Erratum to "Evaluation of clear cell subtypes of ovarian and uterine malignancies with anti-PD-L1 and anti-PD1 immunohistochemical expression and their association with stage and survival" [Gynecol. Oncol. 155 (2019) 483-488].

This was a retrospective study of paraffin-embedded pure ovarian or uterine CCCs from 1992 to 2017. We assessed stage, endometriosis, and survival time. Immunohistochemical (IHC) staining for PD-1 associated TILs, PD-L1 percentage positivity, and PD-L1 Combined Positive Score (CPS) were performed.

Of the 46 eligible patients, 35 were pure ovarian CCCs and 11 pure uterine CCCs. Most (29/46, 63.0%) were FIGO Stage I or II. We found 34.3% of ovarian tumors and 60% of the uterine tumors were PD-L1 CPS ≥1. PD-1 positive lymphocyteswere present in 39.4% of ovarian tumors and 80% of the uterine tumors. When correlated to stage, ovarian cancer PD-L1 CPS was ≥1 in 28.6% stage I/II, 66.7% stage III, and 0% stage IV cancers (p = 0.03) and PD-1 positive lymphocytes were found in 33.3% stage I/II, 66.7% stage III and 20% stage IV cancers (p=0.227). Within the uterine cohort, there were no significant differences in expression between stages. Multivariate analysis revealed no other significant correlations. There were no differences in overall survival for PD-L1 CPS positive versus negative cohorts among the ovarian cancer population (p= 0.79).

Clear cell carcinomas (CCCs) of the ovary and uterus are rare and associated with poor prognosis. Information regarding expression of PD-1 positive tumor infiltrating lymphocytes or PD-L1 within gynecologic clear cell malignancies is limited and their role as a biomarker has not been explored.

While limited by sample size, these findings suggest that more advanced ovarian cancer is less likely to express PD-L1 CPS, and that uterine cancers are more likely to have PD-1 positive lymphocytes than ovarian cancers. This biomarker information may better inform exploration of immune checkpoint therapy targeting. The publisher would like to apologise for any inconvenience caused.