Biomarkers, Genetic Testing and More Make Way in GU Cancers

Following the 2025 Annual ASCO Genitourinary (GU) Cancers Symposium, Dr. Chandler Park, a medical oncologist of Genitourinary Medical Oncology at the Norton Healthcare Institute in Louisville, Kentucky, sat down for an interview with CURE®, in which he shared his greatest takeaways from the meeting.

“The ASCO GU Symposium is the Super Bowl for prostate, kidney and bladder cancer [treatment]. All the different cancer doctors, scientists and researchers get together to advance the field for our patients. Regarding the most significant advances in terms of kidney, bladder and prostate cancer, I would say there's one [specific update that shines] in each specialty,” Park emphasized.

In the interview, Park broke down the three biggest studies, in his opinion, to have come out of the ASCO GU Symposium, highlighting studies across kidney, bladder and prostate cancers. To read more of our conversation with Park, click here.

What was the biggest takeaway from the meeting in terms of kidney cancer treatment?

A lot of our patients that are [being] treated for colon cancer or ovarian cancer have a blood test that's been known to be predictive of how bad the cancer is or if the treatment is going to work. In colon cancer, we have a blood test called carcinoembryonic antigen [CEA]; in ovarian cancer, it is called CA 125, which is prognostic and predictive. Now, in kidney cancer, we didn't have anything until we had some new data presented here at ASCO GU. The study that was presented was shared by Dana-Farber Cancer Institute, [in Boston, Massachusetts,] and it has to do with the KIM-1 kidney marker.

This study looked at patients that received immune therapy for stage four renal cell cancer, and [investigators] checked the blood for KIM-1 — called the kidney injury molecule one — and they followed patients at the beginning before treatment, and then they followed this blood test after three cycles of treatment. What they found is that this seems to be a very reliable blood marker that oncologists can follow. This way [we] can know if this treatment is working or not.

I think one of the toughest things, for me, is when you start somebody on treatment, and then having to wait for the scan for two or three months to see if the treatment is working. This is something that I think is very significant, and I can see it becoming something that's part of the clinic, where patients and families could check this to ask, ‘How's the treatment working?’ and ‘Is this treatment going to continue to be effective?’

What was the biggest takeaway from the meeting in terms of bladder cancer treatment?

Now, the second study that that seems to be very interesting is for our patients with bladder cancer. Bladder cancer has five stages, [beginning with] stage 0 when the cancer is inside the bladder, and it's just on the surface of [the first] layer, and that's called non-muscle invasive bladder cancer. The cancer is like if you put a seed on the ground, growing and forming roots, it forms a stalk. Bladder cancer slowly gets bigger, and the roots go into the muscle. If the cancer is in the muscle, that's called muscle-invasive bladder cancer, and that's called stage 2 bladder cancer.

One of the studies that [was shared] at ASCO GU — which I think is very promising — is called the RETAIN-2 clinical trial. What question does the RETAIN-2 clinical trial answer? Whenever I see a patient in clinic, there's three things they take think about whenever we give them a diagnosis of bladder cancer that's in the muscle: one, ‘Is this treatment that we're going to provide curable?’ and the answer is [hopefully] yes. Not everybody gets cured, but the goal is to cure. The second question we have is, ‘Do I have to take the bladder out?’ and unfortunately, a lot of our patients do have to take the bladder out. We can cure people with radiation, but there are a lot of patients that do not want to have radiation, nor do they want to have a cystectomy.

In the RETAIN-2 clinical study, patients received chemotherapy and immunotherapy — that's called neoadjuvant treatment — and once they received a treatment, the urologist went back into the bladder to look around, so if they did not see any cancer, that is called a pathological complete response. Now, the standard of care in that situation today is to still do surgery. However, in this study, they decided to kind of see, do they really need [surgery]? The patients got randomized after they received chemotherapy, and then they did evaluation cystoscopy, and if they didn't find any cancer, patients randomized to an arm where they could do surveillance, [meaning to] just look in the bladder, every three or six months. To be in that group, they looked at genetic markers to see if they have certain high risk genetic markers.

In the RETAIN-2 study, which is a very small study, so this is something they will have to continue, 82% of patients that received chemotherapy, and went [on to] observation remain cancer free. I see something like this taking off as a larger study and becoming — hopefully —a mainstream approach.

What was the biggest takeaway from the meeting in terms of prostate cancer treatment?

The third study that is in the prostate cancer field is the TALAPRO-2 study. The [trial looked at] patients with prostate cancer, when they're diagnosed. There are two types of prostate cancer: one is called metastatic-hormone sensitive prostate cancer, and that means that these patients are still sensitive to testosterone, so we give them testosterone blockers — kind of like estrogen blockers for patients with breast cancer; but the more aggressive type is called castrate-resistant prostate cancer. This [diagnosis] is very tough and we want to find new treatments for this.

In TALAPRO-2, patients got randomized to Xtandi [enzalutamide], which is considered a great standard of care treatment for metastatic castration-resistant prostate cancer, and the other arm received Xtandi plus Talzenna [talazoparib], which is considered a PARP inhibitor. Now, PARP inhibitors are something that we might all hear about when we treat for patients in ovarian cancer, breast cancer and pancreatic cancer, and the key is they need these genetic markers called BRCA1 and BRCA2. It was very similar in the prostate cancer world, where patients had to have either the BRCA1 or BRCA2 mutations; these mutations could be either in the germline or the somatic.

Germline is whenever a buccal swab or blood check [is done] to see if [patients] inherited BRCA1/BRCA2 genes. Now, what's somatic mutation? Imagine if I have a black mark on my hand, and that mark is melanoma. If they take a biopsy of this black part of my hand, and they take a biopsy of my normal hand, the DNA of that cancer is completely different from the skin, and that is called somatic mutation. If there's a BRCA1/BRCA2 mutation inside the cancer, then you could qualify for a PARP inhibitor. Now, with all that said, that is considered a select patient population; we must see if the patients qualify for a PARP inhibitor in this study.

What makes this study, as we considered it, a highlight at ASCO GU, is they didn't look at that in terms of randomizing patients to the study, they took all comers. It was close to 800 patients, a large phase 3 trial, in which patients got randomized to Xtandi versus Xtandi plus Talzenna, and there was a 20% decrease in terms of the cancer.

A lot is based upon the molecular subgroups, but it is encouraging that if a patient shows up with metastatic castration-resistant prostate cancer [we could refer to this]. Although I recommend everybody [complete testing], not everybody practices in the big city. Some people practice in rural America, and they might not have access [to germline and somatic testing]. So if they don't have access, and these oncologists see patients… [they should focus on family history of cancer], as there might be some kind of genetic concern for cancer. In these situations, I would consider this based upon the ASCO GU study. Now, it is not FDA approved yet, but I anticipate it will be, so we'll cross our fingers.

Those are the three impactful studies that I see for patient care [following the ASCO GU Symposium].

Transcript has been edited for clarity and conciseness.

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