Abstract
L19‐IL2 and L19TNFα are fusion proteins composed of L19(scFv), specific for the angiogenesis‐associated ED‐B containing fibronectin isoform and IL‐2 or TNFα. Because of the tumor targeting properties of L19, IL‐2 and TNFα concentrate at therapeutic doses at the tumor vascular level. To evaluate the therapeutic effects of L19‐IL2 and L19mTNFα in neuroblastoma (NB)‐bearing mice, A/J mice bearing Neuro2A or NIE115 NB were systemically treated with L19‐IL2 and L19mTNFα, alone or in combination protocols. Seventy percent of Neuro2A‐ and 30% of NIE115‐bearing mice were cured by the combined treatment with L19‐IL2 and L19mTNFα, and further rejected a homologous tumor challenge, indicating specific antitumor immune memory. The immunological bases of tumor cure and rejection were studied. A highly efficient priming of CD4^+^ T helper cells and CD8^+^ CTL effectors was generated, paralleled by massive infiltration in the tumor tissue of CD4^+^ and CD8^+^ T cells at day 16 after tumor cell implantation, when, after therapy, tumor volume was drastically reduced and tumor necrosis reached about 80%. The curative treatment resulted in a long‐lasting antitumor immune memory, accompanied by a mixed Th1/Th2 type of response. Concluding, L19‐IL2 and L19mTNFα efficiently cooperate in determining a high percentage of NB cure that, in our experimental models, is strongly associated to the generation of adaptive immunity involving CD4^+^ and CD8^+^ T cells.