Clinical Trials in Genitourinary Cancers: MAGNITUDE, PROOF 302, CYTOSHRINK

December 21, 2020
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In today’s podcast, members of the Cancer.Net Editorial Board discuss 3 clinical trials that are exploring new treatment options across prostate, bladder, and kidney cancer. This podcast will be led by Dr. Timothy Gilligan, Dr. Neeraj Agarwal, Dr. Tian Zhang, and Dr. Brian Shuch.



ASCO: You’re listening to a podcast from Cancer.Net. This cancer information website is produced by the American Society of Clinical Oncology, known as ASCO, the world’s leading professional organization for doctors who care for people with cancer.

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. The mention of any product, service, organization, activity, or therapy should not be construed as an ASCO endorsement. Cancer research discussed in this podcast is ongoing, so clinical trials described here may no longer be enrolling patients, and final results are not yet available.  

Before any new cancer treatment can be approved for general use, it must be studied in a clinical trial in order to prove it is safe and effective. In today’s podcast, members of the Cancer.Net Editorial Board discuss 3 clinical trials that are exploring new treatment options across prostate, bladder, and kidney cancer.

This podcast will be led by Dr. Timothy Gilligan, Dr. Neeraj Agarwal, Dr. Tian Zhang, and Dr. Brian Shuch.

Dr. Gilligan is an Associate Professor and Medical Oncologist at the Cleveland Clinic Taussig Cancer Center. He has no relevant relationships to disclose.

Dr. Agarwal directs the Genitourinary Oncology Program at the Huntsman Cancer Institute at the University of Utah. He has served in a consulting or advisory role for Janssen and Bristol-Myers Squibb.

Dr. Zhang is an assistant professor of medicine at Duke University School of Medicine and is a medical oncologist at Duke Cancer Institute. She has served in a consulting or advisory role for Janssen and Bristol-Myers Squibb.

Dr. Shuch is the director of the Kidney Cancer Program at UCLA Health and the Alvin & Carrie Meinhardt Endowed Chair in Kidney Cancer Research at the institution. He has served in a consulting or advisory role for Bristol-Myers Squibb.

View full disclosures for Dr. Gilligan, Dr. Agarwal, Dr. Zhang, and Dr. Shuch at Cancer.Net.

Dr. Gilligan: Hi, I'm Dr. Timothy Gilligan from the Cleveland Clinic Taussig Cancer Institute. I'm joined today by Dr. Neeraj Agarwal from the Huntsman Cancer Institute and the University of Utah and Dr. Tian Zhang from the Duke Cancer Institute and Brian Shuch from the UCLA Institute of Urologic Oncology. Today, we're going to discuss 3 ongoing trials in prostate cancer, bladder cancer, and kidney cancer. As you may know, clinical trial are the way that doctors are able to find better treatment for diseases like cancer. Patient participation is vital for clinical trials. By participating in the clinical trial, you can directly help researchers develop better treatment, reduce side effects, and even reduce the risk of cancer altogether. The 3 trials we'll discuss today were chosen by members of the Cancer.Net Editorial Board Genitourinary Cancers Panel from the trials in progress abstracts that were presented at ASCO 2020 Genitourinary Cancers Symposium. Because these are ongoing clinical trials, final results from these studies are not yet available. I'd like to note that none of us have any direct involvement in any of these trials. To view our full disclosures, please visit the show notes for this episode on Cancer.Net. We're going to start with Dr. Agarwal and a study looking at prostate cancer, the MAGNITUDE trial. [A Study of Niraparib in Combination With Abiraterone Acetate and Prednisone Versus Abiraterone Acetate and Prednisone for Treatment of Participants With Metastatic Prostate Cancer (MAGNITUDE)] Dr. Agarwal, can you tell us a little bit about this study?

Dr. Agarwal: This is a large phase III trial of 1,000 patients. This trial includes patients who have progressive, metastatic, castrate-resistant prostate cancer and have never received any other systemic therapy for their castrate-resistant prostate cancer.

