Background 

A new treatment called Enfortumab Vedotin and Pembrolizumab (EVP) is now the main option for people with advanced bladder cancer. This treatment helps the body’s immune system fight cancer and has doubled survival time compared to older chemotherapy drugs. However, about half of patients still see their cancer get worse or die within a year of starting EVP. Because of this, researchers are looking for ways to make EVP work even better. 

What the Study Proposes to Address 

Past studies have shown that what we eat can affect how our immune system works through bacteria that live in our gut, called the “gut microbiome.” In earlier research, Dr. Guercio found that eating more fiber and less sugar (especially fructose) helped bladder cancer patients respond better to immunotherapy. This improvement was likely due to a chemical made by certain gut bacteria called butyrate, which helps boost the immune system. Since EVP is also an immune-based treatment, this study will explore whether a diet high in fiber and low in sugar can help patients respond better to EVP. Researchers will collect diet information using a detailed questionnaire and will study stool samples to learn about patients’ gut bacteria when they start treatment. 

Why This Research is Important 

This study could help find simple, low-risk ways to make cancer treatment more effective by focusing on nutrition and gut health. It will not change what patients eat or how they are treated, but it will help scientists see whether diet and gut bacteria affect how well EVP works. This research could also help reduce health differences among people who live in areas with poor access to healthy foods. In the future, this work could lead to new diet-based approaches that improve survival and empower bladder cancer patients to make food choices that strengthen their treatment results. 

None Reported as of August 2025

None Reported as of August 2025

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Background 

Immunotherapy is a newer type of treatment that has changed the way doctors care for patients with bladder cancer that has spread. For some people, it works very well, controlling the disease for a long time with fewer side effects than chemotherapy. But the challenge is that up to 80% of patients do not respond to immunotherapy at all. Researchers want to find ways to help more patients benefit from this treatment. 

Recent research shows that the gut microbiome—the community of bacteria that naturally live in the intestines—can affect how the immune system works. This may also influence whether a patient responds to immunotherapy. Diet is one of the biggest factors that can shape the gut microbiome. Early studies in patients with melanoma, another type of cancer, suggest that diet can change the bacteria in the gut and improve chances of responding to treatment. However, no one has studied this connection in bladder cancer. 

What This Research Proposes to Address 

This study used a detailed dietary questionnaire developed at Harvard to look at what patients with bladder cancer eat and drink. The researchers then looked to see if certain eating patterns are linked to better results with immunotherapy and to the presence of specific gut bacteria. Importantly, patients did not need to change their diets or treatments—the study only observed their habits and outcomes. 

Why This Research Is Important 

If researchers can identify which foods or diets help patients respond better to immunotherapy, it could give people with bladder cancer a simple way to improve their chances of success. This knowledge would also help doctors give patients more personalized guidance about diet during treatment. 

In the long run, this project has the potential to empower patients with choices that could strengthen their immune system, improve their treatment response, and make immunotherapy more effective for a larger number of people. 

Final Report Summary

Immunotherapy has changed the way doctors treat bladder cancer that has spread. For some patients, it works very well and controls the cancer with fewer side effects than chemotherapy. But the problem is that about 80% of patients do not respond to it, and researchers want to find ways to improve these results. 

One promising area of research looks at the gut microbiome, which is the community of bacteria living in the intestines. These bacteria play an important role in how the immune system works and may affect how patients respond to immunotherapy. Since diet has a big influence on the gut microbiome, researchers believe it could also impact treatment outcomes. 

Early studies in patients with another type of cancer, melanoma, suggest this might be true. For example, some studies showed that a high-fiber diet could be helpful, while others linked certain gut bacteria connected to coffee and wine to better responses. However, no one has studied this connection in bladder cancer patients yet. 

This research is important because it could lead to simple changes—like diet choices—that may improve how well immunotherapy works for people with bladder cancer. 

None Reported as of August 2025

None Reported as of August 2025

NA