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Supplementary Figure 4. Ki-67 staining of non-HER2 gene amplified USC xenografts. Unlike the HER2 amplified models, no changes in proliferation were seen upon treatment with lapatinib and/or trastuzumab in SPEC2 (A) and EnCa2 (B) xenografts. Tumors harvested at the completion of each in vivo treatment study were subjected to Ki-67 immunohistochemical analysis. Scale bars: 100 µm.

Purpose: Uterine serous carcinoma (USC) is an aggressive subtype of endometrial cancer that commonly harbors HER2 gene amplification. We investigated the effectiveness of HER2 inhibition using lapatinib and trastuzumab in vitro and in xenografts derived from USC cell lines and USC patient-derived xenografts.Experimental Design: Immunohistochemistry and FISH were performed to assess HER2 expression in 42 primary USC specimens. ARK1, ARK2, and SPEC2 cell lines were treated with trastuzumab or lapatinib. Cohorts of mice harboring xenografts derived from ARK2 and SPEC2 cell lines and EnCa1 and EnCa2 primary human USC samples were treated with either vehicle, trastuzumab, lapatinib, or the combination of trastuzumab and lapatinib. Acute and chronic posttreatment tumor samples were assessed for downstream signaling alterations and examined for apoptosis and proliferation.Results:HER2 gene amplification (24%) correlated significantly with HER2 protein overexpression (55%). All models were impervious to single-agent trastuzumab treatment. Lapatinib decreased in vitro proliferation of all cell lines and in vivo growth of HER2-amplified xenografts (ARK2, EnCa1). In addition, dual therapy with trastuzumab and lapatinib resulted in significant antitumor activity only in ARK2 and EnCa1 tumors. Dual HER2 therapy induced on target alteration of downstream MAPK and PI3K pathway mediators only in HER2-amplified models, and was associated with increased apoptosis and decreased proliferation.Conclusions: Although trastuzumab alone did not impact USC growth, dual anti-HER2 therapy with lapatinib led to improved inhibition of tumor growth in HER2-amplified USC and may be a promising avenue for future investigation. Clin Cancer Res; 20(24); 6517–28. ©2014 AACR.

Supplementary Table 1. Clinical characteristics of the 42 USC patients whose tissue specimens were utilized for HER2 immunohistochemical and FISH analyses.

Supplementary Figure 3. Mouse weight changes over the course of each four-arm treatment study. In all experiments, lapatinib and trastuzumab treatments did not significantly affect mouse weights. Mice were weighed weekly, and the percent changes in weight compared to baseline weights (100%) are shown. Error bars represent the standard error of the mean.

Supplementary Figure 2. Anti-tumor activity of single agent lapatinib treatment was observed in HER2 amplified ARK2 xenografts (p = 0.02), while no response was seen in non-HER2 amplified SPEC2 xenografts. Mice harboring tumors derived from ARK2 or SPEC2 cell lines were treated with either vehicle or lapatinib. Tumors were measured twice weekly, and the percent change in tumor volume compared to baseline volume (100%) is shown. Error bars represent the standard error of the mean.

Supplementary Figure Legends. The supplementary figure legends are in this document as requested.

For adult granulosa cell tumors (aGCTs), the preferred treatment modality is surgery. Chemotherapy and anti-hormonal therapy are also frequently used in patients with recurrent aGCT. We aimed to review the existing literature on the response to chemotherapy and anti-hormonal therapy in patients with aGCT. Embase and MEDLINE were searched from inception to November 2021 for eligible studies. Objective response rate (ORR) was calculated as the total number of cases with a complete response (CR) or a partial response (PR). Disease control rate (DCR) was defined as the sum of cases with CR, PR or stable disease (SD). A total of 10 studies were included that reported on chemotherapy and 13 studies were included that reported on anti-hormonal therapy. The response rates of the 56 chemotherapy regimens that could be evaluated resulted in an ORR of 30% and DCR of 58%. For anti-hormonal therapy, the results of 73 regimens led to an ORR of 11% and a DCR of 66%. Evidence on systemic therapy in aGCT only is limited. For both chemotherapy and anti-hormonal therapy, the ORR is limited, but the response is considerably higher when patients achieving SD are included. New approaches are needed to provide more evidence and standardize treatment in aGCT.

