Case of metastatic clear cell odontogenic carcinoma with response to chemoimmunotherapy.

Our patient initially presented with 6 months of left jaw pain and gingival bleeding, leading to the discovery of a radiolucent left maxillary mass on dental evaluation. A biopsy confirmed clear cell odontogenic carcinoma, and the patient was treated with definitive surgery and radiation for localised disease. Unfortunately, the patient was found to have pulmonary metastases 3 months after initial management and was subsequently treated with a combination of cytotoxic chemotherapy and immunotherapy with a partial response. To our knowledge, this is the first case demonstrating the successful use of chemoimmunotherapy in metastatic clear cell odontogenic carcinoma.

Targeting PDGF signaling of cancer-associated fibroblasts blocks feedback activation of HIF-1α and tumor progression of clear cell ovarian cancer.

Ovarian clear cell carcinoma (OCCC) is a gynecological cancer with a dismal prognosis; however, the mechanism underlying OCCC chemoresistance is not well understood. To explore the intracellular networks associated with the chemoresistance, we analyze surgical specimens by performing integrative analyses that combine single-cell analyses and spatial transcriptomics. We find that a chemoresistant OCCC subpopulation with elevated HIF activity localizes mainly in areas populated by cancer-associated fibroblasts (CAFs) with a myofibroblastic phenotype, which is corroborated by quantitative immunostaining. CAF-enhanced chemoresistance and HIF-1α induction are recapitulated in co-culture assays, which show that cancer-derived platelet-derived growth factor (PDGF) contributes to the chemoresistance and HIF-1α induction via PDGF receptor signaling in CAFs. Ripretinib is identified as an effective receptor tyrosine kinase inhibitor against CAF survival. In the co-culture system and xenograft tumors, ripretinib prevents CAF survival and suppresses OCCC proliferation in the presence of carboplatin, indicating that combination of conventional chemotherapy and CAF-targeted agents is effective against OCCC.

SLFN11 is a BRCA Independent Biomarker for the Response to Platinum-Based Chemotherapy in High-Grade Serous Ovarian Cancer and Clear Cell Ovarian Carcinoma.

BRCA1/2 mutations are robust biomarkers for platinum-based chemotherapy in epithelial ovarian cancers. However, BRCA1/2 mutations in clear cell ovarian carcinoma (CCC) are less frequent compared with high-grade serous ovarian cancer (HGSC). The discovery of biomarkers that can be applied to CCC is an unmet need in chemotherapy. Schlafen 11 (SLFN11) has attracted attention as a novel sensitizer for DNA-damaging agents including platinum. In this study, we investigated the utility of SLFN11 in HGSC and CCC for platinum-based chemotherapy. SLFN11 expression was analyzed retrospectively by IHC across 326 ovarian cancer samples. The clinicopathologic significance of SLFN11 expression was analyzed across 57 advanced HGSC as a discovery set, 96 advanced HGSC as a validation set, and 57 advanced CCC cases, all of whom received platinum-based chemotherapy. BRCA1/2 mutation was analyzed using targeted-gene sequencing. In the HGSC cohort, the SLFN11-positive and BRCA mutation group showed significantly longer whereas the SLFN11-negative and BRCA wild-type group showed significantly shorter progression-free survival and overall survival. Moreover, SLFN11-positive HGSC shrunk significantly better than SLFN11-negative HGSC after neoadjuvant chemotherapy. Comparable results were obtained with CCC but without consideration of BRCA1/2 mutation due to a small population. Multivariate analysis identified SLFN11 as an independent factor for better survival in HGSC and CCC. The SLFN11-dependent sensitivity to platinum and PARP inhibitors were validated with genetically modified non-HGSC ovarian cancer cell lines. Our study reveals that SLFN11 predicts platinum sensitivity in HGSC and CCC independently of BRCA1/2 mutation status, indicating that SLFN11 assessment can guide treatment selection in HGSC and CCC.

Successful treatment of hidradenocarcinoma using ALA-PDT combined with local narrow margin excision.

