Improved Survival Outcomes of African America Men with mCRPC Treated with Sipuleucel-T - Kelvin Moses

April 23, 2019

Kelvin Moses explores the clinical benefit of sipuleucel-T treatment in African American men with advanced prostate cancer in this conversation with Alicia Morgans. A large volume of evidence has demonstrated that African American men have an increased risk of developing mCRPC and have higher mortality as compared with Caucasian men. Sipuleucel-T has demonstrated a survival benefit in men with metastatic castration-resistance prostate cancer (mCRPC) and it is well tolerated. Todays discussion focuses on an analysis of data pooled from 3 phase III, multicenter studies, demonstrating that sipuleucel-T improves overall survival in African Americans patients with mCRPC and that this improved survival is a durable and persistent response.

Kelvin Alexander Moses, MD, PhD Associate Professor Department of Urology, Director of the Comprehensive Prostate Cancer Clinic, Vanderbilt Health, Vanderbilt University, Nashville, Tennessee

Alicia Morgans, MD, MPH Associate Professor of Medicine in the Division of Hematology/Oncology at the Northwestern University Feinberg School of Medicine in Chicago, Illinois.

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Alicia Morgans: Hi. My name is Alicia Morgans, and I'm a medical oncologist at Northwestern University. I am so excited to have here with me today Dr. Kelvin Moses, who is an Associate Professor in the Department of Urology at Vanderbilt University, as well as the Director of the Comprehensive Prostate Cancer Clinic there where they treat advanced prostate cancer, metastatic and castration-resistant prostate cancer. Thanks so much for joining me today, Kelvin.

Kelvin Moses: Glad to be here. Thank you for the invitation.

Alicia Morgans: Of course. I wanted to speak with you about sipuleucel-T and a really provocative abstract that you presented at GU ASCO just a few months ago, looking at survival outcomes of African American men with metastatic castration-resistant prostate cancer, who were treated with sipuleucel-T and trying to tease out the benefit that they may have from treatment and how that might be different as compared to Caucasian men. I'd love to hear... Can you give us an overview of that study?

Kelvin Moses: Absolutely. It's been known for quite a while now that sipuleucel-T has a survival benefit among men with metastatic cancer or resistant prostate cancer and that, in general, it's quite well tolerated, very few side effects. We wanted to look at the data in terms of different ethnic groups who were evaluated during the trials, the pivotal trials, that led to the approval of sipuleucel-T. 

It's well known that black men, in general, have worse disease at the time of diagnosis of prostate cancer and higher mortality from prostate cancer, and so the point of evaluating black men in the context of sipuleucel-T and to see if some of those differences in mortality could be mitigated. Pooling data from the three Phase 3 studies, we looked at survival among black and white men with metastatic cancer or resistant prostate cancer, and then also looked at the number needed to treat to benefit, essentially, the lower the number needed to treat the benefit, the greater the "benefit" for these patients in that they're not exposed to additional complications at the... greater complications in the face of lower risk of death.

Alicia Morgans: So, really, really provocative. How does this particular analysis add to what we heard from Dr. Sartor a few years ago, really kind of looking at some of the primary data, or... I'm not sure. Perhaps it was data from the PROCEED registry that suggested there's differential benefit between African American men and Caucasian men.

Kelvin Moses: Definitely. It really follows up nicely with what Dr. Sartor found from the PROCEED registry. If you'll remember from the Schellhammer paper, they show that when the PSA was evaluated and quintiled, the lowest quintiles showed extended survival, or greater survival, than those with higher PSA. Then within the PROCEED registry, Dr. Sartor showed that black men have an even greater response, or sorry, greater survival benefit compared to white men and this was statistically significant.

