ASCO Daily News Promising New Therapies in Non-Muscle Invasive Bladder Cancer
Dr. Sumanta (Monty) Pal and Dr. Petros Grivas discuss innovative new intravesical therapies and other recent advances in the treatment of non-muscle invasive bladder cancer.
TRANSCRIPT
Dr. Sumanta (Monty) Pal: Hello and welcome. I'm Dr. Monty Pal here at the ASCO Daily News Podcast. I'm a medical oncologist and professor and vice chair of academic affairs at the City of Hope Comprehensive Cancer Center in Los Angeles. And I'm really delighted to be your new host here.
Today's episode is going to really sort of focus on an area near and dear to my heart, something I actually see in the clinics, and that's bladder cancer. We're specifically going to be discussing non-muscle invasive bladder cancer, which actually comprises about 75% of new cases.
Now, in recent years, there's been a huge shift towards personalized bladder-preserving strategies, including innovative therapies and new agents that really are reducing reliance on more primitive techniques like radical cystectomy and radiation therapy. And I'm really excited about this new trend. And really at the forefront of this is one of my dear friends and colleagues, Dr. Petros Grivas. He's a professor in the Department of Medicine and Division of Hematology Oncology at the University of Washington. It's going to take a while to get through all these titles. He's taken on a bunch of new roles. He is medical director of the International Program, medical director of the Local and Regional Outreach Program, and also professor in the Clinical Research Division at the Fred Hutch Cancer Center. Petros, welcome to the program.
Dr. Petros Grivas: Thank you so much, Monty. It's exciting for me to be here.
Dr. Sumanta (Monty) Pal: Just FYI for our audience, our disclosures are available in the transcript of this episode.
We're going to get right into it, Petros. Non-muscle invasive bladder cancer, this is a really, really challenging space. We see a lot of recurrence and progression of the disease over time, about 50% to 70% of patients do have some recurrence after initial treatment, and about 30% are ultimately going to progress on to muscle-invasive or metastatic disease.
Now, I will say that when you and I were in training, non-muscle invasive bladder cancer was something that was almost relegated to the domain of the urologist, right? They would use treatments such as BCG (Bacillus Calmette-Guérin) in a serial fashion. It was rare, I think, for you and I to really enter into this clinical space, but that's all changing, isn't it? I mean, can you maybe tell us about some of the new therapies, two or three that you're really excited about in this space?
Dr. Petros Grivas: Monty, you're correct. Traditionally and conventionally, our dear friends and colleagues in urology have been managing patients with non-muscle invasive bladder cancer. The previous term was superficial bladder cancer. Now, it has changed, to your point, to non-muscle invasive bladder cancer. And this has to do with the staging of this entity. These tumors in superficial layers of bladder cancer, not invading the muscularis propria, the muscle layer, which makes the bladder contract for urine to be expelled.
As you said, these patients have been treated traditionally with intravesical BCG, one of the oldest forms of immunotherapy that was developed back in the 1970s, and this is a big milestone of immunotherapy development. However, over the years, in the last 50 years, there were not many options for patients in whom the cancers had progression or recurrence, came back after this intravesical BCG. Many of those patients were undergoing, and many of them still may be undergoing, what we call radical cystectomy, meaning removal of the bladder and the lymph nodes around the bladder. The development of newer agents over the last several years has given the patients the option of having other intravesical therapies, intravesical meaning the delivery of drugs, medications inside the bladder, aiming to preserve the bladder, keep the bladder in place.
And there are many examples of those agents. Just to give you some examples, intravesical chemotherapy, chemotherapy drugs that you and me may be giving intravenously, some of them can be given inside the bladder, intravesical installation. One example of that is a combination of gemcitabine and docetaxel. These drugs are given in sequence one after the other inside the bladder, and they have seen significant efficacy, good results, again, helping patients keeping the bladder when they can for patients with what we call BCG unresponsive non-muscle invasive bladder cancer. And again, there's criteria that the International Bladder Cancer Group and the FDA developed, how to define when BCG fails, when we have BCG unresponsive non-muscle invasive bladder cancer.
Dr. Sumanta (Monty) Pal: And we're actually going to get into some of the FDA requirements and development pathways and so forth. What I'm really interested in hearing, and I'm sure our audience is too, are maybe some of the new intravesical treatments that are coming around. I do think it's exciting that the gemcitabine and docetaxel go into the bladder indeed, but what are some of the top new therapies? Pick two or three that you're excited about that people should be looking out for in this intravesical space.
