Carbonic Anhydrase IX-Targeted Near-Infrared Dye for Fluorescence Imaging of Hypoxic Tumors Sakkarapalayam M. Mahalingam Haiyan Chu Xin Liu Christopher P. Leamon Philip S. Low 10.1021/acs.bioconjchem.8b00509.s001 https://acs.figshare.com/articles/journal_contribution/Carbonic_Anhydrase_IX-Targeted_Near-Infrared_Dye_for_Fluorescence_Imaging_of_Hypoxic_Tumors/7112042 Use of tumor-targeted fluorescence dyes to help surgeons identify otherwise undetected tumor nodules, decrease the incidence of cancer-positive margins, and facilitate localization of malignant lymph nodes has demonstrated considerable promise for improving cancer debulking surgery. Unfortunately, the repertoire of available tumor-targeted fluorescent dyes does not permit identification of all cancer types, raising the need to develop additional tumor-specific fluorescent dyes to ensure localization of all malignant lesions during cancer surgeries. By comparing the mRNA levels of the hypoxia-induced plasma membrane protein carbonic anhydrase IX (CA IX) in 13 major human cancers with the same mRNA levels in corresponding normal tissues, we document that CA IX constitutes a nearly universal marker for the design of tumor-targeted fluorescent dyes. Motivated by this expression profile, we synthesize two new CA IX-targeted near-infrared (NIR) fluorescent imaging agents and characterize their physical and biological properties both <i>in vitro</i> and <i>in vivo</i>. We report that conjugation of either acetazolamide or 6-aminosaccharin (i.e., two CA-IX-specific ligands) to the NIR fluorescent dye, S0456, via an extended phenolic spacer creates a brightly fluorescent dye that binds CA IX with high affinity and allows rapid visualization of hypoxic regions of solid tumors at depths >1 cm beneath a tissue surface. Taken together, these data suggest that a CA IX-targeted NIR dye can constitute a useful addition to a cocktail of tumor-targeted NIR dyes designed to image all human cancers. 2018-09-06 00:00:00 tumor-targeted NIR dyes CA IX-targeted NIR dye CA IX-targeted near-infrared mRNA levels cancer debulking surgery tumor-targeted fluorescence dyes Carbonic Anhydrase IX-Targeted Near-Infrared Dye hypoxia-induced plasma membrane protein carbonic anhydrase