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Dr. Tanya Dorff On Chemotherapy For Prostate Cancer

Dr. Tanya Dorff is a medical oncologist who serves as associate clinical professor in the Department of Medical Oncology & Therapeutics Research and the Head of the Genitourinary Cancers Program at City of Hope, a research and treatment center for cancer based in Duarte, California.

Dr. Dorff’s research interests in prostate cancer range from clinical trials in PSA-recurrent prostate cancer to the role of fasting in chemotherapy tolerability to CAR T cells that are primed to target prostate cancer tissue.

She leads one of the largest clinical trial portfolios in genitourinary cancers.

Dr. Dorff spoke with Prostatepedia about chemotherapy for prostate cancer.

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Why did you become a doctor?

Dr. Tanya Dorff: When I was around three years old, I decided that what I wanted to do with my life was help people. And being a concrete thinker as a three-year-old, I felt like being a doctor was the only way to do that.

Have you had any patients over the years who have changed how you view the art of medicine or how you view your own role?

Dr. Dorff: There are so many who have influenced me. My mom had a rare form of leukemia when I was in college. It was uniformly fatal. But they had recently developed a new treatment with the discovery of a specific translocation of the retinoic acid receptor for acute promyelocytic leukemia (APL). All-trans retinoic acid was developed, and she received it as experimental (at the time) through compassionate access. She was cured, and she’s still alive today. That influences how I feel about clinical trials and translational science. If we hadn’t understood that biology, we couldn’t have designed the overwhelmingly effective treatment.

How is chemotherapy used today for men with prostate cancer?

Dr. Dorff: When I started treating prostate cancer, chemo was pretty much our only tool besides standard hormone therapy. It worked, but it was sort of end-of-the-line. People didn’t tolerate it very well, in part, because we used it in really advanced cases. Then, the drugs like Zytiga (abiraterone) and Xtandi (enzalutamide) came out, dramatically improved the situation for prostate cancer patients, and chemotherapy got pushed later and later.

The CHAARTED study was presented five years ago. That study showed that using chemotherapy early with the initiation of hormone therapy dramatically improved survival, above and beyond using it later. About 75% of the patients on the control arm got the chemo when they became resistant, so it was a pretty good experiment of now versus later, and not now versus never. To see that just using it early added an extra year or more of life for these men was really profound. That reinforced the strong role chemotherapy has in this disease.

With which other kinds of agents is chemotherapy frequently combined?

Dr. Dorff: Combinations with Taxotere (docetaxel) have never yet been successful in prostate cancer. There was Taxotere (docetaxel) with a high-dose Vitamin D, which was not only negative in that it failed to improve outcomes, but patients who received the combination actually fared worse. There was Taxotere (docetaxel) with Revlimid (lenalidomide), Taxotere (docetaxel) with atrasentan, Taxotere (docetaxel) with GVAX… All of these combinations have failed.

One of the ASCO presentations that prostate cancer physicians might remember most vividly is a slide presented by David Quinn in his presentation of the negative results of the SWOG S0421, the study of Taxotere (docetaxel) alone or with atrasentan. He showed a slide of a graveyard, implying that any drug tried in combination with Taxotere (docetaxel) is doomed to fail.

Why do you think that is? Is it just that the combination is too toxic?

Dr. Dorff: I don’t know. I don’t think it’s too toxic. All of these combinations go through safety before they go into Phase III, and you can combine them safely. I do not understand why combinations fail. Maybe it goes back to biology. Why would the combination succeed? You want something that makes the chemo work better, or you want the chemo to make the drug work better. That’s where we should probably start when planning combination studies. Even then, things that look good in early testing can fail in Phase III, so in some cases it may be that we need to sub-classify patients in order to design more successful trials.

Maybe a more interesting question when we’re talking about combinations is: how do we get the best use of the chemo and do the least damage to the patients?

At University of Southern California, we started a study looking at a fasting-mimic diet to make the Taxotere (docetaxel) better. We found preliminary evidence that fasting prior to chemotherapy reduced toxicity, and I envision that could have two specific benefits in men with prostate cancer who might get Taxotere (docetaxel).

One might be that if we could mitigate toxicity, more men would actually receive it. There was a lot of therapeutic nihilism out in the community about how chemotherapy doesn’t work so well for prostate cancer, or that these older patients can’t handle it. If we could ratchet down the toxicity, maybe more prostate cancer patients would actually get chemo.

The second benefit might be that if we could reduce toxicity to normal host cells, we would be more likely to get in full doses on time, which might make it work better against the cancer versus what happens now, which is that we frequently dose-reduce and dose-delay because of toxicities. The fasting-mimic diet study is still ongoing but these are the outcomes I was hoping for when designing it.

How long are they fasting before they start the chemo? What does that look like?

Dr. Dorff: They fast for 48 hours on a fasting mimic diet, which means they get vegetable broth and an energy drink. So, it’s a liquid, low calorie diet. It’s hard, so that’s part of why the study is still ongoing.

In our earlier trial, in which we did fasting with platinum chemo for up to 72 hours (48 before and 24 after the chemo dose), people really swore by it. They really felt like they had so much less toxicity compared to chemo cycles in which they didn’t fast.

With the fasting mimic diet (created by L-Nutra), because it’s not pure fasting, we extended it to three days before chemo. The first day is a fairly robust number of calories, just plant based and with specific amino acids left out, which is felt to be part of the effect. Then there’s the two days before chemo with lower calories, and one day after. After fasting or the fasting-mimic diet the body needs a bridging diet for the first meal, and the L-Nutra regimen also included supplements to replenish the body.

If someone reading this is interested in participating, can they contact you directly or should they contact someone else?

Dr. Dorff: Sure, they can contact me directly at tdorff@coh.org. But the trial is going on only at USC, so they may wish to contact the clinical trials office at USC or the medical oncology group at USC.

Are you combining diet with chemo instead of another agent?

Dr. Dorff: Yes.

What kinds of side effects can patients expect from chemotherapy? What are you hoping to reduce?

Dr. Dorff: One of the most concerning side effects is the peripheral neuropathy, which can become permanent, but I don’t want to scare any readers.

Can you explain what that is?

Dr. Dorff: It’s damage to the small nerves out in the fingers and toes that can manifest as numbness or pins and needles, burning kinds of discomfort. That can be permanent.

Is there anything patients can do before or during getting chemo to reduce the likelihood of that happening?

Dr. Dorff: Not that we know of.

There’s no way to predict who might suffer from that or not?

Dr. Dorff: It’s not a complete no. We know patients who already have some preexisting neuropathy, whose nerves are already damaged, are more susceptible, for instance patients with diabetic nerve damage. That’s one reason we might try to get them Jevtana (cabazitaxel) instead of Taxotere (docetaxel) because Jevtana (cabazitaxel) doesn’t impact the nerves in the same way. I’m not sure if that’s what patients worry about, but that’s one of my number one concerns because I’ve seen patients a few years after chemo who are still vexed by the neuropathy.

If Jevtana (cabazitaxel) doesn’t result in neuropathy, why wouldn’t you use that agent over Taxotere (docetaxel)?

