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Genomics + Prostate Cancer Care

Dr. David J. VanderWeele is an Assistant Clinical Investigator in the Laboratory of Genitourinary Cancer Pathogenesis at the National Cancer Institute. He is particularly interested in investigating the progression of clinically significant prostate cancer.

Prostatepedia spoke with him about how genomics impacts patient care.

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What is genomics, and how does it differ from genetics?

Dr. VanderWeele: Typically if you’re talking about genetics, you’re talking about an individual gene or a small set of genes. When you refer to genomics, you’re referring to all the genes or a very large set of genes. Genomics usually refers to the genes–the DNA sequence. But sometimes genomics is also used to refer to when those genes get expressed (as RNA), or to other changes to the DNA that don’t change the DNA sequence (also called epigenetics).

What do and don’t we know about why some men develop curable or indolent prostate cancers while some develop widely lethal diseases?

Dr. VanderWeele: A lot of effort has been put into trying to learn more about the genes you inherit from your parents and how that influences the likelihood that you’re diagnosed with cancer. Most of that effort has been unable to identify which alterations in your genes make it more likely that you will get an aggressive versus an indolent cancer.

As many of your readers probably know, many people get indolent prostate cancers. In fact, many autopsy studies have looked at patients who have died of other reasons and have never been diagnosed with prostate cancer. Once men reach their 70s or 80s, it looks like more than half of men develop prostate cancer. Of course, those are relatively slow-growing cancers.

The most information that we have now is that men who come from families with breast and ovarian cancer syndrome appear to be more likely to get cancer and more likely to get aggressive cancer. These involve BRCA1, BRCA2, and other DNA repair genes in a similar pathway. Though there aren’t FDA-approved therapies yet, there are trials suggesting that these patients are also more likely to respond to certain therapies approved for breast and ovarian cancer.

This is a pretty small subset of all the men with prostate cancer, but the percentages increase with any kind of measurement of aggressiveness. If you look at people with localized cancer, that percentage increases if you have high-grade cancer versus low-grade cancer. The percentage increases if you compare people with advanced castrate-resistant prostate cancer to those with localized cancer.

If you look at the length of time between a man’s diagnosis and when he dies, that rate increases significantly the shorter that time is. That is just looking at three of these genes, BRCA1, BRCA2, and ATM. If you look at a broader number of these DNA repair related genes, it looks like ten to twelve percent of all patients with castrate-resistant prostate cancer harbor a mutation that they inherited from their parents. It seems likely that for most of those patients, that inherited gene contributed to their prostate cancer.

That has led to some debate about how often we should test for mutations in these genes. Is that a high enough number that we should test everyone with castrate-resistant prostate cancer? Should we still rely on family history to provide guidance for which people should be tested?

Is it really expensive to test those men? Why wouldn’t you just go ahead and test?

Dr. VanderWeele: Depending on how you do it, testing costs have come down quite a bit.

But when you’re testing for genes that could potentially be passed on to your offspring, or that siblings or other family members may have inherited, there are implications for your other family members, not just for you.

Some members of your family may definitely want to know that information and think that more information is better. Others may feel that if they find out that they harbor that gene mutation, they will just feel like they’re waiting for the other shoe to drop. It’s not information that they’d want to know.

Generally, we advise people to get counseling to help them think through some of these issues before getting tested for genes they’ve inherited from their parents.

Do we know why some men respond to certain drugs and therapies and others don’t?

Dr. VanderWeele: There’s a lot of interest in that. There has been some progress made in terms of identifying the biomarkers that might suggest which patients are more likely to respond to which types of therapies. At this point, however, most patients still get treated with most therapies.

There are some genetic biomarker-driven therapies that look like they’re on the horizon. Patients with mutations in BRCA2, ATM, and related genes are more likely to respond to a type of therapy called PARP inhibitors, which are currently approved for patients with ovarian or breast cancer, but not yet for prostate cancer.

There was a single Phase II study that showed that patients who had loss of a specific tumor-suppressor gene called

PTEN are more likely to respond to a certain type of targeted therapy. There are larger ongoing trials to demonstrate that these are indeed predictive biomarkers for response to these therapies.

