The Influence of Different Spacers on Biological Profile of Peptide Radiopharmaceuticals for Diagnosis and Therapy of Human Cancers

Preclinical evaluation of a new technetium-99m labeled neurotensin analogue for NTSR1 targeted radionuclide imaging

Neurotensin is a regulatory peptide that can act as a growth factor on different types of normal and cancerous cells. Binding of Neurotensin to relevant receptors leads to cell proliferation, survival, migration and invasion by changing intracellular enzyme activity. Therefore, the design of a neurotensin-based radiopeptide plays an important role in targeted imaging or therapy of neurotensin receptor-positive tumors. A [Lys8]-neurotensin (7-13) peptide was synthesized and attached to HYNIC as a chelator via a linker. The labeling procedure was carried out at 100 °C for 10 min using 99mTc as a radionuclide and EDDA/tricine as coligands. Stability of the labeled peptide in human serum was determined using RTLC and HPLC methods. The receptor binding internalization was studied using HT-29 colon carcinoma cells, and tissue biodistribution was evaluated in mice bearing CT-26 tumors. The [99mTc]Tc-Tricine/EDDA/HYNIC-GABA-[Lys8]-neurotensin (7-13) peptide demonstrated a labeling yield of over 98 %, a specific activity of 37.00 GBq/µmol, high stability in human serum, a nanomolar range of Kd, and a tumor uptake of 0.36 ± 0.15 % ID/g at 1-h post-injection. These results suggest that the labeled peptide is a suitable imaging agent for neurotensin receptor-positive tumors.

Medicinal (Radio) Chemistry: Building Radiopharmaceuticals for the Future

Radiopharmaceuticals are increasingly playing a leading role in diagnosing, monitoring, and treating disease. In comparison with conventional pharmaceuticals, the development of radiopharmaceuticals does follow the principles of medicinal chemistry in the context of imaging-altered physiological processes. The design of a novel radiopharmaceutical has several steps similar to conventional drug discovery and some particularity. In the present work, we revisited the insights of medicinal chemistry in the current radiopharmaceutical development giving examples in oncology, neurology, and cardiology. In this regard, we overviewed the literature on radiopharmaceutical development to study overexpressed targets such as prostate-specific membrane antigen and fibroblast activation protein in cancer; β-amyloid plaques and tau protein in brain disorders; and angiotensin II type 1 receptor in cardiac disease. The work addresses concepts in the field of radiopharmacy with a special focus on the potential use of radiopharmaceuticals for nuclear imaging and theranostics.

Vitamin-based radiopharmaceuticals for tumor imaging

Advances in nuclear medicine, such as single photon emission computed tomography (SPECT) and positron emission tomography (PET), are among the most sensitive methods that can be used in diagnostic imaging and radionuclide therapy with higher efficiency and reduced toxicity benefits. In order to improve the success of treatment, it is also important to develop methods that can be used when lesions can be detected at the earliest stages. Vitamins are macromolecules that play a crucial role in numerous biological processes in both animals and humans. Escalating development of vitamin-based radiopharmaceuticals for application in the diagnosis and treatment of cancers. In this review, we aimed to discuss about recent research utilizing radio-labeled vitamins for targeted tumor imaging.