Purpose: Uterine serous carcinoma (USC) is an aggressive subtype of endometrial cancer that commonly harbors HER2 gene amplification. We investigated the effectiveness of HER2 inhibition using lapatinib and trastuzumab in vitro and in xenografts derived from USC cell lines and USC patient-derived xenografts. Experimental Design: Immunohistochemistry and FISH were performed to assess HER2 expression in 42 primary USC specimens. ARK1, ARK2, and SPEC2 cell lines were treated with trastuzumab or lapatinib. Cohorts of mice harboring xenografts derived from ARK2 and SPEC2 cell lines and EnCa1 and EnCa2 primary human USC samples were treated with either vehicle, trastuzumab, lapatinib, or the combination of trastuzumab and lapatinib. Acute and chronic posttreatment tumor samples were assessed for downstream signaling alterations and examined for apoptosis and proliferation. Results: HER2 gene amplification (24%) correlated significantly with HER2 protein overexpression (55%). All models were impervious to single-agent trastuzumab treatment. Lapatinib decreased in vitro proliferation of all cell lines and in vivo growth of HER2-amplified xenografts (ARK2, EnCa1). In addition, dual therapy with trastuzumab and lapatinib resulted in significant antitumor activity only in ARK2 and EnCa1 tumors. Dual HER2 therapy induced on target alteration of downstream MAPK and PI3K pathway mediators only in HER2-amplified models, and was associated with increased apoptosis and decreased proliferation. Conclusions: Although trastuzumab alone did not impact USC growth, dual anti-HER2 therapy with lapatinib led to improved inhibition of tumor growth in HER2-amplified USC and may be a promising avenue for future investigation. Clin Cancer Res; 20(24); 6517–28. ©2014 AACR.

Objective Uterine serous carcinoma (USC) represents an aggressive subtype of endometrial cancer. We sought to understand Notch pathway activity in USC and determine if pathway inhibition has anti-tumor activity. Methods Patient USC tissue blocks were obtained and used to correlate clinical outcomes with Notch1 expression. Three established USC cell lines were treated with gamma-secretase inhibitor (GSI) in vitro . Mice harboring cell line derived or patient derived USC xenografts (PDXs) were treated with vehicle, GSI, paclitaxel and carboplatin (P/C), or combination GSI and P/C. Levels of cleaved Notch1 protein and Hes1 mRNA were determined in GSI treated samples. Statistical analysis was performed using the Wilcoxon rank sum and Kaplan–Meier methods. Results High nuclear Notch1 protein expression was observed in 58% of USC samples with no correlation with overall survival. GSI induced dose-dependent reductions in cell number and decreased levels of cleaved Notch1 protein and Hes1 mRNA in vitro . Treatment of mice with GSI led to decreased Hes1 mRNA expression in USC xenografts. In addition, GSI impeded tumor growth of cell line xenografts as well as UT1 USC PDXs. When GSI and P/C were combined, synergistic anti-tumor activity was observed in UT1 xenografts. Conclusions Notch1 is expressed in a large subset of USC. GSI-mediated Notch pathway inhibition led to both reduced cell numbers in vitro and decreased tumor growth of USC some xenograft models. When combined with conventional chemotherapy, GSI augmented anti-tumor activity in one USC PDX line suggesting that targeting of the Notch signaling pathway is a potential therapeutic strategy for future investigation.

