This protein plays a key role during embryo development and is found in the fetal liver and gastrointestinal tract [29]

This protein plays a key role during embryo development and is found in the fetal liver and gastrointestinal tract [29]. poor prognosis and high mortality rate [2]. Molecular analyses of gastric tumors include methods to test changes in the genes (e.g., gene amplification assessed using in situ hybridization, ISH) and/or in the manifestation of proteins, mostly via immunohistochemistry (IHC) [3]. With this context, detection of human being epidermal growth element receptor 2 (HER2) in GC often includes methods to determine gene amplification and HER2 protein expression [4]. However, these different methodologies do not usually give similar results and can become misleading when defining patient selection for anti-HER2 systemic therapy. Regrettably, gastric malignancy is definitely a malignancy with high heterogeneity, at least in the establishing of HER2 status. Determining HER2 status through multiple biopsies of the same patient could reduce the false- negatives and false-positives observed in GC [3]. Whole-body molecular imaging is also a powerful technique to be used in match to IHS and IHC, as it allows the visualization of main tumors and metastases in the same patient [5,6]. Tumor cells often have upregulated glucose transporters (GLUT). Fluorodeoxyglucose (FDG) positron emission tomographyCcomputed tomography (PET-CT) offers improved the staging of GC by combining functional (PET) and anatomical (CT) imaging to visualize tumor areas with high metabolic activity [7,8]. However, not all tumor CHMFL-KIT-033 lesions are passionate for FDG and non-tumor cells also communicate GLUTs [7,8]. The use of FDG-PET is associated with false-negative and false-positive CHMFL-KIT-033 images that could misdirect therapy planning and decrease diagnostic accuracy. With this context, PET has developed into immunoPET, wherein antibodies with high specificity CHMFL-KIT-033 for antigens overexpressed or distinctively indicated in tumor cells are labeled with PET radiometals [5,9,10,11,12,13,14]. In addition to PET, antibodies radiolabeled with solitary photon emission computed tomography (SPECT) radiometals allow noninvasive, highly sensitive imaging of GC [15,16]. Another attractive antibody-based imaging strategy utilizes comparatively innocuous fluorescent imaging probes that when conjugated to antibodies can be directed specifically to tumor-associated antigens and visualized with high tumor-to-background ratios [17,18,19,20]. In sum, antibodies labeled with PET/SPECT radiometals or fluorescent dyes allow for visualization of specific antigens present in gastric tumors or metastasesa vital component of analysis that also localizes the primary lesion to inform treatment options and allows clinicians to monitor disease progression. This review will focus on full-length antibodies labeled with PET radiometals, SPECT radiometals, and fluorescent dyes that have been used preclinically and clinically to image gastric tumors. 2. ImmunoPET and ImmunoSPECT with Full-Length Antibodies in GC ImmunoPET and immunoSPECT are imaging techniques that use antibody-based radiotracers. ImmunoPET and immunoSPECT have been utilized for the non-invasive imaging of gastric malignancy in both preclinical and medical studies. The first section of the review will discuss the use of immunoPET in GC focusing on the antigens carcinoma-associated antigen (MG7) [14], programmed death-1 (PD-1) [16], cadherin-17 (CDH17) [15], human CHMFL-KIT-033 being epidermal growth element receptors 2 and 3 (HER2 [5,9,21,22,23,24] and HER3 [12]), hepatocyte growth element (HGF [11]), and the mesenchymal-epithelial transition element (MET) [10]. CHMFL-KIT-033 As demonstrated in Table 1, FDA-approved or newly developed antibodies focusing on membrane antigens were radiolabeled with gallium-68 (68Ga), technetium-99m (99mTc), indium-111 (111In), copper-64 (64Cu), zirconium-89 (89Zr), and bromine-76 (76Br) and utilized for PET or SPECT imaging of gastric tumors. Table 1 Radiolabeled antibodies used in molecular imaging of gastric tumors.

Biological Magic size Target Antibody Radioisotope Main Findings Reference

BGC-823 subcutaneous xenograftsMG7MG768GaAccumulation in the tumor, liver, and kidneys.[14]BCG-823 orthotopic tumorsPD-1JS00199mTcAccumulation in the tumor, blood, liver, and kidneys.[16]AGS subcutaneous xenograftsCDH17D2101111InOptimal tumor build up was achieved at 96 h after 111In-DS2101 administration.[15]NCIN87 subcutaneous xenograftsHER2H32 IgG,75 IgG,61 IgG, and trastuzumab111In111In-labeled 61 IgG showed KR1_HHV11 antibody the highest tumor accumulation.[21]Patient-derived gastric xenografts and patientstrastuzumab64CuThe combination of 64Cu-NOTA with trastuzumab showed higher tumor uptake than trastuzumab.