Administration of recombinant Flt3L was shown to be effective in the expansion of DCs and safe for healthy volunteers,48 increase the frequencies of peritumoral DCs in metastatic colon cancer patients49 and restore responsiveness to anti-PD-1 therapy in patients with lymphoma when combined with radiotherapy and administration of polyI:C.50 Ongoing clinical trials will reveal whether Flt3L in combination with other immunostimulatory agents including TLR ligands and anti-CD40 can induce durable clinical responses and prolong survival in patients with melanoma. Here, PDCD1 is linked to lymphoma.