Hidradenocarcinoma is a rare malignancy of sweat gland differentiation. It is known for its high rate of recurrence and metastasis, which has a serious impact on human health and aesthetics. However, the treatment options for this disease are limited, making prompt and appropriate treatment is a daunting challenge. In this report, we present the first successful cure of hidradenocarcinoma using 5-aminolevulinic acid photodynamic therapy (ALA-PDT) combined with local narrow margin excision on the left side of the forehead in an elderly woman. No recurrence during one year of follow-up after the combined therapy. This case will provide a valuable reference for more efficient management of similar cases in clinic.

A phase 2 study of dasatinib in recurrent clear cell carcinoma of the ovary, fallopian tube, peritoneum or endometrium: NRG oncology/gynecologic oncology group study 0283.

OBJECTIVE: Gynecologic cancers are traditionally managed according to their presumed site of origin, without regard to the underlying histologic subtype. Clear cell histology is associated with chemotherapy refractoriness and poor survival. Mutations in SWI/SNF chromatin remodeling complex member ARID1A, which encodes for BAF250a protein, are common in clear cell and endometriosis-associated endometrioid carcinomas. High-throughput cell-based drug screening predicted activity of dasatinib, a tyrosine kinase inhibitor, in ARID1A-mutant clear cell carcinoma. METHODS: We conducted a phase 2 clinical trial of dasatinib 140 mg once daily by mouth in patients with recurrent or persistent ovarian and endometrial clear cell carcinoma. Patients with measurable disease were enrolled and then assigned to biomarker-defined populations based on BAF250a immunohistochemistry. The translational endpoints included broad next-generation sequencing to assess concordance of protein expression and treatment outcomes. RESULTS: Twenty-eight patients, 15 of whom had tumors with retained BAF250a and 13 with loss of BAF250a were evaluable for treatment response and safety. The most common grade 3 adverse events were anemia, fatigue, dyspnea, hyponatremia, pleural effusion, and vomiting. One patient had a partial response, eight (28%) had stable disease, and 15 (53.6%) had disease progression. Twenty-three patients had next-generation sequencing results; 13 had a pathogenic ARID1A alteration. PIK3CA mutations were more prevalent in ARID1A-mutant tumors, while TP53 mutations were more prevalent in ARID1A wild-type tumors. CONCLUSIONS: Dasatinib was not an effective single-agent treatment for recurrent or persistent ovarian and endometrial clear cell carcinoma. Studies are urgently needed for this rare gynecologic subtype.

Impact of the number of cycles of platinum-based chemotherapy for early stage ovarian clear cell carcinoma on survival: a retrospective study.

BACKGROUND: Ovarian clear cell carcinoma (OCCC) is a unique subtype of ovarian epithelial ovarian cancer. The number of chemotherapy cycles for early-stage patients is still debated. This study aimed to evaluate whether at least 4 cycles of adjuvant platinum-based chemotherapy have better prognostic value than 1-3 cycles in early-stage OCCC. METHODS: We retrospectively retrieved data from 102 patients with stage I-IIA OCCC between 2008 and 2017. All patients underwent complete surgical staging followed by adjuvant platinum-based chemotherapy. Kaplan-Meier curves and Multivariate Cox analysis were performed to estimate 5-year overall survival (OS) and progression-free (PFS) according to the number of chemotherapy cycles. RESULTS: Among stage I-IIA disease, twenty (19.6%) patients received 1-3 cycles, and eighty-two (80.4%) patients received at least 4 cycles of adjuvant chemotherapy. Univariate analysis revealed that the patients in 1-3cycles group had not significantly improved 5-year OS and PFS than those in the ≥ 4 cycles group (5-year OS: hazard ratio [HR] 1.21; 95% confidence interval [CI] 0.25- 5.78, p = 0.1), and 5-year PFS: HR 0.79; 95% CI 0.26- 2.34, p = 0.1). In the multivariate analysis, there was no impact of 1-3 versus ≥ 4 cycles of chemotherapy on 5-year OS (HR 1.21, 95% CI 0.25-3.89, p = 0.8) or 5-year PFS (HR 0.94, 95% CI 0.32-2.71, p = 0.9). The potential independent risk factors associated with 5-year OS and PFS included the surgery approach and FIGO stage. CONCLUSION: The number of cycles of platinum-based chemotherapy could not be associated with a survival benefit for patients with early-stage OCCC.

