SPI1 and neoplasm: Furthermore, bi-specific PD-L1/4-1BB antibody could promote proportion of DC subsets, upregulate the expression of DC costimulatory molecules and DC activation markers, thus strengthening DC cell-T cell interaction, and generating a positive feedback loop of tumor microenvironment.37 Here, we provided evidence that lenalidomide resistance mediated by PU.1 could be counteracted by bi-specific PD-L1/4-1BB antibody, suggesting combination of immune checkpoint modulation as promising immunotherapy in FL.