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Poly ADP-ribose polymerase inhibitors (PARPi) are first-line maintenance therapy for ovarian cancer and an alternative therapy for several other cancer types. However, PARPi-resistance is rising and there is currently an unmet need to combat PARPi-resistant tumors. Here, we created an immunocompetent, PARPi-resistant mouse model to test the efficacy of combinatory PARPi and euchromatic histone methyltransferase 1/2 inhibitor (EHMTi) in the treatment of PARPi-resistant ovarian cancer. We discovered that inhibition of EHMT1/2 resensitizes cells to PARPi. Markedly, we show that single EHMTi and combinatory EHMTi/PARPi significantly reduced PARPi-resistant tumor burden and that this reduction is partially dependent on CD8 T cells. Altogether, our results show a low-toxicity drug that effectively treats PARPi-resistant ovarian cancer in an immune-dependent manner, supporting its entry into clinical development and potential incorporation of immunotherapy. Implications: Targeting the epigenome of therapy-resistant ovarian cancer induces an anti-tumor response mediated in part through an anti-tumor immune response.
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Neoplasias de los Genitales Femeninos , Complicaciones Posoperatorias , Pirazoles , Piridonas , Humanos , Femenino , Piridonas/uso terapéutico , Piridonas/efectos adversos , Piridonas/administración & dosificación , Pirazoles/uso terapéutico , Pirazoles/efectos adversos , Neoplasias de los Genitales Femeninos/cirugía , Complicaciones Posoperatorias/prevención & control , Pronóstico , Tromboembolia/prevención & control , Tromboembolia/etiología , Inhibidores del Factor Xa/uso terapéuticoRESUMEN
Despite the success of poly-ADP-ribose polymerase inhibitors (PARPi) in the clinic, high rates of resistance to PARPi presents a challenge in the treatment of ovarian cancer, thus it is imperative to find therapeutic strategies to combat PARPi resistance. Here, we demonstrate that inhibition of epigenetic modifiers euchromatic histone lysine methyltransferases 1/2 (EHMT1/2) reduces the growth of multiple PARPi-resistant ovarian cancer cell lines and tumor growth in a PARPi-resistant mouse model of ovarian cancer. We found that combinatory EHMT and PARP inhibition increases immunostimulatory double-stranded RNA formation and elicits several immune signaling pathways in vitro. Using epigenomic profiling and transcriptomics, we found that EHMT2 is bound to transposable elements, and that EHMT inhibition leads to genome-wide epigenetic and transcriptional derepression of transposable elements. We validated EHMT-mediated activation of immune signaling and upregulation of transposable element transcripts in patient-derived, therapy-naïve, primary ovarian tumors, suggesting potential efficacy in PARPi-sensitive disease as well. Importantly, using multispectral immunohistochemistry, we discovered that combinatory therapy increased CD8 T-cell activity in the tumor microenvironment of the same patient-derived tissues. In a PARPi-resistant syngeneic murine model, EHMT and PARP inhibition combination inhibited tumor progression and increased Granzyme B+ cells in the tumor. Together, our results provide evidence that combinatory EHMT and PARP inhibition stimulates a cell autologous immune response in vitro, is an effective therapy to reduce PARPi-resistant ovarian tumor growth in vivo, and promotes antitumor immunity activity in the tumor microenvironment of patient-derived ex vivo tissues of ovarian cancer.
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BACKGROUND: Venous thromboembolism is a preventable complication of gynecologic cancer surgery that leads to postoperative morbidity and mortality. This study compared apixaban with enoxaparin to identify whether apixaban had the same safety and efficacy for patients undergoing gynecologic cancer surgery. METHODS: The study identified patients with a gynecologic malignancy who underwent surgery and were prescribed apixaban at discharge between June 2020 and April 2023. International Classification of Diseases 10 codes were used to identify patients who had a thromboembolism within 90 days or a bleeding event within 60 days after surgery. The rates of events for patients prescribed apixaban were compared with those for a historical cohort of patients who received enoxaparin. Fisher's exact tests were used to compare categorical variables, and t tests were used to compare continuous variables. A logistic regression was performed to compare the odds of thromboembolism between the two groups. RESULTS: Baseline patient characteristics differed in terms of body mass index (BMI), race, route of surgery, and type of cancer. Of the 490 patients in the apixaban cohort, 12 (2.4%) had a thromboembolism compared with 3 (2.1%) of the 138 patients in the enoxaparin group (adjusted odds ratio [aOR], 1.02; 95% confidence interval [CI] 0.30-4.70; p > 0.999). The odds ratio was adjusted for BMI, age, and route of surgery. A bleeding event occurred for 1 (0.2%) of the 490 patients in the apixaban group and for 1 (0.7%) of the 138 patients in the enoxaparin group. CONCLUSIONS: This validation study showed that apixaban is a safe and effective method of postoperative venous thromboembolism prophylaxis. The data provide support to previous data and guideline updates recommending the use of apixaban for postoperative prophylaxis.
