Abstract
Human trophoblast cell-surface marker (Trop-2) is a surface glycoprotein originally identified in human placental tissue and subsequently found to be highly expressed by various types of human epithelial solid tumors. We investigated the efficacy of sacituzumab govitecan, an antibody-drug conjugate (ADC) comprised of a humanized anti- Trop-2 antibody, conjugated with active metabolite of irinotecan (SN-38), on Trop-2 positive cervical cancer cell lines and a xenograft model. Trop-2 expression was evaluated in 147 primary cervical tumors by immunohistochemistry, real-time polymerase chain reaction, and flow cytometry. For in vitro experiments, two Trop-2 positive (CVX-8, ADX-3), and one Trop-2 negative (ADX-2) cell lines were used. A cell line with a strong Trop-2 expression (CVX-8) was used to test in vivo antitumor activity in xenografts models. Out of 147 primary cervical cancers, 113 were squamous cell carcinomas (SCCs), and 34 were adenocarcinoma/adenosquamous carcinomas. Moderate to strong diffuse staining was seen in 95% (108/113) of SCCs, and 81% (29/34) of adenocarcinoma/adenosquamous cancers on immunohistochemistry. Trop-2 positive cell lines were highly sensitive to sacituzumab govitecan in vitro, with IC50 values in the range of 0.18 to 0.26 nM (p = 0.02, and p = 0.04 for CVX-8, and ADX-3, respectively). In xenografts, a significant tumor growth inhibition was seen after twice-weekly intravenous administration of the drug for three weeks (p < 0.0001, and p = 0.001 for sacituzumab govitecan vs naked antibody, and sacituzumab govitecan vs control-ADC, respectively). Overall survival at 90 days was significantly improved in the sacituzumab govitecan group (p = 0.014). In conclusion, sacituzumab govitecan may represent a novel targeted therapy option in cervical cancer patients overexpressing Trop-2.