At the 2024 ASCO Genitourinary Cancers Symposium, Benjamin Lowentritt, MD, Chesapeake Urology, Towson, Maryland, shares results from a real-world study comparing the PSA response from apalutamide vs enzalutamide among patients with metastatic castration-sensitive prostate cancer.

The real-world data in this study suggests apalutamide yields a deep, early PSA response by 6 months in more patients than enzalutamide.

Transcript: 

I’m Ben Lowentritt, I'm the director of the Prostate Cancer Program at Chesapeake Urology in Maryland. I'm really thrilled to be here, and we're talking today about our poster presentation on the PROMPT 1 study, which was a real-world evidence look at data around patients receiving apalutamide or enzalutamide for metastatic castration-sensitive prostate cancer [mCSPC]. 

This is actually the continuation of some work we've been doing over the past several years, looking at data extracted from the electronic medical record of a number of different community-based urology practices; we're now getting close to 100 urology practices who've provided data to this dataset and we're looking back for a number of years, back to the original approval of these agents which was in 2019, so over the last several years we've been able to compile data from the real-world exposure of the use of these treatments in mCSPC. 

Specifically we're trying to look at outcomes for those patients starting on therapy, on what we can get out of the medical record, which is predominantly the [prostate specific antigen] PSA. What this is looking at for the PROMPT 1 study was looking for patients starting on apalutamide or enzalutamide in the mCSPC space, how strong of a response they had in their PSA,  both looking at the depth of response, which is PSA 90, as well as the speed to get to that level—so how quickly did the patients get to a PSA 90? What we saw, and which is interesting, we've now seen this in a number of different cuts of the data and we've just added more and more patients to it, we're about 8-900 patients in each group at this point, we're continuing to see that there does appear to be a difference, and patients that will receive apalutamide are more likely to get to a PSA 90 and do it more quickly, and that difference is sustained over the year that we're following the patients. So, the response at 3 and 6 months are indicators that we've seen in other studies, in prospective studies that have meaningful outcomes related to the suggestion of response. These are really important numbers and it's really interesting to see. 

Now it comes with all the caveats that this is real-world evidence and it's not a direct head to head in a structured environment like you might see in a clinical trial, but that doesn't mean that the data is not interesting and not reflective of what's actually happening. We do a lot to make sure that the data is as clean as possible and that we're identifying correct patients. We start with a dataset that's 15, 16, 17,000 patients to get down to the roughly 1,500 that we evaluated. There are a lot of patients that if we're not sure that they're castrate-sensitive, if we're not capturing the start of their treatment, they might fall off, so we feel like it's a valid data set, we've done as much as we can to make it as informative as possible. I think this just adds to the many different things that we have to consider when we're choosing a treatment for patients with mCSPC, and it also helps just kind of confirms the importance of PSA as a marker and reaffirms that we need to be paying attention to it. 

It also impacts how I follow patients; if I know that I have a patient that gets to that very low PSA, I'm able to keep them maybe not coming in as frequently, maybe I can monitor them less frequently or the flip side of that being those that don't have the depth of PSA response, I need to be a lot more proactive about monitoring and seeing if they need other therapies. I think it keeps this concept front of mind, it's very interesting data that helps us in looking at how patients are responding in the real-world setting, and the fact that there's a difference that's sustained is an interesting one, we don't know if that's related to patient adherence, if that's related to dose reductions and other things that might impact that, that's a little bit beyond what we can get from real-world evidence, but it is a really interesting set of data.

Source:

Lowentritt BH, Du S, Pilon D, et al. Real-world comparison of prostate-specific antigen (PSA) response in patients with metastatic castration-sensitive prostate cancer (mCSPC) treated with apalutamide (APA) or enzalutamide (ENZ). Presented by ASCO Genitourinary Cancers Symposium; January 25-27, 2024; San Francisco, California. Abstract 51