bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 3172: Prognostic and therapeutic implication of programmed death ligand 1 (PD-L1), microsatellite instability, and PIK3CA gene in lipoarcoma
Authors: Kim Hyo Song , Jeon Hyae Min , Lee Jae Seok , Kim Soo Hee , Lee Young Han , Hur Hyuk , Kim Sung Hoon , Kim Seung Hyun , Jeung Hei-Cheul
Published: August 2019

Background: With the promising efficacies with personalized approach, we tested clinically relevant molecular target programmed death ligand 1 (PD-L1), microsatellite Instability (MSI), and PIK3CA molecules in liposarcoma to provide practical guide.

Methods: A consecutive series of 74 liposarcoma patients who underwent curative resection between 2005 and 2016 were assessed using immuno-molecular panels: PD-L1 (22C3 pharmDx assay) and mismatch repair proteins (MLH1, PMS2, MSH2, and MSH6) by immunohistochemistry (IHC), MSI using PCR, and PIK3CA mutation/amplification using pyrosequencing and fluorescence in situ hybridization.

Results: For all the cases, PD-L1 was positive only in tumor infiltrating lymphocytes (TILs), while no PD-L1 expression was found on tumor cell and 23% were tumors with PD-L1+ TILs. PD-L1+ TILs was significantly predominant in abdominal site (P=0.004) and had significantly longer overall survival than PD-L1- TILs (5 year OS 84.4% vs 60.8%, P=0.007). Regarding the MSI status, 2 well differentiated liposarcoma showed MSI [MSI-H (n=1) and MSI-L (n=1)]. For concordance with mismatch repair protein using IHC, only 1 out of 8 with concurrent loss of MLH1, MSH6, and PMS2 showed MSI-H (D2S123, D17S250). Activating PIK3CA mutation was detected in 7 patients [9.5%, exon 9 (n=4) and exon 20 (n=3) mutation] and 6 cases were PD-L1-TIL group. PIK3CA copy number gain were detected in 18 (24.3%) cases and significantly associated with PD-L1+TIL tumors (P=0.045).

Conclusions: With our comprehensive immuno-moleuclar panel, liposarcoma need to be categorized based on the molecular genomic subtype and this may facilitate the development of successful future clinical trials using molecular agents.

Citation Format: Hyo Song Kim, Hyae Min Jeon, Jae Seok Lee, Soo Hee Kim, Young Han Lee, Hyuk Hur, Sung Hoon Kim, Seung Hyun Kim, Hei-Cheul Jeung. Prognostic and therapeutic implication of programmed death ligand 1 (PD-L1), microsatellite instability, and PIK3CA gene in lipoarcoma [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 3172.
Abstract 3186: A novel combination therapy for treating advanced drug resistant acute lymphoblastic leukemia
Authors: Vicioso Yorleny M. , Beck Rose , Gram Herman , Asthana Abhishek , Zhang keman , Wong Derek , Letterio John , Parameswaran Reshmi
Published: August 2019

Purpose: Drug resistance and relapse are two major problems in Acute Lymphoblastic Leukemia (ALL) as these patients do not respond to chemotherapy. We observed BAFF-R expression on drug resistant and relapse B-ALL patient cells. We wanted to explore the in vivo therapeutic efficacy of a BAFF-R antibody, optimized for antibody dependent cellular cytotoxicity (ADCC), against drug resistant ALL cells.

Experimental design: ADCC assay was performed using primary human natural killer (NK) cells isolated from normal donors or ALL patients. NK cell mediated cytotoxicity was measured using Calcein-AM assay. Immunocompromised NSG mice were used for in vivo xenograft model of ALL.

Results: We found that anti-BAFF-R antibody enhanced NK cell mediated killing of drug resistant ALL cells in vitro. Early treatment with anti-BAFF-R antibody and NK cells significantly reduced disease burden in xenograft ALL models and increased overall mice survival. However, in advanced disease, the efficacy of NK cells to mediate ADCC is reduced. ALL cells are known to produce TGF beta, that causes NK cell dysfunction. We found that ALL cells produce TGF-β and co-culturing ALL cells with NK cells lead to a decrease in CD16 expression on NK cells, which is reversible by addition of EW-7197, a potent TGF-beta receptor I inhibitor. We found that EW-7197 treatment improved anti-BAFF-R antibody mediated ADCC of drug resistant ALL cells, in vivo, even if treatment is started late.

