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Objectives: To evaluate safety and efficacy of durvalumab (D) in combination with paclitaxel (P) and carboplatin (C) in newly diagnosed, advanced-stage, high grade, non-mucinous ovarian cancer (OC). To investigate informative pharmacodynamic changes including proteome changes and immune-related pathways by treatment with immuno-oncology therapy in combination with chemotherapy. Methods: In this single arm phase II study, patients (pts) with untreated, advanced stage (III/IV) OC dispositioned to neoadjuvant chemotherapy (NACT) received D (750mg) with weekly P (80mg/m2) and C (AUC6) after baseline tissue biopsy. Matched biopsies were obtained at tumor reductive surgery (TRS) after 3 cycles. Progression-free survival (PFS) and overall survival (OS) were estimated using Kaplan-Meier method. Reverse-phase protein arrays (RPPA) were performed on pre- and post-treatment tissues. Protein expression alteration and an enriched Reactome pathway analysis using differentially expressed proteins between pre- and post-treatments were assessed. Results: 19 pts were enrolled and 18 treated. Median age was 63 and 50% had stage III disease. No dose-limiting toxicities were observed. 94% of pts had an adverse event (AE). Most common AEs were anemia (94%), neutropenia (83%), fatigue (72%), hyperglycemia (73%), and thrombocytopenia (66%). Immune-related AEs observed included hyperthyroidism (22%), hypothyroidism (22%), diarrhea (6%), hypophysitis (6%). Eighty-three percent had optimal interval TRS, 70% had a pre-operative response by RECIST (PR=11, CR=1). At 13 months (mo) median follow up, 9 pts (50%) had disease progression and median PFS was 14.5 mo (95% CI: 9.2 - NA). Median OS was not reached; OS rate at 18 mo was 69% (95% CI 0.21 - 0.91). Fifty-five tumor specimens were available from 9 pts (31 pre- and 24 post-treatment). Thirteen significantly differentially expressed proteins among 211 proteins (adj. p Citation Format: Shannon N. Westin, Sanghoon Lee, Li Zhao, Ying Yuan, Jimin Wu, Richard Hajek, Sara Sharafi, Larissa A. Meyer, Nicole D. Fleming, Amir Jazaeri, Robert L. Coleman, Karen H. Lu, Gordon B. Mills, Jianhua Zhang, Andrew Futreal, Anil K. Sood. Pharmacodynamic changes by durvalumab in combination with chemotherapy in women with untreated, advanced stage ovarian cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT188.

Background: Prior molecular characterization efforts for high-grade serous ovarian cancer (HGSOC) were restricted to those who had upfront surgical debulking with variable treatment paradigms. Thus, we sought to examine molecular and cellular differences between clinically defined groups (tumor tissues from patients who had complete gross resection (CGR) versus those who were triaged to neoadjuvant chemotherapy (NACT) and experienced either excellent or poor response. Methods: Tumor biopsies were collected from three patient groups managed under a systematic surgical algorithm: CGR after primary surgery (R0, n=10); poor tumor response to NACT (NACT-PR, n=10); excellent tumor response to NACT (NACT-ER, n=10). Primary and multiple metastatic tumor sites per each patient were obtained pre-treatment and subjected to comprehensive omics analyses including high-pass whole-genome (WGS) and targeted deep DNA sequencing. Results: An average of 71 nonsynonymous somatic mutations from each sample for 75 samples with high-purity tumors (≥75%) by WGS were identified from each sample for the entire cohort. Fourteen ovarian-cancer-associated genes were found mutated in our patient cohort and, as expected, the most frequently mutated gene was TP53 in both primary and metastatic sites in all three groups. TP53 nonsense mutations were exclusively identified in the NACT-ER (36.0%) and NACT-PR groups (15.4%), while in the R0 group most TP53 mutations were missense mutations (62.5%). Nonsense mutations in CSMD3 and PIK3CA were exclusively identified in both primary and metastatic sites in the NACT-PR group. The most frequent copy number variations (CNVs) in the R0 were copy number gain/loss of CSMD3 (67%) and copy number loss of NF1 (54%) and CDK12 (50%) in both primary and metastatic sites. Interestingly, copy number losses of NF1 were significantly lower in the NACT groups (18%, p=0.002), especially in the NACT-PR (8%, p=0.0004), when compared to the R0 group (54%). We also identified significant less observation of chromothripsis-like patterns, and a significantly higher level of strong-binding neoantigens in the R0 than in the NACT groups. Conclusions: Our findings using HGSOC samples obtained from patients treated on a prospective algorithm identified distinct molecular abnormalities, and could have prognostic and therapeutic implications for patients with HGSOC. Citation Format: Sanghoon Lee, Li Zhao, Shannon N. Westin, Nicholas W. Bateman, Amir A. Jazaeri, Nicole D. Fleming, Karen H. Lu, Robert L. Coleman, Gordon B. Mills, Jianhua Zhang, Thomas P. Conrads, George L. Maxwell, P. Andrew Futreal, Anil K. Sood. High-depth whole genome sequencing of clinically-annotated high-grade serous ovarian cancers [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2510.

Background: High-grade serous ovarian cancer (HGSOC) remains the leading cause of death from gynecologic malignancies. Here, we examined tumoral proteome changes following neoadjuvant chemotherapy (NACT) to identify potential predictive and prognostic biomarkers of response to primary chemotherapy. Methods: A total of 65 tissue specimens from 10 patients with advanced-stage HGSOC were collected from matched pre- and post-NACT (3 cycles of dose-dense paclitaxel and carboplatin). Protein expression was assessed using reverse-phase protein arrays (RPPA). All relative protein levels using 297 antibodies were normalized by the expression level of pre-treatment samples, and then protein expression alterations and functional analyses were performed by Reactome pathway analysis followed by statistical analysis. Results: The protein expression patterns of samples tended to cluster according to the time point (pre- and post-treatment) by a non-supervised clustering analysis using all the proteins assessed in the RPPA panel. Five differentially expressed proteins among 239 proteins (adj. p Conclusion: Our findings identified significant proteomic alterations following NACT, and could provide insights into interval proteomic alterations following induction chemotherapy in advanced-stage ovarian cancer patients. These data present information to optimize future clinical trial designs for patients with ovarian cancer. Citation Format: Sanghoon Lee, Li Zhao, Joseph Celestino, Kelly M. Rangel, Richard A. Hajek, Mark S. Kim, Sara E. Sharafi, Jinsong Liu, Nicole D. Fleming, Karen H. Lu, Jianhua Zhang, P. Andrew Futreal, Gordon B. Mills, Shannon N. Westin, Anil K. Sood, Amir A. Jazaeri, Robert L. Coleman. Functional proteomic aberrations post-chemotherapy with paclitaxel and carboplatin in patients with advanced ovarian cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2941.