Dr. Dorff: Because insurance typically won’t cover it. Head-to-head, they were compared in the FIRSTANA trial, and they were equally effective; one wasn’t much better than the other. So, insurance companies can say that Jevtana (cabazitaxel) is not more effective; it’s equally effective. Taxotere (docetaxel) is a fraction of the price because it’s off-patent, and Jevtana (cabazitaxel) is actually approved specifically in post-Taxotere (docetaxel) patients, so it’s off-label to use it first-line. You can make a case when you have a guy with neuropathy, but even if you have a guy without neuropathy, you sure would like to leave him without neuropathy at the end of his treatment.

We start to see the neuropathy around dose five. If you stop, it’s more reversible, but if you keep going, that’s where it can become permanent, and so again, when we’re getting to how we can enhance the efficacy, if we could get more doses in without being limited by neuropathy, maybe we would do better with the drug, or maybe we just avoid the neuropathy, have equal efficacy and patients suffer less. There’s two ways we can win.

Equal efficacy and side effects are a huge issue for men.

Dr. Dorff: Patients really worry about hair loss. I don’t think we’re impacting that with the diet, unfortunately. That is reversible. They also complain about the taste changes and mouth sensitivity because that really impacts eating.

Does that go away once chemotherapy is finished, or does that linger after?

Dr. Dorff: That goes away.

It’s just while they’re getting chemo that they lose sense of taste?

Dr. Dorff: Yes, but it’s a long time to not be able to taste.

And the hair loss only happens while they’re getting chemo, too? It comes back?

Dr. Dorff: Yes, it grows back.

What combinations with Taxotere (docetaxel) do you think will work best?

Dr. Dorff: The ongoing combinations that I think people are still interested in are platinum with taxane and carboplatin with Jevtana (cabazitaxel). That’s an important combination for the more aggressive variants.

Part of how we think Taxotere (docetaxel) chemotherapy works is that it interferes with antigen receptor (AR) translocation in the cell to the nucleus, because the microtubules are needed for that. It still may be more for patients whose cancer is using a lot of AR signaling whereas platinum is more for cancer that might not be as dependent on that mechanism. That combination is pretty important.

There are some other biologics being studied together with Taxotere (docetaxel), but I’m not sure that those will be successful. There’s Taxotere (docetaxel) with immunotherapy, but we have the negative GVAX trial that tried combining vaccines with Taxotere (docetaxel). We are also combining it with Xofigo (radium-223), which is a little interesting, but I don’t know why those agents would necessarily help each other. Again, when you’re looking at a combination, it’d be nice if there were a reason to expect synergy.

What about favorite sequences?

Dr. Dorff: We know that after you’ve had Zytiga (abiraterone) or Xtandi (enzalutamide), you can induce the androgen receptor splice variants such as AR-V7. These are associated with less responsiveness to Zytiga (abiraterone) or Xtandi (enzalutamide). Patients might want to go from Zytiga (abiraterone) straight to Xtandi (enzalutamide), but we know there’s a lower likelihood of success, and we know AR-V7 is a big part of that. If we sequence in chemo, since they’ve shown that AR-V7 positive patients still benefit from chemo, I view the optimal sequence as Zytiga (abiraterone) or Xtandi (enzalutamide), followed by wiping out the AR-V7 population with a chemo drug, and then going to Zytiga (abiraterone) or Xtandi (enzalutamide) next. We don’t know for sure if that’s what happens when we use that type of sandwich approach, but it has theoretical appeal, and that’s how I talk to patients about it. The other way to go is a clinical trial, especially for combination with Zytiga (abiraterone) or Xtandi (enzalutamide).

What about the side effects profile when you do those kinds of sequencing?

Dr. Dorff: Hormone drugs like Zytiga (abiraterone) and Xtandi (enzalutamide) have much better side effect profiles, generally speaking, but the chemo side effects are largely reversible, and we tell patients that it’s not forever. There are good days and bad days, so it’s important to note that most people are not feeling bad every single day that they’re on the chemo. I don’t think the side effects vary based on sequence.

Some of my colleagues feel that when they use chemotherapy up front like in the CHAARTED study, they see more side effects if they start the chemo right away, but they see fewer side effects if they wait a month or two into the hormone therapy to add the chemo.

Is that because the patients become used to the side effects and learn how to manage them before you add something else?

Dr. Dorff: No, because the side effects are totally different between the two treatments. This is speculative, but I think you debulk. I think that part of the reason people get a lot of chemo side effects is that when we’re killing a lot of cancer there’s a big inflammatory reaction. You can feel sick from it, and we see that anecdotally in certain patients. If you can debulk the cancer a little bit with a couple months of hormone therapy, and then give the chemo, it might be better tolerated.

That’s interesting. So as the cancer’s dying, it throws off some kind of signal?

Dr. Dorff: It does. There’s a lot of dead stuff that has to be cleared by the body, and maybe that means it doesn’t have as much attention to do the healing that it needs to do with the chemo. I don’t know; that’s purely speculation.

Is there anything else you think men should know about chemotherapy for prostate cancer?

Dr. Dorff: First and foremost, chemo is effective. People downplay the role but CHAARTED really showed us that this is a good tool. We are working on tools that have fewer side effects. I’m working on whether diet can help mitigate side effects, and other people are looking at things like exercise, but the bottom line is that chemo is a good tool.

But still some patients draw a line in the sand and say they’ll never receive chemo because they’ve seen other patients getting chemo for other cancers. The chemo we use for other cancers is different than what we use for prostate, and every person’s reaction to chemo is different. Of course, you can’t erase that impression that’s made on you when you see someone who you care about struggling through chemo, but it doesn’t mean that’s what your experience is going to be.

Your doctor’s job, and your oncologist’s job, is to make it livable, to allow you to still do the things you want to do and to keep you safe and healthy through your chemo. There are tricks up our sleeves that we use to make that happen.

Sometimes patients are surprised to hear that they can actually feel better on chemo.

Why would that be?

Dr. Dorff: Because sometimes the cancer’s driving their side effects. It’s a catch-22. There are patients who might want to wait until they’re feeling better to get chemo, but if they’re feeling bad from the cancer, it’s really the chemo that’s going to make them feel better.

I have patients who’ve been unable to eat, in too much pain to really get out and do anything, and when they start chemo, they feel better, they eat better, they have more energy, and they can do more. If you take someone with no cancer symptoms, sure, the chemo’s going to make them feel worse. But if you take somebody with cancer symptoms, they may actually feel better.

That’s interesting because there’s this whole cultural perception of chemo as being catastrophic. The idea that chemo would make you feel better seems bizarre, but it makes sense the way you explain it.

Dr. Dorff: Yes, I think a lot of patients are shocked to hear it, and I think that’s a good thing to put out there.

Do you have any suggestions for men as to how to handle side effects before going into it?

Dr. Dorff: Communication with your doctor is the way to be successful in your chemo. A lot of people don’t want to bother the doctor, or they want to tough it out, but the earlier they tell the doctor that there’s a side effect, the easier it is for the doctor to intervene and reverse it. There’s no medal at the end of chemo for not having had to take a treatment for a side effect or not having called the doctor. Just pick up the phone and call. That’s how your doctor can do their best by you, and how you can be most successful with your treatment.

