One immunocytokine format, composed by two L19 scFv domains in tandem diabody format linked to an IL2 payload at the C-terminus (named L19L19-IL2), had significantly superior tumor targeting properties, as reflected by the highest percentage of injected dose-per gram of the immunocytokine in the tumor, compared to the other tested formats (except for the GGSGG candidate where L19L19-IL2 had a higher accumulation but not significantly superior). Here, IL2 is linked to neoplasm.