CTLA4 and neoplasm: However, preclinical studies in multiple tumor models where antibodies to PD-L1, PD-1 and CTLA-4 are used as a monotherapy have not achieved much success (Grosso and Jure-Kunkel, 2013; Highfill et al., 2014; Kim et al., 2014; Guo et al., 2015; Hu-Lieskovan et al., 2015; Ngiow et al., 2015).