Dr. Petros Grivas: For sure, for sure. In terms of the new up-and-coming therapies, there are a couple that come to mind. One of them is called TAR-200, T-A-R 200. This agent is actually a very interesting system. It's an intravesical delivery of a chemotherapy called gemcitabine, the one that I just mentioned a few minutes ago, that is actually being delivered through what we call a pretzel, which is like a rounded [pretzel-shaped] structure working like an osmotic pump, and that is being delivered inside the bladder intravesically by urologists. And this drug is releasing, through the osmotic release mechanism, this chemotherapeutic drug, gemcitabine, inside the bladder. And this can be replaced once every 3 weeks in the beginning. And the data so far from early-phase trials are really, really promising, showing that this agent may be potentially regulatory approved down the road. So TAR-200 is something to keep in mind.
And similarly, in the same context, there is a different drug that also uses the same mechanism, and this osmotic release, this pretzel, it's just encoded with a different agent. The different agent is an FGFR inhibitor, a target therapy called erdafitinib, a drug that you and me may give in patients with metastatic urothelial carcinoma if they have an FGFR3 mutation or fusion. And that drug is called TAR-210.
Dr. Sumanta (Monty) Pal: And can I ask you, in that setting, do you have to have an FGFR3 mutation to receive it? Or what is the context there?
Dr. Petros Grivas: So for TAR-210, TAR-2-1-0, usually there is a checking to see if there is an FGFR3 mutation or fusion. And the big question, Monty, is do we have adequate tissue, right? From a limited tissue on what we call the TURBT, right, that urologists do. And now there is a lot of development in technology, for example, urine circulating tumor DNA to try to detect these mutations in the urine to see whether the patient may be eligible for this TAR-210. Both of those agents are not FDA approved, but there are significant promising clinical trials.
Dr. Sumanta (Monty) Pal: So now let's go to a rapid-fire round. Give us two more agents that you're excited about in this intravesical space. What do you think?
Dr. Petros Grivas: There is another one called cretostimogene. It's a long name.
Dr. Sumanta (Monty) Pal: They really make these names very easy for us, don't they?
Dr. Petros Grivas: They are not Greek names, Monty, I can tell you, you know. Even my Greek language is having trouble pronouncing them. The cretostimogene, it's actually almost what we call a growth factor, a GM-CSF. The actual name of this agent is CG0070. This is a replicating mechanism where GM-CSF is replicating in cells. And this agent has shown significant results again, like the TAR-200, in BCG unresponsive non-muscle invasive bladder cancer. I would say very quickly, two agents that actually were recently approved and they're already available in clinical practice, is nadofaragene firadenovec, another long name. That's a non-replicating vector that has the gene of interferon alfa-2b that stimulates the immune system in the bladder. It's given once every 3 months. And the last one that was, as I mentioned, already FDA approved, it's an interleukin-15 superagonist. It's another long name, which is hard to pronounce, but I will give it a try. It's a drug that was recently actually approved also in the UK. The previous name was N-803. It's given together with BCG as a combination for BCG unresponsive non-muscle invasive bladder cancer.
Dr. Sumanta (Monty) Pal: This is a huge dilemma, I think, right? Because if you're a practicing, I'm going to say urologist for the moment, I guess the challenge is how do you decide between an IL-15 superagonist? How do you decide between a pretzel-eluting agent? How do you decide between that and maybe something that's ostensibly, I'm going to guess, cheaper, like gemcitabine and docetaxel? What's sort of the current thinking amongst urologists?
Dr. Petros Grivas: Multiple factors play into our account when the decision is being made. I discuss with urologists all the time. It's not an easy decision because we do not have head-to-head comparisons between those agents. As you mentioned, intravesical chemotherapy with gemcitabine and docetaxel has been used over the years and this is the lowest cost, I would say, the cheapest option with good efficacy results. Obviously, the nadofaragene firadenovec every 3 months and the interleukin-15 superagonist, N-803, plus BCG have also been approved. The question is availability of those agents, are they available? Are they reimbursed? Cost of those agents can come into play. Frequency of administration, you know, once every 3 months versus more frequent. And of course, the individual efficacy and toxicity data, preference of the patients; sometimes the provider, the urologist, may have something that they may be more familiar with. But we lack this head-to-head comparison. Of course, I want to make sure I mention that radical cystectomy may still be the option for appropriate patients. So that complicates also the decision making and has to be individualized, customized, and personalized, taking into account all those factors. And there is not one size fitting all.