Conclusion: Combination treatment using BAFF-R antibody, NK cells and EW-7197 is a potential strategy to treat advanced drug resistant ALL patients with BAFF-R expressing blasts.

Citation Format: Yorleny M. Vicioso, Rose Beck, Herman Gram, Abhishek Asthana, keman Zhang, Derek Wong, John Letterio, Reshmi Parameswaran. A novel combination therapy for treating advanced drug resistant acute lymphoblastic leukemia [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 3186.
Abstract 3197: BI-907828, a novel and potent MDM2-p53 antagonist, acts synergistically in a triple combination with anti-PD-1 and anti-LAG-3 antibodies in syngeneic mouse models of cancer
Authors: Rudolph Dorothea , Weyer-Czernilofsky Ulrike , Reschke Markus , Sykora Martina , Rinnenthal Jörg , Blake Sophia , Gremel Gabriela , Wernitznig Andreas , Gollner Andreas , Kraut Norbert , Moll Jürgen
Published: August 2019

MDM2-p53 antagonists block the interaction between the Tumor Protein p53 and MDM2, its key negative regulator, and represent a new therapeutic concept for cancer therapy. MDM2-p53 antagonists are designed to restore p53 activity in TP53 wild-type tumors. Several MDM2-p53 antagonists are currently being evaluated in early clinical development. BI-907828 is a novel and potent MDM2-p53 antagonist with optimized drug-like properties that has shown efficacy in human tumor xenograft models at daily low oral dose as well as intermittent high dose schedules. Recent preclinical studies in syngeneic mouse models of cancer have demonstrated that BI-907828, apart from its direct tumor-targeting activity, also has immunomodulatory activity shown to contribute to efficacy. Single-agent BI-907828 induced anti-tumor immunological memory that controlled tumor growth in a re-challenge study. Moreover, a dual combination with an anti-mouse PD-1 checkpoint inhibitor resulted in synergistic efficacy in a syngeneic mouse model of cancer (AACR 2018, abstract 4866). Here we present data for the triple combination of BI-907828 with two checkpoint inhibitors. In syngeneic mouse tumor models (Colon-26 and B16-F10), the combination of BI-907828 with tool antibodies against mouse PD-1 and mouse LAG-3 shows high response rates of 50-90% with tumor regressions observed for even very large tumors. Moreover, efficacy of the triple combination is superior to each single agent and all dual combinations. An antibody-mediated depletion study suggests a contribution of CD8+ T cells but not of CD4+ T cells to full efficacy of the triple combination. FACS analysis of tumors isolated from Colon-26 tumor-bearing mice indicates that treatment with the triple combination leads to expansion of tumor-infiltrating CD8+ T cells. In summary, BI-907828 is a novel, potent, orally bioavailable MDM2-p53 antagonist that shows synergistic efficacy in a triple combination with antibodies targeting the immune checkpoints PD-1 and LAG-3 in syngeneic mouse models of cancer. BI-907828 is currently under evaluation in a Phase I clinical study (NCT03449381).

Citation Format: Dorothea Rudolph, Ulrike Weyer-Czernilofsky, Markus Reschke, Martina Sykora, Jörg Rinnenthal, Sophia Blake, Gabriela Gremel, Andreas Wernitznig, Andreas Gollner, Norbert Kraut, Jürgen Moll. BI-907828, a novel and potent MDM2-p53 antagonist, acts synergistically in a triple combination with anti-PD-1 and anti-LAG-3 antibodies in syngeneic mouse models of cancer [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 3197.
Abstract 3199: Targeting LHRH-R to improve immune response in ovarian cancer
Authors: Kim Mark S. , Ma Shaolin , Leuschner Carola , Lee Sanghoon , Coleman Robert L. , Sood Anil K.
Published: August 2019

Background: While immune checkpoint inhibitors have revolutionized the treatment of multiple cancers, such therapies have had limited efficacy in ovarian cancer. We hypothesized that a lytic peptide could stimulate local immune response and enhance efficacy of checkpoint blockade. Here, we tested the effects of a synthetic lytic peptide targeting the luteinizing hormone receptor (LHRH-R), EP-100, on immune therapy in ovarian cancer models.

Methods: We carried out series of in vitro (MTT assay, immunoblot analysis, cytokine array, and immune profiling assay) and in vivo (orthotopic mouse model) experiments to determine the biological effects of EP-100 monotherapy and its combination with checkpoint blockade, α-PD-L1.