Purpose: There is limited success with chemotherapeutic agents in women with advanced or recurrent endometrial cancer. Dysregulation of the PI3K/RAS signaling pathways in endometrial cancer have been well documented. However, responses with mTOR inhibitor such as temsirolimus have been modest. Previously we have shown that metformin prevents temsirolimus-induced AKT activation. Therefore, we enrolled patients with advanced endometrial carcinoma in the expansion cohort of a phase I study of temsirolimus in combination with metformin. Methods: Patients with advanced endometrial cancer refractory to or relapse after standard therapies, ECOG performance status 0 or 1, and with significant organ function reserve were enrolled. Patients were administered intravenous temsirolimus 25mg weekly and oral metformin 2000 mg daily in 28-day cycles. Response was assessed every 2 cycles by clinical evaluation, tumor markers, and imaging per RECIST 1.1. All toxicities were graded using NCI CTCAE, version 4.0. Results: Forty patients were treated. Median age is 67 years (range, 33-78). Drug-related adverse events of any grade were reported in 34 patients. The most common toxicities were mucositis (n=13), AST increase (n=13), anorexia (n=12), diarrhea (n=12) and anemia (n=10). Eleven grade 3 drug-related adverse events were reported. They were anemia (n=2), thrombocytopenia (n=2), mucositis, fatigue, weight loss, hypokalemia, hypophosphatemia, AST increase and ALT increase (n=1 each). Of the 33 patients evaluable for response, objective response was seen in 2 (6%) patients. Both had partial response (PR) and were on the study for 8.7 and 18.2 months respectively. In addition, 13 (39%) patients had stable disease (SD), including 11 with SD ≥4 months, representing a clinical benefit rate of 39%. Molecular characterization of tumor was available for 35 patients. Thirty of 35 patients had molecular alterations in the PI3K and/or RAS pathway. Of the 30 patients, 1 had benign PI3K mutation and 4 were not evaluable for response. Of the remaining 25 patients with PI3K and/or KRAS pathway, 11 (44%) had either objective response or SD ≥4 months. Eighteen of them had molecular alteration only in the PI3K pathway. Seven of 18 (39%) had objective response or SD ≥4 months. Importantly, all 3 patients who had molecular alterations in both the PI3K and RAS pathway achieved SD ≥4 months, while 3 of the 4 patients with exclusive resistant KRAS mutation had progressive disease. Collectively, of the 13 patients with either objective response or SD ≥4 months, 11 (85%) patients had molecular alteration in the PI3K and/or RAS pathway. Conclusion: Temsirolimus in combination with metformin was well tolerated. Anti-tumor activity was seen in patients with advanced/refractory endometrial cancer, particularly in patients with molecular alterations in the PI3K and/or RAS pathway that warrants further study. Citation Format: Aung Naing, Daniel Karp, Sarina A. Piha-Paul, Shubham Pant, Vivek Subbiah, Diane C. Bodurka, Siqing Fu, Amir A. Jazaeri, Shumei Kato, Kathleen Schmeler, Alpa Nick, Yali Yang, Fechukwu O. Akhmedzhanov, Senait Fessahaye, Jing Gong, Bettzy Stephen, Amber M. Johnson, Pamela T. Soliman, Anil K. Sood, Funda Meric-Bernstam, Karen H. Lu. Temsirolimus in combinaton with metformin in patients with advanced or refractory endometrial cancers [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT163.

The role of immune checkpoint inhibitors (ICPIs) in ovarian cancer continues to be refined. The presence of intratumoral T cells in ovarian tumors correlates with improved survival and progression, suggesting that immune modulation, such as by ICPIs, may be beneficial. However, a better understanding of the immune effects following ICPI use, particularly in those with a long progression free survival, is needed. Thus, we used imaging mass cytometry (IMC) to compare the tumor immune landscape of patients with ovarian cancer before and after a CTLA4 immune checkpoint inhibitor treatment to determine the association between alterations in immune landscapes and progression free survival. Fine needle biopsies were obtained from 8 patients with recurrent platinum-resistant ovarian carcinoma enrolled in a phase 2 randomized trial evaluating the efficacy of Tremelimumab and Durvalumab (CTLA4 and PDL1 checkpoint inhibitors, respectively) in recurrent ovarian cancer treatment. Each patient had a pre-treatment biopsy and on-treatment biopsy after 3 cycles of CTLA4 inhibitor therapy. Progression free time (PFS) was recorded with 3 patients with a long PFS (>180 days) and 5 with short PFS ( Formalin fixed paraffin embedded (FFPE) tissue sections were stained for IMC analysis via Fluidigm protocol with 34 metal-tagged antibodies to detect various cell and immune related markers. The IMC data was obtained using the Fluidigm Helios CyTOF instrument and Hyperion Imaging System laser ablation module. A novel image informatics pipeline through Matlab was used to assess the image intensity of each marker and cell location. Using the developed image informatics pipeline, cell types and locations were analyzed for 16 samples from 8 patients. In all patients, mean CD8+ T cell densities had an increased trend in on-treatment vs pre-treatment samples (205.6 v 129.9 cells/mm2, p=0.086). An analysis of cell location found that in all patients on-treatment, the mean number of CD8+ T cells adjacent to M2 macrophages increased significantly (0.09 v. 0.17 cells, p = 0.0460) as well as the mean number of CD8+ T cells adjacent to B7H4+ tumor cells (0.035 v. 0.01 cells, p = 0.046). Furthermore, patients with a long PFS had a significantly higher number of CD8+ cells neighboring B cells on-treatment than short PFS (0.12 v. 0.27 cells, p=0.028). Using IMC and novel image informatics pipeline, we found that patients with recurrent ovarian cancer treated with Tremelimumab with a long PFS mounted a significant immune response compared to patients with a short PFS, with a higher number of CD8+ T cells neighboring B cells after treatment. For all patients, the immune landscape altered after treatment. To our knowledge, this is the first known use of IMC to demonstrate immune response in ovarian cancer following ICPI therapy. Overall, IMC and image informatics pipeline are robust tools that simultaneously analyze multiple biomarkers and spatial location of cells to better assess the tumor immune microenvironment and cellular interactions. Citation Format: Han Cun, Emily M. Hinchcliff, Ying Zhu, Sammy Ferri-Borgogno, Rita Cheng, Jared K. Burks, Stephen T. Wong, Amir A. Jazaeri, Samuel C. Mok. Identification of a novel biomarker response in a prospective clinical trial of immune checkpoint blockade in recurrent ovarian carcinoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3267.

High-grade serous ovarian carcinoma (HGSOC) is the most common and lethal form of epithelial ovarian cancer. While HGSOCs respond well to platinum and taxane chemotherapy, the majority of patients eventually relapse with treatment-resistant tumors. This new and ominous resistance property of recurrent tumors is generally thought to be acquired in a process aided by the mutagenic activities of the chemotherapy itself. However, using advanced and robust technology that enables the direct cloning of cancer stem cells (CSCs) from HGSOCs, our study challenges the notion that chemotherapy resistance is acquired. In particular, patient-specific “libraries” of CSCs generated from therapy-naive tumors show that, while the majority of the CSCs are rapidly killed by platinum-taxane treatment, a discrete subset is highly resistant to these drugs to which they had no prior exposure. More telling is that these pre-existing, platinum-taxane resistant CSCs also display a profound “polyresistance” to a wide range of unrelated chemotherapeutic drugs. Importantly, gene expression profiles of polyresistant CSCs are highly uniform within a particular patient and clearly distinct from those of sensitive clones. This finding suggests that resistant clones within a patient carry the same gene signature, suggesting that resistance is a singular and knowable event in each patient. Comparing the resistance gene expression signatures across patients is revealing a very limited set of common pathways involving nuclear receptors that likely hold the key to the polyresistance phenomena. Taken together, our study supports the concept that these poly-resistant variants exist and can be cloned from most if not all HGOC patients. Further, the cloning of these polyresistant cells sets in motion the possibility that such variants can be exploited to identify both key pathways of polyresistance and drugs that specifically and pre-emptively eliminate these clones to prevent onset of recurrent disease. Citation Format: Jingzhong Xie, Yusuke Yamamoto, Audrey-Ann Liew, Bailiang Wang, Rajasekaran Mahalingam, Marcin Duleba, Wei Rao, Suchan Niroula, Kristina Goller, Yanting Zhang, Shan Wang, Amir Jazaeri, Peter Davies, Suzy Torti, Giulio Draetta, Matthew Anderson, Molly Brewer, Christopher Crum, Frank McKeon, Wa Xian. Pre-existing, poly-resistant cancer stem cells in high-grade serous ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr A78.