There are companies like FoundationOne and GenomeDX that look at the molecular features of a man’s cancer. Are those tests useful? What do they tell a patient?

Dr. VanderWeele: The FoundationOne test looks for mutations, deletions, or amplifications of specific genes that are relevant for a wide array of cancers. There are a lot of companies offering this type of sequencing.

Many hospitals offer their own version of it. A FoundationOne type of test can tell you if you have a mutation in BRCA2 or ATM. They should also be able to tell you if you have a deletion in PTEN. When they detect a mutation is present, however, generally they are not looking to determine if you inherited those changes from your parents versus the mutation being present only in the tumor cells.

These genetic tests are more popular in other types of cancers, because for prostate cancer there aren’t yet any FDA-approved therapies that would be given based on the results of these tests. These tests will become more popular as we make progress in demonstrating the benefit of these specific therapies and in our ability to predict which patients are most likely to respond.

If a patient reading this gets one of those tests, is it likely that his doctor is going to know what to do with the results? Will the results actually impact his treatment?

Dr. VanderWeele: There are probably a small number of patients who will have a result that will directly impact their therapy. At this point, the way that it would impact therapy is that it might suggest that they should find a clinical trial testing a specific type of drug.

I see.

Dr. VanderWeele: There are also other commercially available prostate specific genetic tests, like the one performed by GenomeDX, that are mostly aimed at men with localized prostate cancer who are trying to decide how aggressive their therapy should be. Typically, this means whether they should pursue active surveillance or get surgery or radiation.

Sometimes these tests are also used to determine if a patient should get radiation after undergoing a prostatectomy or if he should just continue to follow PSA numbers. The prostate specific gene expression tests are RNA-based tests, which are a little different.

They measure the levels of expression of a few specific genes. Tests like FoundationOne look for mutations, amplifications, or deletions of genes—which means they are DNA-based tests.

Tests like Decipher are more widely used now, right?

Dr. VanderWeele: Yes. They’re probably used mostly by urologists. My sense is that how often urologists order those tests and how heavily they rely on them versus other ways to predict the risk level of the prostate cancer varies quite a bit from urology practice to urology practice.

Subscribe to read the rest of Dr. VanderWeele’s thoughts on how genomics impacts prostate cancer care.


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Can Decipher Change Your Prostate Cancer Treatment Plan?

Dr. John Gore is a clinician, surgeon, researcher, and educator specializing in urologic oncology and general urology at the University of Washington.

Prostatepedia spoke with him about how Decipher changes the way doctors treat men with prostate cancer.

What is Decipher?

Dr. Gore: Decipher is from a family of genomic tests. In general, it tries to look at some of the alterations in people’s genes associated with cancer or its progression. Decipher attempts to create a panel of genes associated with the likelihood of a cancer coming back. It takes that panel of genes and integrates it with clinical information to calculate the risk of developing spread of cancer to sites that could be detected clinically, like the bones or the lymph nodes, within five years after prostate cancer surgery.

When is a man likely to encounter this test? After that initial biopsy when he is first diagnosed? After his prostatectomy?

Dr. Gore: The most common scenario would be after surgery. If a man has his prostate removed and the pathology shows that he has a cancer that by all accounts seems to have been successfully treated with the surgery, Decipher may not be the right test for him.

If he has some high-risk features— his cancer is potentially encroaching on the shell of his prostate, he has a positive surgical margin, or there is involvement of the seminal vesicles that sit behind the prostate—then he might benefit from Decipher.

That way we can ask if—in addition to knowing that he had some high-risk pathology features—he appears genomically to have a high-risk cancer?

What do the results look like? Do they change how a man is going to be treated post-surgery? How?

Dr. Gore: The actual report that a patient or doctor gets tells them the probability, or percent risk, that he will have clinical metastases within five years of having his prostate removed for prostate cancer. In general, those numbers tend to be in the single digits to low teens. It’s not a common event.

For most people, prostate cancer surgery successfully treats their cancer. That is why this is best used on higher-risk individuals.

In our study, we looked at a cadre of patients who were either found to have high-risk features at the time of their prostate cancer surgery, or now their PSA is subtly rising after going to zero after surgery. Those patients should potentially have more aggressive treatment.