Dr. Gilligan: Why don't we clarify for listeners what we mean by castrate-resistant prostate cancer? Who are these patients?

Dr. Agarwal: When patients present with advanced prostate cancer which has [spread] to different parts of the body, that is called metastatic prostate cancer. And the most effective strategy, which is the backbone of treatment of these patients, is androgen deprivation therapy or castration therapy, which blocks the production of testosterone from the gonads. At this point of time, utilizing medical castration [with drugs] or surgical castration can effectively slow down the progression of cancer.

Dr. Gilligan: So these are patients who are already on first-line hormonal therapy to lower their testosterone level?

Dr. Agarwal: Yes. Once they start progressing on this first-line castration therapy, we call this state to be castrate-resistant prostate cancer. So this is the patient population which is having disease progression on first-line therapies for the advanced prostate cancer, and now, testosterone levels are low, but still, the prostate cancer is progressing.

Dr. Gilligan: So what's the current standard of care for this population of patients who are progressing on first-line hormonal therapy?

Dr. Agarwal: In the last 2, 3 years, the treatment of castration-sensitive prostate cancer, which is the newly diagnosed advanced prostate cancer we were just talking about, has changed dramatically. Multiple drugs which are being used, or were being used, in the castrate-resistant prostate cancer have moved to the setting of castration-sensitive prostate cancer. Having said that, many patients with castration-resistant prostate cancer have not yet received any of those drugs. So as an example, in this clinical trial, a patient could have received chemotherapy with docetaxel in the first-line therapy setting or a newly-diagnosed metastatic prostate cancer setting. But then when they have disease progression, the most commonly utilized medications are either abiraterone or enzalutamide, both are oral pills, we call them novel hormonal therapies. So those are still the backbone of treatment for castrate-resistant prostate cancer.

Dr. Gilligan: So for patients going on this study, what would the treatment be on the trial?

Dr. Agarwal: Patients will be randomized to treatment with abiraterone, which is a novel hormonal therapy, plus prednisone, which is utilized with abiraterone to negate the side effects of abiraterone, plus/minus a new class of drug known as a PARP inhibitor. And in this trial, the drug which is being used is called niraparib. Niraparib is a novel drug, a PARP inhibitor, and just to elaborate a little bit more on PARP inhibitors, this class of drug have recently been approved [to treat patients with] the later phases of castrate-resistant prostate cancer. So 2 drugs, olaparib and rucaparib, were recently approved by FDA in those patients who have had disease progression on novel hormonal therapy plus/minus docetaxel chemotherapy, so for pretty late phases of prostate cancer or castrate-resistant prostate cancer. In this trial, a PARP inhibitor is being moved upstream so that patients don't have to wait for disease progression or novel hormonal therapy or chemotherapy in metastatic castrate-resistant prostate cancer, and they will have the availability of this drug upfront in this setting of newly diagnosed metastatic castrate-resistant prostate cancer.

Dr. Gilligan: When this drug is used in the more advanced setting, it's limited to patients who have particular mutations. Is that the case in this study as well?

Dr. Agarwal: This trial is targeting the strategy to 2 different patient populations. So 1 patient population is that [in which the] tumor has defects or mutations in the DNA repair genes. We call them homologous recombination repair mutations. I put it simply, DNA repair gene mutations. So there is a cohort of patients, a group of patients, among these 1,000 patients, who will harbor DNA repair gene-related defects in the tumors. And there is another cohort of patients who do not have to have those defects, and we call them unselected patients. This trial is enrolling both groups of patients, and, in fact, the patients' unselected cohort has actually completed accrual. So the trial is now only looking at those patients who are harboring DNA repair gene-related defects in the tumors. Just to complete the story in this context, as you said, the drugs olaparib and rucaparib, which have already been approved in the later phases of castrate-resistant prostate cancer, they are only approved for patients who are harboring DNA repair defects.

Dr. Gilligan: So for the patients who can go on the trial now, who have these defects, the question this trial is asking then is, does it help to use this treatment earlier on rather than waiting until later?

