Clinical Trials As a Prostate Cancer Treatment Option | What You Should Know

Katherine Banwell:

Hello and welcome. I’m Katherine Banwell, your host for today’s program. Today we’re going to discuss prostate cancer research advances and the role of clinical trials and moving treatment developments forward. Before we meet our guest, let’s review a few important details.   

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Well, let’s meet our guest today. Joining me is Dr. Sumit Subudhi. Dr. Subudhi, thanks for being with us. Would you introduce yourself? 

Dr. Subudhi:

Hi. I’m Sumit Subudhi. I’m an associate professor in the GU Medical Oncology department at MD Anderson Cancer Center. And I exclusively treat patients with advanced prostate cancer. And I’ve been doing it for about a decade. 

Katherine:

Thank you. I’d like to begin with an update on prostate cancer research. Would you walk us through the newer classes of treatments that are showing promise? 

Dr. Subudhi:

Yeah, in clinical trials, there are classes of drugs known as androgen receptor degraders. And so, the androgen receptor is a protein that basically is the mouth of the prostate cancer. That’s how I like to describe it. And it actually allows testosterone, which is the food, to be eaten by the mouth, and it actually helps the cancer grow. 

And what these drugs do is they actually degrade or break down the mouth of the cancer. And, therefore, it starves the cancer to death, and that’s actually the concept. And they seem to be showing some exciting activity in clinical trials, especially in those patients who are resistant to the second-generation hormonal drug that you may have heard of already, such as enzalutamide (Xtandi), apalutamide (Erleada), and darolutamide (Nubeqa). So, I think is something that we’re looking forward to seeing more data on. 

Another class of drugs are antibody drug conjugates or ADCs.  

And these are what I think of as heat-seeking missiles. So, one part of the drug actually recognizes the cancer, and the other part of the drug actually has a payload that sort of releases a bomb or sort of like chemotherapy-type agent right where the cancer’s located and kills the cancer in that way. And we’re seeing some great clinical activity in prostate cancer with this class of drugs. 

And then the final one is bispecifics, and in particular T-cell bispecifics. So, T cells are part of the immune system that actually help kill the cancer.  

And, unfortunately, prostate cancer, like some other cancers like pancreatic and glioblastoma, have few T cells inside it. And, therefore, a lot of the immunotherapies that many people have heard about, such as ipilimumab (Yervoy) and pembrolizumab (Keytruda), they’re not very responsive in patients with prostate cancer. And it’s because there’s few T cells in prostate cancer.  

What the T-cell bispecifics do is they actually have one part of the drug that actually recognizes the cancer and the other part that recognizes T cells. So, like a bulldozer, it brings T cells right into the prostate cancer and helps kill the cancer that way.  

Katherine:

Now there are some inhibitors as well. Is that correct? 

Dr. Subudhi:

Yeah. So, the immune checkpoint inhibitors have been around for a while. And, basically, in combination, they seem to be more effective in prostate cancer. But when given alone as monotherapy, they’re less effective. 

Katherine:

Are these treatments specifically for patients with advanced prostate cancer? 

Dr. Subudhi:

All of them are actually in trials in patients with advanced prostate cancer. And I define advanced prostate cancer as either having metastatic disease, meaning the cancer has spread to other parts of the body outside of the prostate.  

Examples include lymph node, the bone, the lung, the liver. But there are so few trials in patients with locally advanced prostate cancer. What I mean by that is they have high-grade prostate cancer, but it’s local, or it’s just in regional lymph nodes. And some of these classes of drugs are being evaluated in that setting as well. 

Katherine:

Let’s shift to talk about your research. What are you excited about right now? 

Dr. Subudhi:

So, my research focuses on immune checkpoint therapies, which are the inhibitors that you were referring to and understanding how to make them work better in prostate cancer. 