We showed that if a patient had the Decipher test, physicians’ recommendations changed. If your Decipher results showed a lower risk score, your doctor was more likely to recommend observation.

Patients with a higher risk Decipher score were more aggressively treated. They were recommended to go ahead and get additional radiation to the area where their prostate was removed, rather than just active surveillance.

The bottom line is that Decipher changes how men are treated?

Dr. Gore: Yes. We have some follow-up data we just presented at the American Society of Clinical Oncology, Genitourinary meeting in February that showed that those treatment recommendations were actually followed 80% of the time.

You said only men who are high-risk should really be tested. Not everyone getting prostate cancer surgery needs a Decipher Test?

Dr. Gore: That’s right.

Is Decipher widely accepted in the medical community? If a man in rural Minnesota goes to his local urologist or local community oncologist, will he likely be offered the Decipher Test? If not, should he ask his doctor to order it?

Dr. Gore: I think it’s definitely worth requesting it. One thing that has come up is insurance payer coverage, not just for the Decipher Test, but also for other tests like it. The bar that some of these companies have to cross to get their test approved is fairly high.

Some insurance companies are asking if the test not only changes treatment for patients. The trial they’re looking for will compare patients who got the Decipher Test with patients who didn’t to see if the decisions that were made impacted cancer outcomes. If, for example, your Decipher results say you’re high-risk, and you get radiation based on that information, was that the correct decision? The challenge is that prostate cancer is immensely slow-growing. Even when it’s high-risk, even when it’s aggressive, we’re talking about clinical outcomes that take years and years to manifest. It imposes an irrationally onerous burden to prove that these tests are the right thing.

You could wait 10 years to find out if the treatment decisions were correct. Meanwhile, time is passing and these men need to make choices…

Dr. Gore: Absolutely.

Join us to read the rest of Dr. Gore’s thoughts on the Decipher test for prostate cancer.


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Differences Between Prostate Cancer Genomic Tests

Eric A. Klein, MD, is an international leader in the biology and management of prostate cancer. Dr. Klein serves as Chairman of the Glickman Urological & Kidney Institute at the Cleveland Clinic.

Prostatepedia spoke with him about the differences between the various genomic tests available to prostate cancer patients.

Dr. Eric Klein: These tests measure the expression of genes in prostate cancer. That’s what they’re designed to do. They predict the likelihood of your having higher-grade cancer or cancer that penetrates the rind around the prostate (called extraprostatic extension), or cancer in the lymph nodes or seminal vesicles. These tests predict that better than biopsy or plain old Gleason grading. This gives us a leg up in deciding who is a good candidate for surveillance.

If your biopsy only shows Gleason 6, but you actually have higher-grade cancer in the prostate, or you have some cancer that’s through the rind or in the seminal vesicles, you’re not a good candidate for surveillance. We know that from decades of doing radical prostatectomies. These patients are at highest risk for progression and that’s what these tests measure.

They also tell us whether a pure Gleason 6 cancer is one of the 5-10% that has molecular features of high-grade cancer.

These are biopsy-based tests. For example, if a patient has a biopsy that shows Gleason 6 cancer and otherwise favorable features, such as a PSA below 10, and a PSA density below 0.15, we wonder whether he’s a candidate for surveillance. We always do a confirmatory test after a first biopsy. Decipher can also be used after the prostate has been removed to help decide on the need for additional treatment.

A genomic test like this is appropriate in some patients. An MRI of the prostate is appropriate in others. Sometimes it’s appropriate to get both. We don’t have enough experience to know which is the best test for which scenario, although I have some ideas about that. Then, once we confirm that the patient has a low-grade cancer that lacks molecular features of high-grade cancer, we feel confident in putting him on surveillance.

The results can do two things. They can confirm that the patient is a candidate for surveillance. Sometimes they can convince a reluctant patient that surveillance is the right thing. We don’t want to over-treat people who have low-grade cancers that aren’t going to kill them because the side effects of treatment are worse than the likelihood of his dying of cancer. Sometimes, the results can convince a physician that surveillance is the right thing. If you look at the criteria for putting people on surveillance, it’s mostly patients who have just a minimal amount of cancer–low-grade cancer, a Gleason 6 on a biopsy.