Selective Inhibition of L-type Amino Acid Transporter 1 Suppresses Cell Proliferation in Ovarian Clear Cell Carcinoma.

BACKGROUND/AIM: Ovarian clear cell carcinoma (OCCC) is a histological type of ovarian cancer that is refractory to chemotherapy and has poor prognosis, which necessitates the development of novel treatment therapies. In this study, we focused on L-type amino acid transporter 1 (LAT1), which is involved in cancer growth, and investigated the effect of its selective inhibition on cell proliferation in OCCC. MATERIALS AND METHODS: The inhibitory effect of nanvuranlat (JPH203), a LAT1 selective inhibitor, on the cellular uptake of [3H] leucine was evaluated using the OCCC cell line JHOC9, which expresses the LAT1 protein. In addition, the kinetics of cell proliferation and changes in phosphorylation of the mTOR pathway were analyzed. The correlation between LAT1 expression and progression-free survival (PFS) was evaluated using clinical specimens of OCCC. RESULTS: Nanvuranlat inhibited [3H] leucine intracellular uptake and cell proliferation in a dose-dependent manner in JHOC9 cells. In addition, it suppressed the activity of the mTOR signaling pathway, which is thought to inhibit cancer cell proliferation. LAT1 expression was most frequent in OCCC among clinical specimens of epithelial ovarian cancer. A correlation between LAT1 expression and PFS was observed in OCCC. CONCLUSION: LAT1 selective inhibition suppresses cell proliferation via the mTOR pathway by inhibiting leucine uptake in OCCC. This study illustrates the potential of using LAT1 selective inhibition as a treatment strategy for OCCC.

Treatment for ovarian clear cell carcinoma with combined inhibition of WEE1 and ATR.

BACKGROUND: Standard platinum-based therapy for ovarian cancer is inefficient against ovarian clear cell carcinoma (OCCC). OCCC is a distinct subtype of epithelial ovarian cancer. OCCC constitutes 25% of ovarian cancers in East Asia (Japan, Korea, China, Singapore) and 6-10% in Europe and North America. The cancer is characterized by frequent inactivation of ARID1A and 10% of cases of endometriosis progression to OCCC. The aim of this study was to identify drugs that are either FDA-approved or in clinical trials for the treatment of OCCC. RESULTS: High throughput screening of 166 compounds that are either FDA-approved, in clinical trials or are in pre-clinical studies identified several cytotoxic compounds against OCCC. ARID1A knockdown cells were more sensitive to inhibitors of either mTOR (PP242), dual mTOR/PI3K (GDC0941), ATR (AZD6738) or MDM2 (RG7388) compared to control cells. Also, compounds targeting BH3 domain (AZD4320) and SRC (AZD0530) displayed preferential cytotoxicity against ARID1A mutant cell lines. In addition, WEE1 inhibitor (AZD1775) showed broad cytotoxicity toward OCCC cell lines, irrespective of ARID1A status. CONCLUSIONS: In a selection of 166 compounds we showed that inhibitors of ATR and WEE1 were cytotoxic against a panel of OCCC cell lines. These two drugs are already in other clinical trials, making them ideal candidates for treatment of OCCC.

Patients with stage IA ovarian clear cell carcinoma do not require chemotherapy following surgery.

BACKGROUND: Ovarian clear cell carcinoma (OCCC) is an infrequent histological subtype of epithelial ovarian cancer (EOC). The present study aimed to investigate whether chemotherapy is indispensable for patients with stage IA OCCC. METHODS: Data were collected from the Surveillance, Epidemiology and End Results database between 2004 and 2015. All subjects were diagnosed with stage IA OCCC, according to their postoperative pathological reports. In the present study, 1038 patients were retrospectively investigated, among whom 692 patients received chemotherapy. Propensity score matching (PSM) was performed to prevent selection bias. The multivariate Cox proportional hazards model was used to analyze the correlation between variables and 5-year overall survival. RESULTS: An equal number of patients (n = 346) who did or did not undergo chemotherapy after PSM were further enrolled in the study. The results showed that the mortality of OCCC increased for the patients aged ≥50 years. In addition, older age was associated with lower 5-year overall survival (p < 0.05). However, chemotherapy did not extend the 5-year overall survival (p = 0.524) of patients with stage IA OCCC, according to the multivariate Cox regression analysis. CONCLUSIONS: Chemotherapy did not affect the overall survival of patients with stage IA OCCC following surgery.