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Enoxaparina , Neoplasias de los Genitales Femeninos , Complicaciones Posoperatorias , Pirazoles , Piridonas , Humanos , Femenino , Piridonas/uso terapéutico , Piridonas/efectos adversos , Piridonas/administración & dosificación , Pirazoles/uso terapéutico , Pirazoles/efectos adversos , Persona de Mediana Edad , Neoplasias de los Genitales Femeninos/cirugía , Complicaciones Posoperatorias/prevención & control , Enoxaparina/uso terapéutico , Enoxaparina/administración & dosificación , Tromboembolia Venosa/prevención & control , Tromboembolia Venosa/etiología , Inhibidores del Factor Xa/uso terapéutico , Inhibidores del Factor Xa/efectos adversos , Estudios de Seguimiento , Anciano , Pronóstico , Procedimientos Quirúrgicos Ginecológicos/efectos adversos , Estudios Retrospectivos , Anticoagulantes/uso terapéutico , Anticoagulantes/administración & dosificaciónRESUMEN
There is considerable interest in quantifying anti-PEG antibodies, given their potential involvement in accelerated clearance, complement activation, neutralization, and acute reactions associated with drug delivery systems. Published and commercially available anti-PEG enzyme-linked immunosorbent assays (ELISAs) differ significantly in terms of reagents and conditions, which could be confusing to users who want to perform in-house measurements. Here, we optimize the ELISA protocol for specific detection of anti-PEG IgG and IgM in sera from healthy donors and in plasma from cancer patients administered with PEGylated liposomal doxorubicin. The criterion of specificity is the ability of free PEG or PEGylated liposomes to inhibit the ELISA signals. We found that coating high-binding plates with monoamine methoxy-PEG5000, as opposed to bovine serum albumin-PEG20000, and blocking with 1% milk, as opposed to albumin or lysozyme, significantly improve the specificity, with over 95% of the signal being blocked by competition. Despite inherent between-assay variability, setting the cutoff value of the optical density at the 80th percentile consistently identified the same subjects. Using the optimized assay, we longitudinally measured levels of anti-PEG IgG/IgM in cancer patients before and after the PEGylated liposomal doxorubicin chemotherapy cycle (1 month apart, three cycles total). Antibody titers did not show any increase but rather a decrease between treatment cycles, and up to 90% of antibodies was bound to the infused drug. This report is a step toward harmonizing anti-PEG assays in human subjects, emphasizing the cost-effectiveness and optimized specificity.
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Doxorrubicina , Ensayo de Inmunoadsorción Enzimática , Inmunoglobulina G , Inmunoglobulina M , Polietilenglicoles , Humanos , Doxorrubicina/análogos & derivados , Ensayo de Inmunoadsorción Enzimática/métodos , Inmunoglobulina G/sangre , Inmunoglobulina G/inmunología , Inmunoglobulina M/sangre , Inmunoglobulina M/inmunología , Femenino , Masculino , Adulto , Persona de Mediana Edad , Liposomas , Neoplasias/tratamiento farmacológico , Neoplasias/inmunologíaRESUMEN
Despite the success of Poly-ADP-ribose polymerase inhibitors (PARPi) in the clinic, high rates of resistance to PARPi presents a challenge in the treatment of ovarian cancer, thus it is imperative to find therapeutic strategies to combat PARPi resistance. Here, we demonstrate that inhibition of epigenetic modifiers Euchromatic histone lysine methyltransferases 1/2 (EHMT1/2) reduces the growth of multiple PARPi-resistant ovarian cancer cell lines and tumor growth in a PARPi-resistant mouse model of ovarian cancer. We found that combinatory EHMT and PARP inhibition increases immunostimulatory dsRNA formation and elicits several immune signaling pathways in vitro. Using epigenomic profiling and transcriptomics, we found that EHMT2 is bound to transposable elements, and that EHMT inhibition leads to genome-wide epigenetic and transcriptional derepression of transposable elements. We validated EHMT-mediated activation of immune signaling and upregulation of transposable element transcripts in patient-derived, therapy-naïve, primary ovarian tumors, suggesting potential efficacy in PARPi-sensitive disease as well. Importantly, using multispectral immunohistochemistry, we discovered that combinatory therapy increased CD8 T cell activity in the tumor microenvironment of the same patient-derived tissues. In a PARPi-resistant syngeneic murine model, EHMT and PARP inhibition combination inhibited tumor progression and increased Granzyme B+ cells in the tumor. Together, our results provide evidence that combinatory EHMT and PARP inhibition stimulates a cell autologous immune response in vitro, is an effective therapy to reduce PARPi resistant ovarian tumor growth in vivo, and promotes anti-tumor immunity activity in the tumor microenvironment of patient-derived ex vivo tissues of ovarian cancer.
