Satoshi Kashiwagi

Topical pH Sensing NIR Fluorophores for Intraoperative Imaging and Surgery of Disseminated Ovarian Cancer

AbstractFluorescence‐guided surgery (FGS) aids surgeons with real‐time visualization of small cancer foci and borders, which improves surgical and prognostic efficacy of cancer. Despite the steady advances in imaging devices, there is a scarcity of fluorophores available to achieve optimal FGS. Here, 1) a pH‐sensitive near‐infrared fluorophore that exhibits rapid signal changes in acidic tumor microenvironments (TME) caused by the attenuation of intramolecular quenching, 2) the inherent targeting for cancer based on chemical structure (structure inherent targeting, SIT), and 3) mitochondrial and lysosomal retention are reported. After topical application of PH08 on peritoneal tumor regions in ovarian cancer‐bearing mice, a rapid fluorescence increase (< 10 min), and extended preservation of signals (> 4 h post‐topical application) are observed, which together allow for the visualization of submillimeter tumors with a high tumor‐to‐background ratio (TBR > 5.0). In addition, PH08 is preferentially transported to cancer cells via organic anion transporter peptides (OATPs) and colocalizes in the mitochondria and lysosomes due to the positive charges, enabling a long retention time during FGS. PH08 not only has a significant impact on surgical and diagnostic applications but also provides an effective and scalable strategy to design therapeutic agents for a wide array of cancers.

Fast and Durable Intraoperative Near‐infrared Imaging of Ovarian Cancer Using Ultrabright Squaraine Fluorophores

AbstractThe residual tumor after surgery is the most significant prognostic factor of patients with epithelial ovarian cancer. Near‐infrared (NIR) fluorescence‐guided surgery is actively utilized for tumor localization and complete resection during surgery. However, currently available contrast‐enhancing agents display low on‐target binding, unfavorable pharmacokinetics, and toxicity, thus not ideal for clinical use. Here we report ultrabright and stable squaraine fluorophores with optimal pharmacokinetics by introducing an asymmetric molecular conformation and surface charges for rapid transporter‐mediated cellular uptake. Among the tested, OCTL14 shows low serum binding and rapid distribution into cancer tissue via organic cation transporters (OCTs). Additionally, the charged squaraine fluorophores are retained in lysosomes, providing durable intraoperative imaging in a preclinical murine model of ovarian cancer up to 24 h post‐injection. OCTL14 represents a significant departure from the current bioconjugation approach of using a non‐targeted fluorophore and would provide surgeons with an indispensable tool to achieve optimal resection.