Immuno-PET of the Hepatocyte Growth Factor Receptor Met Using the 1-Armed Antibody Onartuzumab

Journal of Nuclear Medicine

Elaine M. Jagoda¹  Peter Choyke¹  Donald P. Bottaro¹  Stephanie Histed¹  Jeff N. Tinianow¹  Veerendra Bhadrasetty¹  Lawrence Szajek¹  Chang Paik¹  Mark Williams¹  Joe-Marie Jose-Dizon¹  Gabriela Kramer-Marek¹  Kristen Raffensperger¹  Mark Merchant¹  Lixin Lang¹  Fabiola Cecchi¹  Jan Marik¹  Lauren Rosenblum¹  Esther Mena¹ 

关键词: immuno-PET imaging;    Met receptor;    ⁷⁶Br-onartuzumab;    ⁸⁹Zr-df-onartuzumab;    MetMAb;   

DOI  :  10.2967/jnumed.111.102293

学科分类：医学（综合）

来源: Society of Nuclear Medicine

【 摘 要 】

The overexpression and overactivation of hepatocyte growth factor receptor (Met) in various cancers has been linked to increased proliferation, progression to metastatic disease, and drug resistance. Developing a PET agent to assess Met expression would aid in the diagnosis and monitoring of responses to Met-targeted therapies. In these studies, onartuzumab, the experimental therapeutic 1-armed monoclonal antibody, was radiolabeled with 76Br or 89Zr and evaluated as an imaging agent in Met-expressing cell lines and mouse xenografts. Methods: 89Zr-desferrioxamine (df)-onartuzumab was synthesized using a df-conjugate; 76Br-onartuzumab was labeled directly. Met-binding studies were performed using the human tumor–derived cell lines MKN-45, SNU-16, and U87-MG, which have relatively high, moderate, and low levels of Met, respectively. Biodistribution and small-animal PET studies were performed in MKN-45 and U87-MG xenografts. Results: 76Br-onartuzumab and 89Zr-df-onartuzumab exhibited specific, high-affinity Met binding (in the nanomolar range) that was concordant with established Met expression levels. In MKN-45 (gastric carcinoma) xenografts, both tracers cleared slowly from nontarget tissues, with the highest uptake in tumor, blood, kidneys, and lungs. 76Br-onartuzumab MKN-45 tumor uptake remained relatively constant from 18 h (5 percentage injected dose per gram of tissue [%ID/g]) to 48 h (3 %ID/g) and exhibited tumor-to-muscle ratios ranging from 4:1 to 6:1. In contrast, 89Zr-df-onartuzumab MKN-45 tumor uptake continued to accumulate from 18 h (10 %ID/g) to 120 h (23 %ID/g), attaining tumor-to-muscle ratios ranging from 20:1 to 27:1. MKN-45 tumors were easily visualized in imaging studies with both tracers at 18 h, but after 48 h 89Zr-df-onartuzumab image quality improved, with at least 2-fold-greater tumor uptake than nontarget tissues. MKN-45 tumor uptake for both tracers correlated significantly with tumor mass and Met expression and was not affected by the presence of plasma shed Met. Conclusion: 89Zr-df-onartuzumab and 76Br-onartuzumab specifically targeted Met in vitro and in vivo; 89Zr-df-onartuzumab achieved higher tumor uptake and tumor-to-muscle ratios than 76Br-onartuzumab at later times, suggesting that 89Zr-df-onartuzumab would be better suited to image Met for diagnostic and prognostic purposes.

【 授权许可】

Unknown