Ovarian clear cell carcinoma (CCC) is one of the most malignant types of ovarian carcinomas, particularly at advanced stages. Unlike the more common type of ovarian cancer, high-grade serous carcinoma, ovarian CCC is often resistant to platinum-based chemotherapy, and therefore an effective treatment for this tumor type at advanced stages is urgently needed. In this study, we analyzed 97 ovarian CCCs for sequence mutations in KRAS, BRAF, PIK3CA, TP53, PTEN, and CTNNB1 as these mutations frequently occur in other major types of ovarian carcinomas. The samples included 18 CCCs for which affinity-purified tumor cells from fresh specimens were available, 69 microdissected tumors from paraffin tissues, and 10 tumor cell lines. Sequence mutations of PIK3CA, TP53, KRAS, PTEN, CTNNB1, and BRAF occurred in 33%, 15%, 7%, 5%, 3%, and 1% of CCC cases, respectively. Sequence analysis of PIK3CA in 28 affinity-purified CCCs and CCC cell lines showed a mutation frequency of 46%. Samples with PIK3CA mutations showed intense phosphorylated AKT immunoreactivity. These findings demonstrate that ovarian CCCs have a high frequency of activating PIK3CA mutations. We therefore suggest that the use of PIK3CA-targeting drugs may offer a more effective therapeutic approach compared with current chemotherapeutic agents for patients with advanced-stage and recurrent CCC.

One of the major immune checkpoints responsible for immune evasion in cancer cells is the interaction between programmed cell death-1 (PD-1) and its ligand (PD-L1). Since human trophoblastic cells display many of the features of malignant cells such as the ability to invade normal tissue including blood vessels and are apparently not eradicated by the host immune system, we undertook the present study to determine whether PD-L1 was upregulated in different types of trophoblastic cells during normal pregnancy and in gestational trophoblastic diseases. Immunohistochemistry using an anti-PD-L1 specific antibody demonstrated that in early and term normal placentas, PD-L1 was highly expressed in syncytiotrophoblast and to a much lower extent in intermediate trophoblastic cells located in the chorion laeve and implantation site. PD-L1 immunoreactivity was undetectable in cytotrophoblastic cells. This staining pattern in normal placenta was recapitulated in various types of gestational trophoblastic disease. PD-L1 was highly expressed by syncytiotrophoblast in complete moles and choriocarcinomas. The intermediate trophoblastic neoplasms, placental site trophoblastic tumors and epithelioid trophoblastic tumors, showed variable PD-L1 immunoreactivity but at a lower intensity than in the neoplastic syncytiotrophoblast in choriocarcinoma. In addition, we observed PD-1 positive lymphocytes located within the implantation site and in trophoblastic tumors. In summary, this study describes a novel mechanism for trophoblastic cells to create a tolerogenic feto-maternal interface by upregulating PD-L1 in syncytiotrophoblast and in intermediate trophoblast. Trophoblastic tumors may also use PD-L1 expression to evade the host immune response thereby promoting their survival.

BACKGROUND The clinical course of patients with uterine leiomyosarcoma (LMS) is difficult to predict with the currently available categorical staging systems of the American Joint Committee on Cancer (AJCC) and the International Federation of Gynecology and Obstetrics (FIGO). The objective of the current study was to develop and validate a novel, clinically relevant, individualized prognostic model for patients with uterine LMS. METHODS Patients with uterine LMS who presented at the authors’ institution from 1982 to 2008 were analyzed. The nomogram model was chosen based on the clinical evidence and statistical significance of the predictors, including age at diagnosis, tumor size, histologic grade, uterine cervix involvement, extrauterine spread, distant metastases, and mitotic index. Five-year overall survival (OS) was the predicted endpoint. The concordance probability (CP) was used as a predictive accuracy measure and compared with the CP of current staging systems. The model was internally validated using 200 bootstrap samples to correct for over fitting. RESULTS One hundred eighty-five of 270 patients were eligible for the nomogram analysis. The median follow-up was 5.4 years, and the median OS was 3.75 years (95% confidence interval, 3-6 years). The CP of the newly developed nomogram was 0.67 (95% confidence interval, 0.63-0.72). This was superior to predictions based on AJCC and FIGO staging. The bootstrap-validated CP was 0.65 with good calibration accuracy. CONCLUSIONS The authors developed and internally validated a uterine LMS-specific nomogram to predict 5-year OS. This novel, individualized prognostic model outperforms traditionally used categorical staging systems and may be useful for patient counseling and for better selection of patients for adjuvant therapy trials.

The assessment of an accurate mitotic index (MI) is one of the major parameters in the proper classification of uterine smooth muscle tumors. This assessment can be hampered by the presence of increased number of apoptotic bodies or piknotic nuclei, which frequently mimic mitoses. Phospho-histone H3 (PHH3) is a recently described immunomarker specific for cells undergoing mitoses. In this study, we evaluated the MI of 2 subsets of uterine smooth muscle tumors--6 leiomyosarcomas (LMS) and 6 smooth muscle tumors of undetermined malignant potential (STUMP)--using PHH3-labeled sections and hematoxylin and eosin (H&E)-stained slides. In the STUMP group, the MI on H&E ranged from 0 to 9 mitoses/10 high-power fields (HPFs) (mean, 3.2), and in the LMS group, it ranged from 0 to 37 mitoses/10 HPFs (mean, 19). PHH3 showed 0 to 16 mitoses/10 HPFs (mean, 3.8) in the STUMP group and 0 to 61 mitoses/10 HPFs (mean, 26) in the LMS group. In 7 cases, the MI difference (MID) between H&E-stained and PHH3-stained slides varied from 0 to 3 mitoses (mean, 1.6). In only one LMS, the PHH3 MI was lower than on H&E-stained slides (MID 7). The MI on H&E-stained and PHH3-stained slides were comparable in 7 cases, 5 of which were STUMPs. In 4 other cases, 3 of which were LMS, the PHH3 MI was significantly higher than the one obtained on H&E. The higher MI obtained with PHH3-labeled sections in some cases is most likely due to the recognition of true mitoses by the antibody, which were initially misinterpreted as apoptotic bodies and/or piknotic nuclei on H&E and not included in the formal count, and the fact that the phosphorilation of histone H3 starts just before the prophase and at this stage mitoses cannot be identified by H&E.