Results: We found that LHRH-R positive murine ovarian cancer cells (ID8, IG10, IF5, and 2C12) were sensitive to EP-100 and were specifically killed at low micromolar levels through LHRH-R. The in vivo syngeneic mouse models (ID8 and IG10) demonstrated that EP-100 reduced tumor volume, tumor weight, and ascites volume as a single agent. The greatest effects on tumor volume reduction and ascites volume were observed with the combination of EP-100 and α-PD-L1 antibody, indicating a potentially synergistic effect in vivo. Immune profiling of tumors showed that the population of CD8+ T cells, NK cells, dendritic cells, and macrophages were significantly increased in tumor and ascites treated with α-PD-L1, EP-100 and in the combination group. However, monocytic myeloid suppressor cells, B cells, and regulatory T cells were decreased in tumors treated with α-PD-L1, EP-100 and in the combination group. We found similar effects of EP-100 combination with α-PD-L1 antibody in ascites from each group. These data indicate that EP-100 promotes a tumor microenvironment that is favorable for immune response. In vitro cytokine arrays revealed that EP-100 induced IL-1α, IL-33, CCL20, VEGF, and LDLR secretion. Among them, we validated increasing Il-33 level following EP-100 treatment in vivo and in vitro and determined the specific biological role of CD8+ T cell activation with IL-33 gene silencing using siRNA and Cas9-CRISPR approaches. In addition, we found that CD8+ T cell expressed a low level of LHRH-R and had minimal direct effects from EP-100. Conclusion: These data demonstrate strong efficacy of EP-100 and checkpoint blockade therapy. Our results provide new directions to enhance the efficacy of immune therapies for ovarian cancer.

Citation Format: Mark S. Kim, Shaolin Ma, Carola Leuschner, Sanghoon Lee, Robert L. Coleman, Anil K. Sood. Targeting LHRH-R to improve immune response in ovarian cancer [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 3199.
Abstract 3200: Immunotuning CD8+ T cells with BCAT1 inhibition to increase the efficacy of anti-PD-1 therapy and to eradicate moderately immunogenic tumors
Authors: Papathanassiu Adonia E. , Kim Dong-Wook , Park Kwon-Sik , Ko Jeong Hun , Behmoaras Jacques V.
Published: August 2019

Activation and differentiation of adaptive and innate immune cells require metabolic reprogramming involving diverse metabolic processes. Understanding these processes affords the opportunity to influence and ultimately re-direct the function and fate of these cells. Here, we present data suggesting that exposure of newly activated human CD8+ T cells to a small molecule inhibitor (ERG245; 50-400 μM) of BCAT1 (the cytosolic isoform of the enzyme responsible for the first step in the catabolism of leucine, isoleucine, and valine) resulted in inhibition of T cell proliferation, inhibition of IFNγ and Granzyme B production, and upregulation of PD-1. The antiproliferative effect, as determined by CFSE dilution, required inhibition of BCAT1 during the first 24 hrs of T cell activation and it was reversible upon early withdrawal of the inhibitor. Early withdrawal of ERG245 reversed the observed immunosuppression, ultimately giving rise to CD8+ T cells with higher proliferative capacity and increased cytotoxicity compared to untreated control cells. Exposure of CD8+ T cells to ERG245 resulted in a distinct metabolic phenotype including reduced concentrations of α-ketoglutaric acid (αKG), and lower levels of trimethylation of the lysine 4 (K4) and lysine 27 (K27) sites of histone 3 (H3), which implies that BCAT1 inhibition has epigenetic effects on human CD8+ T cells by modulating αKG-dependent histone demethylases. Similar observations were made with CD8+ T cells, isolated from the spleens of Bcat1 KO mice. In vivo, ERG245 (given at 5 mg/kg ip, bid at days 0, 1 and 2 of treatment), dramatically increased the efficacy of an anti-PD-1 antibody (clone RMP1-14; given at 10 mg/kg at days 0, 4, 7, and 11 of treatment) in the CT26 colon cancer model. Specifically, the combination of ERG245 and anti-PD-1 eradicated established tumors within a week of treatment initiation (cure rate of >80%), whereas the monotherapies (ERG245 or anti-PD-1 alone) did not improve the disease outcome. The data suggest that the temporal exposure of moderately immunogenic tumors to BCAT1 inhibition sensitizes the tumors to checkpoint inhibition.