Dr. Sumanta (Monty) Pal: So I think we discussed five intravesical therapies. As you point out, and you know, I'm going to get some calls about this: I think I referred to radical cystectomy as being a more primitive procedure. Not true at all. I think it's something that still is, you know, a mainstay of management in this disease space. But I guess it gets even more complicated, am I right, Petros? Because now we have systemic therapies that we can actually apply in this non-muscle invasive setting for at this point, refractory disease. Can you maybe just give us a quick two-minute primer on that?
Dr. Petros Grivas: Absolutely, and systemic therapies now come into play, as you said. And a classical example of that, Monty, came from the KEYNOTE-057 trial that we published about 6 years ago. This is intravenous pembrolizumab, given intravascularly, intravenously, as opposed to the previously discussed intravesical administration of agents. Pembrolizumab was tested in that KEYNOTE-057 trial and showed efficacy about, I would say, one out of five patients, about 20%, had a complete response of the tumor in the bladder in a year after starting the treatment. Again, it's hard to compare across different agents, but obviously when we give something intravenously, there is a risk of toxicity, side effects systemically, what we call immune-related adverse events. And this can also play in the decision making, right? When you have intravesical agents versus intravascular agents, there is different toxicity profiles in terms of systemic toxicity. But intravenous pembrolizumab has been an option, FDA approved, since, if I remember, it was early 2020 when this became FDA approved. There are other agents being tested in this disease, but like atezolizumab through the SWOG study that Dr. Black and Dr. Singh led, but atezolizumab is not FDA approved for this indication. Again, this is for BCG unresponsive, high-risk, non-muscle invasive bladder cancer.
Dr. Sumanta (Monty) Pal: So maybe teach us how it works, for instance, at an expert center like the Fred Hutch. When you see a patient with non-muscle invasive bladder cancer, there's obviously the option of surgery, there's the intravesical therapies, which I imagine the urology team is still really at the helm of. But then, I guess there has to be consideration of all options. So you've got to bring up systemic therapy with agents like pembrolizumab. In that context, are you involved that early on in the conversation?
Dr. Petros Grivas: That's a great discussion, Monty. Paradigm is shifting as we mentioned together. The urologists have been treating these patients and still they are the mainstay of the treaters, the managers in this disease. But medical oncologists come to play more and more, especially with the FDA approval of intravenous pembrolizumab about 5 years ago [GC1] [KM2] . We have the concept of multidisciplinary bladder cancer clinic here at Fred Hutch and University of Washington. This happens every Tuesday morning, and we're very excited because it's a one-stop shop for the patients. We have the urologist, a medical oncologist, radiation oncologist, and experts from radiology and pathology, and we all review cases specifically with muscle-invasive bladder cancer. But every now and then, we see patients with BCG unresponsive non-muscle invasive bladder cancer.
And this is where we discuss and we talk to the patient about pros and cons of all those options. And that's a classic example where medical oncologists may start to see those patients and offer their input and expertise. In addition to that, sometimes we have clinical trials, we may see these patients because there are systemic agents that may be administered in this setting. We have the SunRISe trial program that includes also a systemically administered checkpoint inhibitor. So that's another example where we see patients either in the context of multi-clinic or in individual solo clinics to counsel the patients about the pros and cons of the systemically administered agents in the context of clinical trials. Usually checkpoint inhibitors are the class of agents that are being tested in this particular scenario.
Dr. Sumanta (Monty) Pal: I can see a scenario where it's really going to require this sort of deep dive, much in the way that we do for prostate cancer, for instance, where the medical oncologist is involved very early on and planning out any sort of systemic therapy component of treatment or at the very least, at least spelling out those options. I think it's going to be really interesting to see what this space looks like 5 or 10 years down the road.
