Atezolizumab is a targeted immunotherapy used in the treatment of bladder cancer. This medication helps the body’s own defense mechanisms recognize and combat cancer cells. It was among the first new drugs approved for metastatic urothelial carcinoma in over 30 years, marking a significant advancement in treatment options.
Understanding How Atezolizumab Fights Cancer
Atezolizumab functions as an immune checkpoint inhibitor, targeting PD-L1 (Programmed Death-Ligand 1). PD-L1 is found on tumor cells and immune cells, where it binds to PD-1 (Programmed Death-1) and B7.1 receptors on T-cells. This interaction acts as a “brake” on the immune system, preventing T-cells from recognizing and attacking cancer cells.
By blocking the interaction between PD-L1 on cancer cells and PD-1/B7.1 on immune cells, atezolizumab “releases the brakes” on the immune response. This allows T-cells to become activated and destroy tumor cells. The medication is a humanized monoclonal antibody designed to interfere with this binding, enhancing T-cell immunity against the tumor.
Identifying Eligible Patients
Atezolizumab is typically considered for patients with advanced or metastatic urothelial carcinoma, which is the most common type of bladder cancer. It may be prescribed when the cancer has progressed during or after initial platinum-based chemotherapy. Additionally, it can be an option for individuals who are not able to receive cisplatin-based chemotherapy.
The expression level of PD-L1 on tumor cells and tumor-infiltrating immune cells can play a role in determining eligibility, with higher levels sometimes correlating with better responses. While PD-L1 testing is sometimes used, clinical activity can still be observed even in tumors classified as PD-L1 negative.
Receiving and Managing Treatment
Atezolizumab is administered intravenously, meaning it is given directly into a vein through an infusion. The typical frequency for treatment is every three weeks. The first infusion usually lasts about 60 minutes, but if it is well-tolerated, subsequent infusions may be reduced to approximately 30 minutes.
During treatment, patients are regularly monitored for side effects and to assess treatment response. This monitoring includes regular laboratory tests, physical examinations, and imaging scans like CT scans. The total number of planned cycles can vary, but some regimens involve a total treatment time of around one year.
What to Expect from Atezolizumab Treatment
Patients undergoing atezolizumab treatment may experience side effects, although many are mild to moderate. Common side effects include fatigue, rash, and diarrhea. Some individuals may also experience immune-related side effects, which occur when the immune system becomes overactive and attacks healthy tissues.
These immune-related side effects, while less common, can be more serious and may affect organs such as the thyroid (leading to thyroid issues), lungs (pneumonitis), or colon (colitis). Management of side effects often involves close monitoring and, if needed, temporary interruption of treatment or the use of corticosteroids to suppress the immune response. Benefits include tumor shrinkage and disease control, with some patients experiencing durable responses that can last for years. While responses vary, the treatment has shown to improve overall survival in some cases, offering a less toxic alternative to traditional chemotherapy for certain patients.