e18035 Background: Uterine leiomyosarcoma (ULMS) is a rare tumor with limited therapeutic options and no clearly established best treatment sequence strategy. Methods: Women with ULMS between 2013-2018 were identified. Clinical data was collected; descriptive statistics were performed and predictors of overall survival (OS) and progression free survival (PFS) were analyzed. Results: 189 patients were included. Median age was 53 (20-84), 91% had grade 3 tumors and 51.3% had stage IB disease. 50% underwent surgery followed by chemotherapy (n = 94, 49.7%) and 37% had surgery only (n = 70). 49 patients retained their ovaries; there was no difference in OS by oophorectomy status (p = 0.71). Estrogen and progesterone receptor (ER/PR) status, positive in 41% and 33% respectively, was not independently associated with OS (p = 0.23, p = 0.12) nor did it impact OS among those with oophorectomy and without (p = 0.70). The most common adjuvant therapy regimens were gemcitabine/docetaxel (gem/doce, 64%) or ifosphamide/doxorubicin (ifos/doxo, 19%). There were no differences in the regimens prescribed by physician specialty (gynecologic oncology vs other, p = 0.21). 147 patients (78%) experienced a recurrence or progression. For the 73 patients who received gem/doce as adjuvant therapy, 58.9% recurred and were most commonly treated with doxo containing regimens (67%). Of the 22 patients treated with ifos/doxo, only 3 recurred and each received a different second line regimen. For those not treated with adjuvant therapy (70 patients), 58.2% recurred and were treated with gem/doce (62%) and ifos/doxo (24%). In early stage patients, the majority received surgery only (45%) or surgery followed by chemotherapy (44%). There was no difference in OS in those who received adjuvant therapy and those who did not (p = 0.39). 46 (24%) had molecular testing and 37 had identified mutations. The most common mutation found was P53 (n = 25, 54%) followed by RB1 (8, 17%), PTEN (7, 15%), and BRCA (2, 4%). Conclusions: Recurrence occurred in 78% of patient despite many women undergoing adjuvant therapy after surgery. Oophorectomy did not influence OS, even though 41% of tumors were ER positive. The sequence of treatment was not associated with OS, however, the risk for recurrence in patient treated with adjuvant Ifos/Doxo was 14% compared to 59% in gem/doce. This finding warrants additional evaluation to determine the optimal adjuvant therapy for these women.

SUMMARY The diversity and heterogeneity within high-grade serous ovarian cancer (HGSC), which is the most lethal gynecologic malignancy, is not well understood. Here, we perform comprehensive multi-platform omics analyses, including integrated analysis, and immune monitoring on primary and metastatic sites from highly clinically annotated HGSC samples based on a laparoscopic triage algorithm from patients who underwent complete gross resection (R0) or received neoadjuvant chemotherapy (NACT) with excellent or poor response. We identify significant distinct molecular abnormalities and cellular changes and immune cell repertoire alterations between the groups, including a higher rate of NF1 copy number loss, and reduced chromothripsis-like patterns, higher levels of strong-binding neoantigens, and a higher number of infiltrated T cells in the R0 versus the NACT groups., Graphical Abstract, In Brief High-grade serous ovarian cancer (HGSC) patients with no gross residual disease (R0) after primary surgery have the greatest improvement in clinical outcomes. A deep understanding of molecular and cellular heterogeneity of HGSC is lacking. Findings by Lee et al. highlight major molecular and cellular differences between clinically defined subgroups of HGSC.

Composition of the intestinal microbiome has been shown to impact generation of a tumor-specific immune response following chemotherapy and immune checkpoint blockade. We hypothesized that the local and intestinal microbiota may also impact immune activation and radiation response. We prospectively assessed the microbiota and T-cell repertoire of 30 cervical cancer patients throughout CRT. Greater diversity of the intestinal microbiome was associated with exceptional response and development of clonal T-cell expansion. Predominance of immunosuppressive Lactobacillus species in the cervix was associated with failure to expand clonal T-cells and decreased relapse-free survival. Patients with a robust response to CRT developed clonal expansion of T-cells, suggesting that highly radiation responsive cervical cancers generate an antigen specific immune response. Depletion of gut microbiome diversity and presence of vaginal Lactobacillus were associated with decreased presence of activated CD8 T-cell infiltration and decreased radiation response in an orthotopic model of HPV cancer, suggesting that microbial diversity is required for generation of effective antitumor immunity in radiation responsive HPV cancers.

OBJECTIVE: Early-phase data have demonstrated induction of antibody responses to a polyvalent vaccine conjugate (Globo-H, GM2, MUC1-TN, TF) with adjuvant OPT-821. We sought to determine if this combination decreases the hazard of progression or death compared to OPT-821 alone in patients with ovarian cancer in second/third clinical complete remission following chemotherapy. Secondary and translational objectives were overall survival (OS), safety, and immunogenicity. METHODS: From 2010–2013, patients were randomized (1:1) to receive OPT-821±vaccine-KLH conjugate subcutaneously at weeks 1, 2, 3, 7, 11, and then every 12 weeks (total 11). Dose delay or reduction was not permitted. Patients were removed for pre-defined dose-limiting toxicity. RESULTS: Of 171 patients randomized, 170 were treated. Most had disease of serous histology (85%), stage 3 disease at diagnosis (77%), and had received 2 prior regimens (68%). 32% received >6 treatment cycles [median 6, each arm (p=0.33)]. 77% discontinued due to progression, 4% due to toxicity, and 1 due to myeloid dysplastic syndrome (MDS). Maximum toxicity was grade 4 MDS and depression/personality change (1 each, unlikely related) and others including grade 3 gastrointestinal disorders (n=21, 4 related). Lesser adverse events were injection site reactions (82%) and fever (11%). Estimated HR for progression-free survival (PFS) of the vaccine+OPT-821 to OPT-821 arm was 0.98 (95% CI: 0.71–1.36). At a median follow-up of 60 months, median OS was 47 and 46 months, respectively. CONCLUSIONS: Vaccine+OPT-821 compared to OPT-821 alone was modestly immunogenic and did not prolong PFS or OS. Multi-remission patients are a viable, well-defined population for exploring innovative consolidation and maintenance approaches.

Anoikis, a cell death mechanism triggered upon cell-matrix detachment, is regarded as a physiological suppressor of metastasis that can be regulated by a diverse array of signals. The protein encoded by GDF2 is BMP9 and is a member of the bone morphogenetic protein family and the transforming growth factor (TGF) β superfamily with emerging yet controversial roles in carcinogenesis. In an attempt to identify the function of growth and differentiation factor 2 (GDF2) in epithelial systems, we examined the signaling machinery that is involved and cell fate decisions in response to GDF2 in ovarian and breast epithelia. We find that GDF2 can robustly activate the SMAD1/5 signaling axis by increasing complex formation between the type I receptor serine threonine kinases activin receptor-like kinase (ALK) 3 and ALK6 and the type II receptor serine threonine kinase BMPRII. This activation is independent of cross talk with the SMAD2-transforming growth factor β pathway. By activating SMAD1/5, epithelial cells regulate anchorage-independent growth by increasing anoikis sensitivity that is dependent on GDF2’s ability to sustain the activation of SMAD1/5 via ALK3 and ALK6. Consistent with a role for GDF2 in promoting anoikis susceptibility, the analysis of cell lines and patient data suggests epigenetic silencing of GDF2 in cancer cell lines and increased promoter methylation in patients. These findings collectively indicate an antimetastatic role for GDF2 in ovarian and breast cancer. The work also implicates loss of GDF2 via promoter methylation-mediated downregulation in promotion of carcinogenesis with significant relevance for the use of epigenetic drugs currently in clinical trials.

Use of immune checkpoint inhibitors targeting cytotoxic T-lymphocyte-associated antigen 4 and programmed cell death protein 1 have led to improved survival outcomes for advanced solid-tumor malignancies. This report helps the reader gain a better understanding of adverse events in patients with ovarian cancer on checkpoint inhibitor therapy. We describe 3 hypothetical case vignettes of patients with gynecologic cancer on checkpoint inhibitor immunotherapy and discuss common immune-related adverse events. The typical presentation and onset of immune-related events are different from those associated with conventional chemotherapy. This report highlights the importance of early recognition and management of these events.

Immune-targeted therapies have demonstrated durable responses in many tumor types with limited treatment options and poor overall prognosis. This has led to enthusiasm for expanding such therapies to other tumor types including gynecologic malignancies. The use of immunotherapy in gynecologic malignancies is in the early stages and is an active area of ongoing clinical research. Both cancer vaccines and immune checkpoint inhibitor therapy continue to be extensively studied in gynecologic malignancies. Immune checkpoint inhibitors, in particular, hold promising potential in specific subsets of endometrial cancer that express microsatellite instability. The key to successful treatment with immunotherapy involves identification of the subgroup of patients that will derive benefit. The number of ongoing trials in cervical, ovarian, and endometrial cancer will help to recognize these patients and make treatment more directed. Additionally, a number of studies are combining immunotherapy with standard treatment options and will help to determine combinations that will enhance responses to standard therapy. Overall, there is much enthusiasm for immunotherapy approaches in gynecologic malignancies. However, the emerging data shows that with the exception of microsatellite unstable tumors, the use of single-agent immune checkpoint inhibitors is associated with response rates of 10– 15%. More effective and likely combinatorial approaches are needed and will be informed by the findings of ongoing trials.