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Early diagnosis and screening of ovarian cancer remain significant challenges to improving patient outcomes. There is an urgent need to implement both established and modern strategies to address the "early detection" conundrum, especially as new research continues to uncover the complexities of the disease. The discussion provided is the result of a unique research conference focused on reviewing early detection modalities and providing insight into future approaches.
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â¢Cardiac metastasis is a rare complication of squamous cell carcinoma of the cervix.â¢Biologic agents may be a useful treatment modality for cardiac metastasis of squamous cell carcinoma of the cervix.â¢Multidisciplinary approach is required to treat cardiac metastasis of squamous cell carcinoma of the cervix.
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Metastatic and recurrent cervical cancer is difficult to treat with limited options following platinum-based chemotherapy. Tisotumab vedotin (TV) is an antibody drug conjugate (ADC) targeted at a tissue factor (TF), which is a cell surface protein that is upregulated in the majority of cervical cancers. Prior clinical trials have demonstrated efficacy of TV in metastatic and recurrent cervical cancer with an objective response rate of 24-26 % with an 8.3 month duration of response. In this case series, we present 3 patients with recurrent or progressive cervical cancer of three different histologies (squamous cell, adenocarcinoma, and human papillomavirus (HPV)-independent gastric type carcinomas). We demonstrate a 100 % complete response rate with average time of complete response of 4.33 months. The duration of response was not reached as none of our patients had a confirmed progression at the time of writing this manuscript, but the mean time since the initiation of treatment was 6.1 months. In concordance with the clinical trials, our patients tolerated TV well although the grade 3 ocular toxicities were higher in our patients compared to prior data. This case series presents data confirming the efficacy and tolerability of TV in patients with recurrent cervical cancer, including an HPV-independent gastric type cervical cancer.
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Based on findings from The Cancer Genome Atlas and the Proactive Molecular Risk Classifier for Endometrial Cancer algorithm, endometrial carcinoma can now be stratified into 4 prognostically distinct subgroups based on molecular alterations and immunohistochemical (IHC) aberrations. In this study, we describe the de novo adoption and clinical reporting of prognostic subgroup classification based on next-generation sequencing (NGS) and IHC analyses of all endometrial carcinoma resections at a single institution, framed by the Exploration, Preparation, Implementation, and Sustainment model. Results from the first 13 months show 188 tumors underwent analysis by a combination of IHC and a medium-sized (56 analyzed genes) NGS-based assay. All cases were assigned as either POLE (POLE-mutated) (5.3%), mismatch repair deficient (27.7%), no specific molecular profile (45.7%), or p53 abnormal (21.3%) inclusive of multiple-classifier cases. NGS-based analysis revealed additional distinctions among the subgroups, including reduced levels of PI3K pathway activation in the p53 abnormal subgroup, an increased rate of CTNNB1 activating mutation in the no specific molecular profile subgroup, and lower TP53 mutation variant allele frequencies in POLE and mismatch repair deficient subgroups compared with the p53 abnormal subgroup. Overall, we describe the testing protocol, reporting, and results of a combination of NGS and IHC to prospectively prognosticate endometrial carcinomas at a single tertiary care center.
