What Patients With Prostate Cancer Should Know About the EMBARK Trial

Findings from the phase 3 EMBARK trial, which enrolled more than 1,000 patients with prostate cancer, recently resulted in the approval of Xtandi (enzalutamide) for non-metastatic castration-sensitive prostate cancer (nmCSPC) with biochemical recurrence at high-risk for metastasis by the Food and Drug Administration (FDA).

“It was (a) study that we've been following in the prostate cancer community for many years now. …This study was really looking at how we can add treatments like hormone treatments that you might have received during your radiation therapy, or a drug called enzalutamide, or Xtandi, the brand name, to see if we can actually prevent the cancer from returning at some point,” explained Dr. Stephanie Berg, a medical oncologist for the Dana-Farber Cancer Institute’s Lank Center of Genitourinary Oncology and an instructor of medicine at Harvard Medical School.

During EMBARK, results of which were published in The New England Journal of Medicine, 1,068 patients were treated with Xtandi plus Lupron, placebo plus Lupron or Xtandi as a monotherapy. After five years, metastasis-free survival was 87.3% for patients in the combination treatment group, 71.4% for those treated with Lupron and placebo and 80% for the monotherapy cohort.

Xtandi, approved by the FDA for metastatic castration-resistant prostate cancer in 2012, is the first androgen receptor signaling inhibitor approved for patients with ncCSPC who are at high risk for biochemical recurrence, determined by rising levels of prostate-specific antigen (PSA), a protein associated with the presence of prostate cancer in the body.

Berg discussed EMBARK and some of its key findings.

Transcript:

It was (a) study that we've been following in the prostate cancer community for many years now. So, it was really great to see the New England Journal paper that was published a few months ago. And to remind everybody, EMBARK was actually a very large phase 3 trial, not just in the United States, but actually it was an international trial as well. And it looked at men (who) had a PSA doubling time of less than nine months.

So, what that means is after you have treatment for your prostate cancer, either surgery or radiation, your oncologist follows your PSA and they follow it really closely, because we know that there could be a chance that cancer might be coming back. And the PSA test is a really sensitive way that we can find that out. So, this study was really looking at how we can add treatments like hormone treatments that you might have received during your radiation therapy, or a drug called enzalutamide, or Xtandi, the brand name, to see if we can actually prevent cancer from returning at some point. So, that was the big takeaway.

The one thing to mention about this and on the label of how the drug is approved is that if you were to receive this enzalutamide or Xtandi, with or without the LHRH agonist like leuprolide, it can actually be held after 36 weeks. So that's about eight months of treatment, depending on how the PSA responds, which I think is a really important point, because in cancer medicine, especially in prostate cancer, we're really trying to learn how we can give effective therapy for shorter periods of time and still have good outcomes versus saying, 'You're going to be on a medication forever.' And I know that that can cause a lot of anxiety as well, when your doctor tells you, 'You're going to be on this forever,' when we know forever is not really the word that we should be saying a lot of the times when we have good data to say we can hold things, or we can reassess at intervals to make sure that it's effective.

I think it's really important when you talk to your doctor about the data and (if) this combination will be right for you in this setting if you meet (the criteria of) how the men that were rolling this trial with this PSA doubling time these high-risk features, is really focusing on quality-of-life. I think it's something to note, (that) when this trial had three different treatment arms, there really wasn't an improvement in quality of life, they just said there are no new safety or side effects noted. But they didn't really say that men were maybe living better, they all kind of had the same symptoms, especially fatigue, which is a big one.

Transcript has been edited for clarity and conciseness.

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