Citation Format: Adonia E. Papathanassiu, Dong-Wook Kim, Kwon-Sik Park, Jeong Hun Ko, Jacques V. Behmoaras. Immunotuning CD8+ T cells with BCAT1 inhibition to increase the efficacy of anti-PD-1 therapy and to eradicate moderately immunogenic tumors [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 3200.
Abstract 3201: Rigosertib, a Ras mimetic, inhibits melanoma cell viability and synergizes with anti-PD1 to promote anti-tumor immune responses
Authors: Yan Chi , Reddy Premkumar E. , Richmond Ann
Published: August 2019

Activating mutations in BRAF or NRAS are present in 40% and 21% of melanoma patients, respectively, leading to enhanced cell survival and proliferation. Rigosertib (RGS) is a non-ATP-competitive small molecule RAS mimetic that has the potential to block RAS-RAF-MEK-ERK and PI3K-AKT-mTOR signaling pathways and interfere with CRAF interaction with PLK1 and consequently its centrosomal localization. Here, we demonstrate that RGS inhibits the cell viability at µM levels of human (including A375/SKMel2/SKMel5/HS294T) and murine (including B16F10 and YUMM2.1/3.3/4.1/5.2) melanoma cell lines with a variety of somatic mutational backgrounds. We discovered that RGS treatment immediately (<15mins) and constantly (up to 24hrs) suppresses PI3K-AKTT308 and mTORC2-AKTSer473 phosphorylation. Using the murine melanoma cell line YUMM3.3 (BrafV600E/wtCdkn2-/-), we showed that RGS monotherapy, elevated the production of mitochondrial reactive oxygen species, promoted cellular apoptosis, suppressed mitosis in vitro, and inhibited tumor growth in C57BL/6 mice. The optimal in vivo dose of RGS (300mg/kg), which exhibited >50% inhibition of tumor volume and tumor weight, was well tolerated in mice. RGS-treated tumors exhibited an inflammatory tumor microenvironment (TME) with enrichment of dendritic cells and CD45-MHCII+ cells, elevation in frequency and activation of both CD4+ and CD8+ T cells and NK cells, but a decrease in the level of tumor-infiltrating macrophages. Of note, treatment with RGS plus αPD-1 checkpoint blockade synergistically inhibited tumor growth by ~70%. The RGS + αPD-1 combination treatment, but not the monotherapies, reduced the frequency of exhausted PD-L1+LAG3+TIM3+ CD8+ T cells at the tumor sites, as well as in the tumor-draining lymph nodes. Conclusion: These results suggest that RGS, which is a Ras mimetic, may be used in combination with anti-PD-1 immunotherapies to enhance anti-tumor immunity and optimize the treatment of melanoma. This combination therapy warrants a clinical study.

The authors sincerely thank Onconova Therapeutics, Newtown, PA 18940 for kindly supplying Rigosertib for this work.

Citation Format: Chi Yan, Premkumar E. Reddy, Ann Richmond. Rigosertib, a Ras mimetic, inhibits melanoma cell viability and synergizes with anti-PD1 to promote anti-tumor immune responses [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 3201.
Abstract 3203: Intratumoral STING activation normalizes tumor vasculatures and synergizes with anti-angiogenic therapy to enhance cancer immunity
Authors: Yang Hannah , Kim Hyojoong , Kim Joo Hoon , Chon Hong Jae , Kim Chan
Published: August 2019

Purpose: The stimulator of interferon genes (STING) signaling pathway is a critical link between innate and adaptive immunity, and induces anti-tumor immune responses. STING is expressed in vasculatures, but its role in tumor angiogenesis has not been elucidated. Here we investigated STING-induced tumor vascular remodeling and the potential of STING-based combination immunotherapy.

Experimental Design: We examined the endothelial STING expression pattern and clinical implications in human malignancies. STING-induced vascular remodeling was studied using STING-deficient or wild-type mice. Implanted LLC tumors and transgenic MMTV-PyMT breast tumors were intratumorally injected with STING agonists (cGAMP or RR-CDA), with or without anti-VEGFR2 antibody and/or immune checkpoint inhibitors. The tumor microenvironment was evaluated by histologic and immune profiling analyses.

