Mayo Clinic Mar 13 2025 A discovery by Mayo Clinic researchers may help explain why immunotherapy hasn't been helpful for many patients with metastatic colorectal cancer. In findings published in  Clinical Cancer Research, the team identified specific proteins - fibronectin and smooth muscle actin - within colorectal cancer tissues that are associated with resistance to immunotherapy treatment. Immunotherapy  is a major advance in treating cancer, but many patients, including those with