Advances in Immuno–Positron Emission Tomography: Antibodies for Molecular Imaging in Oncology

Abstract

Identification of cancer cell-surface biomarkers and advances in antibody engineering have led to a sharp increase in the development of therapeutic antibodies. These same advances have led to a new generation of radiolabeled antibodies and antibody fragments that can be used as cancer-specific imaging agents, allowing quantitative imaging of cell-surface protein expression in vivo. Immunopositron emission tomography (immunoPET) imaging with intact antibodies has shown success clinically in diagnosing and staging cancer. Engineered antibody fragments, such as diabodies, minibodies, and single-chain Fv (scFv) -Fc, have been successfully employed for immunoPET imaging of cancer cell-surface biomarkers in preclinical models and are poised to bring same-day imaging into clinical development. ImmunoPET can potentially provide a noninvasive approach for obtaining target-specific information useful for titrating doses for radioimmunotherapy, for patient risk stratification and selection of targeted therapies, for evaluating response to therapy, and for predicting adverse effects, thus contributing to the ongoing development of personalized cancer treatment.

Radretumab Radioimmunotherapy in Patients with Brain Metastasis: A 124I-L19SIP Dosimetric PET Study

“…2 and 4; Table 1). Our results are consistent with those published by Wu and colleagues, who showed the advantages of using antibodies in mini-antibody format (functionally equivalent to SIP) and 124 I as a PET radionuclide (44,45).…”

Olfactory receptor 51E1 as a novel target for diagnosis in somatostatin receptor-negative lung carcinoids

“…In our study, OR51E1 has shown more extensive membrane localization compared with SSTR2, SSTR3, and SSTR5, which are targeted by most of the clinically available SSAs. These findings indicated that OR51E1 might display a higher uptake in LC cells, compared with the SSA-based diagnostics, after developing appropriate procedures of immuno-positron emission tomography (PET; Knowles & Wu 2012) by means of OR51E1 monoclonal antibodies with high receptor binding affinity. Indeed, OR51E1 has shown an advantage over SSTRs as it has prevalence across the entire spectrum of LCs, even in OctreoScan-negative and/or SSTR non-IR LCs, independent of tumor size.…”

Noninvasive positron emission tomography and fluorescence imaging of CD133 + tumor stem cells

“…S3A). Particularly remarkable was the much higher tracer uptake liver [an organ exhibiting relatively high unspecific activity because of high blood perfusion, antibody metabolism, and potential transchelation of 64 Cu (28,36)]. The tumor-to-contralateral background, tumor-to-blood pool, and tumor-to-liver contrasts were 21.4 ± 8.2, 2.7 ± 0.9, and 2.6 ± 0.8 at 24 h and 32.8 ± 19, 6.4 ± 2.5, and 5.4 ± 1.8 at 48 h p.i., respectively.…”