In vitro studies have suggested that the Cables1 gene regulates epithelial cell proliferation, whereas other studies suggest a role in promoting neural differentiation. In efforts to clarify the functions of Cables1 in vivo, we conducted gain- and loss-of-function studies targeting its ortholog (cables1) in the zebrafish embryo. Similar to rodents, zebrafish cables1 mRNA expression is detected most robustly in embryonic neural tissues. Antisense knockdown of cables1 leads to increased numbers of apoptotic cells, particularly in brain tissue, in addition to a distinct behavioral phenotype, characterized by hyperactivity in response to stimulation. Apoptosis and the behavioral abnormality could be rescued by co-expression of a morpholino-resistant cables1 construct. Suppression of p53 expression in cables1 morphants partially rescued both apoptosis and the behavioral phenotype, suggesting that the phenotype of cables1 morphants is due in part to p53-dependent apoptosis. Alterations in the expression patterns of several neural transcription factors were observed in cables1 morphants during early neurulation, suggesting that cables1 is required for early neural differentiation. Ectopic overexpression of cables1 strongly disrupted embryonic morphogenesis, while overexpression of a cables1 mutant lacking the C-terminal cyclin box had little effect, suggesting functional importance of the cyclin box. Lastly, marked reductions in p35, but not Cdk5, were observed in cables1 morphants. Collectively, these data suggest that cables1 is important for neural differentiation during embryogenesis, in a mechanism that likely involves interactions with the Cdk5/p35 kinase pathway.

Background Subsets of high grade endometrial cancer (EnCa) over-express HER2 (ERBB2), yet clinical trials have failed to demonstrate any anti-tumor activity utilizing trastuzumab, an approved platform for HER2 positive breast cancer (BrCa). A truncated p95HER2 variant lacking the trastuzumab binding site may confer resistance. The objective of this investigation was to characterize the expression of the p95HER2 truncated variant in EnCa. Materials and methods With institutional approval, 86 high grade EnCa tumors were identified with tumor specimens from surgeries performed between 2000 and 2011. Clinical data were collected and all specimens underwent tumor genotyping, HER2 immunohistochemistry (IHC, HercepTest®), HER2 fluorescent in situ hybridization (FISH), along with total HER2 (H2T) and p95HER2 assessment with VeraTag® testing. Regression models were used to compare a cohort of 86 breast tumors selected for equivalent HER2 protein expression. Results We identified 44 high grade endometrioid and 42 uterine serous carcinomas (USC). IHC identified high HER2 expression (2+ or 3+) in 59% of the tumors. HER2 gene amplification was observed in 16 tumors (12 USC, 4 endometrioid). Both HER2 gene amplification and protein expression correlated with H2T values. High p95HER2 expression above 2.8RF/mm 2 was observed in 53% ( n =54) with significant correlation with H2T levels. When matched to a cohort of 107 breast tumors based on HercepTest HER2 expression, high grade EnCa presented with higher p95 levels ( p Conclusions These data demonstrate that compared to BrCa, high grade EnCa expresses higher levels of p95HER2 possibly providing rationale for the trastuzumab resistance observed in EnCa.

Alterations in the PI3K pathway are prevalent in endometrial cancer due to PIK3CA mutation and loss of PTEN. We investigated the anti-tumor activity of the PI3K inhibitor NVP BKM-120 (BKM) as a single agent and in combination with standard cytotoxic chemotherapy in a human primary endometrial xenograft model.NOD/SCID mice bearing xenografts of primary human tumors with and without PIK3CA gene mutations were divided into two and four arm cohorts with equivalent tumor volumes. BKM was administered alone and in combination with paclitaxel and carboplatin (P/C) and endometrial xenograft tumor volumes were assessed. Tumors from the BKM, P/C, P/C+BKM and vehicle treated mice were processed for determination of PI3K/AKT/mTOR pathway activation.In both single agent experiments, BKM resulted in significant tumor growth suppression starting at days 5-10 compared to the linear growth observed in vehicle treated tumors (p0.04 in all experiments). Tumor resurgence manifested between days 14 and 25 (p0.03). When BKM was combined with P/C, this resistance pattern failed to develop in three separate xenograft lines (p0.05). Synergistic tumor growth suppression (p0.05) of only one xenograft tumor with no detected PIK3CA mutation was observed. Acute treatment with BKM led to a decrease in pAKT levels.Independent of PIK3CA gene mutation, BKM mediated inhibition of the PI3K/AKT/mTOR pathway in endometrial tumors precludes tumor growth in a primary xenograft model. While a pattern of resistance emerges, this effect appears to be mitigated by the addition of conventional cytotoxic chemotherapy.

