Comment by f6v

First issue is that tumors don't necessarily have to be highly immunogenic, e.g. there're tumors that don't present many neoantigens on the surface. This means immune cells can't easily recognize them. Second issue is that tumor microenvironment evolves to be immunosuppressive. There're many different signals that regulate immune cells activation and simply having antigen-specific cells isn't enough. But as someone said in a sister thread, what you're describing is a basis for multiple clinical trials that combine antigen release with immune activation.