173P First-in-human study to evaluate the safety and clinical activity of FS222: A tetravalent bispecific antibody targeting PD-L1 and CD137, in patients with advanced solid tumors. (December 2022) - De Velasco Oria, G.A.; Garralda, E.; Moreno Garcia, V.; Melero, I.; Victoria Ruiz, I.; Indacochea, A.; Cervantes, A.; Oberoi, A.; Jones, D.; Lakins, M.A.; Kayitalire, L.