We published a study in the Journal of Urology recently that showed that even among patients with high-volume

Gleason 6 cancer in multiple cores— four or five remove cores—many have no molecular features of high-grade cancer. In the past, they haven’t traditionally been considered good candidates for surveillance, but based on the biology of their tumor, they are good candidates for surveillance.

You may have someone who has a couple of cores of low-grade cancer, maybe a PI-RADS 4 lesion on MRI.

You’re not sure if they’re a good candidate for surveillance or not. If a genomic test confirms the absence of molecular features of high-grade cancer, you can put the patient on surveillance. That is the kind of information that genomic tests provide. They have their nuances.

Oncotype and Decipher are good for patients with very low, low, and favorable intermediate-risk disease. Prolaris is best validated for patients who have intermediate risk disease. It doesn’t have good discriminatory value for low-grade cancers. Generally, they all measure gene expression and they’re all are used in the same way.

These tests help determine whether or not someone is a candidate for surveillance. At the moment, we don’t use these tests based on biopsy to determine which treatment to give a patient, but that’s coming. Post-prostatectomy, Decipher can help tell us that.

There are challenges to active surveillance. Say we put someone on surveillance and he starts out with 1 core of Gleason 6 cancer. A year later, he is re-biopsed and has 3 cores of Gleason 6 cancer. We don’t know whether that’s true biologic progression that requires treatment, if all that Gleason 6 cancer was there in the beginning and was just not sampled by biopsy, or if the patient grew some new Gleason 6 cancer that doesn’t have any biologic potential.

This isn’t established yet, but I believe we can use these tests for what I call serial biologic monitoring, meaning you biopsy patients a year or three apart. These tests, for the very first time, allow us to measure true changes in biology as opposed to just changes in what we see on biopsy, which may underestimate what’s going on in the prostate. This is a new paradigm.

Another common scenario is a man who has a low-grade cancer on initial biopsy (1 core, Gleason 6) and a year later has a little bit of Gleason 3+4 with 5% pattern 4 and 95% pattern 3. In the past, that would always trigger treatment. But it’s my belief, based on what we’ve learned from these tests, that this is probably not correct. Many of those men can still stay on surveillance.

Join us to read the rest of Dr. Klein’s thoughts on genomic tests for prostate cancer.

 


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Genetic Testing + Counseling

Ms. Merel Nissenberg is the President of the National Alliance of State Prostate Cancer Coalitions, a nation-wide organization comprised of state prostate cancer coalitions dedicated to saving men’s lives and enhancing the quality of life of prostate cancer patients and their families through awareness, education, and the development of a public policy network.

She talks to Prostatepedia about guidelines for genetic testing in men with prostate cancer.

Much has been written or suggested about the genetic component of some prostate cancers. For example, a family history of prostate cancer can increase a man’s risk of such a diagnosis. There have also been articles about the genetic component of certain breast cancers: BRCA1 and BRCA2 have historically been strongly implicated in the familial pathway for that diagnosis. What is more recent is the now more-firmly established connection between certain mutations like BRCA1 and BRCA2 and prostate cancer. However, guidelines for genetic testing in men with prostate cancer have been limited.

Recently, the Journal of Clinical Oncology published a special article entitled “Role of Genetic Testing for Inherited Prostate Cancer Risk: Philadelphia Prostate Cancer Consensus Conference 2017” following the Prostate Cancer Consensus Conference held in Philadelphia on March 3-4, 2017. Members of the panel strongly agreed that men should engage in shared or informed decision-making on the issue of genetic testing.

Panel members emphasized the strength of the inherited predisposition of prostate cancer, noting higher risks with BRCA1, BRCA2, and HOXB13 genes. The panel noted that prostate cancer patients with BRCA2 mutations have poor prostate cancer-specific outcomes. We now consider the link between prostate cancer and DNA mismatch repair (MMR) gene mutations to be stronger than we suspected, adding a specific opportunity for treatment. In fact, up to 12% of men with metastatic prostate cancer have inherited genetic mutations, mostly with BRCA1, BRCA2, and ATM. And targeted agents for these specific mutations confer better outcomes for these patients.