Uterine serous carcinoma (USC) is an aggressive subtype of endometrial cancer that commonly harbors HER2 gene amplification. Clinical trial has demonstrated that USC is impervious to trastuzumab therapy, though the mechanism is poorly understood. Since HER3 mediated signaling has been implicated in trastuzumab resistance in breast cancer, we sought to understand the relevance of HER3 activation in USC xenografts derived from the HER2 gene amplified (HER2:Chr 17 > 15) non-immortalized USC cell line ARK2. Cohorts of mice harboring xenografts derived from ARK2 were treated with either vehicle, trastuzumab (10 mg/kg IP BIW), lapatinib (150 mg/kg QD oral gavage) or the combination of trastuzumab and lapatinib for 21 days. Acute and chronic post treatment tumor samples were assessed for downstream signaling alterations. Single agent trastuzumab had no impact on xenograft growth compared to vehicle. Lapatinib alone resulted in significant tumorstatic effects (p < 0.01) and dual therapy with trastuzumab and lapatinib induced synergistic activity that significantly decreased tumor volume compared to all other arms (p < 0.01). Single agent trastuzumab was associated with rapid elevation in pHER3 levels with unchanged pAKT and pERK expression compared to vehicle. These elevated pHER3 levels were similarly elevated after the 21 day treatment. Anti-tumor activity observed in the lapatinib and dual lapatinib/trastuzumab arm was not associated with any alterations in pHER3 levels following 21 day treatment, though acute elevations in pHER3 were noted in the dual HER2 blockade arm at 24 hours after treatment. In conclusion, trastuzumab alone failed to impact USC xenograft growth and this innate resistance was associated with an elevation in pHER3 levels that was still evident in xenografts at the end of the treatment period. Unlike single agent trastuzumab, treatment arms that utilized lapatinib demonstrated significant anti-tumor activity with no increase in pHER3 above vehicle over the course of treatment. These data highlight HER3 activation as a possible trastuzumab resistance mechanism in USC that can be abrogated through the addition of lapatinib. Citation Format: Silvia F. Hernandez, Celeste DiGloria, Jolijn Groeneweg, Darrell Borger, Rosemary Foster, Bo Rueda, Whitfield Growdon. Phosphorylated HER3 levels associated with trastuzumab resistance in HER2 gene amplified uterine serous carcinoma xenograft tumors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 658. doi:10.1158/1538-7445.AM2015-658

