Prevalence of PD-L1 in Cervical Cancer Patients and the Potential for Combining an Immune Checkpoint Inhibitor With Lenvatinib

BACKGROUND/AIM: Cervical cancer is the fourth most common cause of cancer-related deaths in women worldwide. The potential for targeted therapy against the immune checkpoint programmed death 1 (PD-1)/programmed death-ligand 1 (PD-L1) and receptor tyrosine kinases was examined in cervical cancer patients and cell lines.

MATERIALS AND METHODS: On tissue microarrays, PD-L1 was analyzed in 123 samples of patients with cervical cancer using immunohistochemistry. In SiHa, HeLa, and CaSki cervical cancer cell lines we examined the combination of lenvatinib with a PD-1/PD-L1 inhibitor using cell viability assays, the activation of cell signaling pathway proteins using western blots and gene expression using quantitative reverse transcriptase-PCR.

RESULTS: Of 113 evaluable samples, 90 (79.6%) had more than 1% PD-L1 positive cells. The single treatment with the PD-1/PD-L1 inhibitor resulted in the greatest reduction in growth for CaSki and lenvatinib in HeLa cells. In contrast, the combined treatment of lenvatinib with the PD-1/PD-L1 inhibitor demonstrated a significantly stronger impeded proliferation compared to the single treatment in all three cell lines. Moreover, the combined treatment caused significantly less phosphorylation of the signaling molecules ERK and S6 in SiHa and of S6 and STAT3 in HeLa cells but not in CaSki. All treatments diminished the mRNA levels of PD-L1, Il-8, and FGFR in SiHa cells.

CONCLUSION: PD1 is frequently expressed in cervical cancer samples. Combining lenvatinib with a PD-1/PD-L1 inhibitor diminished proliferation of cervical cancer cell lines. Consequently, this combination might be a promising option to treat cervical cancer. Signaling pathways involved in tumor cell growth are blocked by the combined treatment but still a model of the underlying mechanism cannot be drawn.