Additional Study Information: The purpose of this research study is to study the safety and efficacy of GSK3901961 and GSK3845097 when used to treat synovial sarcoma or non-small cell lung cancer and to examine if your tumor affects how the study drug works. You will need to receive chemotherapy for 3 to 4 days (depending on your age and your medical condition) before you are given GSK3901961 or GSK3845097. This is the first time these drugs have been used in humans. No people have ever been treated with GSK3901961 or GSK3845097. After your infusion of GSK3901961 or GSK3845097 you will be hospitalized.