Cobimetinib and Atezolizumab in Treating Participants With Advanced or Refractory Rare Tumors

This phase II trial studies how well cobimetinib and atezolizumab work in treating participants with rare tumors that have spread to other places in the body (advanced) or that does not respond to treatment (refractory). Cobimetinib may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Immunotherapy with monoclonal antibodies, such as atezolizumab, may help the body’s immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Giving cobimetinib and atezolizumab may work better in treating participants with advanced or refractory rare tumors.