Results: Endothelial STING expression was correlated with enhanced T-cell infiltration, reduced lymphovascular invasion, and prolonged survival in human colon and breast cancer. Intratumoral STING activation normalized tumor vasculatures, as shown by increased pericyte coverage and intact basement membrane, which was mediated by upregulation of vascular stabilizing genes (e.g., Angpt1, Pdgfrb, and Col4a) and endothelial-lymphocyte interaction genes. These effects were dependent on type I interferon signaling and CD8+ T cells. STING activation also induced M1-like macrophage polarization within tumors. Notably, STING-based immunotherapy was maximally effective when combined with VEGFR2 blockade and/or immune checkpoint blockade (αPD-1 or αCTLA-4), leading to complete regression of immunotherapy-resistant tumors.

Conclusions: Our data show that intratumoral STING activation can normalize tumor vasculature and the tumor microenvironment, providing a rationale for combining STING-based immunotherapy and anti-angiogenic therapy.

Citation Format: Hannah Yang, Hyojoong Kim, Joo Hoon Kim, Hong Jae Chon, Chan Kim. Intratumoral STING activation normalizes tumor vasculatures and synergizes with anti-angiogenic therapy to enhance cancer immunity [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 3203.
Abstract 3212: Patient-level pharmacodynamics of response to combined ipilimumab and nivolumab for gastric cancer using a human autologous ex-vivo platform, CANscript
Authors: Kapoor Vidushi , Smalley Munisha , Basak Nandini Pal , Basu Abhishek , Biswas Manjusha , Mandal Manas Kumar , Roy Pinaki , Majumder Pradip K. , Goldman Aaron
Published: August 2019

Background: Combined cancer immunotherapy is an emerging paradigm for the treatment of cancer. PD-L1, the cognate receptor for the programmed death receptor 1 (PD-1) is expressed in up to 40% of gastric/gastroesophageal junction (GEJ) tumors. Despite this, patients show modest responses to PD-1 inhibitors. A recent clinical trial, Checkmate-032, demonstrated superior efficacy when PD-1 inhibitor, Nivolumab, was combined with CTLA-4 inhibitor, Ipilimumab. Despite this, biomarkers that predict clinical response remain poorly understood.

Methods: Here, with informed consent under IRB, fresh tumor biopsies were obtained from a randomly-selected cohort of gastric/GEJ patients (N=39). We then employed CANscriptTM, a clinically-validated human autologous ex-vivo tumor platform to interrogate the pharmacodynamics and prognostic efficacy (M-Score) of nivolumab +/- ipilimumab. PDL-1 status was determined for every patient by immunohistochemistry, flow cytometry was performed to analyze intratumor CD4+ and CD8+ T-cell profiles before and after treatment, and RNA seq. gene expression was performed to understand mechanistic changes under drug pressure.

Results: We predicted, based on M-Score, that single agent nivolumab results in an overall response rate (ORR) of 10%, which closely matched previous single agent results from Checkmate-032 (10%). In contrast, we determined the combination of ipi+nivo resulted in a response rate of 20%, a finding consistent with reported clinical data (Checkmate-032; ORR 18%). Interestingly, we determined that only 28% of patients who responded to the ipi+nivo combination were predicted to respond to the monotherapy, suggesting the increased efficacy of the combination. RNA seq revealed unique features of adaptive immunity in the subset of patients who were predicted to respond to the combination immunotherapy, while PD-L1 status was a less-important biomarker to predict response.

Conclusions: These results demonstrate the utility of the CANscript system to profile clinical response of immunotherapy. Our efforts may better inform clinical trial design and patient stratification before therapy to improve the potential for response.

Citation Format: Vidushi Kapoor, Munisha Smalley, Nandini Pal Basak, Abhishek Basu, Manjusha Biswas, Manas Kumar Mandal, Pinaki Roy, Pradip K. Majumder, Aaron Goldman. Patient-level pharmacodynamics of response to combined ipilimumab and nivolumab for gastric cancer using a human autologous ex-vivo platform, CANscript [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 3212.
Abstract 3227: Differential expression of T cell co-inhibitory receptors: KLRG1 alignment with cytotoxicity and adaptive resistance mechanisms
Authors: Greenberg Steven A. , Thompson Evan , Gulla Stefano V.
Published: August 2019

Introduction: KLRG1 is a lymphocyte co-inhibitory, or immune checkpoint, receptor expressed predominantly on late-differentiated effector and effector memory CD8+ T and NK cells.

Methods: We studied KLRG1 expression in human blood and tumor samples from available genomic datasets.