Dr. Agarwal: Absolutely. So given these are oral therapies, reasonably well tolerated, better tolerated than traditional chemotherapies, it makes sense to move these oral pills to upfront or earlier settings where more patients can be candidates for these drugs which can be taken at home, and these patients don't have to have disease progression on chemotherapy to [receive] these medications. Just to complete, Tim, I just want to add that there are 2 endpoints of this trial. One is radiographic progression-free survival, which is the primary endpoint, and the secondary endpoint is overall survival and many other endpoints we'd like to see, like pain progression or toxicities and so on. Radiographic progression-free survival means how long these drugs or drug combination is able to contain the disease from progressing [or worsening] as detected by the scans. We hope that this trial will show delayed progression on the novel combination compared to abiraterone.

Dr. Gilligan: Thank you. So one last question, are there any known risks that patients should be aware of? What are the side effects of this class of medication?

Dr. Agarwal: Yes. Two major side effects. Every drug has side effect. And so do niraparib and abiraterone. So abiraterone is already approved for patients with metastatic castrate-resistant and castration-sensitive prostate cancer. So I'm not going to elaborate much on abiraterone. Regarding niraparib, this class of drug, including olaparib and rucaparib which I earlier mentioned, they have this class of side effects, which belong to this class of drugs. And 1 of the most common side effects is anemia, which is low hemoglobin, and which happens because these drugs can also slow down the replication of red [blood] cells. Other less common side effects are decrease in the platelet counts and decrease in the white cell counts. But they happen with much lesser degree compared to anemia. Another common side effect is nausea. Nausea and vomiting can happen, and we have to keep an eye on nausea and vomiting because the side effect can easily be prevented or treated with anti-nausea medications. There are many other side effects which are less common, and I won't get into them, but these are the 2 most common side effects, which are fortunately easy to handle in the clinic.

Dr. Gilligan: And I just want to repeat what you said before that there is accrual still going on for the study, but it's limited to patients who have particular mutations in their cancers.

Dr. Agarwal: Yes. So currently the study is not accruing for those patients who do not have those DNA repair general-related events. But it is still accruing patients, looking for patients who are known to have those mutations in the prostate cancer.

Dr. Gilligan: What proportion of patients with prostate cancer have these kinds of mutations?

Dr. Agarwal: Depending upon the study, I would say up to 20% of patients can have DNA repair gene-related defects in their tumors. So it is very important to bring this up with our clinical or medical oncologists who are treating patients with metastatic or advanced prostate cancer, and especially with approval of 2 drugs, it is very important that every single patient who is deemed to be a candidate for treatment with this class of drug, PARP inhibitor, undergoes comprehensive genomic profiling or simply speaking, mutation testing of their prostate cancer tumors.

Dr. Gilligan: Thank you. And I think that's worth emphasizing. This is an example of personalized cancer care based on the genomics of the individual's tumor which is happening more and more, and as Dr. Agarwal said, if you have metastatic prostate cancer, we are recommending a standard of care that people get genomic testing now. So this is an example of a step in that direction. So thank you, Dr. Agarwal.

Dr. Zhang, why don't we move on and talk about the bladder cancer trial that you were going to discuss, the PROOF 302, that also has a personalized genomic component to it, I believe. [Study of Oral Infigratinib for the Adjuvant Treatment of Subjects With Invasive Urothelial Carcinoma With Susceptible FGFR3 Genetic Alterations]

Dr. Zhang: In bladder cancer, we've come to a place where the genomic profiling is very important to find FGFR mutations or fusions, and this subset of patients that have FGFR mutations or fusions, these patients tend to have good responses to now standard of care treatments in the metastatic setting. And this particular trial is looking at using a drug called infigratinib in this patient population, specifically targeting that FGFR and inhibiting it. This is a trial in the adjuvant setting for patients who have urothelial cancer of either the bladder or of the ureters and upper tract who received surgery and then go onto this trial or treatment with infigratinib versus a placebo.

Dr. Gilligan: Can you spell out for our listeners who the group of patients are who are going to be eligible for the study?