Aside from that, staying active is really important. Getting out and walking, even if you’re not exercising per se, but just moving around and not being sedentary is important for circulating the blood. We don’t want you to get a blood clot during chemotherapy because you’re not moving. It helps you expand your lungs, so maybe it can help keep your respiratory tract and heart healthier. Go into chemo as fit as possible, and try to maintain activity and mobility during treatment.

Read the rest of this month’s conversations about chemotherapy for prostate cancer.


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How You Can Participate in Genomic Research

Dr. Eliezer Van Allen, Assistant Professor of Medicine at Harvard Medical School, a clinician at Dana-Farber/Partners Cancer Care, and an Associate Member at the Broad Institute of MIT and Harvard, focuses on computational cancer genomics, using new technology in precision medicine, and resistance to targeted prostate cancer therapies.

Prostatepedia spoke with him about how even those of you in remote areas can participate in nationwide genomic research study for men with advanced or metastatic prostate cancer.

What is it about medicine and caring for patients that keeps you interested and engaged?

Dr. Eliezer Van Allen: There are two answers to that question. One, the scientific answer, is that it’s been so remarkable to see how quickly advances that we’ve learned from studying patients with cancer have immediately translated into the clinic and have impacted my patients’ lives. It’s impacted people I don’t know, and that cycle of innovation is becoming quicker. It’s so exciting. It’s a privilege to be part of that from a professional level.

The other answer is more of a humanistic thing. I went into medicine because of my experiences at Camp Kesem, which is a camp for kids whose parents had cancer. It was a life-changing experience to be involved with that and to help drive it from the beginning. Whether or not any individual therapy works for any of my advanced cancer patients, there’s a human element to this job that’s very profound. That is also a privilege, to be involved with that day-to-day, no matter what.

Camp Kesem is still around, right?

Dr. Van Allen: Yes, it’s growing amazingly. There are over 100 camps now around the country, and thousands of families are involved. It’s wonderful.

Have you had any patients who changed either how you view the art of medicine or your own role?

Dr. Van Allen: Absolutely. At some level, every single patient both challenges and reinforces aspects of what it means to be a doctor and deliver care. Each in their own way has changed the way I think about things. There are obviously some stories that stand out and some experiences.

Some of the patients who’ve had the most catastrophic outcomes and succumbed to the disease in rapid form have taught me the most about what it means to live your life to the fullest, whatever that means to you. I have a lot of respect for them.

It’s a special thing to care for people at the particular moment, when they face big life questions.

Dr. Van Allen: About eight or nine years ago, I wrote a piece for the Journal of Clinical Oncology’s Art of Oncology series. It was about this one patient I had as a first-year fellow who had this positive thinking attitude in the wake of the most potentially catastrophic scenarios up until he passed away. It was such a surreal thing. In that case, it was rare, but I think it teaches you a lot about what it means to be human and how hard this disease is.

What is the goal of the Metastatic Prostate Cancer Project?

Dr. Van Allen: The Metastatic Prostate Cancer Project is a patient-driven research project whereby, rather than expecting the patients to come to us to join and participate in advanced research, we bring the project to their doorstep, and we engage with patients in new ways. We give patients an opportunity to share information about themselves and share their tumor specimens for us to do genetic testing. The goal is building the largest genomic registry of prostate cancer that we can learn from, and in so doing, accelerate that discovery to translation cycle even more.

Can you give us some updates on how the project has been going since you launched?

Dr. Van Allen: We launched this project in January 2018 in a patient population that is known not to talk about their disease in any venue, under any circumstances, to anyone. There’s no social media presence for this disease space, or at least on the surface, and frankly, we would’ve been thrilled had ten people signed up. Our sister project, the Metastatic Breast Cancer Project, has a loud and overt presence of women taking selfies with their saliva kits, so we weren’t sure how this was going to work.

We’re a little past a year from launch and over 700 men have engaged in research, given us consent to access their samples, filled out the patient-reported survey, and joined this Count Me In movement. It’s remarkable, but not only have these 700 men signed up, we’re already at the other end of the cycle of this project now, and we’ve generated complete data sets for the initial wave of these men. By complete data set, I mean genetic, clinical, and patient-reported data, and we’ve put that data out to the entire community in the research setting to learn from.

This proves the principle that we mean what we say when we’re generating data for the community. We’re not trying to build a silo here. This is patient-demanded, and therefore patient-driven, from day one. From every aspect across the board, it’s been remarkable and exciting to see how we’ve done so far.

We are 150% absolutely still looking for patients. We’ll always be looking for patients. Anyone who’s interested should feel comfortable to go to MPCProject.org and click Count Me In.

What kinds of patients should join? Anyone with prostate cancer?

Dr. Van Allen: This project is for advanced or metastatic prostate cancer, which means prostate cancer that’s left the gland. That could be folks with local, regional prostate cancer involved in the lymph nodes, folks with biochemical recurrence only (only PSA detected in the blood), and all the way to patients with heavily pretreated, advanced disease that’s spread to bone, liver, or wherever. Anyone in that spectrum is considered advanced or metastatic from our perspective.

The project is basically unending, right?

Dr. Van Allen: That’s the goal, releasing it as fast as we can.

Do you just release the data, or are you also forming collaborations with other institutions or projects?

Dr. Van Allen: We’ll release the data. We’re obviously going to try to learn from it ourselves and use it to come up with perhaps new drug targets, biomarkers, and whatnot, but also we would like to connect with other efforts that are spiritually aligned in any way that’s feasible.

One of the best outcomes would be that some researcher who is in no way affiliated with our project finds our data useful and uses it for their research to inform what they do. We’re already starting to see that happen with our sister projects where there are scientists and labs that we are not affiliated with who are using the data to inform how they think about their research and their projects. All of those outcomes are on the table, and we’re excited to pursue all of them.

Is there anything else you want patients to know about how the project is doing, about further studies you’re doing, or other studies you think people may find interesting?

Dr. Van Allen: This is a patient-driven project. Some of the patients who’ve given us feedback on their experiences so far have also prompted questions that we can ask that we, in our little academic bubble, probably would’ve never thought of. That’s how we’re starting to dive into things that are driven by patient experiences or that we’re observing in the patients who have signed up, down to questions that might seem curious but are illuminating, ones that we hadn’t intended initially.

For example, in the first patient data release, when asked if they had surgery for their prostate, almost half the patients marked: “unknown.” We can compare that to their medical record and sort that out, but it provides a window into something that wasn’t the initial intent of the project. That feedback opened up a lot of interesting questions and opportunities for research that we hadn’t necessarily anticipated up to that point.

Men didn’t know if they’d had prostate cancer surgery or not?

Dr. Van Allen: It may have been the way we asked the question. It may have been that patients were interpreting what they were supposed to answer. We don’t know. The point is that this is not something we initially set out to do, but it is an early example of how patients can guide where the research needs to go.