Cell-free circulating linear DNA is being explored for noninvasive diagnosis and management of tumors and fetuses, the so-called liquid biopsy. Previously, we observed the presence of small extrachromosomal circular DNA (eccDNA), called microDNA, in the nuclei of mammalian tissues and cell lines. Now, we demonstrate that cell-free microDNA derived from uniquely mapping regions of the genome is detectable in plasma and serum from both mice and humans and that they are significantly longer (30%–60% >250 bases) than cell-free circulating linear DNA (∼150 bases). Tumor-derived human microDNA is detected in the mouse circulation in a mouse xenograft model of human ovarian cancer. Comparing the microDNA from paired tumor and normal lung tissue specimens reveals that the tumors contain longer microDNA. Consistent with human cancers releasing microDNA into the circulation, serum and plasma samples (12 lung and 11 ovarian cancer) collected prior to surgery are enriched for longer cell-free microDNA compared with samples from the same patient obtained several weeks after surgical resection of the tumor. Thus, circular DNA in the circulation is a previously unexplored pool of nucleic acids that could complement miRNAs and linear DNA for diagnosis and for intercellular communication. Implications: eccDNA derived from chromosomal genomic sequence, first discovered in the nuclei of cells, are detected in the circulation, are longer than linear cell-free DNA, and are released from normal tissue and tumors into the circulation. Mol Cancer Res; 15(9); 1197–205. ©2017 AACR.

INTRODUCTION: High-grade ovarian cancer (HGOC) shows excellent responses to standard-of-care surgery and paclitaxel/carboplatin therapy only to relapse 6-24 months later with typically resistant disease. While the origin of this recurrent, resistant disease is unclear, most believe it is acquired by the action of chemotherapeutics. Using novel stem cell technology that enables the cloning of cancer stem cells (CSCs) from epithelial cancers, we have generated large libraries of CSCs from multiple cases of HGOC. And while the vast majority of these CSC clones are killed by standard-of-care chemotherapeutic drugs, a minor fraction shows profound resistance not only to paclitaxel/carboplatin but to a wide range of structurally unrelated chemotherapeutic drugs to which these cells had no prior exposure. We describe screens for drugs that selectively target this resistant CSC population. METHODS: Libraries of 10- to 100,000 CSC clones were generated from individual, therapy naïve, HGOC resections using technology we developed for cloning so-called “adult” stem cells from normal columnar epithelia (Wang et al., 2015, Nature, 522, 173). RESULTS: Paclitaxel/carboplatin resistant CSCs were identified in CSC libraries derived from therapy naïve tumors at ratios of 1:50 to 1:300. By copy number variation, these resistant variant clones proved distinct from the bulk of CSCs, and by gene expression analysis varied from sensitive clones by more than 700 differentially expressed genes. Independent resistant clones from the same library clustered with other resistant clones by both copy number variation and gene expression profiles, suggesting the possibility that resistance within a single tumor is dominated by a single type of resistant CSCs. Clones resistant to paclitaxel/carboplatin were screened in a 384-well format against a wide range of experimental drug-like molecules. These pre-existing resistant clones also proved to be profoundly resistant to a large number of structurally unrelated chemotherapeutic drugs. This same screening program identified drugs that act alone or in combination with paclitaxel to eliminate these resistant clones, suggesting a route to personalized medicine for addressing the problem of recurrent disease in HGOC. CONCLUSIONS: Tumors from patients with HGOC possess clonogenic CSCs including variants that are resistant to a broad spectrum of chemotherapeutics to which they have not been exposed. It is likely that such CSCs would survive standard-of-care chemotherapy and contribute to the recurrent disease seen in HGOC. We have identified known and experimental drugs that specifically eliminate these resistant variants and the overall platform represents a potential strategy to addressing the problem of recurrent disease in these patients. Citation Format: Jingzhong Xie, Yusuke Yamamoto, Marcin Duleba, Bailiang Wang, Rajasekaran Mahalingam, Shan Wang, Wei Rao, Suchan Niroula, Clifford Stephan, Peter Davies, Amir Jazaeri, Giulio Draetta, Molly Brewer, Matt L. Anderson, Christopher P. Crum, Frank McKeon, and Wa Xian. PRE-EXISTENCE OF POLY-RESISTANT CANCER STEM CELLS IN HIGH-GRADE OVARIAN CANCER [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr NT-115.

Introduction: The objective was to identify molecular mechanisms and protein networks involved in synthetic lethality as well as mechanisms of adaptive changes to the combination of olaparib (O) combined with inhibitors of the PI3K-AKT axis. Methods: 110 patients with recurrent ovarian, endometrial, and triple negative breast cancer were treated with a combination of O and vistusertib (V) or capivasertib (C) (mTORC1/2 and AKT inhibitors, respectively). We have previously reported durable clinical efficacy of these combinations, regardless of BRCA status. Tumor samples were collected pre-treatment and 30 days post-treatment and reverse-phase protein array (RPPA) was performed. Baseline expression was assessed and change in expression was calculated. Bioinformatics and statistical methods were developed to assess activity of signaling pathways. Pathway scores were determined based on the expression of sets of proteins known to be involved in a specific pathway, including PI3K, RAS/RAF, and DNA damage repair. Association between protein expression and treatment efficacy was determined. Results: We analyzed a total of 55 paired samples from patients treated with O/V (n=25) and O/C (n=30). These included 20 endometrial (37% PR, 31.5% SD, 31.5% PD), 21 ovarian (10% PR, 55% SD, 35% PD) and 14 triple negative breast (15% PR, 23% SD, 62% PD) tumors. Response to O/V was associated with low pre-treatment mTOR pathway activity and led to altered immune activity based on decreased CD4 and PD1 expression. Resistance to O/V was associated with high pre-treatment cell proliferation (high CCNB1, CDK1 and PLK1 protein expression). In contrast, response to O/C was associated with adaptive responses indicated by decreased mTOR activity and induction of the DNA damage checkpoint (high phospho-CHK1, -WEE1 and -CDC2). Resistance was associated with high pre-treatment RTK activity levels (high phospho-HER3, -EGFR, -IGFR, -MET) and AKT-independent activation of mTOR in the on-treatment samples. Conclusion: Analysis of pre- and on-treatment samples from responders and non-responders to PARP and PI3K pathway combination therapy identified biomarkers of patients likely to benefit from therapy and helps to understand molecular mechanisms involved in response and resistance to these drug combinations. Citation Format: Marilyne Labrie, Zhenlin Ju, Jennifer K. Litton, Tae-Beom Kim, Sanghoon Lee, Ken Chen, Pamela T. Soliman, Michael Frumovitz, Larissa A. Meyer, Stacy Moulder, Amir A. Jazaeri, Karen H. Lu, Anil K. Sood, Robert L. Coleman, Gordon B. Mills, Shannon N. Westin. Exploration of markers of synergistic lethality of PARP and PI3K-Akt-mTOR inhibitors in women's cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2070.

