DETERMINE Trial Treatment Arm 02: Atezolizumab in Adult, Paediatric and Teenage/Young Adult Patients With Cancers With High Tumour Mutational Burden (TMB) or Microsatellite Instability-high (MSI-high) or Proven Constitutional Mismatch Repair Deficiency (CMMRD) Disposition

To join this study, the main thing is that a doctor has diagnosed you with cancer, and tests have shown that your cancer has certain genetic features. These features are 'high tumour mutational burden' (TMB-high), 'microsatellite instability-high' (MSI-high), or 'constitutional mismatch repair deficiency' (CMMRD). These are specific changes in your cancer cells that indicate how the cancer might respond to certain treatments.

If you are a woman who could become pregnant, you would need to have a negative pregnancy test before starting treatment and agree to use effective birth control throughout the study and for five months after your last dose of the study drug. Men with partners who could become pregnant would also need to agree to use effective birth control during the same period.

If you decide to take part, your first step will be a 'pre-screening' where a team of experts will review your cancer's genetic information to see if this study treatment might be a good fit. If it seems suitable, you'll go through a 'screening' phase. This involves providing blood samples and, in some cases, a small tissue sample (biopsy) for detailed research tests.

If you are eligible, you will then start receiving the study drug, atezolizumab. You will continue to take the drug for as long as it is helping, and you are not experiencing severe side effects, or until you choose to stop. During this treatment period, you will have regular visits to the clinic, where doctors will monitor your health and how you are responding to the treatment. You will also give blood samples at different times. After you finish taking the study drug, doctors will follow up with you every three months for two years to see how you are doing.