You are being invited to take part voluntarily in this research study because you have a solid tumor that hasn’t responded to previous treatment or has spread to other parts of your body (metastatic), including ovarian, cervical, endometrial, head and neck, squamous cell lung, kidney, prostate, colorectal, gastric, breast, bladder cancer, lung adenocarcinoma, or melanoma. This research study is to test an investigational drug, being developed by Tizona Therapeutics, called TTX-080. 'Investigational' means the drug being tested has not been approved by the United States Food and Drug Administration (FDA). TTX-080 is an antibody made in a laboratory that binds to a protein called HLA-G and blocks its suppressive function. Antibodies are naturally made by the body in reaction against foreign substances (such as bacteria and viruses) that get in the body. Cancer cells use HLA-G to suppress the body’s immune system response and help cancer cells grow. By blocking HLA-G, TTX-080 may help your immune system attack cancer cells. Pembrolizumab and cetuximab are approved in the USA and some other countries, and they are available by prescription to treat different cancers but may not be approved to treat your type of cancer. Pembrolizumab and cetuximab work by helping the immune system to fight cancer.