Complete tumor removal during surgery has a great impact on patient survival. In order to remove the tumor tissue completely with minimal collateral damage to healthy tissues, there is a need for diagnostic tools that will differentiate between the tumor and its normal surroundings [1].
We present here the design, synthesis and characterization of a novel polymeric Turn-ON probe, recently reported by us [2] and composed of N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer bearing self-quenched Cy5 fluorescent dyes. This probe is enzymatically activated by cathepsins, to generate a fluorescent signal. This novel Turn-ON probe was synthesized and characterized in vitro, for its hydrodynamic diameter, quenching, de-quenching, stability, and toxicity properties. Furthermore, in vivo pharmacokinetics and tumor-to-background signal were evaluated in mice bearing orthotopic 4T1 mammary adenocarcinoma tumors. A similar cohort of 4T1 tumor-bearing mice was exploited to evaluate the probe’s utility in image-guided surgery (IGS).
The signal obtained from the tumors during the IGS was stable and delineated the tumor boundaries during the whole surgical procedure, enabling an accurate resection. The control groups that underwent standard surgery under white light only, or under the fluorescence guidance of commercially available ProSense® 680 or 5-Aminolevulinic acid (5-ALA), survived less time and suffered from tumor recurrence earlier than the group that underwent IGS using our Turn-ON probes[3].
This “smart” polymeric Turn-ON probe can potentially assist surgeons to decide in real time during surgery regarding the tumor margins needed to be removed, leading to improved patient outcome.
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