Purpose:Uterineserouscarcinoma(USC)isanaggressivesubtypeofendometrialcancerthatcommonly harbors HER2 gene amplification. We investigated the effectiveness of HER2 inhibition using lapatinib and trastuzumab in vitro and in xenografts derived from USC cell lines and USC patient-derived xenografts. Experimental Design: Immunohistochemistry and FISH were performed to assess HER2 expression in 42 primary USC specimens. ARK1, ARK2, and SPEC2 cell lines were treated with trastuzumab or lapatinib. Cohorts of mice harboring xenografts derived from ARK2 and SPEC2 cell lines and EnCa1 and EnCa2 primaryhumanUSCsamplesweretreatedwitheithervehicle,trastuzumab,lapatinib,orthecombinationof trastuzumab and lapatinib. Acute and chronic posttreatment tumor samples were assessed for downstream signaling alterations and examined for apoptosis and proliferation. Results: HER2 gene amplification (24%) correlated significantly with HER2 protein overexpression (55%). All models were impervious to single-agent trastuzumab treatment. Lapatinib decreased in vitro proliferation of all cell lines and in vivo growth of HER2-amplified xenografts (ARK2, EnCa1). In addition, dual therapy with trastuzumab and lapatinib resulted in significant antitumor activity only in ARK2 and EnCa1 tumors. Dual HER2 therapy induced on target alteration of downstream MAPK and PI3K pathway mediators only in HER2-amplified models, and was associated with increased apoptosis and decreased proliferation. Conclusions: Although trastuzumab alone did not impact USC growth, dual anti-HER2 therapy with lapatinib led to improved inhibition of tumor growth in HER2-amplified USC and may be a promising avenue for future investigation. Clin Cancer Res; 20(24); 6517–28. � 2014 AACR.

5578 Background: Ovarian cancer (OvCa) is the most lethal gynecologic malignancy in the United States. Chemotherapy is effective but seldom curative, mainly due to the development of chemoresistant recurrent disease. Our current research investigates the efficacy of inhibiting the Notch pathway with a gamma-secretase inhibitor (GSI), MRK-003, in an OvCa xenograft model as a single agent therapy and in combination with standard chemotherapy. Methods: Mice bearing xenografts derived from clinically platinum sensitive human ovarian serous carcinomas were treated with GSI or vehicle, or with either vehicle, GSI alone, paclitaxel and carboplatinum (T/C) alone, or the combination of GSI and T/C. In addition, mice bearing xenografts derived from patients with clinically platinum resistant disease were given GSI with or without paclitaxel. Gene transcript levels of several factors in the Notch pathway were analyzed using RT-PCR. Notch1 and Notch3 protein levels were evaluated by western blotting. The Wilcoxon rank-sum test was used to assess significance between the different treatment groups. Results: Expression of Notch1 and Notch3 was highly variable across all analyzed OvCa samples. Treatment with GSI alone significantly decreased tumor growth in 3 of 4 platinum sensitive ovarian tumors (all p < 0.05), as well as in 1 of 3 platinum resistant tumors (p = 0.04). Furthermore, the combination of GSI and paclitaxel was significantly more effective than GSI alone and paclitaxel alone in all platinum resistant ovarian tumors (all p < 0.05). The addition of GSI did not alter the effect of T/C in platinum sensitive tumors. Although the response of each tumor to GSI did not correlate with its endogenous level of Notch expression, 2 of the 3 tumors resistant to paclitaxel but sensitive to the combination of GSI and paclitaxel showed elevated Notch activity by RT-PCR. Conclusions: Inhibition of the Notch signaling cascade with a gamma-secretase inhibitor reduces tumor growth in vivo, most notably in combination with paclitaxel in a platinum resistant setting. These promising findings underscore the need for further investigation of the preclinical and clinical effectiveness of Notch inhibitors in OvCa.

e13564 Background: Alterations in the PI3K pathway are highly prevalent in endometrial cancer due to PIK3CA mutation and loss of PTEN. Given these data, we investigated the anti-tumor activity of the PI3K inhibitor NVP-BKM120 (BKM) as a single agent and in combination with standard cytotoxic chemotherapy in a human primary endometrial xenograft model. Methods: NOD/SCID mice bearing xenografts of primary human tumors with and without PIK3CA gene mutations were randomly divided into two- and four-arm cohorts with equivalent tumor volumes. Three single agent experiments tested the effectiveness of NVP-BKM120 against two endometrioid (PIK3CA wild type and H1047L mutant) and one carcinosarcoma (PIK3CA R88Q mutant) endometrial cancer. Three four arm experiments tested NVP-BKM120 alone and in combination with paclitaxel and carboplatin (P/C) in two endometrioid tumors (both R88Q) and one carcinosarcoma (no PIK3CA mutation detected). Following in vivo study, tumors from the NVP-BKM120 , P/C, P/C+ NVP-BKM120 and vehicle treated mice were processed for determination of PI3K/AKT/mTOR pathway activation. Wilcoxan rank sum analysis was utilized to compare tumor growth across all treatment experiments. Results: In endometrioid single agent experiments, NVP-BKM120 resulted in tumor growth suppression starting at days 5-10 compared to the linear growth observed in vehicle treated tumors (p

