Tumor-Targeting Agents

Monoclonal antibodies are specific molecules with a high affinity for the cell surface proteins. Long circulation time in blood makes them unsuitable for imaging as well as therapy. The process of protein engineering improves antibody’s pharmacokinetics retaining the property of affinity and specificity. Using a single-chain variable fragment as the building block, imaging with antibody variants provides high-contrast, good-quality images using single-photon emission computed tomography (SPECT) and positron emission tomography (PET) scanners. Selective antibody targeting using therapeutic radionuclide is a promising approach for cancer therapy. The success of radioimmunotherapy is limited by prolonged exposure of bone marrow. In vivo pretargeting approach improves tumor targeting properties for imaging as well as treatment. To address the limitations of severe immune-related adverse effects of monoclonal antibodies, new peptide-based immune checkpoint inhibitors with potent antitumor activity but a shorter pharmacokinetics profile developed. Among the newer constructs, development of aptamers is on the way. These oligonucleotide molecules can be crafted to many complex shapes and act as a scaffold for molecular interaction with protein and small molecular targets.