What we're showing in this study is that even with the survival benefits, number one, this benefit is durable, and, number two, there's not an excess number of men who have to be treated in order to garner this benefit. For example, the number needed to treat to benefit at 12 months among the entire populations so the pooled analysis versus black men was both 13, so 13 men had received sipuleucel-T to save one life. At 24 months, that number dropped down to 10 in the pooled analysis, but was five among African American men. Then at 36 months so three years, the pooled analysis showed the number needed to treat to benefit of eight versus three among black men. So, what you're seeing here is a durable and persistent response over time and a greater benefit among black men compared to the pooled population. This is one of the first treatment modalities that has shown such a dramatic benefit among a specific population that is normally known to be at higher risk of death.

Alicia Morgans: Absolutely. You know, it's really interesting to me, too, that it is sort of... If we look across all of these treatments for advanced prostate cancer, this is certainly the greatest benefit that seems at least specific by whatever genes are driving this, whatever genes it seemed to sort of co-localize with race and with the driver of this cancer. This is the most dramatic. 

But it's not a crazy story to tell, either, because we are seeing this in some of the data that's been presented by Susan Halabi and the Duke group that if we can get men treatments, African American men treatment, there's a chance that they have at least as good, if not better in the case of sip-T, a better response to the treatment, so really speaks to a need to get the treatments to the patients. I don't know if you have thoughts about that.

Kelvin Moses: That is an absolutely critical point that you just made, is getting the treatment. Apart from this particular study, I've done research showing that younger men who receive surgical therapy for localized cancer, black and white men can expect similar outcomes. In another study that was done within here, we showed that black men were less likely to get treated at any stage of cancer.

What we showed here that the men who die from prostate cancer are the ones who have high risk, non-localized metastatic disease. In this critical population, if men received treatment, not only are they getting a survival benefit, but then the highest risk group, black men, are gaining an even greater response.

Part of the beauty of this study, though, is to get that information out there so that everybody knows that this is something you can offer to patients and give them that added comfort of knowing that this is something that can be truly beneficial to them.

Alicia Morgans: I think important for sip-T as well, as one of the controversies over the last few years has been, help us understand who is benefiting. There have been all these cries of, well, the PSA is going up and not down. I think that those of us who use the medication in practice recognize that that's just something that we see with sip-T and we see it with radium as well. We don't necessarily see a PSA response, that doesn't mean that the drug isn't working.

But this is one step in helping to identify a population that may be at the higher odds of benefiting from the therapy, so a move in the right direction. Certainly, if we could figure out who those patients are, the number needed to treat to benefit at 36 months, I mean those patients who are still alive at 36 months are probably the patients, as you can see by the drop in numbers that are needed to treat to benefit, those are the patients who are probably benefiting the most. So helping the clinicians understand who are those patients would be really, really helpful, but this is step one.

I really appreciate you bringing it to the table and raising awareness and also helping us think about African American men in general, to think about how do we get these patients access to these therapies. That's going to be a critical part of making sure that the therapies that work on trial are actually helping the patients who need them on a daily basis.

As we wrap up, Kelvin, what is your overarching message regarding the work that you've been doing, and thank you for doing this work.

Kelvin Moses: Absolutely, and I agree with all the points you just made. I believe the overarching theme is let's believe the data. We cannot be so beholden to PSA and the value and potentially hold back patients that could garner a tremendous benefit from particular therapies, and so let's believe the data. 

We've originally shown that sipuleucel-T had a benefit in survival. Then it was shown that the PSA quintile, the lower the PSA, the greater the benefit. Then data showed that African American men garnered the best response as far as survival. Now, we're adding to that showing that a number needed to treat to benefit are men who are living three years with metastatic castration resistant prostate cancer with only three men needed to treat to benefit. It's such a tremendous improvement in the therapeutic options that we have in these men who have what was known to be a fatal disease within a year, so let's believe the data. Let's get our patients treated and give them the benefit that they deserve.

Alicia Morgans: I agree 100%. Thank you for sharing your work, sharing your message and taking the time to do all of that on UroToday. Thanks so much, Dr. Moses.

Kelvin Moses: Absolutely. Thank you for having me.