Results: KLRG1 is differentially expressed from CTLA-4 and PD-1, with predominant expression on cytotoxic CD8 T and NK cells over CD4 T cells. Within the CD8+ T cell population, KLRG1 expression, unlike CTLA-4 and PD-1 expression, is linked to greater antigen-driven differentiation states, with increased expression on CD45RO+CCR7- T effector memory (TEM) and CD45RA+CCR7- T effector memory RA (TEMRA) cells compared to CD45RA+CCR7+ naïve T cells (TN) and CD45RO+CCR7+ central memory T cells (TCM). The cytotoxic potential of CD8+ T cells, as assessed by the presence of cytokine and cytotoxic molecules IFNg, TNFa, perforin and granzyme B, is aligned with KLRG1, but not CTLA-4 or PD-1, expression. In single cell RNAseq analyses, KLRG1+ TILS accounted for 16-48% of CD8+ TILS, a frequency similar to that of PD-1+ TILS, in renal cell carcinoma, hepatocellular carcinoma, melanoma, ovarian cancer, HNSCC, and astrocytoma. KLRG1 expression was numerically increased post-treatment in 20/21 (95%) of datasets, statistically significant in 10/21 (48%), in response to a range of treatments including radiotherapy, chemotherapy, endocrine therapy, and immunotherapies (including ipilimumab, nivolumab, and pidilizumab), over periods of time ranging from 1-25 weeks.

Conclusions: In human blood and tumor samples, KLRG1 expression is aligned with cytotoxic T and NK cell differentiation, and upregulated in human tumor samples after a variety of therapies, potentially contributing to adaptive resistance. The upregulation of KLRG1 could contribute to limited efficacy and adaptive resistance that develops with current immunotherapies, and suggests KLRG1 blockade may work efficaciously, including as a neo-adjuvant therapy.

Citation Format: Steven A. Greenberg, Evan Thompson, Stefano V. Gulla. Differential expression of T cell co-inhibitory receptors: KLRG1 alignment with cytotoxicity and adaptive resistance mechanisms [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 3227.
Abstract 3229: Radiation and chemotherapies result in increasing neoantigen intratumor heterogeneity and resistance to nivolumab in a patient with pleomorphic lung cancer
Authors: Hong Xiaohua , Liu Yuting , Liu Yiying , Hu Yue , Yang Qifan , Wu Di , Zhang Kai , Li Yongchao , Yang Jinsong , Wang Jiaqian , Liu Jun , Liu Li
Published: August 2019

BACKGROUND:Immune checkpoint inhibitors (ICIs) have significantly changed the landscape of cancer treatment, but the response rate of non-small-cell lung carcinoma (NSCLC) to ICIs is less than 30%. Tumor mutational burden (TMB) is the most promising predictive biomarker for NSCLC immunotherapies. However, some NSCLC patients with high-TMB have little response to ICIs. The neoantigen intratumor heterogeneity (ITH), which determined by the ratio of subclonal neoantigen in the tumor, has been verified to be a potential therapeutic biomarker for immunotherapies in some cancer types. Pulmonary pleomorphic carcinoma, a rare subtype of pulmonary sarcomatoid carcinoma, has been shown to respond remarkably to ICIs, but the biomarkers for ICIs in pulmonary pleomorphic carcinoma have not been fully proven. CASE PRESENTATION:A 57 years old female pulmonary pleomorphic carcinoma patient, who underwent surgery, chemotherapy, anti-angiogenic therapy, radiotherapy, and anti-PD1 therapy, with disease relapse at the last, was included in this study. Primary and relapse tumor samples were collected for gene sequencing by a target sequencing panel which covered 811 cancer genes, during ICIs treatment. Peripheral bloods were collected for ctDNA and T cell receptor sequencing every two months. The results showed that the TMB (>10 muts/Mb) was high, but the clonal neoantigen load (1.33 neos/Mb) was low. The neoantigen ITH was increased after chemotherapy and radiotherapy with a score at nearly 0% in the primary tumor but increased to 85.72% in relapse tissues. The clonal neoantigen ratio detected by ctDNA was increased ~0.8 fold, while the high-frequency clonotypes of TCR to neoantigens dropped during ICIs treatment. CONCLUSIONS:Our results indicated that cytotoxic chemotherapy and radiotherapy can induce the subclonal neoantigens production and increase the neoantigen ITH, thus might negatively regulating patients’ response to ICIs therapy. These results highlight that the neoantigen ITH might be an important auxiliary to TMB in predicting patient response to immune therapies. More studies and clinical trials are needed to further validate these results.