TPS2650 Background: Adoptive cell therapy (ACT) with tumor-infiltrating lymphocytes (TIL) has a long history of efficacy in metastatic melanoma, and is being increasingly considered across other solid tumors. Preclinical data generated at MD Anderson Cancer Center has demonstrated the ability to grow TIL from a variety of tumor types including various types of sarcomas, ovarian and pancreas cancers. We are testing the efficacy of TIL across multiple tumor types using two different manufacturing protocols. Methods: We are conducting two ongoing investigator initiated basket TIL therapy trials. The first (NCT03449108) includes cohorts with poorly differentiated soft tissue and bone sarcomas, osteosarcoma, and platinum resistant ovarian cancer. The TIL product used in this trial is an investigational cell product (LN-145, Iovance Biotherapeutics, Inc.). The second trial (NCT03610490) includes cohorts of osteosarcoma, platinum resistant ovarian cancer, and pancreatic cancer (who have progressed on, or received maximal benefit from, front-line therapy). For this trial, TIL are manufactured at MD Anderson Cancer Center using a protocol that includes the use of urelumab (an agonistic anti-CD137 antibody) combined with T cell receptor activation during TIL expansion. In both trials eligible subjects undergo tumor harvest using a surgical excisional biopsy of the tumor for TIL manufacturing, receive a modified cyclophosphamide and fludarabaine lymphodepletion regimen and up to six doses of IL-2 (600,000 IU/kg) following TIL infusion. No intervening therapy is allowed between tumor harvest and initiation of lymphodepletion. The primary endpoint for each cohort is ORR as assessed by investigators using RECIST 1.1 criteria. The Simon’s two stage design is used to monitor the efficacy of each cohort independently. In the first stage, 10 patients will be treated per cohort. If there is no confirmed response in these 10 evaluable patients, the cohort will be terminated. If the cohort moves forward to Stage II, an additional 8 patients will be treated leading to a total of 18 patients. Three or more responders out of 18 treated patients for the cohort will be considered clinically relevant to justify further investigation. Enrollment is ongoing in all cohorts in both trials. An accrual update will be provided at the annual meeting. Clinical trial information: NCT03449108, NCT03610490.

TPS5606 Background: The peritoneal cavity is a frequent site of metastasis and recurrence for gynecologic malignancy, including approximately 80% of epithelial ovarian cancer (EOC) that presents with peritoneal involvement. These observations have led to the use of intraperitoneal (IP) route of administration for traditional cytotoxic chemotherapy. IP immunotherapy is a recognized but under explored area of clinical investigation with many potential advantages. Indeed, IP administered antibodies in both animals and human subjects are associated with absent or much lower peripheral blood concentrations. In addition to higher local and lower systemic exposure, other theoretical advantages include preferential binding to intraperitoneal and intratumoral immune cells, and absorption through the draining lymphatics of the peritoneal cavity. These pelvic and peri-aortic lymph nodes represent the most relevant lymphoid organs and as such may be the ideal site for T cell activation and trafficking back to the peritoneal tumor. Methods: The trial (NCT03508570) is a single-institution phase Ib trial to determine the recommended phase II dosing (RP2D) of IP administration of nivolumab in combination with ipilimumab. For the purpose of dose finding, the assessment period for dose limiting toxicity (DLT) is 12 weeks. The trial starts with a safety lead-in to confirm the safety of IP nivolumab before combining it with ipilimumab. A maximum sample size of 12 will be used to find the RP2D for nivolumab, up to 24 patients for the combination, and a planned expansion will be carried out such that at least 12 EOC patients are treated at RP2D of the intraperitoneal combination strategy. The secondary objectives are to describe the pharmacokinetics and toxicities, and to estimate the clinical benefit rate for the expansion cohort. Translational objectives include description of immunologic and biologic changes in serial blood and IP fluid collections as well as pre and on-treatment biopsies. Eligibility criteria include recurrent or progressive biopsy-confirmed platinum resistant EOC or other gynecologic cancer with measurable peritoneal disease, and no exposure to prior treatment with checkpoint inhibition. Enrollment began in January of 2019 with 3 subjects enrolled to date. Accrual update will be provided at the annual meeting. Clinical trial information: NCT03508570.

2538 Background: There is a high unmet medical need for effective treatments for patients with recurrent, metastatic, or persistent cervical cancer. Most patients are young and survival rates are poor. ORR for second line therapies is between 4 and 14% for chemotherapy and recently approved immunotherapy. Adoptive cell transfer using tumor infiltrating lymphocytes (TIL) have demonstrated durable responses in some patients with recurrent cervical cancer thus offering the potential for long-term disease control. Methods: Study C-145-04 is an ongoing, open-label, multicenter Phase 2 clinical trial evaluating the safety and efficacy of LN-145 TIL therapy in patients with advanced cervical cancer who have undergone at least one prior line of chemotherapy. Prior checkpoint inhibitor therapy is an exclusion criterion. The primary endpoint is ORR per RECIST 1.1; secondary endpoints include duration of response (DOR), disease control rate (DCR), and LN-145 safety. Tumors surgically harvested at local institutions are shipped to central GMP facilities for TIL generation in a 22-day manufacturing process. Final LN-145 TIL product is cryopreserved and shipped to sites. Patients receive one week of preconditioning lymphodepletion (cyclophosphamide, fludarabine), a single LN-145 infusion, followed by up to 6 doses of IL-2 (600,000 IU/kg). Results: As of 4 Feb 2019, 27 efficacy-c patients have received Gen 2 of LN-145, with a mean age of 47 years and 2.6 mean prior lines of therapy. Preliminary efficacy results: ORR was 44% (1 CR, 9 PR, 2 uPR), DCR was 89% at 3.5-month median study follow-up with 11/12 patients maintaining their response. Improved responses were observed in 4 patients with longer follow-up. Mean TIL cells infused was 28x109. Median IL-2 doses administered was 6.0. The adverse event profile was generally consistent with the underlying advanced disease and the profile of the lymphodepletion and IL-2 regimens. Conclusions: LN-145 results in 44% ORR in previously treated cervical cancer patients with acceptable safety and efficacy profile. LN-145 offers patients a viable therapeutic option warranting further investigation. Clinical trial information: NCT03108495.

2571 Background: Current treatment guidelines for immune-mediated colitis (IMC) recommend 4 to 6 weeks of steroids as first-line therapy, followed by nonsteroidal immunosuppressive therapy (NSIST) (infliximab or vedolizumab) in patients who do not respond to steroids. We assessed the effect of early NSIST introduction and number of NSIST infusions on clinical outcomes. Methods: We performed a retrospective review of patients with IMC who received NSIST between January and December 2018. Logistic regression analyses were used to assess associations between clinical features and outcomes of IMC (Table). Results: Of the 1,459 patients who received immune checkpoint inhibitor, 179 developed IMC of any grade; 84 of them received NSIST. Of the 84 patients who received NSIST, 79% were males with mean age of 60. Compared with patients who received NSIST >10 days after IMC onset, patients who received early NSIST (≤10 days) required fewer hospitalizations ( P=0.03), experienced steroid taper failure less frequently ( P=0.03), had fewer steroid tapering attempts ( P

5570 Background: To determine the correlation between surgeon radiology assessment and laparoscopic scoring in patients with newly diagnosed advanced stage ovarian cancer. Methods: Following IRB approval, 14 gynecologic oncologists from a single institution performed a blinded review of radiology imaging from 20 patients with advanced stage ovarian cancer. All patients previously underwent laparoscopic scoring assessment to determine primary resectability at tumor reductive surgery (TRS) using a validated scoring method from April 2013 to December 2017. The patients with predictive index value (PIV) scores < 8 were offered primary surgery and those with a score ≥8 received neoadjuvant chemotherapy (NACT). Surgeons viewed contrasted CT imaging reports and images from all patients in a blinded fashion and recorded PIV scores using the same validated scoring method. Linear mixed models were conducted to calculate the correlation between radiology and laparoscopic score for each surgeon and as a group. Once the model was fit, the inter-class correlation (ICC) and 95% confidence interval was calculated. Results: Radiology review was performed on 20 patients with advanced stage ovarian cancer who underwent laparoscopic scoring assessment. Most patients had stage IIIC disease (85%) and median laparoscopic score was 9 (range 0-14). Surgeon faculty rank included Assistant Professor (n = 5), Associate Professor (n = 4), and Professor (n = 5). Median surgeon experience during the study period with laparoscopic assessment was 13 cases (range 1-28) and TRS was 22.5 cases (range 2-48). The kappa inter-rater agreement was -0.017 (95% CI 0.023 to -0.005) indicating low inter-rater agreement between radiology review and actual laparoscopic score. The ICC in this model was 0.06 (0.02-0.21) indicating that surgeons do not score the same across all the images. When using a clinical cutoff of PIV of 8, the probability of agreement between radiology and actual laparoscopic score was 0.56 (95% CI: 0.49-0.73). Number of laparoscopic cases, TRS cases, or faculty rank was not significantly associated with agreement. Conclusions: Surgeon radiology review did not correlate highly with actual laparoscopic scoring assessment findings in patients with advanced stage ovarian cancer. 44% of patients in our study may have been inadequately triaged by radiology review alone, which may have led to suboptimal TRS. Our study highlights the utility of laparoscopic scoring assessment to determine resectability over radiology assessment alone in ovarian cancer.

