⁸⁹Zr-mAb3481 PET for HER3 tumor status assessment during lapatinib treatment

Abstract

Treatment of human epidermal growth factor receptor 2 (HER2)-driven breast cancer with tyrosine kinase inhibitor lapatinib can induce a compensatory HER3 increase, which may attenuate antitumor efficacy. Therefore, we explored in vivo HER3 tumor status assessment after lapatinib treatment with zirconium-89 (89Zr)-labeled anti-HER3 antibody mAb3481 positron emission tomography (PET). Lapatinib effects on HER3 cell surface expression and mAb3481 internalization were evaluated in human breast (BT474, SKBR3) and gastric (N87) cancer cell lines using flow cytometry. Next, in vivo effects of daily lapatinib treatment on89Zr-mAb3481 BT474 and N87 xenograft tumor uptake were studied. PET-scans (BT474 only) were made after daily lapatinib treatment for 9 days, starting 3 days prior to 89Zr-mAb3481 administration. Subsequently, ex vivo 89Zr-mAb3481 organ distribution analysis was performed and HER3 tumor levels were measured with Western blot and immunohistochemistry. In vitro, lapatinib increased membranous HER3 in BT474, SKBR3 and N87 cells, and consequently mAb3481 internalization 1.7-fold (BT474), 1.4-fold (SKBR3) and 1.4-fold (N87). 89Zr-mAb3481 BT474 tumor uptake was remarkably high at SUVmean 5.6±0.6 (51.8±7.7%ID/g) using a 10 μg 89Zr-mAb3481 protein dose in vehicle-treated mice. However, compared to vehicle, lapatinib did not affect 89Zr-mAb3481 ex vivo uptake in BT474 and N87 tumors, while HER3 tumor expression remained unchanged. In conclusion, lapatinib increased in vitro HER3 tumor cell expression, but not when these cells were xenografted. 89Zr-mAb3481 PET accurately reflected HER3 tumor status. 89Zr-mAb3481 PET showed high, HER3-specific tumor uptake, and such an approach might sensitively assess HER3 tumor heterogeneity and treatment response in patients.

Benefit of Later-Time-Point PET Imaging of HER3 Expression Using Optimized Radiocobalt-Labeled Affibody Molecules

“…HER3 imaging is challenging due to the relatively low overexpression in malignant lesions and moderate endogenous expression in healthy tissue and potential metastatic sites, especially the liver. Radiolabeled antibodies and antibody fragments have been suggested for imaging of HER3-expression [10][11][12]. For example, the anti-HER3 antibody 89 Zr-lumretuzumab provided good imaging contrast 4-7 days after injection and enabled quantification of the uptake in HER3 positive tumors in a small clinical study.…”

“…The long-lived PET isotope zirconium-89 (t 1/2 = 78.4 h) has been used for preclinical and clinical imaging of HER3 expression in combination with antibodies, and nanobodies [10,13,32]. Recently, a HER3-targeting affibody molecule was labeled with 89 Zr and used to detect changes in HER3 expression in response to treatment of breast cancer xenografts with an HSP90 inhibitor [22].…”

Antibody-Targeted Imaging of Gastric Cancer

“…ImmunoPET and immunoSPECT have been used for the non-invasive imaging of gastric cancer in both preclinical and clinical studies. The first section of the review will discuss the use of immunoPET in GC targeting the antigens carcinoma-associated antigen (MG7) [ 14 ], programmed death-1 (PD-1) [ 16 ], cadherin-17 (CDH17) [ 15 ], human epidermal growth factor receptors 2 and 3 (HER2 [ 5 , 9 , 21 , 22 , 23 , 24 ] and HER3 [ 12 ]), hepatocyte growth factor (HGF [ 11 ]), and the mesenchymal-epithelial transition factor (MET) [ 10 ]. As shown in Table 1 , FDA-approved or newly developed antibodies targeting membrane antigens were radiolabeled with gallium-68 ( 68 Ga), technetium-99m ( 99m Tc), indium-111 ( 111 In), copper-64 ( 64 Cu), zirconium-89 ( 89 Zr), and bromine-76 ( 76 Br) and used for PET or SPECT imaging of gastric tumors.…”

“…The use of FDG-PET is associated with false-negative and false-positive images that could misdirect therapy planning and decrease diagnostic accuracy. In this context, PET has evolved into immunoPET, wherein antibodies with high specificity for antigens overexpressed or uniquely expressed in tumor cells are labeled with PET radiometals [ 5 , 9 , 10 , 11 , 12 , 13 , 14 ]. In addition to PET, antibodies radiolabeled with single photon emission computed tomography (SPECT) radiometals allow noninvasive, highly sensitive imaging of GC [ 15 , 16 ].…”

Influence of Residualizing Properties of the Radiolabel on Radionuclide Molecular Imaging of HER3 Using Affibody Molecules

“…This noninvasive test could be performed repeatedly with a minimal discomfort for the patient. Current approaches for development of HER3-imaging probes include the use of radiolabeled antibodies [22][23][24][25][26], antibody fragments [27], nanobody-based tracers [28], short peptides [29], and affibody molecules [30][31][32][33][34][35]. It has to be noted that development of HER3-imaging probes is challenging due to the pattern of HER3 expression.…”