naomi Haas: Sure. I think 2 of the very tolerable triplet regimens have been the combination of the CBM-588 in combination with ipilimumab and nivolumab. Really in those combinations, the authors at least have demonstrated that there has not been a great difference between the two study arms of either the doublet or the doublet in combination with the CBM-588 trial. And that's based on basically changing the bacterial flora of the gut. The Avera trial, which was using the AXL inhibitor in combination with cabozantinib and nivolumab, also seems to have a very tolerable safety profile. Now, this trial was not compared to sort of a standard of care arm, so it's a little bit difficult. A standard of care arm that I would have considered for this clinical trial would have been to use either cabozantinib alone or cabozantinib with nivolumab. Instead, this was more of a dose-finding protocol. So, more work needs to be done with that, but the side effects of that combination additive to what we already know seem to be just infusion reactions from the AXL inhibitor.  The trial that got the most attention so far has been COSMIC-313, which was combining cabozantinib with ipilimumab and nivolumab upfront. And of course, the concern with this triplet combination was that there was more hepatotoxicity seen and it was difficult to know whether the hepatotoxicity was from the combinations of the immune checkpoint inhibitors or the use of the cabozantinib. And although the trial showed an improvement in progression-free survival, it did not show as many complete responses as the comparator arm. And the other concern was that there was quite a bit of dropout due to toxicity. And of course, we don't have the overall survival endpoint for that trial yet. Dr. Pedro Barata: Great, thank you for that. I agree completely. We've seen many different safety profiles with these different triplets.  Let me touch base on a slightly different topic, and that has to do with what kind of strategies can we think to personalize treatment for clear cell RCC in the frontline. And this is not necessarily applicable only to triplet therapy. There are also some efforts with doublets, but the goal is, I would argue, is response adaptive treatment strategies or even the use of upfront biomarkers such as gene expression analysis, for example, to help us guide initial therapy. Can you give us an idea what your thoughts are about what is coming? What do you think the future will look like in terms of developing this like a biomarker-based approach? What kind of factors or markers we can use to select who gets what in the frontline setting? Dr. Naomi Haas: Sure. So, I’ll just highlight ahead of that that one important biomarker that we’re already using is the IMDC criteria, which I think if that algorithm had not been developed, we would be struggling a lot in renal cancer and that’s, of course, the algorithm that uses the thing such as performance status, hemoglobin, calcium, and time for the development of metastatic disease as well as the neutrophil count and the platelet count. And that has helped us divide categories of patients with clear cell renal cell carcinoma into poor risk, intermediate risk, or favorable risk categories. And that was recently validated in the immune therapy combinations that were previously been validated just in VEGF inhibitor therapies.  But the other useful, let’s start with clinical tools that I think are going to be very important are the health-related quality of life tools which primarily measure things such as functional health, as well as toxicity. And one of these is the FKSI-19 score which captures most renal disease-related symptoms, treatments, side effects, and functional well-being. And this has been implemented in some trials and are looked at over time whether the patient’s functional status improves. And patients who are responding to therapies generally will improve as far as their overall well-being. Although that can be difficult as a tool because if patients are experiencing toxicity, those signs might not be apparent. But that’s one tool that’s being used.  Now, people, both patient advocates and patients, have pointed out that it’s very hard to use a tool like this in real life to implement in clinic, but there are efforts being carried out to make these tools a little bit easier so that people can use them day-to-day. So, I can see that being implemented more often.  The others have to do with response assessments, and I think it’s very important to look at immune-related responses which kind of builds on the resist response, but it uses two dimensions of measurement as opposed to one dimension of measurement. And looking at those, we know now that patients who have what we call a deep response, so something better than a 75% shrinkage or even a 90% shrinkage in a very short period of time tend to be those patients who behave like patients who have complete responses. And both progression-free survival and overall survivals seem to be going in a very encouraging way looking at these tools so you could see that this tool could be implemented in real life with treating a patient and if they have a very deep response quickly, you can feel, the physician or the APP, could be very confident that the patient is going to do well for a long period of time. I think the tools that we’re waiting for the most, however, are as you said, the biomarker tools. And this is where we still have a lot of work to do, but one example of this is the transcriptomics which has been conducted in both the atezolizumab-based trials such as the IMmotion trials, and also to some extent with the JAVELIN trials, the avelumab and axitinib trials. And this goes back to looking at the tissues sample and looking at transcriptomics which show mRNA expression as well as some alterations in some of the important genes such as BAP1 and PRBM1.  And those tools have been implemented, especially in the IMmotion trial, there were 7 clusters identified, and two of the clusters are groups of patients whose tumors have transcriptomics that indicate that they would respond well to a VEGF inhibitor. And a couple of them also showed very good responses to immune checkpoint pathways. There were additional pathways which suggested that patients wouldn’t be responsive to either of these. And there is a trial called OPTIC that is funded by the Department of Defense (DOD) which is currently applying these transcriptomics, and then assigning patients to get either a VEGF IO therapy combination or a dual immune checkpoint inhibitor combination, based on their transcriptomics.  And I think what everybody would really like to see is, number 1, that these transcriptomics consistently bear out that there isn't irregularity in using these as predictors. So, they do need to be validated. But I think if there was a quick and easy way to do this, to assign patients to therapies based on these profiles, that would perhaps go a long way in predicting what therapy a patient should start with.  