The nearly ubiquitous development of chemoresistant disease remains a major obstacle against improving outcomes for patients with ovarian cancer. In this investigation, we evaluated the preclinical activity of MLN4924, an investigational inhibitor of the NEDD8-activating enzyme, in ovarian cancer cells. Efficacy of MLN4924 both alone and in combination with platinum was assessed. Overall, single-agent MLN4924 exhibited moderate activity in ovarian cancer cell lines. However, the combination of MLN4924 with cisplatin or carboplatin produced synergistic effects in SKOV3 and ES2 cells, as well as in primary ovarian cancer cell lines established from high-grade serous, clear cell, and serous borderline ovarian tumors. The efficacy of cisplatin plus MLN4924 was also evident in several in vitro models of platinum-resistant ovarian cancer. Mechanistically, the combination of cisplatin and MLN4924 was not associated with DNA re-replication, altered platinum-DNA adduct formation, abrogation of FANCD2 monoubiquitination, or CHK1 phosphorylation. An siRNA screen was used to investigate the contribution of each member of the cullin RING ligase (CRL) family of E3 ubiquitin ligases, the best-characterized downstream mediators of MLN4924's biologic effects. Cisplatin-induced cytotoxicity was augmented by depletion of CUL3, and antagonized by siCUL1 in both ES2 and SKOV3 ovarian cancer cells. This investigation identifies inhibition of neddylation as a novel mechanism for overcoming platinum resistance in vitro, and provides a strong rationale for clinical investigations of platinum and MLN4924 combinations in ovarian cancer. Mol Cancer Ther; 12(10); 1958–67. ©2013 AACR.

Highlights ► Mortality from necrotizing soft tissue infections of the vulva is 14% in this study. ► Multi-disciplinary care may contribute to the lower mortality in this case series.

Our objective was to characterize the intra and peritumoral immune profile in recurrent cervical cancers to identify rational immunotherapy targets.Archival pelvic exenteration specimens were examined using a validated multiplex immuno-fluorescent panel of antibodies against cluster of differentiation 8 (CD8), cluster of differentiation 68 (CD68), forkhead box P3 (FoxP3), programmed cell death protein 1 (PD1), and programmed death-ligand 1 (PD-L1, N=28). Clinical data were abstracted from the electronic medical record.Cytotoxic T cells, macrophages, and regulatory T cells were found in higher densities in peritumoral stroma (CD8+ density 497.7 vs 83.5, p0.0001, CD68+ density 345.0 vs 196.7, p=0.04, FoxP3+ density 214.5 vs 35.6, p0.0001). Antigen experienced T cells (PD1+) were higher in peritumoral compared to tumor tissue (median normalized fluorescence intensity 0.05 vs 0.0085, p0.001). Although there was a higher median density of intratumoral cytotoxic T cells and macrophages compared to regulatory T cells (median density CD8+ 83.5 vs 35.6, p0.05, median density 196.7 vs 35.6, p0.05), the presence of macrophages correlated with the presence of regulatory T cells in tumors (r=0.58, p=0.001).While cytotoxic T cells are present in tumor tissue to varying degrees, their density is lower than in peritumoral stroma, suggesting intratumoral exclusion or destruction of T cells. Higher densities of intratumoral macrophages compared to regulatory T cells suggest macrophages may be important contributors to the immunosuppressive tumor environment. Future directions for combination therapy include altering T cell trafficking and targeting tumor associated macrophages (TAMs) to enhance intratumoral activated T cell density and effect a more robust immune response.

There is mounting evidence that the immune system plays an important role in the development and growth of gynecologic malignancies, and preliminary studies show activity of immune checkpoint inhibitors in ovarian, endometrial, and cervix cancer. In this review, we outline the completed trials of immune checkpoint blockade in the treatment of gynecologic malignancies. In addition, we review the ongoing trials in each disease site. The questions of which patients will benefit from immune checkpoint inhibitors and when immune checkpoint inhibitors should be incorporated into the treatment of gynecologic malignancies continue to be largely unanswered. As preclinical and clinical data emerge regarding predictive markers for response and resistance to immune checkpoint inhibitors, rational combination treatment strategies will help to further develop this emerging field in the treatment of gynecologic malignancies.

During the past decade significant progress in the understanding of stimulatory and inhibitory signaling pathways in immune cells has reinvigorated the field of immuno-oncology. In this review we outline the current immunotherapy based approaches for the treatment of gynecological cancers, and focus on the emerging clinical data on immune checkpoint inhibitors, adoptive cell therapies, and vaccines. It is anticipated that in the coming years biomarker-guided clinical trials, will provide for a better understanding of the mechanisms of response and resistance to immunotherapy, and guide combination treatment strategies that will extend the benefit from immunotherapy to patients with gynecologic cancers.

The tumor microenvironment has an important role in cancer progression. Here we show that miR-148a is downregulated in 15 out of 16 samples (94%) of cancer-associated fibroblasts (CAFs) compared with matched normal tissue fibroblasts (NFs) established from patients with endometrial cancer. Laser-capture microdissection of stromal cells from normal tissue and endometrial cancer confirmed this observation. Treatment of cells with 5-aza-deoxycytidine stimulated the expression of miR-148a in the majority of CAFs implicating DNA methylation in the regulation of miR-148a expression. Investigation of miR-148a function in fibroblasts demonstrated that conditioned media (CM) from CAFs overexpressing miR-148a significantly impaired the migration of five endometrial cancer cell lines without affecting their growth rates in co-culture experiments. Among predicted miR-148a target genes are two WNT family members, WNT1 and WNT10B. Activation of the WNT/β-catenin pathway in CAFs was confirmed by microarray analysis of gene expression and increased activity of the SuperTOPFIash luciferase reporter. We found elevated levels of WNT10B protein in CAFs and its level decreased when miR-148a was re-introduced by lentiviral infection. The 3′-UTR of WNT10B, cloned downstream of luciferase cDNA, suppressed luciferase activity when co-expressed with miR-148a indicating that WNT10B is a direct target of miR-148a. In contrast to the effect of miR-148a, WNT10B stimulated migration of endometrial cancer cell lines. Our findings have defined a molecular mechanism in the tumor microenvironment that is a novel target for cancer therapy.

Objectives The objective of this pilot study was to determine if frailty predicts surgical complications among elderly women undergoing gynecologic oncology procedures. Methods A cohort of gynecologic oncology patients age ≥65, undergoing surgery between March and December 2011 was identified. Frailty was evaluated using a validated assessment tool. The primary outcome measure was 30day postoperative complication rate. Results Forty women were approached for study entry and 37 (92%) enrolled. The mean age was 73years (range 65–95). The majority of women had a malignancy and underwent a major abdominal surgical procedure. Twenty-one women (57%) were not frail, 10 (27%) were intermediately frail and 6 (16%) were frail. There was no difference in age or prevalence of medical comorbidities between groups. Frail women had a significantly higher BMI compared to intermediately frail and not frail women, (36.0, 31.5 and 26.1kg/m 2 , p =0.02). The rate of 30-day surgical complications increased with frailty score and was 24%, versus 67% for women who were not frail as compared to the frail ( p =0.04). Conclusions Pre-operative frailty assessment is well accepted by gynecologic oncology patients and feasible in a clinic setting. Frail women had a higher BMI, indicating that low body weight is not a marker for frailty, and had a significantly higher rate of 30-day postoperative complications in this pilot study. Initial findings support the concept of measuring frailty as a possible predictor for postoperative morbidity that will allow for improved patient counseling and decision making.