I just presented this project at the American Urologic Association meeting, and a gentleman came up to me afterwards. He’s had metastatic prostate cancer for four years and a complete response to cancer immunotherapy, and he wanted to know if he was eligible for this project. Not only is he eligible, but he’s an extraordinary case. We want to understand why. This patient is not within 500 miles of an academic medical center, and he would otherwise never be approachable or available to engage in research. We exchanged information, and he’s going to sign up.

Patients may not realize: they have the power to drive this field forward in this unique way. It’s not something that medicine is used to doing. We want to get the message out that this is all starting with patients and their ability to contribute. That will determine how far this goes.

It’s easy for them to participate: go to the website, fill out the forms, and give a blood sample?

Dr. Van Allen: Yes. You don’t even have to do the blood sample if you don’t want to. It’s exactly what you described. Go to the website, click a few buttons. There’s a very simple online consent form. We’ll send you a saliva kit and a blood biopsy kit and take it from there.

Can you still participate even if you’re in a remote area?

Dr. Van Allen: Yes, anywhere in the United States and Canada. For the blood biopsy, we send you a kit, and you bring it to your next lab draw, PSA test, or whatever, and there are instructions in the kit for the phlebotomist. In some cases, phlebotomists have not been willing or able to participate, so we can provide vouchers to patients to do it at a Quest Diagnostics lab or somewhere convenient to them. The intent here is that the patient bears no financial burden in participating.

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Dr. Daniel George on PSA Recurrence

Dr. Daniel James George is Professor of Medicine and Professor in Surgery at Duke University.

Prostatepedia spoke with him recently about biochemically recurrent prostate cancer.

Have you had any patients whose cases have changed either how you view your own role as a doctor or how you view the art of medicine?

Dr. Daniel George: As we evolve new therapies and indications for treatment, it’s really interesting how that affects our relationships with patients. As an oncologist, my relationships with patients have become more longitudinal. What I mean by that is: people are living longer than ever. I’m beginning to recognize my treatments in the context of not just the short-term endpoint of how to control my patient’s disease in the next few months but in terms of the ramifications for his life and long-term survival. What does it mean in terms of his functional well-being, not simply now, but in a year from now or five to ten years from now?

In many ways, it comforts patients to hear the perspective, that I see them as a long-term survivor, and that I’m thinking about the implications of our treatments in a long-term perspective. That helps the patient invest in his own life and well-being for the long-term, whether that be diet, exercise, sleep, or all these other behavioral interventions that can really impact their quality of life.

You’re basically saying that prostate cancer is becoming more of a chronic disease.

Dr. George: It has been for some patients, and we’re beginning to recognize it more and more for all patients.

We used to think of short-term goals for some of our most advanced cases of prostate cancer—just in terms of disease control or palliation and not worry about the long-term implications of treatment. While on the other end of the spectrum we would have cases where we don’t have to treat the disease at all or maybe treat it minimally in others. Now I’m recognizing prostate cancer as a chronic disease for everybody, and so everybody needs to think of the long-term implications of treatments.

Likewise, we need to think of the implications of our sequential therapies and their cumulative side effects.

Can you define M0 prostate cancer, or biochemically recurrent prostate cancer, for patients?

Dr. George: This is probably confusing because of its name. We refer to prostate cancer in terms of stage. Stage refers to the extent of the disease. The Gleason Score or grade refers to how it looks under the microscope, its aggressiveness. But stage refers to the progression of this disease. Do they have bone metastases? Do they have distant lymph node metastases or other sites of disease? Or is it localized?

We usually use three categories: the T stage, which is the localized tumor, the N stage, which is the lymph node status, and then the M stage, which is the presence of metastases that are distant from the prostate. M0 refers to patients who have no distant metastasis. Think of M0 in terms of patients who are newly diagnosed with prostate cancer.

Recurrent prostate cancer patients are those who’ve had local therapy, surgery, or radiation, and who now have evidence of disease recurrence by PSA. After these treatments, we know that your PSA should be 0 or very low, and it should stay low. If your PSA rises and continues to rise, that’s an indication of disease recurrence. Yet, in many cases, they’re what we call M0 because, when we stage the patient with a bone scan or a CT scan, we can’t see any evidence of cancer. Many of those patients have what we might otherwise refer to as microscopic metastatic disease, disease that’s just below the level of detection. Some of them could have local recurrence or recurrence just within the pelvis and regional nodes that’s not distant. We now know from recent studies that the majority of those patients are going to relapse with distant metastatic disease. In other words, they have distant metastatic disease, but it’s just below the level of detection.

So, this is a bit of a misnomer because we’re treating them with systemic whole-body treatment therapy now because we recognize the risk of distant metastatic disease for the majority of these patients. We’re beginning to use newer imagining techniques, such as PET scans, that could be more sensitive at picking up this microscopic metastatic disease. That shouldn’t deter us from applying the current data to that patient population.

I think of M0 prostate cancer as being low-volume castrate resistant prostate cancer. When we think of it that way, it makes sense that the drugs we’re using work and work even better in that low-volume population. We should use them because M0 is just an early continuation of that metastatic process.

What are these systemic approaches that patients are likely to receive? What are the implications down the line in terms of side effects, and in terms of the longer longitudinal quality of life issues you mentioned earlier?

Dr. George: This is an important aspect of the care for these patients because we have two studies—and a third will soon be reported—that demonstrate a clinical benefit from using what we have broadly termed secondary hormonal therapies, therapies that we add to primary androgen deprivation (ADT) or testosterone suppression.

Patients for whom testosterone suppression has failed can respond to another hormonal intervention later. These are drugs that target the androgen receptor, the protein that testosterone binds to, and inhibits it from signaling. It shuts off what seems to be the most common mechanism for resistance to testicular testosterone suppression. That is an overexpression or overabundance of this receptor, which makes prostate cancer cells sensitive to low levels of residual testosterone in the body.

Xtandi (enzalutamide) and Erleada (apalutamide), in two separate Phase III studies, have demonstrated a clinically significant benefit: a delay in the time to metastasis. The FDA has accepted this as a meaningful endpoint because of the degree of delay. It was associated with about a two-year delay in the time to metastasis in this population.

Patients who were at high risk for developing metastatic disease were in the control arm and developing metastatic disease within about a year of coming on the study for the placebo arm. For the treatment arms, with Xtandi (enzalutamide) or Erleada (apalutamide), we’re seeing a delay of about two additional years. That means three years until the time of metastasis.

The results suggest that we’ve changed the progression of this disease dramatically. In addition, both studies showed a strong trend in favor of the treatment arm for improved overall survival associated with this delay in metastasis. Even though the data may not be as complete because it takes a longer time to report, we’re seeing this correlation in metastasis-free survival, if you will.

Again, I caution the semantics here because these patients do have metastases; they just can’t be seen yet. But the delay in that radiographic appearance of metastasis is associated with an improved survival.

What’s the approach to finding smaller metastases earlier on with the newer imaging techniques? And if they are very small, do you treat them aggressively with radiation, do you continue using the systemic therapies, or do you use a combination?