The panel concluded that: “Identifying genetic mutations of inherited prostate cancer… has implications for cancer risk assessment for men and their families, for precision treatment of metastatic disease, and is being incorporated into guidelines for individualizing prostate cancer screening strategies specifically for male BRCA1 and BRCA2 mutation carriers.”

Unfortunately there are no generally accepted standard guidelines for genetic counseling and genetic testing in prostate cancer, or standards on how to fully interpret results of current panels with multiple gene testing. The information discovered through genetic testing not only informs treatment for the prostate cancer patient himself, but is also an aid to other members of his family, including women who may have a genetic disposition for developing breast cancer. As for the patient, not only does the information potentially help guide prostate cancer treatment, but it also makes both him and his clinician aware of the potential for additional cancers.

The results of the Philadelphia Prostate Cancer Consensus Conference can be read in detail in the Journal of Clinical Oncology 36, no. 4 (February 2018), 414-424. Their considerations included the following:

  • which men should undergo genetic testing for prostate cancer;
  • which genes should be tested based upon clinical or family scenarios;
  • how the testing results should be used to inform screening for prostate cancer; and
  • how results should be used to inform treatment of early stage (localized), advanced stage (high-risk), and metastatic prostate cancer. Genetic testing done thoroughly and properly can help guide screening and treatment decisions.

The National Alliance of State Prostate Cancer Coalitions strongly endorses the use of genetic testing and genetic counseling for prostate cancer, and urges clinicians to read, consider, and follow the scientifically sound suggestions of the 2017 Philadelphia Prostate Cancer Consensus Statement on the Role of Inherited Prostate Cancer Risk. NASPCC will be presenting a Webinar on Genetic Testing and Genetic Counseling in Prostate Cancer on May 9, 2018. It is supported by Myriad Genetics. (Visit https://naspcc.org/index.php/may-9-2018-naspccwebinar to register.)


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Patients Help Shape Prostate Cancer Genomics Study

Joel Nowak is a prostate cancer patient and well-known prostate cancer activist.

Prostatepedia spoke with him about his involvement with the Metastatic Prostate Cancer Project.

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What is the Metastatic Prostate Cancer Project?

Mr. Nowak: This is a joint project between the Broad Institute and the Dana-Farber Cancer Institute. But what is really more important to me is the researchers who are involved: Dr. Corrie Painter and Dr. Eliezer Van Allen are really committed to what they’re doing. They’ve modeled this project off of a metastatic breast cancer project that they also started.

One of the researchers is a cancer survivor, so they understand what it means to have cancer. Their understanding motivates what they’re doing. They’re carrying it forward; they’re not just doing it because they have a grant.

How did you come onboard with the Metastatic Prostate Cancer Project?

Mr. Nowak: My friend Jack Whelan, who I’d worked with at the American Association of Cancer Research Scientist↔Survivor Program, had a very rare blood cancer. Then one day he surprised me by saying he’d been diagnosed with prostate cancer. I thought he was joking at first.

Unfortunately, his cancer progressed really quickly, probably related to all the treatments he had for his blood cancer. The project staff brought me, Jack, and Jan Manarite in to work on the project. They asked me to look at their materials and give a patient’s perspective. They wanted to know if I found value in the project

They asked me to give them specific feedback and suggestions for improvement. Jack, Jan, and I have also brought in two others. Dr. Van Allen’s team has taken all of our suggestions and made the changes.

They also asked us to spread the word, let people know about it, reach out within the prostate cancer community, and help recruit.

What is it about the project that makes it patient-friendly?

Mr. Nowak: The project is patient friendly because once someone consents and says, “Count me in,” the project team does all the work. They send out a package, which we advocates helped redesign, and you just contribute your spit. Then you bring your sample back to the post office or FedEx; it’s all prepaid. Spit it and ship it. That’s the effort.

We also send out blood vials that are also prepaid. Theoretically, you can walk into a lab and they’ll draw your blood for free. Or you can bring the vials to your next doctor’s appointment. You don’t even have to make a special appointment; just ask them to draw an extra tube.

It’s easy.

Mr. Nowak: Yes. It’s easy, and it’s all prepackaged. Either you or the phlebotomist can just put it into the prepaid package and send it off. You don’t have to do much.