MEX3A Mediates p53 Degradation to Suppress Ferroptosis and Facilitate Ovarian Cancer Tumorigenesis.

Epithelial ovarian cancer is a highly heterogeneous and malignant female cancer with an overall low survival rate. Mutations in p53 are prevalent in the major ovarian cancer histotype, high-grade serous ovarian carcinoma (HGSOC), while p53 mutations are much less frequent in other ovarian cancer subtypes, particularly in ovarian clear cell carcinoma (OCCC). Advanced stage OCCC with wild-type (WT) p53 has a worse prognosis and increased drug resistance, metastasis, and recurrence than HGSOC. The mechanisms responsible for driving the aggressiveness of WT p53-expressing ovarian cancer remain poorly understood. Here, we found that upregulation of MEX3A, a dual-function protein containing a RING finger domain and an RNA-binding domain, was critical for tumorigenesis in WT p53-expressing ovarian cancer. MEX3A overexpression enhanced the growth and clonogenicity of OCCC cell lines. In contrast, depletion of MEX3A in OCCC cells, as well as ovarian teratocarcinoma cells, reduced cell survival and proliferative ability. MEX3A depletion also inhibited tumor growth and prolonged survival in orthotopic xenograft models. MEX3A depletion did not alter p53 mRNA level but did increase p53 protein stability. MEX3A-mediated p53 protein degradation was crucial to suppress ferroptosis and enhance tumorigenesis. Consistently, p53 knockdown reversed the effects of MEX3A depletion. Together, our observations identified MEX3A as an important oncogenic factor promoting tumorigenesis in ovarian cancer cells expressing WT p53. SIGNIFICANCE: Degradation of p53 mediated by MEX3A drives ovarian cancer growth by circumventing p53 tumor suppressive functions, suggesting targeting MEX3A as a potential strategy for treating of ovarian cancer expressing WT p53.

Clinical analysis and literature review of a case of ovarian clear cell carcinoma with PIK3CA gene mutation: A case report.

RATIONALE: Ovarian clear cell carcinoma (OCCC) is an uncommon malignant form of 5 subtypes of ovarian cancer, accounting for approximately 5% to 25% of all ovarian cancers. OCCC is usually diagnosed at a young age and an early stage. More than 50% of patients are associated with endometriosis. It shows less sensitivity to platinum-based chemotherapies, high recurrence, and poor prognosis, especially late. However, platinum-based chemotherapies remain the first-line treatment. Meanwhile, new treatment modalities have been explored, including immune checkpoint inhibitors and PI3K-AKT-mTOR pathway inhibitors. PATIENT CONCERN: A 48-year-old Chinese woman, Gravida2 Para1, complained of irregular and painful vaginal bleeding for 4 months. DIAGNOSIS: The patient was diagnosed with stage IC ovarian clear cell carcinoma that presented with a mutation of the phosphatidylinositol 4,5-bisphosphate 3-kinase alpha subunit (PIK3CA) gene. INTERVENTION: We performed an early diagnosis and complete surgical resection of the tumor with platinum-based chemotherapy. OUTCOME: This patient with mutation of the PIK3CA gene was sensitive to platinum-based chemotherapy, showed a significant downwards trend in tumor markers, and was in good health within the year of follow-up. LESSONS: This study described an OCCC case that presented with a PIK3CA mutation and was successfully managed with careful and complete resection of the tumor. This patient with mutation of the PIK3CA gene was sensitive to platinum-based chemotherapy, showed a significant downwards trend in tumor markers, and did not have recurrence after a year of follow-up, indicating a reasonably good prognosis. Therefore, surgery plus platinum drug chemotherapy is still the best strategy for OCCC treatment. In addition, it is recommended for such patients to undergo genetic testing as much as possible to predict the clinical treatment effect.