Citation Format: Xiaohua Hong, Yuting Liu, Yiying Liu, Yue Hu, Qifan Yang, Di Wu, Kai Zhang, Yongchao Li, Jinsong Yang, Jiaqian Wang, Jun Liu, Li Liu. Radiation and chemotherapies result in increasing neoantigen intratumor heterogeneity and resistance to nivolumab in a patient with pleomorphic lung cancer [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 3229.
Abstract 3233: Novel CTLA-4 antibodies of potent antitumor activity were verified in humanized mouse models
Authors: Shen Yuelei , Ni Jian , Yang Benny(Yi) , Gan Tian , Guo Chaoshe
Published: August 2019

CTLA-4 (cytotoxic T-lymphocyte-associated protein 4), is a member of the immunoglobulin superfamily. It is expressed in T cells upon activation and transmits an inhibitory signal to T cells. It is also constitutively expressed in regulatory T cells (Tregs) which is associated with their immunosuppressive phenotype. CTLA-4 is homologous to the co-stimulatory protein CD28, and both receptors bind to the same ligands, CD80(B7-1) and CD86(B7-2). Importantly, cancer cells can be recognized and destroyed by the host’s immune system. In this setting, CTLA-4 functions as a brake to dampen anti-tumor T cell responses, which promote cancer progression.

In this context, we are exploring antibodies that are as effective or exceed the effects of the approved CTLA-4 antibody. Antibodies blocking CTLA-4 are expected to subvert T cell inhibition. Moreover, regulatory T cells residing in the tumor microenvironment are sensitive to anti-CTLA-4 antibody since they have higher expression levels of CTLA-4 compared to activated T cells. Yervoy, the first FDA-approved CTLA-4 antibody, protects a fraction of cancer patients when used alone or in combination with other drugs. Here we report two humanized antibodies whose efficacy is equivalent or exceed that of Yervoy using the pharmacological efficacy evaluation platform established at Biocytogen. Potent inhibition and biological activity were further demonstrated by a series of tests in vitro. In conclusion, we successfully discovered two antibodies that exhibit superior anti-cancer activity in vivo with our humanized CTLA-4 mouse model. Downstream clinical evaluation of these novel antibodies is needed.

Citation Format: Yuelei Shen, Jian Ni, Benny(Yi) Yang, Tian Gan, Chaoshe Guo. Novel CTLA-4 antibodies of potent antitumor activity were verified in humanized mouse models [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 3233.
Abstract 324: BRAF/MEK inhibitors selectively prime melanoma for Mcl-1 dependence and sensitize to Mcl-1 inhibition
Authors: Kump Karson J. , Miao Lei , Ansari Nurul , Lombard David B. , Nikolovska-Coleska Zaneta
Published: August 2019

Frontline treatment for patients diagnosed with metastatic melanoma harboring a V600 BRAF mutation is a combination of BRAF/MEK inhibitors. Despite advances in targeted therapies used to treat melanoma, the majority of patients will relapse due to acquired resistance. The intrinsic apoptotic pathway is frequently dysregulated in cancer, promoting cell survival and resistance mechanisms. The anti-apoptotic Mcl-1 protein was identified as a key resistance factor to vemurafenib, a mutant BRAF inhibitor, and likely plays a role in preventing apoptosis in the context of dual BRAF/MEK inhibitor resistance. Activation of apoptosis by using small molecule inhibitors of the anti-apoptotic Bcl-2 proteins has become a validated therapeutic approach and can re-sensitize cancers to standard of care treatments. We found that melanoma cell lines display a heterogeneous dependency on anti-apoptotic proteins. In this study, we systematically investigated the role of Mcl-1 in vemurafenib resistance in melanoma cell lines using genetic and pharmacological inhibition of Mcl-1. Using the functional BH3 profiling assay, we discovered that melanoma cell lines resistant to vemurafenib are increasingly primed for Mcl-1 dependence. Additionally, applying dynamic BH3 profiling we demonstrated that melanoma cell lines subjected to short term treatment with vemurafenib showed greater dependency upon Mcl-1 for survival, thus serving as a selective priming agent. Consistent with these findings, both vemurafenib resistant and short-term vemurafenib pre-treated melanoma cell lines displayed increased sensitivity to Mcl-1 genetic silencing using siRNA and direct Mcl-1 inhibition using small-molecule inhibitors developed by our group. We further demonstrate significant synergy in the induction of apoptosis induced by the combination of vemurafenib and Mcl-1 inhibitors such as UM-101. In a similar way, Mcl-1 priming and increased sensitivity to Mcl-1 inhibitors was shown in melanoma cells pre-treated with MEK inhibitors. We further studied the mechanism of apoptosis induced by Mcl-1 inhibitors and validated their cellular target engagement. These studies provide evidence that targeting Mcl-1 represents a promising therapeutic strategy for treating patients with resistant melanomas and aids in the design of rational combination therapies before resistance is acquired.