Dr. Zhang: Sure. These are patients who have already undergone surgery for either their bladder cancer or an upper tract tumor. And so these are patients in that 4-month window after surgery, who have already had their surgeries, and it's either for patients who have had prior chemotherapy before their surgeries or not with higher-risk features defined based on each of those populations. But it is for a higher-risk patient population that have a higher risk for having disease recurrence and spread of their urothelial cancers after surgery. In this setting, we really don't have any approved adjuvant treatments. And so the point of this study is really to try to prevent disease recurrence.

Dr. Gilligan: I want to clarify 1 thing. My understanding was for these patients who have not had preoperative chemotherapy, they are not patients who were considered eligible for postoperative cisplatin-based chemotherapy since that is often used in the adjuvant setting. Is that correct?

Dr. Zhang: That's absolutely correct, Tim, and thanks for pointing that out. So if patients had not received preoperative chemotherapy, they have to be ineligible for cisplatin-based chemotherapy, which we would often recommend in the postoperative setting. But if they are not eligible for chemotherapy after surgery and have these higher-risk features, then they would qualify for this study.

Dr. Gilligan: I think it's important for patients to understand that because if considering going on this trial, the standard of care would be just to watch. And so what it's asking is, can we do something instead of just watching that would lower the risk of relapse or worse outcome with the cancer?

Dr. Zhang: Absolutely. I think we always try to recommend proven strategies first, and in this particular case, the recommendation for somebody who is a candidate for chemotherapy after surgery would still be to go with chemo first.

Dr. Gilligan: The genetic testing that will be done to determine eligibility for the study, can you say a little bit more about that?

Dr. Zhang: Sure. My understanding is that the study will take most genomic tests that are currently commercially available, but they have to fulfill the criteria of having FGFR mutations and/or fusions in the tumor in order to go on the study. So we often now will send the surgical specimens for genomic testing, especially in our higher-risk patients that are defined like the study defines. And so that particular patient population, because they're at higher risk for recurrence, we try to identify these FGFR mutations and fusions early on so that we can know whether the standard treatment for these patients would be an option later on.

Dr. Gilligan: Are there cost implications of that for the patients?

Dr. Zhang: Certainly, now some of the commercially available genomic testings are approved by insurance and are billable through insurance, but patients may be responsible for a copay. I want to add 1 more thing about the drug itself because I do think there's some interesting activity of infigratinib that has been published in the last year, and that is in the earlier-phase studies of infigratinib in the metastatic setting, in the more advanced urothelial cancer settings, we saw pretty high response rates as well as disease control rates, particularly in patients who had disease in the upper tracts, so in the ureters and above. And so I think it's promising and potentially very interesting to study this for patients who have had disease removal, and surgeries.

Dr. Gilligan: That's an important point for listeners to understand, that this is an exciting new class of drugs and in patients for whom this treatment is appropriate, we're seeing very good response rates in more advanced disease settings, and there's a natural progression. When we see it work in the advanced setting, we try to move it to an earlier setting to see if we see a similar or greater benefit. As Dr. Agarwal was saying about prostate cancer, we've found a number of times that using drugs earlier works better. This is another example of studying that to see if that's the case here.

Dr. Zhang: I absolutely agree.

Dr. Gilligan: What should listeners know about potential risks or side effects for this class of treatment?

Dr. Zhang: FGFR inhibitors like infigratinib have a class effect, and I think the main toxicities that we've come to see are skin toxicities and nail toxicities, as well as there are some eye toxicities as well. So particularly for patients who are going on these types of treatments, we often will recommend baseline eye exams, and then to follow them on treatment, particularly for any blurry vision or other vision changes that arise. And 1 of the class effects of these FGFR inhibitors is also to cause increases in phosphorus levels [in the blood], and that is due to their inhibition in the renal tubules to prevent phosphorus excretion. And so there was a recent publication also that for patients who develop high phosphorus levels, while getting infigratinib or these FGFR inhibitors, that these patients actually have potentially a higher response rate as well. So I think that has to be proven more in these bigger trials, but it's an interesting biomarker potentially for patients who might have good responses.

