Conjugate comprising interleukin-12 (IL-12) and a single chain targeting portion comprising two antigen binding sites. The targeting portion may comprise an antibody fragment such as a single chain diabody. The conjugate may be a single chain fusion protein. Use of single chain bivalent IL-12 immunocytokine for targeting the extra-cellular matrix (ECM) of tissues, particularly tumour neovasculature antigens, for example fibronectin. Use for treating cancer or pathological angiogenesis in a patient.