And we’re finding out that in prostate cancer there’s about 20 to 25 percent of patients that appear to respond to this type of treatment. But these are patients that don’t have a lot of bone metastases. And these immune checkpoint inhibitors are given in combination. So, they’re not given alone. They’re given with either a combination of anti-CD34 and anti-PD-1 or some other form of that. 

Katherine:

Prostate cancer research really can only move forward through clinical trials and patient participation in those trials. Can you briefly explain what a trial is for people who may not be familiar with the term? 

Dr. Subudhi:

That’s a great question. My own father has prostate cancer. And he had the same exact question when he started his journey in that. 

And so, what I explained to him is that clinical trials are experiments. They’re experiments that are done in our patients.  

So, they’re drugs that are thought to mechanistically kill the cancer cell or at least change the environment around the cancer cell to help people live longer. But these drugs were actually tested in mouse models or in tissue models. And we don’t know if they actually work in patients. 

And so, in clinical trials, we’re actually testing whether these drugs are safe and whether they’re efficacious or beneficial to our patients. So, I want to be very clear. When patients go on clinical trials, we don’t know if it’s going to work on them. And that’s something that they should know that they’re showing a lot of courage and risk in joining these trials.  

But the other point I want to make is that every standard of care drug that is out there actually went through the clinical trial process, and they were approved because they showed benefit in a group of patients. 

Katherine:

Well, how can a prostate cancer patient benefit from participating in a trial? 

Dr. Subudhi:

One of the key benefits is that you get access to drugs that may actually prolong your life or even cure you and that you wouldn’t have access to in trials.  

And so, some of my patients, unfortunately, they’ve exhausted all the standard of care choices that are out there. And the trial’s the only option left versus leaving it up to natural causes of demise from prostate cancer. And so, clinical trials give other opportunities to potentially live longer and have a great quality of life. 

Katherine:

So, they could offer some hope. 

Dr. Subudhi:

Definitely. As far as I’m concerned, yes. And, actually, with my patients, I try to not wait while they’ve exhausted all the treatments to start them on clinical trials, because I feel like we may be able to save some of these treatments in our back pocket for when they’re too exhausted to be coming to our clinic so often. And so, I like to actually try to get them enrolled in clinical trials early on in their journey with prostate cancer. 

Katherine:

I’d like to define some clinical trial terminology to help patients further understand the process. Let’s start with the phases. What occurs during each phase?  

Dr. Subudhi:

So, great question. Phase I is the safety phase. So, all we’re trying to do is find the right dose of the drug that is actually safe to give in the patients. And we’re looking for the maximum tolerated dose. And once we find that dose, then we use that dose to go to Phase II of the trial. And Phase II trials are looking at efficacy. So, looking to see whether the trial is giving you any clinical benefit, meaning the cancer’s shrinking or even disappearing. 

Katherine:

Go on.  

Dr. Subudhi:

And then the third phase is Phase III where you’re testing the current drug, experimental drug, to either standard of care or to a placebo to see whether or not you get a benefit, either a progression-free survival benefit or overall survival benefit. And so, those are the three phases of clinical trials.   

Katherine:

What are the different types of clinical trials? 

Dr. Subudhi:

So, they’re controlled trials. Actually, I should back up. So, there’s open-label trials where everyone that enrolls in the trial will get the experimental drug. So, there is no control arms in these trials. Then there is the control trials where you can either get the drug, or you may get a placebo or standard of care drug.  

There are some trials that allow for crossover, meaning that if you’re in the placebo or standard of care arm, if your cancer progresses, you can actually cross over and get the experimental drug. But I just want to be clear that not all clinical trials have crossover. And if you’re in a control trial, I think that’s an important question to ask your doctors about that. 

But the reason why we do the control trials is that we’ve learned that using historical controls – for example, we’re doing a lot of combination studies with chemotherapy, such as docetaxel (Taxotere), which was FDA-approved in 2004. So, if we’re using historical data from almost 20 years ago, it’s not the same thing as our patients that are being treated with docetaxel now, because their treatment landscape has changed so much, and our patients have changed so much. 

