Radiolabelled peptides in diagnosis and therapy: an introduction

Excerpt

The emergence of peptide receptor radionuclide imaging (PRRI) is highly regarded as a landmark in the diagnosis of tumours and other diseases through interaction with cell membrane receptors. The small size and low molecular weight of peptides, compared to proteins and antibodies, facilitate rapid access to target tissue and similarly, fast clearance from nontarget tissue. The resultant high tumour to background ratio provides a unique opportunity to map the distribution and assess the severity of a variety of tumours by planar and single photon emission computed tomography (SPECT) of ¹¹¹In and ^99mTc labelled peptides. The emergence of radiolabelled peptides for use with PET/CT such as ⁶⁸Ga, ¹⁸F and ⁶⁴Cu, and the use of new receptor binding ligands such as the various DOTA compounds, have revolutionized PRRI and improved its diagnostic power beyond expectation. The inevitable move to utilize this novel technique to deliver peptide receptor radionuclide therapy (PRRT) followed swiftly by replacing diagnostic with therapeutic radionuclides such as ⁹⁰Y and ¹⁷⁷Lu. The main use of PRRI and PRRT remains at present largely restricted to neuroendocrine tumours (NET) expressing somatostatin receptors, but efforts to export these novel techniques to other tumours expressing the same or different receptors are in progress. …