FLT3LG and neoplasm: Using the same HSV backbone, G47Δ-Flt3L was created to stimulate anti-tumor immunity through on site expression of soluble Flt3L, a cytokine capable of differentiating hematopoietic precursors into plasmacytoid and conventional dendritic cells (DCs) and mobilizing them from bone marrow (Barnard et al., 2012).