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Conversations With Prostate Cancer Experts


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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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Using Genomics To Guide Treatment

In March, Prostatepedia is talking about how we’re using (or not using) genomics to guide prostate cancer treatment.

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Dr. Snuffy Myers says in his introduction to the issue:

This month, we’re talking about our understanding of the genetic and molecular mechanisms driving prostate cancer. If we can understand how cancer differs from your body’s normal tissues, we can selectively kill cancer while minimizing damage to normal tissue. As it turns out, this type of research is very difficult.

How can genetic changes cause cancer? How do they determine the biology of the resulting cancer?

Genetic information is stored in DNA. The DNA molecule is like a library filled with instructions for a cell to accomplish various tasks. At any one point, only a small set of the instructions are activated and followed.

In normal biology, the instructions activated are appropriate to the task at hand: liver cells activate instructions for liver structure and function; muscle cells activate instructions for muscle structure and function.

shutterstock_520680199Normally, these cells’ growth and spread are tightly controlled. If you remove half a liver, the liver regrows to its normal size and then stops. Cancers cells’ growth and spread are no longer controlled. Liver cancer cells grow and spread beyond the liver and, if untreated, kill the patient.

How does your body read those DNA instructions?

Your body first creates a RNA molecule that is a copy of the instruction. You use this RNA molecule to produce a protein that makes cells change their structure or behavior. Cancer behavior comes from a set of proteins that promotes inappropriate growth and spread. Several mechanisms cause the production of these protein sets.

The DNA instruction set itself can change, or mutate. We can detect these mutations in DNA instruction sets through DNA sequencing.

shutterstock_440437171.jpgDNA sequencing technology has advanced rapidly and costs less then $1,000/sample. If you can get a sufficiently large biopsy of your cancer, we can sequence the DNA. Foundation Medicine is the largest commercial firm offering this service today.

Unfortunately, mechanisms not involved in DNA mutation, and therefore not detectable by DNA sequencing, can change that RNA copy. Adding the methyl group to DNA commonly alters RNA copy production and plays an important role in prostate cancer. One approach measures RNA copy production of genes important to prostate cancer biology. Tests like Prolaris and Decipher used in early, organ-confined prostate cancer use this approach.

Another approach measures proteins that control prostate cancer behavior or response to treatment. Caris Life Sciences measures the presence or absence of proteins that determine responsiveness to two major prostate cancer chemotherapy drugs called Taxotere (docetaxel) and Paraplatin (carboplatin).

All of these tests require a biopsy. It is often difficult to biopsy prostate cancer and especially bone metastases.

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In advanced prostate cancer, we find cancer DNA in the blood. We can isolate and sequence these cancer DNA fragments to identify mutations in a liquid biopsy.

Guardant Health is the most established company in this area. At my clinic, we’ve used the Guardant360 liquid biopsy extensively to identify hormone-resistance mutations, as well as DNA repair mutations that predict for PARP inhibitor response.

We are only beginning to apply molecular biology to prostate cancer treatment, but the approach has great promise.

Subscribe to read Prostatepedia March 2017: Using Genomics To Guide Treatment.