The 2023 American Society of Clinical Oncology (ASCO) Genitourinary Cancers Symposium will be held in person and online February 16 to 18 in San Francisco, California. This meeting features research in the treatment and care of people with genitourinary (GU) cancers, which is a group of cancers that occur in the urinary tract or the male reproductive tract, including bladder cancer, kidney cancer, and prostate cancer.

You can learn more about research from this symposium by following the #GU23 hashtag on Twitter.

Below are summaries of 2 studies that will be presented at the symposium:

Diets higher in plants associated with lower risk of prostate cancer progression and recurrence

Who does this study affect: People with prostate cancer with little or no spread of disease 

What did this study find: An analysis of data from the Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE) study has shown that individuals with early-stage prostate cancer who reported the highest amounts of plant-based foods in their diets had lower risks of prostate cancer progression and recurrence. Cancer progression is when the cancer continues to grow and/or spread. Recurrence is when the cancer comes back after treatment.

This analysis included 2,038 people with early-stage prostate cancer who chose to complete a diet and lifestyle questionnaire at 3 scheduled times after diagnosis. This questionnaire asked the participants how much and how often they consumed approximately 140 different foods and beverages. Then, their responses were scored based on how much of their diets included plant-based or animal foods. Some examples of plant-based foods included in this study are vegetables, fruits, legumes (foods such as lentils, peas, chickpeas, soybeans, lima beans, and peanuts), and whole grains. The researchers wanted to learn if a diet higher in plant-based foods would impact the risk of prostate cancer progression and recurrence.

The participants were observed for a median of 7.4 years after completing the questionnaire. The median is the midpoint, so half the participants were observed for less than 7.4 years and the other half were observed for more than 7.4 years. Ages of the participants ranged from 43 to 102, with a median age of 72 years. All had prostate cancer with little or no spread of disease.

Cancer progressed in 204 (10%) participants during the observation period. Those who reported diets that included the highest amounts of plants had a 52% lower risk of disease progression and a 53% lower risk of recurrence compared with those whose diets incorporated the lowest amounts of plants.

What does this mean for patients? People with early-stage prostate cancer who reported that their diets included the highest amounts of plant-based foods had a lower risk of disease progression and recurrence.  

“While not all diets are equal in terms of modifiable risk factors for prostate cancer progression, we hope these results guide men at risk to make better, more healthful choices across their entire diet. We’ve known that diets that include vegetables, fruits, legumes, and whole grains are associated with numerous health benefits, including a reduction in diabetes, cardiovascular disease, and overall mortality. We can now add benefits in reducing prostate cancer progression to that list.”

—   lead study author Vivian Liu, BS
University of California, San Francisco
San Francisco, California

Adding talazoparib to enzalutamide helps stop the progression of metastatic castration-resistant prostate cancer

Who does this study affect: People with metastatic, castration-resistant prostate cancer (mCRPC).

What did this study find: Results from the TALAPRO-2 phase 3 international clinical trial showed that a combination treatment using talazoparib (Talzenna) and enzalutamide (Xtandi) stopped or slowed the progression of mCRPC.

mCRPC has spread beyond the prostate gland, and it can no longer be stopped with treatments that lower testosterone levels. There are a few treatment options for people with this diagnosis, including androgen receptor inhibitors, targeted therapy, chemotherapy, immunotherapy, and some radiation therapy. This study looked at combining a type of targeted therapy called a PARP inhibitor (talazoparib) with an androgen receptor inhibitor (enzalutamide). PARP inhibitors destroy cancer cells by preventing them from fixing damage to their DNA, which is influenced by a pathway called homologous recombination repair or HRR. Talazoparib is currently used to treat breast cancer. Androgen receptor inhibitors block testosterone from binding to androgen receptors in cancer cells, which stops testosterone from driving the growth of prostate cancer. Enzalutamide is currently used to treat prostate cancer in several stages. The researchers wanted to see if adding talazoparib to enzalutamide worked better at stopping the disease than enzalutamide alone. 

This study included 805 people with mCRPC, who had mild or no observable symptoms. Participants came from 25 countries. The patients’ age range spanned from 36 to 91, and the median age was 71 years. There were 402 people in the group that received the combination of talazoparib and enzalutamide. There were 403 people in the group that received enzalutamide along with a placebo. Analysis of tumor tissue also showed that about 20% to 25% of the participants’ tumor samples had a genetic change in the HRR pathway.  

The researchers used imaging scans, such as computed tomography (CT) and positron emission tomography (PET)-CT scans, to check whether the disease had been stopped by the treatment. They found that talazoparib plus enzalutamide was 37% better at stopping the disease than the enzalutamide given alone. The researchers also found:  

  • Among those with a change in their HRR pathway, talazoparib plus enzalutamide was 54% better at stopping the disease than placebo plus enzalutamide.   

  • Among those patients who did not have alterations in the HRR pathway, specifically in their tumor tissue, talazoparib plus enzalutamide was 34% better.  

Both treatment groups experienced serious side effects. Nearly 72% of patients receiving talazoparib plus enzalutamide had serious side effects, as well as nearly 41% of patients receiving placebo plus enzalutamide. The most common serious side effect with talazoparib was anemia. By using lower doses, most patients were able to keep taking the treatment. Other side effects that commonly affect quality of life, such as fatigue, nausea, and vomiting, were relatively infrequent.

What does this mean for patients? Adding talazoparib to enzalutamide may help stop or slow the growth of metastatic prostate cancer that no longer responds to treatments that lower testosterone levels.  

“Not only did the combination therapy delay disease progression, it also significantly delayed progression of PSA (prostate-specific antigen) readings and the time until chemotherapy was needed compared with the control group. This is important because advanced prostate cancer can be associated with pain, fractures, suffering, and death. The current standard of care treatments were approved almost a decade ago, leaving a huge unmet need for novel drugs in this setting.”

—    lead study author Neeraj Agarwal, MD, FASCO
Huntsman Cancer Institute
Salt Lake City, Utah


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