It is well established that there is a dynamic relationship between the expanding tumor and the host surrounding tissue. Cancer-associated fibroblasts (CAFs), the most common cellular population found in the tumor microenvironment, supporting tumor growth and dissemination. Here, we set out to determine the factors that may be involved in dramatic alteration of gene expression pattern in CAFs, focusing on microRNA and transcriptional regulators. We established matched pairs of human CAFs isolated from endometrial cancer and normal endometrial fibroblasts. MicroRNA and mRNA analyses identified differential expression of 11 microRNAs, with miR-31 being the most downregulated microRNA in CAFs (p = 0.007). We examined several putative miR-31 target genes identified by microarray analysis and demonstrated that miR-31 directly targets the homeobox gene SATB2, which is responsible for chromatin remodeling and regulation of gene expression, and was significantly elevated in CAFs. The functional relevance of miR-31 and SATB2 were tested in in vitro models of endometrial cancer. Overexpression of miR-31 significantly impaired the ability of CAFs to stimulate tumor cell migration and invasion, without affecting tumor cell proliferation. Genetic manipulation of SATB2 levels in normal fibroblasts or CAFs showed that, reciprocally to miR-31, SATB2 increased tumor cell migration and invasion, while knockdown of endogenous SATB2 in CAFs reversed this phenotype. Introduction of SATB2 into normal fibroblasts stimulated expression of a number of genes involved in cell invasion, migration and scattering. These findings provide new insights into tumor-stroma interaction and document that miR-31 and its target gene SATB2, are involved in regulation of tumor cell motility.

High-grade ovarian cancer is extremely sensitive to chemotherapy and yet usually lethal due to recurrent disease. To address the underlying mechanism of chemotherapy resistance in this disease, we employed novel technology developed to clone normal adult epithelial stem cells to generate libraries of patient-specific, clonogenic tumor cells. These clones possess hallmarks of “cancer stem cells” including long-term self-renewal and recapitulation of tumors of appropriate histology in immunodeficient mice. Significantly, these clonogenic tumor cells possess the overall pattern of genomic alterations of the whole tumor and yet display clone-specific patterns of variation reflecting intratumor heterogeneity that is stable despite months of continuous propagation. Our analyses at the clonal level have revealed a subset that display an intrinsic, pretherapy resistance to paclitaxel and hypervariable genomics in contrast to the bulk of clones sampled from the library. These intrinsically resistant clones share genomic and gene expression profiles with those surviving paclitaxel treatment of the whole library, suggesting a role for intrinsically resistant cells in recurrent disease. Remarkably, known drugs that interfere with signaling pathways enriched in both intrinsically resistant and paclitaxel survivor clones are synthetically lethal with standard-of-care chemotherapy. The targeting of intrinsically resistant clones from patient-specific libraries of cancer stem cells offers new strategies for preempting recurrent disease. Citation Format: Guoqiang Chang, Jinxiu Li, Bailiang Wang, Yusuke Yamamoto, Rajasekaran Mahalingam, Marcin Duleba, Wei Rao, Jingzhong Xie, Shan Wang, Amir Jazaeri, Peter Davies, Suzy Torti, Giulio Draetta, Matthew Anderson, Molly Brewer, Christopher Crum, Frank McKeon, Wa Xian. Cloning and vulnerability of intrinsically resistant subset of ovarian cancer stem cells. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr B05.

Introduction: High-grade ovarian cancer (HGOC) shows excellent responses to standard-of-care surgery and paclitaxel/carboplatin therapy only to relapse 6-24 months later with typically resistant disease. While the origin of this recurrent, resistant disease is unclear, most believe it is acquired by the action of chemotherapeutics. Using novel stem cell technology that enables the cloning of cancer stem cells (CSCs) from epithelial cancers, we have generated large libraries of CSCs from multiple cases of HGOC. And while the vast majority of these CSC clones are killed by standard-of-care chemotherapeutic drugs, a minor fraction shows profound resistance not only to paclitaxel/carboplatin but to a wide range of structurally unrelated chemotherapeutic drugs to which these cells had no prior exposure. We describe screens for drugs that selectively target this resistant CSC population. Methods: Libraries of 10- to 100,000 CSC clones were generated from individual, therapy naïve, HGOC resections using technology we developed for cloning so-called “adult” stem cells from normal columnar epithelia (Wang et al., 2015). Results: Paclitaxel/carboplatin resistant CSCs were identified in CSC libraries derived from therapy naïve tumors at ratios of 1:50 to 1:300. By copy number variation, these resistant variant clones proved distinct from the bulk of CSCs, and by gene expression analysis varied from sensitive clones by more than 700 differentially expressed genes. Independent resistant clones from the same library clustered with other resistant clones by both copy number variation and gene expression profiles, suggesting the possibility that resistance within a single tumor is dominated by a single type of resistant CSCs. Clones resistant to paclitaxel/carboplatin were screened in a 384-well format against a wide range of experimental drug-like molecules. These pre-existing resistant clones also proved to be profoundly resistant to a large number of structurally unrelated chemotherapeutic drugs. This same screening program identified drugs that act alone or in combination with paclitaxel to eliminate these resistant clones, suggesting a route to personalized medicine for addressing the problem of recurrent disease in HGOC. Conclusions: Tumors from patients with HGOC possess clonogenic CSCs including variants that are resistant to a broad spectrum of chemotherapeutics to which they have not been exposed. It is likely that such CSCs would survive standard-of-care chemotherapy and contribute to the recurrent disease seen in HGOC. We have identified known and experimental drugs that specifically eliminate these resistant variants and the overall platform represents a potential strategy to addressing the problem of recurrent disease in these patients. Citation Format: Wa Xian, Frank McKeon, Christopher Crum, Jingzhong Xie, Bailiang Wang, Yusuke Yamamoto, Suzy Torti, Molly Brewer, Matthew Anderson, Amir Jazaeri, Giulio Draetta, Shan Wang, Rajasekaran Mahalingam, Hong Chen, Marcin Duleba, Wei Rao. Pre-existence of poly-resistant cancer stem cells in high-grade ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1994.

Adoptive cell therapy (ACT) may be effective in treating immunogenic tumors with high mutational load, such as melanoma, and virally-associated tumors, like cervical cancer, with several patients in studies performed at various institutions achieving durable, complete responses for years. HPV infection increases mutational load, thus providing additional neoantigen targets ideal for the polyclonal nature of ACT. As outcomes for patients with recurrent, metastatic or persistent cervical cancer remain extremely poor, there is an enormous need for novel immunotherapeutic approaches with curative potential such as ACT. Clinical trial C-145-04 (NCT03108495) is a prospective, phase II multicenter, open-label study evaluating the efficacy of a single autologous tumor infiltrating lymphocyte infusion (LN-145) followed by IL-2 after a non-myeloablative lymphodepletion (NMA-LD) regimen in patients with recurrent, metastatic, or persistent cervical cancer, who have failed at least one prior systemic therapy. The clinical trial requires resection of an adequate size tumor lesion, which is then shipped to a central GMP manufacturing facility for tumor infiltrating lymphocyte (TIL) extraction, expansion, and preparation of the final infusion product (LN-145). One week prior to LN-145 shipment and infusion, patients undergo NMA-LD consisting of cyclophosphamide (60 mg/kg) daily x 2 days followed by fludarabine (25 mg/m2) daily x 5 days. LN-145 is infused 24 hours after the last dose of fludarabine followed by up to 6 doses of IL-2 (600,000 IU/kg) every 8-12 hours. The primary endpoint is the ORR per RECIST v1.1. Secondary endpoints include complete response, duration of response, disease control rate, progression free- and overall survival and safety. Patients must, in addition to the tumor targeted for excision for TIL manufacture, have an additional measurable lesion for assessment of response. Other major eligibility criteria include: adequate bone marrow, liver, pulmonary, cardiac and renal function; ECOG performance status of 0 or 1. Systemic steroids greater than 10 mg/day prednisone equivalents are prohibited as are a history of serious immunotherapy-related adverse events. Citation Format: Amir Jazaeri, Robert Edwards, Robert Wenham, Koji Matsuo, Gini F. Fleming, David M. O'Malley, Brian Slomovitz, Bradley Monk, Robert J. Brown, Sam Suzuki, Igor Gorbatchevsky, Maria Fardis, Emese Zsiros. A phase 2 multicenter study to evaluate the efficacy and safety using autologous tumor infiltrating lymphocytes (LN-145) in patients with recurrent metastatic or persistent cervical carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT172.

