The strength of small: improved targeting of insulin-like growth factor-1 receptor (IGF-1R) with F(ab')₂-R1507 fragments in Ewing sarcomas.

Purpose: To investigate whether F(ab')₂-fragments of the monoclonal Insulin-like Growth Factor-1 Receptor (IGF-1R) antibody R1507 (F(ab')₂-R1507) can successfully target IGF-1R in Ewing sarcomas (ES).

Materials And Methods: BALB/c nude mice were subcutaneously implanted with IGF-1R-expressing human ES xenografts (EW-5 and EW-8) which previously showed heterogeneous or no uptake of indium-111-labelled R1507 IgG ((111)In-R1507), respectively. Mice were injected with (111)In-F(ab')₂-R1507 or (111)In-R1507 as a reference.

Optimization of IGF-1R SPECT/CT imaging using 111In-labeled F(ab')2 and Fab fragments of the monoclonal antibody R1507.

The insulin-like growth factor 1 receptor (IGF-1R) is a potential new target for the treatment of breast cancer. Patients with breast cancer lesions that express IGF-1R may benefit from treatment with anti-IGF-1R antibodies. IGF-1R expression can be visualized using radiolabeled R1507, a monoclonal antibody directed against IGF-1R.