And so, for that reason, control trials give us a better sense of how effective this experimental drug is doing as opposed to comparing it to a historical perspective. 

Katherine:

What other types of clinical trials are available? 

Dr. Subudhi:

So, there are a few other options. So, we talked about open-label where everyone’s guaranteed to get the drug. We talked about a controlled study where you will either get one drug or another. And another type is a randomized trial where a computer decides whether or not you’re going to actually get one drug versus another. It’s not your doctor because a lot of people think that I’m making that decision, and I’m not. It’s actually a random computer. 

And some trials have 1:1 ratio, meaning a 50 percent chance that you’ll get the experimental drug versus the control drug. But other trials have 1:2 ratio or 1:3 ratio. So, that’s something that, again, you have to ask your physician of how these trials are being randomized. 

Katherine:

Well, in a randomized clinical trial, the patient isn’t going to know what drug they’re being given. 

Dr. Subudhi:

Actually, that’s not true. 

Katherine:

Oh, it’s not. 

Dr. Subudhi:

So, you bring up a great question. So, there’s a double-blind randomized clinical trial where not only the patient doesn’t know, but even the physicians and the nurses. No one except for the pharmaceutical company that’s running the trial actually knows who’s actually getting which drug. And it’s only towards the end of the trial that we unblind, and then we share that information. Well, the pharmaceutical company first shares it with the medical team who then shares it with the patient. 

Katherine:

I see. Are there other common clinical trial terms that you think patients should know about and understand? 

Dr. Subudhi:

I think for now those are… 

Katherine:

…they’re the most important?  

Dr. Subudhi:

I think to me those are the most important. And I think that sometimes too much information can bog us down.  

Katherine:

Well, speaking of information, there is a lot out there, some of which may not be very reliable. And that could lead many patients to having misconceptions about clinical trials. Let’s walk through a few common concerns we’ve heard from our community about trials. 

One frequent question is – will I receive a placebo instead of a real treatment? And, first, I’d like you to define placebo. And should this be a concern for patients? 

Dr. Subudhi:

Right. So, placebo is a drug that looks similar to the experimental drug. For example, if the experimental drug is a blue pill, then the placebo will be a blue pill. But it will be a pill that should have no known biological activity.  

If the experimental drug is given intravenously and you get it in a liquid bag, then the placebo will also come in a liquid bag. So, it will look the same. And that’s why both the medical team as well as the patients or their families will not know which drug the patients have received, meaning the experimental drug or the placebo. But the placebos are meant to not have any biological activity. 

Katherine:

So, it shouldn’t be a concern to patients then.   

Dr. Subudhi:

Well, the concern that most of my patients share with me when they hear about placebo-controlled trials is, “Well, if I’m not going to get the experimental drug, why should I do this? I mean what benefit does it have for me?” And so, I tell them that one of the benefits is that we are watching you very carefully. 

Because we don’t know sometimes which drug you’re getting. But in some control trials, like a randomized control trial, we will know because I’m not blinded.  

If you’re in the arm that’s only getting chemotherapy, well, you know you’re not getting an oral pill. So, it’s very clear to the patient what they’re getting. But if they’re getting an oral pill that’s a placebo, we’re watching them very carefully.  

So, we’re watching the patients very carefully in these placebo-controlled trials. And they’re coming in often so that we’re not going to miss any devastating things happening from the cancer. In fact, we’ll pick it up earlier than if they were just getting a standard of care outside of a trial. And for that reason I tell that my patients, “Don’t be worried.” And I always make sure that I have a backup plan. 

So, the backup plan is either they’re going to cross over, meaning the trial allows for them to cross over to get the experimental drug. Or I have another trial that I know that they will qualify for. Or the third alternative is that I actually have a standard of care drug that I’m ready to give them the second I have it so that they don’t have to have those concerns.