5536Background: Despite current treatments patients with persistent/recurrent cervical cancer (CC) after platinum-based chemotherapy have limited therapeutic options with a median survival limited ...

TPS5604Background: Adoptive cell therapy (ACT) with tumor-infiltrating lymphocytes (TIL) has demonstrated efficacy in the treatment of immunogenic tumors with high mutation loads, such as melanoma,...

8 Background: The composition of the vaginal microbiome has been shown to affect clearance of HPV virus and transformation to invasive cancer. Clinical studies correlating the vaginal microbiome with immune activation and response to cancer treatment are lacking. We profiled intratumoral T-cell clonality during radiation therapy and correlated it with the diversity of the vaginal flora. Methods: Thirty patients with newly diagnosed locally advanced cervical cancer were enrolled on a prospective study to characterize changes in the cervical microbiome during chemoradiation. Cervical samples were obtained before radiation therapy and during the 1st, 3rd, and 5th week of radiation therapy. The vaginal microbiome was characterized using 16 sRNA gene sequencing to produce operational taxonomic units (OTU’s) representing individual bacterial species. Disease response was categorized as early response (ER), late response (LR), or nonresponse (NR) on the basis of clinical examination at brachytherapy and 3-month PET/CT. Twenty patients had T-cell receptor β sequencing of DNA performed using the ImmunoSEQ platform. The maximum productive frequency of the top three clones (MP3) was used to assess T-cell clonality. Results: Early response was associated with clonal T-cell expansion with an increase of MP3 of 11.1% during treatment as compared to a decline of 6.1% in patients with LR/NR (p = 0.05). Early response was also associated with lower quantity of observed OTU’s of vaginal microbiota (25.0 [SD 12.68]) vs patients with LR/NR (41.15 [SD = 23.3]) (p = 0·03). Increased MP3 was associated with increased abundance of Corynebacteriales (R = 0.90; p < .0001) , Actinomycetales (R = 0.83; p < .0001) and Bifidobacteriales (R = 0.82; p < .0001) . Decreased MP3 was associated with increased abundance of lactobacillus (R = -0.61; p < .0001). Conclusions: Increased diversity of the vaginal microbiome is negatively associated with outcome, supporting previous clinical studies in non-cancer settings. Specific vaginal bacterial species are associated with increased or decreased T-cell clonality at completion of radiation.

6 Background: Limited data in cancer patients have suggested that chemotherapy and radiation impact local and systemic immune cell populations. Radiation therapy (RT) is known to deplete circulating lymphocytes but is thought to increase local antigen presentation. The dynamics of these competing effects on the kinetics of intratumoral infiltration and expansion of activated and immunoregulatory T cells are unknown. Methods: We prospectively evaluated intratumoral immune infiltration during fractionated RT using multi-spectral flow cytometry. Cervical brushings were obtained from 14 patients before (baseline) and during RT (week 1, 3 and 5). Cells collected from the cervical brushings were stained with a 16-color panel of antibodies that included markers to identify T cell and dendritic cell subsets with activation and suppressor molecules. Changes in immune cell subsets at different time points were evaluated and calculated using matched-pair analysis with Wilcoxon rank sum test. Results: CD3+ T cells declined over the first week of treatment (28% of CD3 at baseline, vs. 14.8% at week 1, p = 0.0273). The percentage of CD3+ cells subsequently increased at 3 weeks (25.6%) and 5 weeks (37.8%). Both CD8+ and CD4+ T cells underwent a decline at week 1 followed by expansion at week 3 and 5. Percentages of regulatory T cells (CD4+Foxp3+) showed a similar trend of reduction and further expansion but did not reach significance. The percentage of CD8+ T cells expressing the T cell activation marker CD69 and the cytotoxic protease Granzyme B (GrzB) continuously increased over time (CD69+: 11.8%, 27.7%, 38.7%, 57.5%, and GrzB+: 23.9%, 53.2%, 48.1%, 58.2%). While the percentage of dendritic cells (CD11c+ CD11b+) was stable during treatment, the subset of activated dendritic cells expressing CD86 increased at week 1 and subsequently declined (week 1, 19.1% vs week 5, 9.8%, p = 0.0642). Conclusions: Activated CD8+ effector T cells expand in the cervix during radiation therapy. Moreover, in the first week of treatment, CD8+ T cells contract while dendritic cells undergo activation suggesting this may be a critical time to intervene to maximize anti-tumor immunity.

TPS77 Background: Adoptive cellular therapy (ACT) has dramatically changed the landscape of immunotherapy; however, only a small proportion of solid tumor patients have benefited from these advances due to i) heterogeneity of tumor antigen expression, ii) tumor escape (e.g. only one target is addressed), or iii) off-target toxicities (e.g. expression of targets on normal tissues). The ACTolog concept, utilizing antigen specific T cells (IMA101) against targets identified by the Immatics’ proprietary XPRESIDENT technology, is intended to overcome these limitations by addressing multiple novel relevant tumor antigens per patient. ACTolog is a personalized, multi-targeted ACT approach in which autologous T-cell products are manufactured against the most relevant tumor target peptides for individual patients whose tumors are positive against a predefined target warehouse. Methods: This study is an open-label first-in-human phase I trial in patients with relapsed or refractory solid tumors expressing at least one target from a warehouse of 8 cancer targets. Key eligibility criteria include: HLA-A*02:01 phenotype, qPCR expression of warehouse target(s), prior established lines of therapy, RECIST v1.1 measurable lesions, and ECOG performance status 0 or 1. At baseline, patients will undergo leukapheresis to collect mononuclear cells for manufacturing of IMA101 cells. Patients will receive their last line of established therapy during the production phase of IMA101. IMA101 will be infused after a pre-conditioning regimen (lymphodepletion) followed by LD-IL2. The primary objective is to assess safety and tolerability of IMA101. Secondary endpoints include overall response rate (RECIST and irRC), PFS and OS. The translational objective is to assess the in vivo persistence and ex vivo functionality of transferred T cells in addition to evaluation of target expression in tumors. Enrollment to the study is currently ongoing. Clinical trial information: NCT02876510 .

Introduction: Our objective was to retrospectively review temozolomide in advanced and recurrent uterine leiomyosarcoma and to determine if tumor O6-methylguanine DNA methyltransferase (MGMT) expression correlated with clinical response. Methods: All patients with advanced or recurrent uterine leiomyosarcoma who received temozolomide during treatment were retrospectively identified. Relevant clinical and pathologic data were collected and compared. O6-Methylguanine DNA methyltransferase expression was assessed by immunohistochemistry and scored by a gynecologic pathologist blinded to clinical outcomes. Results: From 1999 to 2008, 9 cases of leiomyosarcoma were diagnosed; 6 patients received temozolomide. Median follow-up was 54 months (range, 4-114 months). There was 1 patient with complete response, 1 durable partial response (27+ months), 3 stable disease (range, 3-10 months), and 1 progressive disease. Overall, 5 out of 6 patients derived clinical benefit. The patient with a complete response recurred 18 months after her last cycle. Median progression free interval was 15.4 months (95% confidence interval, 9.4-21.4). Two patients died of disease. Temozolomide was well tolerated with no dose-limiting toxicities, and no dose adjustments were required in 64 prescribed cycles. The MGMT expression was inversely correlated with response to temozolomide. Patients with tumors negative for MGMT expression had a median progression free interval of 18.5 months compared with 3 months for those whose tumors were positive, although not statistically significant. Conclusions: Temozolomide is an easily administered, well-tolerated chemotherapeutic option in advanced or recurrent uterine leiomyosarcomas with a reasonable response rate. Assessment of MGMT expression may identify a subset of patients that will respond optimally to this therapy.