Molecular Subclasses of Clear Cell Ovarian Carcinoma and Their Impact on Disease Behavior and Outcomes.

PURPOSE: To identify molecular subclasses of clear cell ovarian carcinoma (CCOC) and assess their impact on clinical presentation and outcomes. EXPERIMENTAL DESIGN: We profiled 421 primary CCOCs that passed quality control using a targeted deep sequencing panel of 163 putative CCOC driver genes and whole transcriptome sequencing of 211 of these tumors. Molecularly defined subgroups were identified and tested for association with clinical characteristics and overall survival. RESULTS: We detected a putative somatic driver mutation in at least one candidate gene in 95% (401/421) of CCOC tumors including ARID1A (in 49% of tumors), PIK3CA (49%), TERT (20%), and TP53 (16%). Clustering of cancer driver mutations and RNA expression converged upon two distinct subclasses of CCOC. The first was dominated by ARID1A-mutated tumors with enriched expression of canonical CCOC genes and markers of platinum resistance; the second was largely comprised of tumors with TP53 mutations and enriched for the expression of genes involved in extracellular matrix organization and mesenchymal differentiation. Compared with the ARID1A-mutated group, women with TP53-mutated tumors were more likely to have advanced-stage disease, no antecedent history of endometriosis, and poorer survival, driven by their advanced stage at presentation. In women with ARID1A-mutated tumors, there was a trend toward a lower rate of response to first-line platinum-based therapy. CONCLUSIONS: Our study suggests that CCOC consists of two distinct molecular subclasses with distinct clinical presentation and outcomes, with potential relevance to both traditional and experimental therapy responsiveness. See related commentary by Lheureux, p. 4838.

Sintilimab combined with bevacizumab in relapsed/persistent ovarian clear cell carcinoma (INOVA): an investigator-initiated, multicentre clinical trial-a study protocol of clinical trial.

BACKGROUND: Ovarian clear cell carcinoma (OCCC) has an abysmal prognosis with a median overall survival (OS) of 25.3 months because of a low response to chemotherapy. The 5-year disease-specific survival rate after recurrence is 13.2%, with more than two-thirds of the patients dying within a year. Therefore, it is urgent to explore new therapeutic options for OCCC. Based on the characteristic immune-suppressive tumour microenvironment derived from the gene expression profile of OCCC, the combination of immunoantiangiogenesis therapy might have certain efficacy in recurrent/persistent OCCC. This trial aims to evaluate the efficacy and safety of sintilimab and bevacizumab in patients who have failed platinum-containing chemotherapy with recurrent or persistent OCCC. METHOD AND ANALYSIS: In this multicentre, single-arm, open-label, investigator-initiated clinical trial, 38 patients will be assigned to receive sintilimab 200 mg plus bevacizumab 15 mg/kg every 3 weeks. The eligibility criteria include histologically diagnosed patients with recurrent or persistent OCCC who have been previously treated with at least one-line platinum-containing chemotherapy; patients with Eastern Cooperative Oncology Group (ECOG) performance status 0-2 with an expected survival greater than 12 weeks. The exclusion criteria include patients previously treated with immune checkpoint inhibitor and patients with contraindications of bevacizumab and sintilimab. The primary endpoint is the objective response rate. The secondary endpoints are progression-free survival, time to response, duration of response, disease control rate, OS, safety and quality of life. Statistical significance was defined as p<0.05. ETHICS AND DISSEMINATION: This trial was approved by the Research Ethics Commission of Tongji Medical College of Huazhong University of Science and Technology (2020-S337). The protocol of this study is registered at www. CLINICALTRIALS: gov. The trial results will be published in peer-reviewed journals and at conferences. TRIAL REGISTRATION NUMBER: NCT04735861; Clinicaltrials. gov.

OSI-906 restores the sensitivity of ovarian clear cell carcinoma to cisplatin by targeting the IGF1R/AKT pathway.