Another useful tool is the development of artificial intelligence. And there are a number of companies that are looking at these tools. We're implementing this retrospectively in the ASSURE trial, which was the adjuvant seraphinib synontib or placebo trial, for patients at high risk for RCC. And we're working with a company to identify, using AI, looking at the slides. And I think that if these kinds of techniques, which are already being used in prostate cancer, are something that can be developed, then what I could see in the future is that a patient's slide could be tested very quickly, and that that might also indicate things that perhaps we can't see under the microscope, as far as either a response to treatment or a risk. So, you could use that in the adjuvant setting to predict whether a patient might need adjuvant therapy or not. So I can see those being implemented.  And then the third is looking at cell-free DNA. And there are many different mechanisms that have been tested in other solid tumors, using either circulating tumor DNA or cell-free DNA. Now, the circulating tumor DNA seems to be a little bit more difficult to assess in metastatic kidney cancer because it doesn't have the mutational burden and doesn't seem to have as many mutations and things floating around that can be captured. However, cell-free DNA, which has the capability of measuring DNA methylation profiles, does seem to be showing some promise, and there have been some publications.  So this has also been tested in cancers of all stages and can be measured in both the plasma and in the urine. And that could be another helpful tool that needs to be validated, but that could be used to start a patient on treatment. And if the amounts of cell-free DNA went down with therapy, that could be a good indication, perhaps in advance of imaging, that a patient is doing well with therapy.  So those are some examples that I see potentially being used in the future to help direct therapy, provided that we can make these tools, that we can validate these tools, and secondly, that these tools are relatively inexpensive and that they're nimble, that they could be used right away, that it wouldn't take a long time to get the results back to help guide. Dr. Pedro Barata: For sure. I couldn't agree more. What a masterclass of all the emerging tools that are being investigated in RCC, this is fantastic.  So, I guess maybe one last question before I let you go. We have now a number of doublets, we have perhaps a triplet, if not more. If you were to guess, who do you think will be the ideal population for a triplet therapy? Some, in addition to all the tools you mentioned, maybe sarcomatoid features, etc. that might be part of the AI complement to what you mentioned earlier. But if you were to guess, do you think that 5 years from now, we're going to be offering a triplet therapy, whatever that triple therapy might be, to everybody, to certain populations? What can you tell us to help us predict what might happen in the near future to make us think about a thoughtful, shared decision-making process and try to predict who might be the ideal population for triplet therapy? Dr. Naomi Haas: So, I don't think we're going to use triplet therapy in everybody. And in fact, I hope we don't use triplet therapy in everybody because I have patients who have responded to single-agent nivolumab and remained in a continuous CR many years after they were treated that way. And I have other patients who really progressed very rapidly or relapsed very quickly after doublet therapy combinations. So, I think that what I would see in the future would be using the triplet therapy combinations in the challenging patients, the patients who we know we're not getting as far along with the doublet approach. And that's really our challenge. And I would see that perhaps some of this transcriptomics which indicates that there are subsets of renal cell carcinoma which are not going to respond well to a VEGF inhibitor or to an immune checkpoint inhibitor, that those are areas where there might be other relevant pathways where maybe the signal isn't quite as good with– maybe they have some response, but not an optimal response. And then combining another pathway into that would be a way forward to achieve a complete response in those populations.  I also want to emphasize that it may be that triplet therapy isn't the way to go, but that triplet therapy can be more of an adaptive design where a doublet therapy is started, and then the third drug, a triplet, is added at a later time. And an example of that is PDIGREE, which is the combination of ipilimumab and nivolumab. And then following imaging, patients are assigned, depending on the response, to get either cabozantinib alone, cabozantinib with nivolumab, or to continue on just nivolumab alone. And that might be a better way to address toxicity. But some of these other triplet combinations, one could also see- you could start, for example, with ipilimumab and nivolumab, and if they were having a response but you wanted to heighten the response, maybe adding the CBM-588 as an adaptive response or adding a CDK inhibitor, but sort of staggering the combination so that you spare patients some of the toxicity. So, I think all of those approaches need to be tested. Dr. Pedro Barata: That is fantastic. Dr. Haas, this is an incredible podcast. You did highlight several triplet combinations that are currently under investigation. You highlighted very, very important ongoing clinical trials. You touched base on what the future might bring as far as tools that might help us decide or optimize patient selection. We talked about adaptive designs. So really outstanding work. And also, I think this reflects the fantastic work in the manuscript that you wrote in the 2023 ASCO Educational Book.  So, thank you so much, Dr. Haas, for the incredible work that you have done and you continue to do in the GU field, and for taking the time to share your insights with us today on the ASCO Daily News Podcast. It's truly been a pleasure to chat with you today. Dr. Naomi Haas: Thank you.  Dr. Pedro Barata: Thank you again. And thank you also to our listeners for joining us today. Really happy with talking about this topic with Dr. Haas. You can also find links to the studies that we discussed today in the transcript of this episode. And finally, if you value the insights that you hear on the ASCO Daily News Podcast, please take a moment to rate, review and subscribe wherever you get your podcast.  So again, it has been a privilege to be here today with Dr. Haas. Thank you for joining us and have a good day.   Disclaimer: 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.   Follow today’s speakers:  Dr. Pedro Barata @PBarataMD Dr. Naomi Haas   Follow ASCO on social media:  @ASCO on Twitter  ASCO on Facebook  ASCO on LinkedIn    Disclosures:  Dr. Pedro Barata: Honoraria: UroToday Consulting or Advisory Role: Bayer, BMS, Pfizer, EMD Serono, Eisai, Caris Life Sciences, AstraZeneca, Exelixis, AVEO, Dendreon Speakers’ Bureau (Inst): Caris Life Sciences, Bayer, Pfizer/Astellas Research Funding (Inst.):  Blueearth, AVEO, Pfizer, Merck   Dr. Naomi Haas: Consulting or Advisory Role: Pfizer, Merck Sharp & Dohme, Calithera, Eisai, Exelisis, AVEO, Roche/Genentech Expert Testimony: Lilly