In closing, I wanted to go through something that I think is so different in this space, at least for the time being, and that is the paradigm for FDA approval. When you and I have our fellows in the clinics, we always say, "Look, you know, the paradigm in this disease and that disease and the other disease needs to be phase 3 randomized trials, right? Big thousand patient experiences where you're testing clinical endpoints." That's tough in non-muscle invasive bladder cancer, right? Because thankfully, outcomes can actually be quite good, you know, in this setting, right? It's tough to actually estimate overall survival in some of these early-stage populations. Tell me what the current regulatory bar is, and this is a tough thing to do in 2 minutes or less but tell me where you see it headed.
Dr. Petros Grivas: You alluded to that before, Monty, when I was giving the background and we talked about the regulatory approval. And I have to very quickly go back in time about 10 years ago because it's important for context that can help us in other disease types too. We had workshops with the FDA and the NCI with the help of the International Bladder Cancer Group and other colleagues. And we try to define a framework, what endpoints are meaningful for those patients in this disease. It was a multidisciplinary, multiple stakeholders meeting, where we tried to define what is important for patients. What are the available agents? What are the trial designs we can accept? And what are the meaningful endpoints that the regulatory agencies can accept for regulatory approval? And that was critical in that mission because it allowed us to design clinical trials, for example, single-arm trials in a disease where there was no standard of care. There was intravesical valrubicin and chemotherapy anthracycline that was approved for many years, but was not practically used in clinical practice, despite being approved, the valrubicin. And because of that, the FDA allowed these single-arm trials to happen.
And obviously the endpoint was also discussed in that meeting. For example, for carcinoma in situ, complete response, clinical complete response, because the bladder remains intact in many patients, clinical complete response was a meaningful primary endpoint, also duration of response is also very important. So what is the durable clinical complete response in 1 year or 18 months is relevant. And when you have papillary tumors like Ta or T1 with CIS, for papillary tumors, event-free survival becomes one of the key endpoints and you look at it over time, for example, at 12 or 18 months, what is the event-free survival? So clinical complete response, duration of response, event-free survival, depending on the CIS presence or papillary tumors, I think these are endpoints that have allowed us to design those trials, get those agents approved.
Now, the question going forward, Monty, and we can close with that is, since now we have the embarrassment of riches, many more options available compared to where we were 6 and 7 years ago, is now the time to do randomized trials? And if we do randomized trials, which can be the control group? Which of those agents should be allowed to be part of the control group? These are ongoing discussions right now with the NCI, with other agencies, cooperative groups, trying to design those trials and move forward from here.[GC3]
Dr. Sumanta (Monty) Pal: Well, it's awesome to have you here on the program so we can get some early looks into some of these conversations. I mean, clearly, you're at the table at a lot of these discussions, Petros. So I want to thank you for sharing your insights with us today. This was just tremendous.
Dr. Petros Grivas: Thank you, Monty. You know, patients in the center, I just came back from the Bladder Cancer Advocacy Network meeting in Washington, D.C., and we discussed all those questions, the topics you very eloquently mentioned and asked me today, and patients gave us great feedback and patients guide us in that effort. Thank you so, so much for having me and congratulations for the amazing podcast you're doing.
Dr. Sumanta (Monty) Pal: Oh, cheers, Petros, thanks so much.
And thank you to the listeners who joined us today. If you really like the insights that you heard on this ASCO Daily News Podcast, please rate, review, and subscribe wherever you get your podcasts. Thanks, everyone.
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.
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Disclosures:
Dr. Sumanta (Monty) Pal:
Speakers' Bureau: MJH Life Sciences, IntrisiQ, Peerview
Research Funding (Inst.): Exelixis, Merck, Osel, Genentech, Crispr Therapeutics, Adicet Bio, ArsenalBio, Xencor, Miyarsian Pharmaceutical
Travel, Accommodations, Expenses: Crispr Therapeutics, Ipsen, Exelixis
Dr. Petros Grivas:
Consulting or Advisory Role: Merck, Bristol-Myers Squibb, AstraZeneca, EMD Serono, Pfizer, Janssen, Roche, Astellas Pharma, Gilead Sciences, Strata Oncology, Abbvie, Bicycle Therapeutics Replimune, Daiichi Sankyo, Foundation Medicine, Bicycle Therapeutics, Eli Lilly, Urogen Pharma, Tyra Biosciences
Research Funding (Inst.): Bristol-Myers Squibb, Merck, EMD Serono, Gilead Sciences, Acrivon Therapeutics, ALX Oncology, ALX Oncology, Genentech
Travel, Accommodations, Expenses: Gilead Sciences