Immunotherapy for Bladder Cancer – The Promise, the Pros, and the Cons
Immunotherapy, including the use of antibody-drug conjugates (ADC), has revolutionized the treatment of various cancer types, including bladder cancer. ADC is a drug delivery system designed to target a cancer cell specifically. It is made of a combination of an antibody and a chemotherapy drug. The antibody is a manufactured protein with specific properties that allow it to attach to certain proteins in a cancer cell. The antibody recognizes the cancer cell and connects to its surface. If the antibody also carries a chemotherapy drug, combining the antibody and the chemotherapy drug will bring the drug directly to the cancer cells.
However, as is the case with any cancer treatment, immunotherapy has advantages and disadvantages:
The Pros of Immunotherapy for Bladder Cancer
- Targeted Therapy:
- Immunotherapy creates a specific detection and delivery system to reduce possible side effects. Essentially, this therapy type delivers chemotherapy medication directly to cancer cells and will likely not damage normal healthy cells. Modern science has enabled the identification of specific receptors or proteins in cancer cells that are not found in normal cells. From this differentiated approach, it is possible to synthesize antibodies that recognize these cancer-related proteins on the surface of the cancer cells, leaving healthy cells as they are.
- Long-lasting Response:
- In some cases, immunotherapy can induce a durable response, meaning the cancer may not return for an extended period. This is particularly promising for patients with advanced-stage disease.
- Potential for Complete Response:
- Immunotherapy has the potential to eradicate all cancer cells, leading to a complete response and a "no evidence of disease" prognosis.
- Improved Quality of Life:
- Compared to traditional chemotherapy, immunotherapy can result in fewer side effects, such as hair loss, nausea, and fatigue, thus improving patients' quality of life.
The Cons of Immunotherapy for Bladder Cancer
- Immune-Related Adverse Events:
- One of the main drawbacks of immunotherapy is the risk of immune-related adverse events (irAEs). These can range from mild symptoms like skin rashes, neuropathy, fatigue, diarrhea, reduced appetite, and hair loss to severe conditions affecting organs like the lungs, kidneys, or thyroid. While these side effects are often manageable, they can sometimes be life-threatening.
- Not Effective for All Patients:
- Immunotherapy works best in patients with specific biomarkers that indicate a robust immune response. Each type of cancer may have its particular types of surface proteins. However, there is also overlap and common proteins among groups of different cancers. Specifically, in terms of bladder cancer, a monoclonal antibody has been synthesized to a surface protein called Nectin-4. In 2023, the FDA approved an ADC combining the monoclonal antibody against Nactin-4 and a chemotherapeutic drug for patients with metastatic bladder cancer. This treatment is efficacious in treating patients in this specific group.
- This form of immunotherapy is used in patients with metastatic bladder cancer. Currently, it is used more often in a clinical trial setting or as a secondary type of treatment for patients who have not had a good result with more traditional forms of chemotherapy.
- Not all patients with bladder cancer will benefit from this treatment. Unfortunately, metastatic bladder cancer generally carries a poor prognosis. However, immunotherapy has increased rates of survival. While obtaining a definitive cure is impossible, it has allowed patients to live a longer life with a reasonably good quality of life associated with the increased duration.
- High Cost:
- Immunotherapy drugs can be expensive, making them inaccessible to many patients.
- Complex Treatment Regimen:
- Immunotherapy often requires a complex treatment regimen, including frequent doctor visits and blood tests to monitor for side effects.
When is Immunotherapy Appropriate for Bladder Cancer?
Immunotherapy is typically considered for patients with advanced-stage bladder cancer that has progressed despite other treatments. However, the specific eligibility criteria can vary depending on the patient and the type of immunotherapy used.
The Future of Immunotherapy for Bladder Cancer
As research advances, we can expect further improvements in immunotherapy for bladder cancer. Ongoing clinical trials are exploring new combinations of immunotherapy drugs and other treatments to enhance efficacy and minimize side effects.