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BACKGROUND AND AIMS: Most cancer patients require surgery for diagnosis and treatment. This study evaluated whether cancer is a risk factor for perioperative arterial ischemic events. METHODS: The primary cohort included patients registered in the National Surgical Quality Improvement Program (NSQIP) between 2006-2016. The secondary cohort included Healthcare Cost and Utilization Project (HCUP) claims data from 11 U.S. states between 2016-2018. Study populations comprised patients who underwent inpatient (NSQIP, HCUP) or outpatient (NSQIP) surgery. Study exposures were disseminated cancer (NSQIP) and all cancers (HCUP). The primary outcome was a perioperative arterial ischemic event, defined as myocardial infarction or stroke diagnosed within 30 days after surgery. RESULTS: Among 5,609,675 NSQIP surgeries, 2.2% involved patients with disseminated cancer. The perioperative arterial ischemic event rate was 0.96% among patients with disseminated cancer versus 0.48% among patients without (HR, 2.01; 95% CI, 1.90-2.13). In Cox analyses adjusting for demographics, functional status, comorbidities, surgical specialty, anesthesia type, and clinical factors, disseminated cancer remained associated with higher risk of perioperative arterial ischemic events (HR, 1.37; 95% CI, 1.28-1.46). Among 1,341,658 surgical patients in the HCUP cohort, 11.8% had a diagnosis of cancer. A perioperative arterial ischemic event was diagnosed in 0.74% of patients with cancer versus 0.54% of patients without cancer (HR, 1.35; 95% CI, 1.27-1.43). In Cox analyses adjusted for demographics, insurance, comorbidities, and surgery type, cancer remained associated with higher risk of perioperative arterial ischemic events (HR, 1.31; 95% CI, 1.21-1.42). CONCLUSIONS: Cancer is an independent risk factor for perioperative arterial ischemic events.
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Primary clear cell adenocarcinoma of the vagina represents a rare form of cancer historically correlated with in-utero diethylstibestrol (DES) exposure. Mainstay treatment modalities include surgery, radiation, and chemotherapy. There has been a growing interest in immunotherapy in the field of oncology. KEYNOTE 826 demonstrated that patients with persistent, recurrent, or metastatic cervical cancer including patients who had adenocarcinoma showed improved progression and overall survival by the addition Pembrolizumab to chemotherapy plus or minus bevacizumab. To date, there are no documented cases using pembrolizumab as adjuvant treatment for active or recurrent vaginal clear cell adenocarcinoma. We present a case of a young patient with recurrent vaginal clear cell carcinoma who showed a complete and durable response to Pembrolizumab.
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OBJECTIVES: Clear cell carcinoma is a high-risk subtype of endometrial cancer. Some patients have a mixture of clear cell carcinoma with other histologic types (endometrioid or serous) or cannot be neatly assigned to one of these types. Protocol GOG-8032 within GOG-210 was designed to determine whether these tumors differ from pure clear cell carcinoma in stage at diagnosis, initial pattern of spread, or patient survival. METHODS: The term "mixed" was applied to tumors with multiple identifiable components, and "indeterminate" was applied to tumors with features intermediate between different histologic types. Three hundred eleven women with pure, mixed, or indeterminate clear cell carcinoma were identified in a larger cohort of patients undergoing hysterectomy for endometrial cancer in GOG-210. Histologic slides were centrally reviewed by expert pathologists. Baseline and follow-up data were analyzed. RESULTS: One hundred thirty-six patients had pure clear cell carcinoma and 175 had a mixed or indeterminate clear cell pattern. Baseline clinicopathologic characteristics were similar except for a small difference in age at presentation. Univariate survival analysis confirmed the significance of typical endometrial cancer prognostic factors. Patients in the mixed categories had disease-free and overall survival similar to pure clear cell carcinoma, but the indeterminate clear cell/endometrioid group had longer survival. CONCLUSION: In clear cell endometrial cancer, the presence of a definite admixed endometrioid or serous component did not correlate with a significant difference in prognosis. Patients whose tumors had indeterminate clear cell features had better prognosis. Some of these tumors may be endometrioid tumors mimicking clear cell carcinoma.