Dr. George: There is a mix of presentations of patients. When we image with a novel PET-imaging tracer, we’re going to see more than one site of disease in most patients. We’re going to see multiple lymph nodes, multiple bone metastases, or maybe lymph and bone metastases.

For a subset of about 20 percent of patients, we see this disease limited to only lymph node disease or only one or two bone metastases. We refer to this as oligometastatic disease, which we have yet to biologically define. Clinically, we know that it’s associated with a longer survival.

Oligometastatic prostate cancer raises the question of whether or not these patients could be managed with therapy localized to those sites, therapy that does not necessarily expose them to further systemic therapy. We don’t have a lot of data in the castrate-resistant setting, but in the hormone-naïve setting, there are some data that suggest that there can be a delay in the time to initiating subsequent hormonal therapy by doing that.

There’s a study out of Europe, but the median effect was relatively small, just a few months. It’s not clear that this is going to be a meaningful difference for most patients, but it is something that can be discussed.

A lot of those treatment approaches can be done with minimal intervention, external radiation, ablations, or limited surgery. Those will be options. But in the majority of these patients that we do this molecular imaging for, we’re going to find evidence of more than one site of disease or multiple lesions. This suggests that they need a systemic therapy approach.

It’s reasonable to extrapolate this data because we know from the placebo arm of these studies that these patients went on to develop metastases in their bone scan or CT scan within months, 50 percent of them within a year, and many of them in just a few months of their subsequent scan. The likelihood is, if we’d done the molecular imaging at baseline on these patients,we would have seen it. Yet still, in this population, we’re seeing a treatment effect.

We see the treatment effect regardless of what level of PSA doubling time you have. In patients who have a PSA doubling time of just two or three months, we see a dramatic treatment effect. In patients who have a doubling effect of eight or ten months, we still see a dramatic treatment effect in terms of prolongation in the time to metastasis—fewer events in those cases, but still, we see that treatment effect.

The PSA doubling time is an important parameter that we’re using now, in addition to these imaging stats, to determine who we should treat with these drugs and their prognosis.

Isn’t doubling time an indication of the aggressiveness of the disease?

Dr. George: It is. We knew this earlier in disease prior to hormones. PSA doubling time was very prognostic for time to metastasis and overall survival. It’s been less studied in the castrate-resistant setting, when patients have progressed on primary hormonal therapy, but we’re still seeing it there. In fact, the results are really dramatic.

There were some abstracts at the Genitourinary Cancer Symposium (GU ASCO) around this data. There have been reports from these two Phase III studies with Xtandi (enzalutamide) and Erleada (apalutamide) that demonstrate this. We believe there is a strong correlation between a shorter PSA doubling time—a shorter time to bone metastasis—and shorter overall survival.

Just to put these studies into context, the requirements were that PSA doubling times were less than ten months. If doubling time is a year or longer, these are slow-growing cancers. Even though they’re castrate-resistant, these are patients who will live for many years with no metastasis, so it’s reasonable just to observe their disease. For the studies, the median or 50th percentile PSA doubling time was around four months. That’s really short and aggressive.

That’s why we saw that the average time to metastasis was just about a year in the control arms. It’s important to recognize where your patient is in this continuum because it guides whether we should treat him like we did on the study, or if their disease is too slow growing to justify the treatment.

What other considerations are important for patients who fall into this category?

Dr. George: The important thing for patients to know: not to worry. I know that as a physician, it’s easy to say ‘don’t worry about your rising PSA level,’ but as a patient, it is hard to ignore.

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Dr. Maha Hussain On Biochemical Recurrence

Dr. Maha Hussain is the Genevieve Teuton Professor of Medicine in the Division of Hematology, Department of Medicine, and the Deputy Director of the Robert H. Lurie Comprehensive Cancer Center of the Northwestern University Feinberg School of Medicine.

Prostatepedia spoke with her recently about biochemically recurrent prostate cancer.

What is biochemical recurrence?

Dr. Hussain: A biochemical recurrence implies that an individual with prostate cancer who has received therapy now has evidence of disease activity as reflected by their PSA blood test. In the context of negative imaging, the PSA is a flag. It generally indicates a relapse. Generally speaking, when the patient has a rising PSA, they get imaged. If the scans are negative, then this becomes purely biochemical recurrence.

Why is this a disease state that we’re particularly focused on? What are some of the key issues in how we approach treating these men?

Dr. Hussain: There are two settings of biochemical recurrence. One is the non-metastatic hormone sensitive setting. This means a patient has had local therapy with surgery and their prostate was taken out, or they’ve had radiation therapy with or without hormonal treatment, and now they have a PSA that’s going up. This implies there is cancer activity. Generally, imaging is done, and most of the time, conventional imaging such as bone and CAT scan are negative.

While not imminently harmful, non-metastatic hormone sensitive biochemical recurrence has significant psychological implications for the patient because it reminds them that there is cancer activity in their body that’s growing.

With regard to management, salvage radiation plus hormone therapy is the standard of care for patients who developed PSA-only relapse post radical prostatectomy as it reduces risk of mets and improves longevity. While there are options for patients who had radiation therapy plus hormonal therapy, they are not optimal.

For example, while hormone therapy is an option for patients whose PSA started to increase after salvage radiation and hormonal therapy, the totality of the data to date does not suggest significant benefit for early hormone therapy versus waiting until there’s a reason to treat.

This population; non-metastatic hormone sensitive PSA relapse, tends to live quite long, and some may not develop visible mets. The speed by which the PSA starts to go up and how fast it increases—what we call doubling time—can imply earlier versus later development of metastatic disease. Detailed discussion is needed to address options, pros and cons of treatment, and potential options for clinical trials.

The other setting of biochemical recurrence is the non-metastatic but castrate-resistant setting, which differs from the previous setting in that patients were treated with hormone therapy and now their PSA is rising while on therapy; that is the rising PSA is occurring despite the fact that hormone therapy has lowered their testosterone levels to the castration range. This is a different clinical phase of disease where the cancer has shown that it is no longer responsive biologically to the hormonal therapy that they are receiving. We know that, given enough time, cancer will show up. We know also that the speed by which the cancer is growing, as reflected by the PSA rate of increase, has an implication as to how soon the cancer will show up on the scans.

This is an area of an unmet need for decades, until last year when two drugs were FDA-approved for this particular patient population, specifically Erleada (apalutamide) and Xtandi (enzalutamide) based on significantly delaying time to development of metastasis. At this year’s American Society of Clinical Oncology GU (ASCO GU) conference, there was also positive data from another trial with Darolutamide in this disease setting. I believe the drug is in front of the FDA at this moment for review.

These three trials were done in a population of patients who had a worse prognosis as reflected by their fast PSA doubling time—a doubling time of 10 months or less. This is because these patients are likely to show metastases within an average of about two to two and a half years.

The issue is whether there is benefit for people who don’t have that kind of PSA doubling time. What if the doubling time is one or two years? It certainly is an area where we need to think about value to that patient.

For both Erleada (apalutamide) and Xtandi (enzalutamide), the FDA approval did not specify the doubling time requirement. The FDA approved it in all patients who have non-metastatic castrate-resistant disease. Clearly one size does not fit all. It’s critical to make shared decisions between the patient and the treating physician with regard to the value of the treatment, the risks from the cancer, the risks from the treatment, the treatment objectives, and when to initiate therapy.