Part of the consenting process is the release of the medical records. The project does the sequencing of the blood and saliva, and if applicable, we ask for tissue. There’s not a lot of tissue in prostate cancer, generally, so that was one of the issues I brought up. I wanted to ensure that no one’s tissue is used up and withheld from them for the purposes of this research, because you never know when we’ll need your own tissue for treatment decisions. We advocates said this was a big issue, so the project will only use a small piece and return it. You need to get it back: you just never know when you’ll need it yourself.

You need to look out for yourself.

Mr. Nowak: Yes. It’s appropriate to be selfish in this particular situation. The only thing you have to do as a patient is read the consent, discuss it with the appropriate people at the project, sign the paperwork, spit, and bleed. That’s all we have to do. Everything else is handled by the project. You don’t even know it’s happening; it’s all behind the scenes.

This is a research project, not a clinical trial, but even with clinical trials everything gets de-identified. That means that your personal information is safe, but you also get no follow-up information. As a patient advocate, I asked what they could do to give some feedback to patients. They were very open to having this conversation, but they are sensitive about overpromising anything. We don’t want to mislead anyone.

If we start seeing trends in the data, we will give some feedback. We can’t tell individuals that they have gene mutations or not, for example, because their sample was de-identified. But if, hypothetically, we see samples from 300 people with a combination of at least three gene mutations and that 285 people with a particular mutational sequence respond to Xtandi (enzalutamide) but not to Zytiga (abiraterone), then we will give feedback.

But this is exciting. When we start seeing trends or possible trends, the project will release information to people who participate. There will be aggregate data feedback. We’ll be able to publish relationships. It doesn’t of course stop me as a patient from going to my doctor and getting sequenced. Probably all of us should be sequenced anyway.

The patient can follow up as he chooses…

Mr. Nowak: Exactly. Then they could say, “I’ve been sequenced, and I have this mutation.” That is just an additional talking point with your doctor from the aggregate data. I’m excited about that. That’s going to give some people another thing to consider when deciding between treatments.

Why should men participate? Did you participate?

Mr. Nowak: I did. Jack and I fought over who would be Patient 1. I had respect for Jack, so I told him he could be Patient 0, and I’d be Patient 1. Technically, I’m Patient 2. Men should participate for a number of reasons. First of all, we have to think about the next generation. My prostate cancer is genetically linked. My father had it. His brother died from it, and his only child, who’s older than I, who had been treated. My grandfather had prostate and breast cancers, and my great-grandfather died of prostate problems. Many of us have or are going to have kids, so we should make it a little better for them if we can.

I spend a lot of time working with people and helping them figure out how to have a conversation with their doctor about treatment. Anything that can give us more information and more points of conversation is important. Aggregate data might help us have better conversations that may help make better decisions going forward.

This is one of those rare research projects where I could possibly benefit directly. As I start going through treatment protocols and so forth, I have no idea where they may find something that works better for me. It’s just going to guide my decision-making. Maybe it’ll extend my life because I made a better decision thanks to the project.

We also need to understand cancer more generally in terms of genetics and its microenvironments. We need to understand cancer not only as separate diseases. Prostate cancer only describes the organ from which the cancer originates. It doesn’t really describe my disease or another’s. We need to drill down and understand the type of prostate cancer that one has and how it relates to cancer generally. That is going to guide us in making better decisions.

This type of research is invaluable. There are no risks. There is nothing invasive. The more we understand, the better future research will be, whether for specific treatments or a better understanding of biomarkers, which we have a terrible dearth of knowledge about. To me, it’s a no-brainer for us who are going to benefit at no cost.

I hope men sign up.

Mr. Nowak: Yes. That’s our goal. Now that we have IRB (Internal Review Board) approval, our next step is to get men signed up.

To participate visit https://mpcproject.org/home

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The Genomic Revolution Comes To Prostate Cancer

Dr. Oliver Sartor, the Laborde Professor of Cancer Research in the Medicine and Urology Departments of the Tulane School of Medicine, is one of the leading researchers in advanced prostate cancer today. He is also the editor-in-chief of Clinical Genitourinary Cancer and the author of more than 300 scientific papers.

Dr. Sartor puts this month’s conversations about prostate cancer genomics into context for us.

