肿瘤细胞外核苷酸酶 CD73 靶向诊疗放射性示踪剂的设计、合成及临床前评价

High levels of adenosine are often associated with immunosuppression in malignant tumors, acting through adenosine receptors to inhibit the functions of T cells and NK cells.

The ectonucleotidase CD73, as a key enzyme that catalyzes adenosine monophosphate to adenosine, plays an important role in the tumor immune microenvironment and promotes resistance to immune checkpoint blockade, and thus was regarded as an important biomarker for tumor prognosis. The inhibition of overexpressed CD73 was also believed as a promising strategy to restore tumor immune function in anti-tumor therapies.

However, the in vivo evaluation of CD73 expression in patients is still challenging. In this investigation, a series of novel non-nucleotide small-molecule targeting CD73 was developed, and the most potent compounds (HX-6 and HX-8) were radiolabeled with 68 Ga for in vivo PET imaging of CD73 expression. The highest tumor uptake of [ 68 Ga]Ga-HX-6 and [ 68 Ga]Ga-HX-8 in CD73-positive LS174T xenograft mice was 6.

98 ± 0. 74 %ID/g and 6. 31 ± 0. 99 %ID/g, respectively, both significantly higher than that observed in the blocked and CD73-negative tumors. Considering its relatively lower IC 50 value, HX-6 was selected for labeling with 177 Lu to conduct a preliminary radio-ligand anti-tumor therapy. 37 MBq of [ 177 Lu]Lu-HX-6 for 4 cycles displayed favorable anti-tumor efficacy when used alone or combined with anti-PD-1 agent.

Thus, [ 68 Ga]Ga-HX-6 and [ 177 Lu]Lu-HX-6 may be used as a theranostic pair for non-invasive CD73 imaging and anti-tumor therapies.