Some good news about this disease phase is, because it’s invisible cancer, and while this means there’s micrometastatic disease, the patient has some time to think about things and also monitor carefully.

In my experience, probably about 8 to 9 out of 10 patients elect to be on treatment because of the concern over worsening disease and the value based on the clinical trials. There are some patients who feel great, and if they’re not going to have an issue tomorrow, then they want to wait a few months before deciding on treatment. That’s perfectly reasonable.

Isn’t that true for a variety of situations in prostate cancer, that you have time to gather a variety of opinions?

Dr. Hussain: Correct in general, but specially for this disease space because no one is going to die overnight from a PSA that’s not controlled. That’s to put it bluntly. There is that room. Patients should talk with their physician about that and discuss risk-benefit ratios as all therapies have side effects.

For certain patients, those side effects might be more important, especially for those who have significant cardiovascular disease. It becomes important to incorporate risk-benefit and close monitoring, but it doesn’t mean that no treatment should ever be done.

Do you have any other advice for men in this situation?

Dr. Hussain: One thing to remember for men with hormone-sensitive biochemical recurrence who have had salvage therapy or post radiation and hormonal therapy is that if therapy is to be done, it ought to have a good reason. Lowering the PSA alone is not the objective; clinical benefit should be the objective.

There is potential harm from treatment in the absence of proof that giving hormone therapy for a PSA of let’s say 0.5 or 0.6 will have a benefit. One has to balance the risks from the treatment and both physical and monetary risks to the patient and ultimately implement a shared decision.

These conversations with patients can be long and potentially stressful to the patient. Yes, hormone therapy can be given. The issue is not whether it can be given but whether it should be given, and if so, when.

There’s a fair amount of population-based data that suggests there’s no clear advantage, but there’s limited prospective clinical trial data. I would encourage patients to discuss these issues with their physicians, understand the upsides and downsides, and also discuss opportunities for clinical trials. Clinical trials are one space in which we need informative data and partnerships with patients to come up with better answers.

For patients who had radical prostatectomy (surgical removal of the prostate), and then their PSA is going up, their best treatment option is salvage therapy, which involves radiation with hormonal treatment.

Based on the more recent data from Radiation Therapy Oncology Group (RTOG), the radiation involves the prostate bed and the pelvis to include the pelvic lymph nodes with four to six months of hormone treatment. This is something that should be discussed with the care team. Radiation alone is not enough, and certainly the data indicate the combination is better with regard to outcomes. If the patient doesn’t want to do the hormones, that’s fine, but the hormones can reduce risk of progression and potentially add to overall survival.

The other side would be situations where patients have had radiation therapy and have received hormonal treatment as part of their primary treatment. Then they stopped the therapy, and now months or years later, the PSA is rising. That’s a different scenario. The issue is whether to resume hormone therapy or not. That’s when a careful conversation is necessary between patients and their physician because there is no compelling data that say it’s necessary to do the hormone therapy.

So, there are a variety of situations.

Dr. Hussain: Yes and/or access to clinical trials. We know the phases of prostate cancer now. The same disease state now has multiple phases, and it’s becoming complicated. That’s important because this speaks to the importance of personalizing care for the patient at all levels.

We’re becoming more and more personalized about how we categorize the different disease states.

Dr. Hussain: Yes, absolutely, and we do individualize the care. A 50-year-old who comes in with non-metastatic castrate-resistant prostate cancer and no comorbidities has a very different disease than someone who is 85, had a stroke, and is in a wheelchair.

Patients should ask their physicians specifically about the type of biochemical recurrence they have, their expected prognosis based on their PSA doubling time, their risk-benefits ratio, and which scientific information from prospective clinical trials can help guide their decisions. Patients should ask for educational material, and doctors should help patients make a decision that’s not based on being afraid but being informed about the choices, pros, and cons.

Would you give similar recommendations to anyone along any stage of the disease progression?

Dr. Hussain: Absolutely. Informed decisions are critical in every disease setting. But biochemical recurrence is a complicated phase of disease. In the setting of metastatic disease, it’s relatively easy in that there is no question regarding the disease risks. Earlier therapy, before symptoms or before the disease worsens, is better generally. This a disease setting that is likely to cause harm if therapy is delayed significantly.

But with non-metastatic hormone sensitive biochemical relapse, a patient can go for years without having any visible metastasis. It’s more complicated when there’s no imminent danger. At the end of the day, I tell patients with non-metastatic hormone sensitive disease in whom there is no clear data to support benefit from systemic therapy, that this is a gray area where we don’t have compelling data to say that giving hormone treatment is going to give a meaningful benefit. Therefore, one option is we monitor closely with interval PSA checks and periodic imaging. Based on doubling times and trends, what new evidence that comes up, and patient comfort we can watch. Once the patient is informed about the specifics, it is fascinating that the majority tends to be comfortable with watching and about a third are not comfortable with not getting therapy. There is not a one-size-fits-all approach. Personalized shared decision is critical.

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Merel Nissenberg On Non-Metastatic Castrate-Resistant Prostate Cancer

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Non-metastatic castrate-resistant prostate cancer (nmCRPC) is a clinical state in which a patient on androgen-deprivation therapy (ADT) has a rising PSA but there are no radiological findings of metastases on CT or bone scan. Management of nmCRPC is evolving quickly, but it is a field in which there have been recent drug approvals amid a strong and growing interest in keeping patients metastasis-free for as long as possible. About 10-20% of prostate cancer cases are castrate-resistant, but nearly 16% of those castrate-resistant patients have no evidence of metastatic disease at the time their castrate-resistance is diagnosed.

Not all nmCRPC disease is the same. For some patients, observation is a viable option; for other patients—especially those with a PSA doubling time of less than or equal to 10 months—randomized Phase III clinical trials have shown a benefit and an increase in metastasis-free survival with the use of Xtandi (enzalutamide) or Erleada (apalutamide). New imaging techniques on the horizon may also be very helpful in assessing nmCRPC patients.

In February 2018, the FDA approved Erleada (apalutamide) for nmCRPC patients and was the first such FDA-approved treatment for this subset of patients—i.e. those who are no longer responding to ADT but who have no radiological evidence of metastasis. The Erleada (apalutamide) approval followed the release of the results of SPARTAN, a randomized clinical trial of 1,207 patients in which patients received either Erleada (apalutamide) or placebo, discussed at the American Society of Clinical Oncology Genitourinary (ASCO GU) Meeting in February of this year. All of the patients who were enrolled also received hormone therapy. The exciting results showed that the median metastasis-free survival for patients in the Erleada (apalutamide) arm was 40.5 months versus 16.2 months for the placebo group. Both applications received priority review from the FDA due to the exciting results with clear benefit for nmCRPC patients.