“We can divide genomics into two different categories. The first category is germline genomics, which is the DNA with which you’re born. It’s clear that about 12% of people with advanced prostate cancer will have alterations in their inherited DNA, in particular in genes involved with DNA repair. Most common of these alterations are BRCA2. There are a variety of others that are somewhat prevalent, including ATM, CHEK2, and BRCA1. There are others that are more rare.

The implications of these germline mutations are significant for the patient: in certain configurations they may predispose a cancer to be sensitive to certain therapies, such as PARP inhibitors or platinum-based chemotherapy or (rarely) immunotherapy. There is more complexity, but knowing the germline mutation helps the informed clinician make decisions. In my practice, we test all patients with advanced prostate cancer for these germline mutations. (A National Comprehensive Cancer Network guideline suggests the same approach.)

These germline mutations represent the DNA with which you’re born. That DNA is going to have repercussions if also mutated in your family members. Men who have some of these DNA repair mutations have an increased risk of prostate cancer. In addition, there is a small increased risk of pancreatic cancer and male breast cancer for those with some of the germline mutations. Around 30% of men with BRCA2 will be diagnosed with prostate cancer in their lifetime, but that cancer is more likely to be aggressive if diagnosed. With regards to females, it’s particularly important. Females with DNA repair defects are more likely to have breast and ovarian cancer. Female with DNA repair mutations, in particular BRCA1/

BRCA2, ought to consider having their breasts or ovaries removed at an appropriate time. Prophylactic surgery has been demonstrated to be potentially life-saving for those individuals. The risk of breast cancer may be as high as 70% and the risk of ovarian cancer may be as high as 40%.

Thus, for these germline mutations there are implications for treatment and implications for the patient’s family.

We should be doing prostate cancer screening earlier in men with these DNA repair defects for prostate cancer; we should be doing biopsies at a PSA of 3 or higher, and perhaps even lower, for younger men known to be at risk. Starting screening at age 45 has been suggested by some. In addition to germline genomics, we need to also talk about somatic genomics. Data indicates that about 60% of individuals who have a DNA repair germline mutation are likely to have another second genetic mutation occur within their tumor. In addition, many of the tumors can acquire an alteration in their tumor DNA even when the germline is normal.

Taken together, about 20 to 25% of men may have DNA repair mutations in their tumor’s DNA. That makes them particularly sensitive to certain therapies such as the PARP inhibitors, as I mentioned earlier, or platinum chemotherapy. When you have two DNA repair mutations in the same cell, the likelihood of response to these agents appears fairly high.

There are also other DNA defects of considerable interest, such as alterations of the mismatch repair genes MSH-2 and MSH-6. When these alterations do occur, there is a potentially increased probability of responding to immunotherapy such as the new PD-1 inhibitors.

Overall, the guiding light today in genetics in my practice is to look at both the germline DNA and the tumor DNA. I choose to look at the tumor DNA circulating free DNA (cfDNA) tests, in particular the Guardant Health assay. The ability of other assays to corroborate the Guardant Health findings is not yet clear. There is clear data to indicate that different assays give different results, but nevertheless, I think in the early exploratory phase we’re in now, it’s important to begin to test patients in order to better understand their genomics and hopefully guide us towards better therapies. This will happen part of the time but certainly not all of the time.

There is more to the story of prostate cancer genetics. We’ve looked at androgen receptor mutations that can have implications for a response to Androgen Receptor directed therapy, such as Xtandi (enzalutamide), Zytiga (abiraterone), and Erleada (apalutamide). We’re dissecting a number of permutations that occur. It’s a complex scenario, because very few men have only one mutation. Most have multiple mutations. And in most cases, these mutations are not targetable with current therapies. This is very important for people to know.

Everybody thinks if they get a genomics test that means they’ve got a treatment. It’s not the case. Many times we get the genomics results and find that there are no known treatments we can use for that man’s particular alteration. That said, there is a subset of men who will have informative genomics while many more people will have non-informative genomics.

There is a final issue I’d like to discuss. There is currently a bit of a debate amongst physicians over the utility of PARP inhibitors such as Lynparza (olaparib) as compared to platinum chemotherapy. But it is noteworthy that platinum-based chemotherapies are inexpensive compared to PARP inhibitors. This does not require a clinical trial. (Most men will access PARP inhibitors through a clinical trial, although sometimes insurance companies are willing to try.)