Dr. Gilligan: So for patients who had urothelial cancer resected or at high risk for relapse, this is an exciting new option for them, if they have the right genomic composition of the cancer and would not otherwise receive chemotherapy. So thank you for the summary.

Okay. So now we're going to talk about kidney cancer and the CYTOSHRINK discussion. [SBRT With Combination Ipilimumab/Nivolumab for Metastatic Kidney Cancer (CYTOSHRINK)] And we have Dr. Brian Shuch with us to discuss that. Brian, can we start off with who this study is designed for?

Dr. Shuch: It's really designed for patients with metastatic kidney cancer. Could be any type of kidney cancer, presenting with metastatic disease. We call that de novo metastatic disease. So they would have their primary tumor still in place in their kidney, with disease outside of that organ in other locations.

Dr. Gilligan: So these are patients with-- they have the tumor in their kidney, it's spread somewhere else, and they haven't had any other treatment so far? They haven't had any surgery or any drugs?

Dr. Shuch: Correct. These will be patients that are treatment-naïve that are going to start on their first course of treatment, which, in general, would be a discussion of either surgery or systemic therapy.

Dr. Gilligan: So at this point in time, what's the standard of care for such patients?

Dr. Shuch: We used to take every patient to surgery upfront. We call that a cytoreductive nephrectomy. Since we've had much better agents in recent years, and these agents have a lot of activity, we've done less upfront surgery as it appears that some patients may not benefit from racing off to the OR. So these are patients that generally would get started on systemic therapy first because this population, and this trial, has some risk factors for worse disease. We call that intermediate- or poor-risk features.

Dr. Gilligan: So these are patients who we would not normally do surgery on because it doesn't seem to help them, unlike some of the other patients who we do, the good-risk patients.

Dr. Shuch: Well, we are investigating that in other trials, but there are plenty of patients who are not going to run right to surgery, and these are the ones that we would consider deferring surgical management of the primary tumor. We would get started on systemic therapy, and we would reassess how they would be [treated] in the future, whether surgery was an option. But there are emerging entities such as radiation, which we'll discuss, which could be another exciting approach.

Dr. Gilligan: So if a patient that was going to go on this trial didn't go on the trial, they would most likely be treated with medications at this point in time. Is that correct?

Dr. Shuch: Correct. There'd be standard medications which are available off clinical trial which are right now dual therapy with 2 immune agents, or an immune agent and a tyrosine kinase inhibitor. So these are standard drugs that are available off a trial. Patients get started on therapy, and we see how they do later for other treatment options.

Dr. Gilligan: So what is this study looking at? What's the new thing that it's introducing and the question that it's asking?

Dr. Shuch: So kidney cancer, 10, 15 years ago, there was never really any role for radiation except for very rare circumstances. But now we have newer types of radiation where we're doing radiation at much higher doses in shorter time periods, and we call that ablative dosing. And as we've used that in brain and bone lesions for kidney tumors, and with excellent efficacy, with great—what we call local control. That has been applied to the primary tumor as well, and that's been used in many fields, that type of alternative radiation approach. We call that stereotactic radiation or the term radiosurgery, which is really a misnomer. It's just high dose ablative radiation, and it can be used in the primary tumor as a way maybe to kill the tumor.

Dr. Gilligan: And what is that outcome that we're hoping for? How would success be measured if this trial is positive?

Dr. Shuch: Well, we do know for small tumors, it seems to be a fairly effective measure at stopping tumors from growing. In this situation, it's employed after initiation of systemic therapy. Half the patients will get this radiation therapy to that primary kidney tumor, and the goal is to see if it delays progression of the disease. What we call progression is generally growth of lesions that are existing, or development of new lesions, new spots around the body. So the goal is to see if radiation with the standard immune therapy would delay progression versus the standard immune therapy alone.

Dr. Gilligan: So just to reiterate then, I guess for patients who are on this trial, normally they would get treated just with the immunotherapy or combined immunotherapy and targeted therapy, and what we're asking here is, if we give them radiation too, do they do better? Do we delay progression of disease? That we keep things under control longer, that they live longer?

