Interestingly, pDC are increased in the bone marrow of MM patients, and whilst they are believed to contribute to immune cell dysfunction within the tumor microenvironment, engagement of pDC pattern recognition receptors (PRR), namely TLR-9, can restore pDC function and promote T cell proliferation [48] - a concept worth considering in the context of CVA21 engagement of alternative PRRs. This evidence concerns the gene TLR9 and neoplasm.