The results of another trial known as the PROSPER Trial were also first presented at the 2018 ASCO GU Meeting. In PROSPER, with 1,401 participants, men with nonmetastatic castrate-resistant prostate cancer (nmCRPC) were given either Xtandi (enzalutamide) or placebo; these were men in whom the PSA doubling time was 10 months or less, but, again, there was no evidence of disease seen by CT or bone scan or by MRI. Those nmCRPC patients receiving Xtandi (enzalutamide) had delayed time to metastatic disease or death (whichever occurred first) by a median of 21.9 months, versus placebo (36.6 months compared to 14.7 months), signifying a 71% reduction of the risk for metastasis or death. Another result: Xtandi (enzalutamide) delayed the time until men needed additional cancer treatment, compared to placebo (a median of 39.6 months compared to 17.7 months). On July 13, 2018 the FDA approved Xtandi (enzalutamide) for the treatment of nmCRPC patients.

This means that men with nonmetastatic castrate-resistant prostate cancer now have two choices that they did not have before, when they would simply be continued on ADT. We still do not know, however, if the added Xtandi (enzalutamide) or Erleada (apalutamide) will increase overall survival for these patients.

[This article deals only with nonmetastatic CRPC. There have also been various trials conducted in the metastatic space, and there are other trials currently underway or planned involving anti-androgens such as Zytiga (abiraterone), including some in combinations with other types of therapy, dealing with metastatic disease (mCRPC patients). One of the trials looking at the metastatic disease space is the PEACE1 Trial, which is looking at the benefit of Taxotere (docetaxel) plus ADT, with or without Zytiga (abiraterone) and prednisone, and with or without radiotherapy. This trial is expected to conclude in October 2018 and may help answer the question of whether it is of benefit to patients to add Zytiga (abiraterone acetate) to Taxotere (docetaxel) in metastatic disease that is still castrate-sensitive. The Phase III STAMPEDE Trial showed that adding Zytiga (abiraterone/ prednisone) to standard ADT lowered the relative risk of death by 37% and improved progression-free survival by 71%, versus ADT alone. The CHAARTED Trial looked at Taxotere (docetaxel) plus ADT or ADT alone in patients with metastatic, castrate-sensitive disease, resulting in a greater median survival in the ADT + Taxotere (docetaxel) arm (57.6 months versus 44.0 months with ADT alone).]

Learn more details about these drugs by viewing the Evidence Report from Institute for Clinical and Economic Review (ICER). ICER also held a public hearing on the topic on September 13, 2018 in Chicago.

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Switching from One Chemo Drug to Another

Dr. Emmanuel Antonarakis is an Associate Professor of Oncology and Urology at the Johns Hopkins University Sidney Kimmel Comprehensive Cancer Center.

Prostatepedia spoke with him recently about his work on the benefit of switching men from Taxotere (docetaxel) to Jevtana (cabazitaxel)— or vice versa—if his PSA doesn’t go down by 30% in the first twelve weeks of treatment.

You’ve published a paper on switching patients from Taxotere (docetaxel) to Jevtana (cabazitaxel) and vice versa. What is the thinking behind switching chemotherapeutic agents? Why would you want to switch agents earlier as opposed to when the first chemotherapy drug stops working?

Dr. Emmanuel Antonarakis: The motivation behind this paper was that the FDA-approved recommended dosing schedule for both Taxotere (docetaxel) and Jevtana (cabazitaxel) is a course of ten doses, given three weeks apart. When patients begin FDA-approved Taxotere (docetaxel) or FDA approved Jevtana (cabazitaxel), they’re often told by their oncologists that they should expect to receive this chemotherapy once every three weeks for up to ten doses. A patient may not receive ten doses or might stop the therapy before he reaches ten doses because he cannot tolerate the therapy and has unmanageable side effects, or his cancer begins to progress before he ever get to dose number ten. If his PSA begins to increase again at dose six or seven or the tumors begin to grow again, his oncologist might ask him to stop chemotherapy.

We then wondered whether the ten doses was a reasonable time to wait or whether there could be an early indicator, or an early sign, of therapy resistance or therapy futility without having to go through six, seven, eight, nine or ten doses.

The idea that we had was to test an early intermediate marker of sensitivity or resistance to the chemotherapy. The best marker of early sensitivity or resistance that we could think of was whether or not a patient had a 30% PSA drop within the first four cycles of therapy. As you recall, if the therapy is given once every three weeks, four cycles basically means 12 weeks, which roughly equates to about three months.

The decision to use this intermediate endpoint was not arbitrary; it was based on some large retrospective meta-analyses that have shown that the strongest predictor of overall survival in patients receiving both Taxotere (docetaxel) and also separately Jevtana (cabazitaxel) was whether or not patients had a 30% PSA reduction after 12 weeks.

Patients who do achieve at least a 30% or greater reduction in the first 12 weeks have a survival that’s longer than patients who don’t achieve that endpoint. We thought, well if this endpoint is strongly correlated to survival, perhaps we can use it as a decision point. If after four doses of therapy or 12 weeks of therapy a patient don’t achieve a 30% reduction in PSA perhaps we should switch him to the other chemotherapy, rather than sticking with it and just waiting for either the toxicity to develop or the PSA or the radiographic disease to progress. That was the hypothesis.

We designed a relatively small study of about 63 patients. We used a 2:1 randomization so they were twice as likely to get Taxotere (docetaxel) compared to Jevtana (cabazitaxel). Approximately 41 patients got Taxotere (docetaxel) first. The other 22 patients, got Jevtana (cabazitaxel) first. Irrespective of which arm they were randomized to, they received the first four doses of chemotherapy in 12 weeks. We checked their PSA every three weeks.

At the end of the fourth dose, if the PSA level had dropped by 30% or more, the patients would continue on the same therapy on which they started. However, if patients did not achieve a 30% reduction or more, they would be switched to the other chemotherapeutic agent.

If a patient had a 25% reduction, we would switch him to the other agent because we thought that was not good enough. If someone received Taxotere (docetaxel), and their PSA dropped by 25%, even though it dropped by 25%, it did not meet that 30% threshold so they would then switch for the fifth dose to receive Jevtana (cabazitaxel) for the remainder of their chemotherapy. The inverse was also true. If the patient received Jevtana (cabazitaxel) first and also did not get a 30% reduction by week 12, in other words four doses, they would also switch to receive Taxotere (docetaxel). The interesting thing that we found in both treatment arms was that the chance that a patient had a favorable PSA response, which was defined as a 50% or more decrease, was higher than we had seen in historical trials using each drug by itself without switching. To put some numbers on that, we found that there was about a 54% chance that patients would have a 50% reduction in PSA if they had to the opportunity to switch from one chemotherapy to the other, compared to about a 45% chance of PSA reduction in the historical data where patients did not switch.

Did it matter if they got Jevtana (cabazitaxel) first or Taxotere (docetaxel) first?

Dr. Antonarakis: What we found out is a bit of a paradox: people could benefit from the switch in both down over time and the availability of non-chemotherapy agents is going up. A lot of these patients who may not have a 30% PSA reduction with one chemotherapy, might choose to do another hormone therapy, a radiopharmaceutical drug like Xofigo (radium-223), immunotherapy like Provenge (sipuleucel-T), or even a PD-1 inhibitor, or potentially a PARP inhibitor.