Among the various histologic subtypes of ovarian cancers (OCs), ovarian clear cell carcinoma (OCCC) represents a great challenge due to its disease aggressiveness and resistance to chemotherapy. IGF1 is overexpressed in epithelial ovarian cancer (EOC), and IGF1 pathway activation is related to the chemoresistance of various cancers. In this study, we found that the expression level of IGF1 was higher in OCCC than in the most common type of OC, high-grade serous adenocarcinoma (HGSC). Then, we investigated the role of IGF1 pathway activation in the progression of OCCC, observing that activation of the IGF1 pathway using IGF1 promoted the proliferation and migration of ES2 cells, while inactivation of the IGF1 pathway using the selective IGF1R inhibitor OSI-906 reversed the alteration mediated by IGF1. Based on the role of the IGF1 pathway in cancer chemoresistance, we proposed that OSI-906 may restore the sensitivity of OCCC to cisplatin. We first validated that IGF1 increased the IC50 value of cisplatin in ES2 cells, while OSI-906 decreased it. Then we confirmed that IGF1 decreased the apoptosis rate of ES2 cells induced by cisplatin, while OSI-906 increased it. Finally, we conducted animal experiments to investigate whether OSI-906 helps cisplatin control the growth of OCCC. As expected, OSI-906 increased the effect of cisplatin in attenuating the growth of OCCC in vivo. Therefore, we conclude that using OSI-906 may be an effective method to restore the sensitivity of OCCC to cisplatin by targeting the IGF1R/AKT pathway.

Pembrolizumab as adjuvant therapy in a patient with Lynch syndrome with synchronous mixed clear cell carcinoma of ovarian origin and endometroid endometrial carcinoma.

A 48-year-old woman was diagnosed with synchronous mixed clear cell carcinoma of ovarian origin and endometroid endometrial carcinoma after presenting with intermenstrual bleeding for 2 years prior. Shortly after diagnosis she became progressively unwell requiring intensive care unit admission with respiratory failure, pleural effusions and pulmonary emboli. Following a total abdominal hysterectomy, bilateral salpingo-oophorectomy, laparotomy and emergency percutaneous thrombectomy, she remained critically unwell and was deemed not safe for chemotherapy. Given a high index of suspicion for Lynch syndrome, the patient was treated with adjuvant pembrolizumab and achieved a complete response. Lynch syndrome was subsequently confirmed through germline genetic testing. The patient made an excellent recovery and remains disease-free at 23 months.

Association between Molecular Genetic Markers of DNA Repair and Cell Cycle Control Genes and Response to Platinum-Based Chemotherapy in Ovarian Cancer Patients.

We analyzed associations of polymorphic markers of DNA repair genes (XRCC1, ERCC2), cell cycle control genes (TP53, MDM2, and CDKN1A), methylation of promoter region, and mutation 5382insC of BRCA1 gene in ovarian cancer with effectiveness of platinumbased chemotherapy assessed by the median of progression-free survival time for markers of DNA repair genes and by relapse risk for all studied markers. An increase in the median of progression-free survival time for carriers of the Gln allele (р=0.025) and Gln/Gln genotype (р=0.022) of the Gln399Arg XRCC1 was observed during the 19-months period after chemotherapy. In carriers of C/C genotype of 5382insC mutation of BRCA1 gene (n=6), no relapses were observed (р=0.035), while 17 of 49 patients without this mutation developed relapses. Of 14 patients with BRCA1 gene function inactivation due to promoter methylation or the presence of the C/C genotype of 5382insC, one relapse was observed (p=0.033). Multivariate analysis revealed an association of markers of the XRCC1, TP53, MDM2 genes, BRCA1 gene inactivation, and type of surgery with the risk of relapse during the follow-up period up to 19 months after the end of chemotherapy (р≤0.0007).

Targeting the IRE1α/XBP1 Endoplasmic Reticulum Stress Response Pathway in ARID1A-Mutant Ovarian Cancers.