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Adenocarcinoma de Células Claras , Carcinoma Endometrioide , Neoplasias Endometriales , Femenino , Humanos , Carcinoma Endometrioide/patología , Estadificación de Neoplasias , Neoplasias Endometriales/patología , Pronóstico , Adenocarcinoma de Células Claras/patología , Útero/patologíaRESUMEN
Venous thromboembolism (VTE) is a major cause of both morbidity and mortality in patients with cancer. Venous thromboembolism, which includes both deep vein thrombosis and pulmonary embolism, affects a sizable portion of patients with malignancy and can have potentially life threatening complications. Accurate assessment of risk as well as diagnosis and treatment of this process is paramount to preventing death in this high risk population. Various risk models predictive of venous thromboembolism in patients with cancer have been developed, and knowledge of these rubrics is essential for the treating oncologist. Subgroups of particular interest are inpatients receiving chemotherapy, postoperative patients after surgical debulking, and patients undergoing radiotherapy. Numerous newer drugs have become available for the prevention of venous thromboembolism in patients with cancer who are at high risk of developing the disease. These include the class of drugs called direct oral anticoagulants, (DOACs) which do not require the same monitoring that other modalities have previously required and are taken by mouth, preventing the discomfort associated with subcutaneous strategies. The appropriate risk stratification and intervention to prevent venous thromboembolism are vital to the treatment of patients with cancer.
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Neoplasias , Embolia Pulmonar , Tromboembolia Venosa , Humanos , Tromboembolia Venosa/etiología , Tromboembolia Venosa/prevención & control , Tromboembolia Venosa/diagnóstico , Anticoagulantes , Embolia Pulmonar/etiología , Embolia Pulmonar/prevención & control , Factores de Riesgo , Neoplasias/tratamiento farmacológicoRESUMEN
Euchromatic histone lysine methyltransferases 1 and 2 (EHMT1/2), which catalyze demethylation of histone H3 lysine 9 (H3K9me2), contribute to tumorigenesis and therapy resistance through unknown mechanisms of action. In ovarian cancer, EHMT1/2 and H3K9me2 are directly linked to acquired resistance to poly-ADP-ribose polymerase (PARP) inhibitors and are correlated with poor clinical outcomes. Using a combination of experimental and bioinformatic analyses in several PARP inhibitor resistant ovarian cancer models, we demonstrate that combinatory inhibition of EHMT and PARP is effective in treating PARP inhibitor resistant ovarian cancers. Our in vitro studies show that combinatory therapy reactivates transposable elements, increases immunostimulatory dsRNA formation, and elicits several immune signaling pathways. Our in vivo studies show that both single inhibition of EHMT and combinatory inhibition of EHMT and PARP reduces tumor burden, and that this reduction is dependent on CD8 T cells. Together, our results uncover a direct mechanism by which EHMT inhibition helps to overcome PARP inhibitor resistance and shows how an epigenetic therapy can be used to enhance anti-tumor immunity and address therapy resistance.
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OBJECTIVE: The Lifestyle Intervention for oVarian cancer Enhanced Survival (LIVES) is a national study of a combined diet and physical activity intervention for stage II-IV ovarian cancer survival, an under-represented cancer in lifestyle behavioral intervention research. Here, we present the data on recruitment, retention, and baseline demographic, clinical and lifestyle behavior characteristics of the LIVES study participants. METHODS: The LIVES study (NRG Oncology/GOG 0225) is a Phase III diet plus physical activity intervention trial testing the hypothesis that ovarian cancer survivors in the lifestyle intervention will demonstrate better progression-free survival than those in the control condition. Study interventions were delivered via centralized telephone-based health coaching. Baseline descriptive statistics were computed for demographic, clinical, and lifestyle behavior characteristics. RESULTS: The LIVES study exceeded its recruitment goals, enrolling 1205 ovarian cancer survivors from 195 NRG/NCORP-affiliated oncology practices across 49 states from 2012 to 2018. The mean age of enrollees was 59.6 years; the majority (69.4%) with stage III disease; 89% White, 5.5% Hispanic; 64% overweight/obese. Baseline self-reported diet showed a mean daily intake of 6.6 servings of fruit and vegetables, 62.7 fat grams, and 21.7 g of fiber. Physical activity averaged 13.0 MET-hours/week of moderate to vigorous physical activity; 50.9 h/week of sedentary time. Retention rates exceeded 88%. CONCLUSION: The LIVES study demonstrates efficiency in recruiting and retaining ovarian cancer survivors in a 24-month study of diet and physical activity intervention with a primary endpoint of progression free survival that will be reported. TRIAL REGISTRATION: ClinicalTrials.govNCT00719303.
