Irregular
hepatectomy plays a prominent role in the treatment of
small hepatocellular carcinoma (HCC) patients with severe cirrhosis
and localized liver metastasis. In clinical practices, intraoperative
tumor boundaries delineation facilitates to accomplish tumor resection
with negative margin, remarkably decreasing the recurrence rates.
Currently, ultrasound (US) and ICG fluorescence-guided surgery has
been used for intraoperative navigation in irregular hepatectomy,
but insufficient specificity results in a limited prevalence. Inspired
by the high resolution of photoacoustic (PA) imaging and established
clinical efficacy of 18F-Alfatide that is specific for
integrin αvβ3-overexpressed tumors,
we herein developed a fluorescent analogue IR820-E[c(RGDfK)]2, and a proof-of-concept intraoperative multispectral PA imaging
navigation for precise irregular hepatectomy using hand-held PA/US
imaging system. An integrin αvβ3-targeted fluorescent contrast agent IR820-E[c(RGDfK)]2 was designed, synthesized, and characterized. In vitro studies were
performed to determine optical and PA properties, affinity and specificity
and biocompatibility. Multispectral PA imaging, the optimal imaging
time point and contrast, multispectral PA imaging-guided irregular
hepatectomy, pharmacokinetics, and safety profile were evaluated in
subcutaneous and orthotopic HCC tumor models. Ex vivo macroscopic
three-dimensions (3D) PA imaging with IR820-E[c(RGDfK)]2 staining was also performed in surgical biospecimens from patients
with HCC. IR820-E[c(RGDfK)]2 has a simple synthetic method
at gram scale, high affinity, and specificity for integrin αvβ3, excellent pharmacokinetic and safety
profile can effectively differentiate tumor from normal liver tissues
in animal models and surgical biospecimens from HCC patients. Preoperative
tumor localization, intraoperative tumor boundaries delineation, and
tumor excision, and postoperative negative margin assessment were
successfully achieved during irregular hepatectomy. This initial attempt
allows one to preoperatively detect tumor lesions, intraoperatively
delineate tumor boundaries and guide tumor resection, and postoperatively
evaluate tumor margin status during irregular hepatectomy. IR820-E[c(RGDfK)]2 has the potential to be an investigational new drug for clinical
use in multispectral photoacoustic imaging-guided irregular hepatectomy.