Evaluation A Novel Radiotracer Targeting Interleukin-6 Receptor Of ^99mTc-HYNIC-Aca-LSLITRL In Ovarian Cancer

Objective: To evaluate a novel radiotracer ^99mTc-HYNIC-Aca-LSLITRL in ovarian cancer with targeting IL-6R. Methods: Western blot analysis and immunofluorescence staining were performed to identify IL-6R expression in ovarian cancer cell lines C13 K and SKOV3.ip. RP-HPLC and TLC were performed to test the polarity of this radiotracer and the stability of this radiopharmaceutical in PBS and serum in vivo and in vitro. The competition binding trails in vivo and in vitro proved the specific binding characters of the novel radiotracer with its receptor. SPECT test and biodistribution analysis with C13 K and SKOV3.ip xenografts animal model demonstrated the imaging and distribution characteristics of radiopharmaceuticals in vivo. The expression of IL-6R in the tumor of these two animal models were also tested by immunohistochemistry technology.Results: The expression of IL-6R was shown to be higher in C13 K cell line than that in SKOV3.ip cell line. The stability of ^99mTc-HYNIC-Aca-LSLITRL in vitro was demonstrated by the purity of radiopharmaceuticals, which was still >90% after incubation in PBS and serum for 6h, and still>95% after 20 min in vivo. SPECT studies and biodistribution analysis demonstrated higher tumor uptake in C13 K cell line than in SKOV3.ip cell line, with P value of statistically significance（p<0.01）. ^99mTc-HYNIC-Aca-LSLITRL was eliminated dominative through urinary system. The staining of IL-6 receptor in C13 K and SKOV3.ip were correlated with the SPECT imaging. Conclusions: ^99mTc-HYNIC-Aca-LSLITRL was a promising probe of SPECT in tumor imaging, monitoring therapy, as it could specifically bind with IL-6R, had a good stability in vivo and in vitro, beyond that it showed excellent tumor uptake and tumor/normal organs uptake.