%0 Journal Article %A Stijn JH Waaijer %A Danique Giesen %A Takahiro Ishiguro %A Yuji Sano %A Naofumi Sugaya %A Carolina P Schröder %A Elisabeth GE de Vries %A Marjolijn N Lub-de Hooge %T Preclinical PET imaging of bispecific antibody ERY974 targeting CD3 and glypican 3 reveals that tumor uptake correlates to T cell infiltrate %D 2020 %R 10.1136/jitc-2020-000548 %J Journal for ImmunoTherapy of Cancer %P e000548 %V 8 %N 1 %X Background Bispecific antibodies redirecting T cells to the tumor obtain increasing interest as potential cancer immunotherapy. ERY974, a full-length bispecific antibody targeting CD3ε on T cells and glypican 3 (GPC3) on tumors, has been in clinical development However, information on the influence of T cells on biodistribution of bispecific antibodies, like ERY974, is scarce. Here, we report the biodistribution and tumor targeting of zirconium-89 (89Zr) labeled ERY974 in mouse models using immuno-positron emission tomography (PET) imaging.Methods To study both the role of GPC3 and CD3 on the biodistribution of [89Zr]Zr-N-suc-Df-ERY974, 89Zr-labeled control antibodies targeting CD3 and non-mammalian protein keyhole limpet hemocyanin (KLH) or KLH only were used. GPC3 dependent tumor targeting of [89Zr]Zr-N-suc-Df-ERY974 was tested in xenograft models with different levels of GPC3 expression. In addition, CD3 influence on biodistribution of [89Zr]Zr-N-suc-Df-ERY974 was evaluated by comparing biodistribution between tumor-bearing immunodeficient mice and mice reconstituted with human immune cells using microPET imaging and ex vivo biodistribution. Ex vivo autoradiography was used to study deep tissue distribution.Results In tumor-bearing immunodeficient mice, [89Zr]Zr-N-suc-Df-ERY974 tumor uptake was GPC3 dependent and specific over [89Zr]Zr-N-suc-Df-KLH/CD3 and [89Zr]Zr-N-suc-Df-KLH/KLH. In mice engrafted with human immune cells, [89Zr]Zr-N-suc-Df-ERY974 specific tumor uptake was higher than in immunodeficient mice. Ex vivo autoradiography demonstrated a preferential distribution of [89Zr]Zr-N-suc-Df-ERY974 to T cell rich tumor tissue. Next to tumor, highest specific [89Zr]Zr-N-suc-Df-ERY974 uptake was observed in spleen and lymph nodes.Conclusion [89Zr]Zr-N-suc-Df-ERY974 can potentially be used to study ERY974 biodistribution in patients to support drug development. %U https://jitc.bmj.com/content/jitc/8/1/e000548.full.pdf