SibTech is focused on theoptimization of biopharmaceutical proteins for multiple applications,including targeted drug delivery, targeted imaging, and derivatization of biomedical surfaces. Based on a platform technology for converting proteins into a format suitable for site-specific conjugation of various payloads, proteins are expressed with a fusion Cys-tag, a 15-aa cysteine-containing peptide, whose thiol group is used for site-specific modifications. SibTech's experience with different Cys-tagged proteins and very diverse payloads suggests that virtually every protein can be Cys-tagged and made to carry a payload without loss of functional activity. This approach allows rapid development of new applications for existing and emerging biopharmaceutical proteins. The firm's work has yielded the first candidate for clinical development, a proprietary Cys-tagged single-chain vascular endothelial growth factor (scVEGF) derivatized with a contrast agent for PET imaging of VEGF receptors. These receptors play a pivotal role in tumor angiogenesis and their inhibition is the major goal of anti-angiogenic therapies. Imaging VEGF receptors in tumor vasculature can provide crucial information for early diagnostics, development and monitoring therapeutic regimens, and rational patient selection for complex and very expensive treatments. Currently, there are no contrast agents for imaging VEGF receptors and our lead candidate is being developed to satisfy this unmet need.
