Trastuzumab emtansine biosimilar (Hetero Biopharma)

Cell surface proteins play crucial roles in various cellular processes, including intercellular communication, adhesion, and immune responses. However, investigating these proteins using single-molecule force spectroscopy (SMFS) has been hindered by challenges in site-specific protein modification while preserving their native state. Here, we introduce a methionine-specific bioconjugation strategy utilizing a bespoke hypervalent iodine reagent for highly selective, rapid, and robust methionine labeling. Since methionine is often the first amino acid incorporated into proteins via initiator tRNA, this approach enables precise N-terminal labeling and attachment, facilitating more reliable SMFS studies. The resulting covalent linkage remains intact during mechanical unfolding or conformational changes of proteins, with a mechanical stability exceeding 600 pN, allowing accurate measurements before detachment from AFM cantilever tips or cell surfaces. Additionally, this method improves sampling rates and data quality. We successfully applied this technique to light-induced protein printing and natural surface protein studies, demonstrating its potential for advancing protein mechanics research in living cells. This strategy provides significant advantages for SMFS in the study of complex cellular systems.

Active targeting is more effective than conventional passive targeted drug delivery systems in increasing therapeutic efficacy and minimizing systemic toxicities. Importantly, the nanoparticle-based targeted drug delivery systems combine active and passive targeting properties and significantly enhance therapeutic efficacy. In this study, we utilized ultrasmall superparamagnetic iron oxide (uSPIO) nanoparticles conjugated with anti-prostate-specific membrane antigen (PSMA) 5D3 monoclonal antibody, mertansine (DM1) antitubulin agent, and fluorophore to develop a targeted uSPIO-5D3-DM1-AF488/CF750 nanotheranostic for PSMA(+) prostate cancer (PC) therapy. This agent enables multimodality in vivo imaging using near-infrared (NIR) fluorescence and magnetic resonance imaging (MRI). uSPIO-5D3-DM1-AF488 is selectively internalized into PSMA-positive cells by receptor-mediated endocytosis, and uSPIO-5D3-DM1-CF750 exhibited 1.62 and 166.2 ng/mL IC₅₀ values in PSMA(+) and PSMA(-) cells, respectively. The image-guided therapeutic study was conducted in vivo in human PC xenograft mouse models bearing bilateral PSMA(±) tumors (n = 10, two 10 mg/kg doses on days 1 and 14). The therapeutic results exhibited a significant control of the growth of PSMA(+) tumors starting at day 5 (p = 0.05) and significantly improved efficacy after day 9 (p = 0.0005) during the treatment period (t = 21 days). We observed the PSMA-specific uptake of uSPIO-5D3-DM1-CF750 in tumors in NIR IVIS Xenogen images and T₁- and T₂-weighted MRI with 20.6% and 42% reduction of overall T₁ and T₂, respectively. Approximately 70% of mice with PSMA(+) tumors treated with uSPIO-5D3-DM1-CF750 survived or did not exceed the threshold level of the tumor size during the treatment. Ex vivo biodistribution study proved 50% and 45% higher uptake of uSPIO-5D3-DM1-CF750 by PSMA(+) tumors compared to untargeted uSPIO-DM1-CF750 by PSMA(+) tumors and uSPIO-5D3-DM1-CF750 by PSMA(-) tumors, respectively. ICP-MS analysis demonstrated a 73% increase in uSPIO-5D3-DM1-CF750 uptake by PSMA(+) tumors compared to PSMA(+) tumors treated with pure uSPIO. The toxicological results reveal the safe profile in systemic toxicities without life-threatening changes in the complete blood count and clinical chemistry profile of toxicology.