A phase I study of the combination of atezolizumab, tiragolumab, and stereotactic body radiation therapy in patients with metastatic multiorgan cancer.

Background: Immunotherapy targeting the PD-1/PD-L1 pathway is a standard of care in a number of metastatic malignancies, but less than a fifth of patients are expected to respond to ICIs (Immune Checkpoint Inhibitors). In a clinical trial, combining the anti-TIGIT (T cell immunoreceptor with Ig and ITIM domains) Mab (monoclonal antibody) tiragolumab with atezolizumab improved outcomes in non-small cell lung cancer. In preclinical models, SBRT (Stereotactic Body Radiation Therapy) could increase expression levels of the inhibitory co-receptors TIGIT and PD-L1.