Endometrial cancer is the most common gynecologic malignancy and the majority of patients are cured with surgery alone. A substantial subset of patients, however, present with high grade uterine papillary serous carcinoma (UPSC) and these patients account for a disproportionate degree of the recurrence, chemoresistance and death associated with endometrial cancer. Novel treatment strategies incorporating molecularly targeted therapies would be of great value in effective clinical management of these tumors. HER2 (ErbB2) hyperactivity has been associated with 10-20% of UPSC, though efforts to target this signature with trastuzumab have yielded no response in a recent prospective trial. In breast cancer, HER2/HER3 (ErbB2/ErbB3) dimerization has been associated with trastuzumab resistance. The expression profile of HER3 in UPSC is currently unknown. The objective of this investigation was to characterize HER2 and HER3 expression in a UPSC series and correlate these findings with clinical outcomes including survival. Under an IRB approved protocol, we identified 33 patients who underwent initial surgical staging at our institution between 2000 and 2009 with archival formalin fixed, paraffin embedded blocks and complete clinical follow up data. These tumor samples were subjected to immunohistochemistry (IHC) for HER2 and HER3 as well as fluorescent in situ hybridization (FISH) to assess the amplification status of the HER2 gene. Non-parametric tests were utilized to test correlation between detected levels of HER2 or HER3 protein expression and HER2 gene amplification and survival analysis was performed using the Kaplan-Meier method. HER2 gene amplification was observed in 34% of the cohort while HER2 protein over-expression, defined as 2+ or 3+ staining, was found in 59% of samples tested. HER2 gene amplification was associated with high HER2 protein expression (p < 0.05). Moreover, HER2 gene amplification was significantly associated with a decreased overall survival (p < 0.05). Finally, HER3 over-expression, defined as 2+ or 3+ staining, was observed in 52% of the entire cohort and HER3 protein levels exhibited a significant inverse relationship to HER2 protein expression and HER2 gene amplification (p < 0.05). These findings suggest that HER2 and HER3 signaling may function independently of one another in UPSC. The observed alterations in HER2 and HER3 expression levels constitute clinically relevant and prevalent signatures in UPSC that merit further investigation to determine the potential benefits of therapies targeting the epidermal growth receptor pathways. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4556. doi:1538-7445.AM2012-4556

Ovarian cancer is the most lethal of all gynecologic malignancies because women commonly present with advanced stage disease and develop chemotherapy refractory tumors. While cytoreductive surgery followed by platinum based chemotherapy are initially effective, ovarian tumors have a high propensity to recur highlighting the distinct need for novel therapeutics to improve outcomes for affected women. The Notch signaling pathway plays an established role in embryologic development and deregulation of this signaling cascade has been linked to many cancers. Recent genomic profiling of serous ovarian carcinoma revealed that Notch pathway alterations are among the most prevalent detected genomic changes. A growing body of scientific literature has confirmed heightened Notch signaling activity in ovarian carcinoma, and has utilized in vitro and in vivo models to suggest that targeting this pathway with gamma secretase inhibitors (GSIs) leads to anti-tumor effects. While it is currently unknown if Notch pathway inhibition can offer clinical benefit to women with ovarian cancer, several GSIs are currently in phase I and II trials across many disease sites including ovary. This review will provide background on Notch pathway function and will focus on the pre-clinical literature that links altered Notch signaling to ovarian cancer progression.