As it turns out, neither the platinum-based chemotherapies nor the PARP inhibitors will be effective forever, so we do need strategies to manage patients after PARP inhibitors or platinum-based chemotherapies fail. Currently, that space is unexplored. We have to gather much more data before we can make conclusions about those with underlying DNA repair defects who have failed platinum-based chemotherapy or PARP inhibitors.

This is an area of active and important investigation that represents a conundrum for many patients today. I’ve got a patient right now going through this. We’re debating what to do next. I’ve tried to be as honest as I can when I say, “I don’t know what to do, but we’ve got to try something.”

We are in the middle of a revolution, but the parts and pieces are not yet clear. For some, understanding tumor genetics at the current level is helpful. For others, it is perplexing and expensive.

Join us to read this month’s conversations about prostate cancer genomics.

(Already a member? You can read all conversations in your copy of April’s Prostatepedia.)


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Neuroendocrine Prostate Cancer

Beltran Himisha

 

 

 

 

 

 

 

Dr. Himisha Beltran, an Assistant Professor of Medicine at Weill Cornell Medical College in New York City, is keenly interested in developing research programs to study neuroendocrine prostate cancer.

We spoke with her about this aggressive form of prostate cancer.

Your research deals with a small subset of patients and is considered a specialized area of research. How did you become interested in neuroendocrine prostate cancer as opposed to another aspect of the disease?

Dr. Himisha Beltran: I take care of prostate cancer patients at all different stages of their disease. We know that not all patients with prostate cancer are the same and they may respond variably to the therapies that we use. My research has focused on understanding mechanisms of treatment resistance and identifying subsets of patients that may benefit from nonstandard approaches.

Neuroendocrine prostate cancer is one subtype within the spectrum of advanced prostate cancer that tends to look and act differently compared to your typical prostate cancer. They tend to be less responsive to standard therapies and often do not make PSA.

That is really what led me to neuroendocrine prostate cancers. I was struck by how some patients had tumors that looked very different under a microscope and acted very different clinically than others looked and acted. By understanding a small subgroup of patients, we can also better understand the entire group. That is really what precision medicine is about: identifying subgroups of patients that either have clinical, molecular, or other features that will help guide treatment. While my research is focused on a small subgroup of men, I think the impact potentially affects many more.

Let’s back up a bit and define neuroendocrine prostate cancer.

Dr. Beltran: Most prostate cancers consist of adenocarcinoma cells, which are derived from normal prostate tissue. They have more glandular prostate features. They express many prostate markers. When we say a cancer is neuroendocrine, we mean that the tumor looks less like a typical adenocarcinoma and has features that look more like neuroendocrine cells, which have a distinctive morphology under a microscope. Neuroendocrine cells tend to be smaller and may not express classical prostate markers such as the androgen receptor, which is the target of many of our drugs like Zytiga (abiraterone) and Xtandi (enzalutamide). These cancers also acquire other distinct molecular features.

What we’ve learned in recent years is that neuroendocrine prostate cancer rarely arises de novo; they most commonly develop in later stages of prostate cancer progression from a preexisting prostate adenocarcinoma as a way for the cancer cells to evade therapy. The tumors try to change their identity to develop new ways to grow. There is a spectrum as tumors progress from androgen-driven prostate adenocarcinoma toward an androgen independent neuroendocrine prostate cancer. Within this spectrum, the cancers may develop mixed or overlapping features, expressing some prostate markers but also acquiring new resistance markers.

Is there any way to predict who is going to develop treatment resistance?

Dr. Beltran: By studying the clinical and molecular features of patients, how cancers evolve with time, and how these features affect the biology of the cancer, we now have better insights into mechanisms of response and resistance to specific therapies. This growing knowledge sets the stage for biomarker development.

We are interested in identifying patients before they develop neuroendocrine prostate cancer. We are investigating the genomics and other molecular features of tumor biopsies and applying this to noninvasive approaches such as liquid biopsies— looking at cancer cells or DNA from cancers that may be detected in the blood. If we can identify patients, we can also select patients most likely to benefit from a neuroendocrine type of regimen.

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