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124I/125I-Fibril-reactive monoclonal antibody .

Authors

Cheng KT.

Source

Molecular Imaging and Contrast Agent Database (MICAD) [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2004-2013.
2006 Dec 07 [updated 2008 Jan 02].

Excerpt

124I-Fibril-reactive monoclonal antibody (124I-11-1F4 MAb) is a radiolabeled antibody that was developed for positron emission tomography (PET) imaging of primary systemic amyloid light –chain (AL) amyloidosis (1). 124I is a positron emitter with a physical half-life (t½) of 4.2 days. 125I-11-1F4 MAb is used for small animal studies. 125I-11-1F4 MAb was also used in the animal investigation for small animal single-photon emission computed tomography (SPECT) studies, but 125I is a low-energy gamma emitter with a long physical half-life (t½) of 60 days. Amyloidosis describes a heterogeneous group of diseases with a common feature of the extracellular deposition of amyloid proteins in various tissues (2). Amyloid is an amorphous, homogeneous, hyaline-like, eosinophilic substance. Despite its homogeneous appearance, it has a fibrillar structure that consists of linear, non-branching, aggregrated fibrils. The abnormal deposition of this relatively inert fibrillar material in the extracellular compartment of various organs leads to interference with normal functions and destruction of involved tissues and organs. At least 13 different proteins have been identified as human amyloid fibril precursors (2, 3). Primary or idiopathic systemic AL amyloidosis is one of the most common subtypes of amyloidosis. It is a pathologic condition of monoclonal plasma cell dyscrasia (4-6). It is frequently characterized by an abnormal neoplastic proliferation of plasma cells, which synthesize amyloidogenic immunoglobulin light chains. The variable region of the light chain is highly mutated, and this translates into structural heterogeneity and several possible mechanistic pathways of fibril formation (7). The disease may involve the heart, kidney, liver, spleen, tongue, nerves, as well as the vascular system and other body organs/tissues (8) Monitoring the pathogenesis of these diseases and their responses to treatments is difficult and has traditionally relied on the histologic evaluation of tissue biopsies, and surveys of surrogate physiologic markers. Thus, a specific and noninvasive method for the estimation of amyloid deposition is needed. Hawkins et al. (9-11) demonstrated the possibility of imaging pathologic deposits in vivo with 123I-labeled human serum amyloid P component (SAP). Antiproteases are also known to be present in amyloid deposits, and 99mTc-labeled aprotinin (an anti-serine protease) has been studied for AL amyloid imaging with some success in Europe (12, 13). Solomon et al. (4, 14) developed a murine amyloid-reactive monoclonal antibody, IgG, 11-1F4 MAb (m11-1F4 MAb), for immunotherapy of AL amyloidosis. This MAb was prepared against a к4 Bence Jones protein. It appeared to react specifically with AL fibrils, regardless of their к or λ constant region isotype or variable region subgroup but did not recognize native (soluble) light chains. The 11-F4 MAb has now been chimerized (c11-1F4 MAb) and is undergoing good manufacturing practice production for phase I and II clinical trials. Wall et al. (1, 15) successfully radioiodinated 11-1F4 MAb with 124I and 125I for in vivo imaging and provided the basis for future clinical trials of 124I-11-1F4 MAb as a potential diagnostic tool in patients with AL amyloidosis and other systemic amyloidoses.

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