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Supervivientes de Cáncer , Neoplasias Ováricas , Humanos , Femenino , Persona de Mediana Edad , Dieta , Estilo de Vida , Ejercicio FísicoRESUMEN
Selective arterial embolization has long been utilized in the field of obstetrics and gynecology as both a prophylactic and therapeutic measure. We present a case of a highly vascularized, poorly differentiated, radiation-related vulvar sarcoma that was resected immediately following selective arterial embolization. Arterial embolization in patients with gynecologic malignancies has been shown to compromise blood supply to the tumor and decrease the risk of hemorrhage and related surgical complications. In this case, the use of embolization prior to surgery appeared to result in a less morbid procedure for the patient with decreased blood loss and improved quality of life thereafter. Based on the presented case, we believe that arterial embolization can be considered a safe preoperative intervention to decrease surgical risk, particularly hemorrhage, at time of resection of highly vascularized vulvar tumors.
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PURPOSE: To compare taxane maintenance chemotherapy, paclitaxel (P) and paclitaxel poliglumex (PP), with surveillance (S) in women with ovarian, peritoneal, or fallopian tube (O/PC/FT) cancer who attained clinical complete response after first-line platinum-taxane therapy. METHODS: Women diagnosed with O/PC/FT cancer who attained clinical complete response after first-line platinum-taxane-based chemotherapy were randomly allocated 1:1:1 to S or maintenance, P 135 mg/m2 once every 28 days for 12 cycles, or PP at the same dose and schedule. Overall survival (OS) was the primary efficacy end point. RESULTS: Between March 2005 and January 2014, 1,157 individuals were enrolled. Grade 2 or worse GI adverse events were more frequent among those treated with taxane (PP: 20%, P: 27% v S: 11%). Grade 2 or worse neurologic adverse events occurred more often with taxane treatment (PP: 46%, P: 36% v S: 14%). At the fourth scheduled interim analysis, both taxane regimens passed the OS futility boundary and the Data Monitoring Committee approved an early release of results. With a median follow-up of 8.1 years, 653 deaths were reported; none were attributed to the study treatment. Median survival durations were 58.3, 56.8, and 60.0 months for S, P, and PP, respectively. Relative to S, the hazard of death for P was 1.091 (95% CI, 0.911 to 1.31; P = .343) and for PP, it was 1.033 (95% CI, 0.862 to 1.24; P = .725). The median times to first progression or death (PFS) were 13.4, 18.9, and 16.3 months for S, P, and PP, respectively. Hazard ratio = 0.801; 95% CI, 0.684 to 0.938; P = .006 for P and hazard ratio = 0.854; 95% CI, 0.729 to 1.00; P = .055 for PP. CONCLUSION: Maintenance therapy with P and PP did not improve OS among patients with newly diagnosed O/tubal/peritoneal cancer, but may modestly increase PFS. GI and neurologic toxicities were more frequent in the taxane treatment arms.
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Neoplasias , Platino (Metal) , Femenino , Humanos , Inutilidad MédicaRESUMEN
High-grade serous ovarian cancer is the deadliest gynecologic malignancy due to progression to resistant disease. Claudin-4 is classically defined as a tight junction protein and is often associated with epithelial cancers. Claudin-4 is aberrantly expressed in nearly 70% of all ovarian cancer tumors and conveys a worse overall prognosis. Elevated claudin-4 expression correlates to increased DNA repair activity and resistance to DNA damaging agents. PARP inhibitors are emerging as an effective therapeutic option for patients with ovarian cancer and function by promoting DNA damage. The study examines the relationship between claudin-4 expression and the response to PARP inhibitors using both genetic and pharmacologic inhibition of claudin-4 in in vitro and ex vivo models of ovarian cancer to examine DNA repair markers and functional activity. Genetic inhibition of claudin-4 results in the downregulation of several DNA damage repair effectors, including 53BP1 and XRCC1. Claudin-4 knockdown did not change homology-directed repair but inhibited nonhomologous end-joining and reduced 53BP1 foci formation. In 15 primary ovarian cancer tumors, higher claudin-4 expression significantly correlated to a dampened PARP inhibitor-mediated antiproliferation response. Further, claudin-4 inhibition in high claudin-4 tumors sensitized tumor sections to PARP inhibition. These data highlight that claudin-4 expression in ovarian cancer tumors could serve as both a marker of PARP inhibitor response and a therapeutic target to improve PARP inhibitor response.