PD-L1 expression in anaplastic thyroid carcinoma treated with lenvatinib

Abstract

Abstract Purpose This study aimed to estimate the proportion of patients with anaplastic thyroid carcinoma (ATC) at our institution who are likely to have the efficacy of immune checkpoint inhibitor (ICI) treatment by investigating programmed cell death ligand 1 (PD-L1) expression. Additionally, we investigated the association between PD-L1 expression and treatment outcomes of lenvatinib in patients with ATC. Methods The 19 lenvatinib-treated patients with ATC whose tissue samples available for immunohistochemistry were included in this study. The tumor proportion score (TPS) ≥1%was determined as positive for PD-L1 expression Results Of the 19 patients, 5 (26%) and 14 (74%) had a partial response to lenvatinib treatment and PD-L1 expression positivity, respectively. The median TPS was 30% in patients with positive PD-L1 expression. The median OS for all 19 patients was 4.8 (95% confidence interval [CI], 2.8–6.6) months with a 6-month OS rate of 36.8%. Furthermore, the median OS for patients with positive or negative PD-L1 expression was 5.3 (95% CI, 1.6–7.8) and 4.2 (95% CI, 1.1–not available) months, respectively (p = 0.277). Conclusion No correlation was observed between the PD-L1 expression in the ATC tissue samples and efficacy of lenvatinib. Furthermore, in our study, 14 (74%) of 19 patients with ATC had PD-L1 expression positivity. Although lenvatinib monotherapy may have limited efficacy, some patients with ATC have the possibility that the addition of ICI on lenvatinib is effective.