Dr. Shuch: Correct. Obviously, living longer is a major factor. That's another objective of the study, but the study doesn't have enough patients or enough power to kind of detect that. The real issue is, does it delay the progression? And progression is important because if you have progression, often patients will progress to another line of therapy, meaning disease is not under good control.

Dr. Gilligan: Are there any known risks from the radiation therapy the patient should be aware of?

Dr. Shuch: Depending on the size of the tumor and the location to other organs, radiation could have some local effects. Obviously, there's some potential damage to surrounding structures such as the skin. There's some radiation that potentially could stray into other surrounding organs like the duodenum on the right side or the liver, the colon, small bowel, the ureter. And those organs generally can have some degree of toxicity. Generally, it's self-limiting with minor long-term effects, but we haven't done this for many, many years because it's a newer emerging modality. We do believe it's safe with large studies of smaller tumors, but patients do need to be aware that there could be some local irritation from radiation.

Dr. Gilligan: Is this trial still open to patients?

Dr. Shuch: So this is a trial based out of Canada by 1 of their cooperative groups in Ontario. It's a small study - only 78 patients - that opened this year. In discussion with the investigators, this study is accruing well, but it is anticipated to be open for another year. Because they're looking at what's called progression-free survival, we're hoping we can have results of this study within the next 2 years. Obviously, it is something open only to Canadian residents right now, but I will tell you that there are other groups in the U.S. that are considering similar types of trials in the Cooperative Group Network.

Dr. Gilligan: There's 1 final point I wanted to give you an opportunity to clarify for our listeners who may not be familiar with the idea of cytoreductive nephrectomy or cytoreductive treatment. So this is a treatment where we are targeting the primary tumor, even though there's other cancer elsewhere in the body that we can't remove. Can you just talk a little bit about the rationale for that, and why we're doing that?

Dr. Shuch: Historically in kidney cancer, when we had no effective therapy, we would have this phenomena: we removed the big bulky tumor, and 1% to 2% of patients would have their distant sites shrink, okay? And whether that was related to an immunologic phenomenon, maybe the tumor was secreting something, or maybe it was just overwhelming the body's defense mechanisms because they had a big tumor making them sick, it was kind of unclear. But we did know in larger trials with immune therapy, when we gave immune therapy in the old days, the agents like interferon-alpha or IL-2, we gave these agents, the primary tumor wouldn't shrink. Sometimes the distant sites could shrink, but it would not lead to what we call complete responses. So anyone who wanted to have a home run therapy where it was hoping to cure them, they would have their primary tumor removed first, and then they would potentially have the systemic immunotherapy. We've done 2 trials which showed, early in the 90s, that if you were able to remove the primary tumor and treat with these older immune agents, patients would have better outcome. And as those agents were pretty ineffective, we thought the survival benefit was really due to removing the big bulky primary. So the rationale for this trial is, you're not removing the big bulky primary tumor, you're potentially killing it with radiation, so you're overall reducing the burden of disease. There are some theoretical benefits of radiation where you kill tumors, and the tumors release what we call antigens. Basically, I try to explain that to people it's basically like a patch. Like a Boy Scout or Girl Scout has a new patch on them, and you'd recognize them as maybe having a badge of like hunting. So the tumor potentially might expose some of these bad patches, and the immune system might wake up and recognize them, and hopefully, then attack other sites of disease. So, again, the goal is either you're reducing the overall burden of disease in the body, or you're maybe allowing the body's immune system to kick in because you're killing a [tumor] there. We're just not sure really the mechanism, but it's been long used in kidney cancer, this idea of reducing the burden of disease.

Dr. Gilligan: Thank you for listening to this podcast. There are many different clinical trials currently enrolling people with genitourinary cancers. If you're wondering whether participating in a clinical trial might be right for you, please talk to your health care team.

ASCO: Thank you, Drs. Gilligan, Agarwal, Zhang, and Shuch.

Visit to learn more about participating in clinical trials. All treatments have side effects—please talk to your health care team about possible side effects to watch out for.

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