The SWI/SNF chromatin-remodeling complex is frequently altered in human cancers. For example, the SWI/SNF component ARID1A is mutated in more than 50% of ovarian clear cell carcinomas (OCCC), for which effective treatments are lacking. Here, we report that ARID1A transcriptionally represses the IRE1α-XBP1 axis of the endoplasmic reticulum (ER) stress response, which confers sensitivity to inhibition of the IRE1α-XBP1 pathway in ARID1A-mutant OCCC. ARID1A mutational status correlated with response to inhibition of the IRE1α-XBP1 pathway. In a conditional Arid1aflox/flox/Pik3caH1047R genetic mouse model, Xbp1 knockout significantly improved survival of mice bearing OCCCs. Furthermore, the IRE1α inhibitor B-I09 suppressed the growth of ARID1A-inactivated OCCCs in vivo in orthotopic xenograft, patient-derived xenograft, and the genetic mouse models. Finally, B-I09 synergized with inhibition of HDAC6, a known regulator of the ER stress response, in suppressing the growth of ARID1A-inactivated OCCCs. These studies define the IRE1α-XBP1 axis of the ER stress response as a targetable vulnerability for ARID1A-mutant OCCCs, revealing a promising therapeutic approach for treating ARID1A-mutant ovarian cancers. SIGNIFICANCE: These findings indicate that pharmacological inhibition of the IRE1α-XBP1 pathway alone or in combination with HDAC6 inhibition represents an urgently needed therapeutic strategy for ARID1A-mutant ovarian cancers.

Preclinical Activity of Plitidepsin Against Clear Cell Carcinoma of the Ovary.

BACKGROUND/AIM: To evaluate the antitumor effects of Plitidepsin against clear cell carcinoma (CCC) of the ovary. MATERIALS AND METHODS: The expression of eEF1A2 in ovarian cancer was assessed by immunohistochemistry. Using ovarian CCC cell lines, the antitumor effect of Plitidepsin was assessed both in vitro and in vivo. By over-expressing or knocking down the eEF1A2 expression, we investigated the role of eEF1A2 in the sensitivity of CCC cells to Plitidepsin. RESULTS: Immunoreactivity to eEF1A2 was observed in 76.2% of CCC, which was significantly higher than other histological subtypes of ovarian cancer. Plitidepsin exhibited significant antitumor activity toward chemonaive and chemoresistant CCC cells both in vitro and in vivo. Ectopic expression of eEF1A2 in CCC cells resulted in increased sensitivity to Plitidepsin. In contrast, eEF1A2 knockdown decreased sensitivity of CCC cells to plitidepsin. CONCLUSION: Plitidepsin, a novel anti-cancer agent that targets eEF1A2, may be a promising agent for treating ovarian CCC.

PDK2 leads to cisplatin resistance through suppression of mitochondrial function in ovarian clear cell carcinoma.

Ovarian clear cell carcinoma (CCC) exhibits an association with endometriosis, resistance to oxidative stress, and poor prognosis owing to its resistance to conventional platinum-based chemotherapy. A greater understanding of the molecular characteristics and pathogenesis of ovarian cancer subtypes may facilitate the development of targeted therapeutic strategies, although the mechanism of drug resistance in ovarian CCC has yet to be determined. In this study, we assessed exome sequencing data to identify new therapeutic targets of mitochondrial function in ovarian CCC because of the central role of mitochondria in redox homeostasis. Copy number analyses revealed that chromosome 17q21-24 (chr.17q21-24) amplification was associated with recurrence in ovarian CCC. Cell viability assays identified an association between cisplatin resistance and chr.17q21-24 amplification, and mitochondrion-related genes were enriched in patients with chr.17q21-24 amplification. Patients with high expression of pyruvate dehydrogenase kinase 2 (PDK2) had a worse prognosis than those with low PDK2 expression. Furthermore, inhibition of PDK2 synergistically enhanced cisplatin sensitivity by activating the electron transport chain and by increasing the production of mitochondrial reactive oxygen species. Mouse xenograft models showed that inhibition of PDK2 with cisplatin inhibited tumor growth. This evidence suggests that targeting mitochondrial metabolism and redox homeostasis is an attractive therapeutic strategy for improving drug sensitivity in ovarian CCC.