A Study of Therapeutic Drug Monitoring-Based Atezolizumab Dosing

Background: A type of drug called monoclonal antibody immune checkpoint inhibitors are often used in cancer treatment. These drugs help the body s immune system fight cancer by blocking proteins that cause cancer cells to grow. One of these drugs (atezolizumab) is approved to treat certain cancers. Researchers want to find out if lower doses of this drug might provide the same benefit with fewer adverse effects. Objective: To test different doses and timing of atezolizumab for people with cancer. Eligibility: People aged 18 years and older with cancer that has spread locally or to other organs. They must be eligible for treatment with the study drug. Design: Participants will be screened. They will have blood tests and imaging scans. They will provide a sample of tissue from their tumor. Atezolizumab is administered through a tube attached to a needle inserted into a vein in the arm. Participants will take this drug alone or combined with other drugs prescribed for their care. The first 2 treatments will be done per the FDA recommended dose and schedule. Before administering the second dose of the study drug, researchers will check the level of the drug in the participant s blood. Depending on those results, their 3rd dose will be scheduled 2 to 6 weeks later. For the 3rd dose of the study drug, participants will switch to the FDA minimum dosage. Dosages of any other drugs will not change. Researchers will continue to test the levels of the drug in participants blood before each treatment for 16 weeks. After that, these levels will be tested every 3 months. Study treatment may last up to 2 years.