It might be difficult to convince a patient who has just failed one chemotherapy after four doses to go immediately to a second chemotherapy. I’m not 100% sure what the future will hold. I also don’t think this is a trial that we could have conducted today.

What would you say to a man reading it? That this is worth talking to his oncologist about or is this just something interesting for him to know about?

Dr. Antonarakis: Patients who are beginning their first chemotherapy should discuss this trial with their oncologist, and together with the oncologist decide in a joint fashion whether switching from one chemotherapy agent to another after four doses might be right for him, especially if he’s tolerating the chemotherapy well. If he tolerates the drug and his PSA has not dropped by 30% or is continuing to increase, then in my opinion rather than continue with the potentially futile therapy, a patient and his oncologist may wish to consider using this trial to guide or justify their choice of switching drugs earlier rather than later. directions. That was fascinating to us because, as we all know

Jevtana (cabazitaxel) was specifically approved by the FDA as a second-line curative therapy only indicated in men who have failed Taxotere (docetaxel) first. Based on that reasoning, one might expect Jevtana (cabazitaxel) to work better after Taxotere (docetaxel) but not Taxotere (docetaxel) after Jevtana (cabazitaxel).

This is not what we found.

We found that in both directions, both from the Taxotere (docetaxel) to Jevtana (cabazitaxel) switch, but also in the Jevtana (cabazitaxel) to Taxotere (docetaxel) switch, there was a significant amount of patients, approximately half, who were salvaged by the crossover therapy. By salvaged, I mean those who did not achieve a 30% PSA reduction with the first drug but did achieve a PSA reduction of 50% or more after crossing over to the second drug.

As I mentioned before, this occurred in both directions, both in patients receiving Jevtana (cabazitaxel) after Taxotere (docetaxel) and Taxotere (docetaxel) after Jevtana (cabazitaxel).

Are the side effects of Jevtana (cabazitaxel) a little bit easier to take than the side effects of Taxotere (docetaxel)?

Dr. Antonarakis: Interestingly, the side effects of Jevtana (cabazitaxel) in the published literature indeed appear to be slightly better. In this particular trial, which was very small obviously, they seemed comparable. In other words, we did not see any appreciable difference between the Taxotere (docetaxel) and the Jevtana (cabazitaxel) overall in terms of side effects. Taxotere (docetaxel) had a little bit more neuropathy nerve damage, which Jevtana (cabazitaxel) did not do. On the other hand, Jevtana (cabazitaxel) had a little bit more neutropenia, while the Taxotere (docetaxel) did not.

I would say that when patients receive these agents in a first-line setting, in other words, when they had not received another chemotherapy previously, their side effects were fairly comparable. I don’t think there was a clear signal in terms of one drug being clearly safer than the other.

Does it matter which you get first?

Dr. Antonarakis: From a side effect perspective, they’re both fairly equivalent in terms of tolerability, with slight differences in neutropenia, which is worse with Jevtana (cabazitaxel) and neuropathy, which is worse with Taxotere (docetaxel).

What is the next step? Are you going to run a similar trial with more patients?

Dr. Antonarakis: One question that arises is if this small randomized trial is enough to change practice. Should a community oncologist or urologist give Taxotere (docetaxel) for four doses and wait to see if the patient’s PSA drops by 30% or more? If it doesn’t drop to 30% or more, should he to switch to Jevtana (cabazitaxel)?

I have to admit that this is something that I have done in my practice a few times, but I really don’t believe that this is ready for clinical practice yet. Yes, in this trial, we showed that the PSA response rates could potentially be improved by this switch strategy. What we did not demonstrate was whether this improves overall survival.

The ultimate question is does switching chemotherapy agents after four doses improve survival, compared to just waiting until we see radiographic or clinical progression to switch agents. That would, as you mentioned, require a larger Phase III randomized study. The idea of study design would be to randomize patients to the switch strategy versus no-switch. We would randomize one group of patients to receive chemotherapy and switch if their PSA did not drop by 30%. The second group of patients would start chemotherapy but would not be given the opportunity to switch, even if their PSA did not drop by 30% or more. The randomization would not necessarily be the randomization to the chemotherapy, but would be randomization to a switch strategy versus a stick-with the first-chemotherapy strategy.

Sanofi, which makes both Jevtana (cabazitaxel) and Taxotere (docetaxel), have not been eager eager to respond to such a study because of financial considerations and also because the patent life of Taxotere (docetaxel) is over and the patent life of Jevtana (cabazitaxel) will be expiring soon.

Unfortunately, we might be left with a Phase II study that may, potentially, not translate into a Phase III study. I think individual patients and individual oncologists may look at these data and might be convinced that some patients might potentially benefit from a switch strategy, especially those who did not have any degree of PSA reduction after four cycles.

An added complexity is that the popularity of chemotherapy is going down over time and the availability of non-chemotherapy agents is going up. A lot of these patients who may not have a 30% PSA reduction with one chemotherapy, might choose to do another hormone therapy, a radiopharmaceutical drug like Xofigo (radium-223), immunotherapy like Provenge (sipuleucel-T), or even a PD-1 inhibitor, or potentially a PARP inhibitor.

It might be difficult to convince a patient who has just failed one chemotherapy after four doses to go immediately to a second chemotherapy. I’m not 100% sure what the future will hold. I also don’t think this is a trial that we could have conducted today.

What would you say to a man reading it? That this is worth talking to his oncologist about or is this just something interesting for him to know about?

Dr. Antonarakis: Patients who are beginning their first chemotherapy should discuss this trial with their oncologist, and together with the oncologist decide in a joint fashion whether switching from one chemotherapy agent to another after four doses might be right for him, especially if he’s tolerating the chemotherapy well. If he tolerates the drug and his PSA has not dropped by 30% or is continuing to increase, then in my opinion rather than continue with the potentially futile therapy, a patient and his oncologist may wish to consider using this trial to guide or justify their choice of switching drugs earlier rather than later.

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Radiation Therapy + The Abscopal Effect

Dr. Charles G. Drake of New York Presbyterian/Columbia University Medical Center, discusses the rare but intriguing abscopal effect.

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Dr. Charles Drake says: There was an article in the New England Journal of Medicine showing an abscopal response with Yervoy (ipilimumab) anti-CTLA-4 in a patient with melanoma. It was a beautifully done paper with nice immunological correlates. After that got published, we found that radiation oncologists and medical oncologists were giving people a combination of immunotherapy and radiation and were telling patients they would get abscopal responses. But that’s a bit overly ambitious. In the clinic, it’s not that easy. It’s going to be a while before we understand what’s needed therapeutically to be able to induce abscopal responses in the majority of patients. It’s going to take a little more work before we can have that happen broadly. On the other hand, if we can make it work, it’ll be fantastic. Dr. Hammers’ trial combining anti- PD-1, anti-CTLA-4, and radiation in kidney cancer is perhaps a more clever approach. That may be what we need to do.

In other words, abscopal responses do happen, but we don’t exactly know why or how and can’t reproduce it?

Dr. Drake: Exactly. And it doesn’t happen nearly as often as we’d like.

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