Mammary tumors were treated with ISIM comprised of intratumoral injections of Flt3L to recruit cDC1s into the TME, radiotherapy to induce immunogenic tumor cell death and maturation of DCs, and in situ administration of TLR3/CD40 agonists to facilitate trafficking of Ag-loaded cDC1s to TdLN and the subsequent priming and expansion of tumor-specific CD8+ T cells29 (Fig. 1a). Here, FLT3LG is linked to breast cancer.