Citation Format: Karson J. Kump, Lei Miao, Nurul Ansari, David B. Lombard, Zaneta Nikolovska-Coleska. BRAF/MEK inhibitors selectively prime melanoma for Mcl-1 dependence and sensitize to Mcl-1 inhibition [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 324.
Abstract 3249: a-TIGIT mediates antitumor activity through multiple mechanisms of action involving activation of intratumor effector T cells and depletion of regulatory T cells
Authors: Preillon Julie , Denies Sofie , Jamart Diane , Carter Matthew J. , Cragg Mark S. , Driessens Gregory
Published: August 2019

T cell Immunoreceptor with Ig and ITIM domains (TIGIT) is a co-inhibitory receptor expressed by lymphocytes, preferentially CD8+ T cells, NK, as well as regulatory T cells (Treg). TIGIT can be bound by several ligands including CD155 and CD112 that are frequently expressed by tumor cells. In cancer, TIGIT expression is upregulated on conventional T cells and even more on regulatory T cells. Co-expression with exhaustion markers such as PD-1 is common, giving a strong rationale for blocking TIGIT as a therapeutic approach for reversing T or NK cell dysfunction linked with cancer progression.

The mechanism of action of novel a-TIGIT monoclonal antibody (mAb) was characterized in vivo in the murine CT26 tumor model. This model mimics the human situation based on expression of TIGIT ligands on tumor cells and infiltration by effector and regulatory T cells that express higher levels of TIGIT compared to splenocytes. Two different isotypes (mIgG2a and mIgG1) of a-TIGIT mAb were used to evaluate anti-tumor efficacy, with only the mIgG2a, deleting isotype able to induce strong antitumor efficacy. The importance of Fc gamma receptors (FcγR) for the antitumor efficacy of a-TIGIT activity was further demonstrated by the use of mice KO for activatory FcγR or by depletion of NK cells which also resulted in the loss of a-TIGIT activity.

The anti-tumor efficacy of a-TIGIT mAb was associated with an increased activity of conventional CD8+ and CD4+ T cells but also with a preferential depletion of Treg within the tumor microenvironment. This activity also correlated with full occupancy of TIGIT receptor in mice.

As it has been shown that TIGIT is expressed on tumor cells in certain hematological cancers, we also established a model of EL4 tumor with engineered TIGIT expression. In this model, a-TIGIT demonstrates a strong antitumor effect that strictly depends on the isotype of the mAb.

Finally, the activity of a-TIGIT was tested in less immunogenic models including of pancreatic PancO2 cancer where it demonstrated some tumor growth delay as a single agent and very strong combination potential with other immune checkpoints.

In summary, these results show that antitumor mediated efficacy of a-TIGIT mAb depends upon target binding and also on interaction with FcγR. These findings support the clinical evaluation of a-TIGIT mAb able to engage those receptors.

Citation Format: Julie Preillon, Sofie Denies, Diane Jamart, Matthew J. Carter, Mark S. Cragg, Gregory Driessens. a-TIGIT mediates antitumor activity through multiple mechanisms of action involving activation of intratumor effector T cells and depletion of regulatory T cells [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 3249.
Abstract 3255: A novel small molecule inhibitor of AhR suppresses the polarization and activity of M2 macrophages
Authors: Garcia Candy , Lemar Hadia , Galang Christina , Joseph James , Gonzalez-Lopez Marcos , Hager Jeffrey , Dillon Michael P. , Aswad Fred J.
Published: August 2019

Tumor associated macrophages, mainly represented by the M2-like phenotype, are a highly immunosuppressive macrophage subset that exert a pro-tumorigenic role in a variety of cancer types. Understanding the factors that promote M2 macrophage differentiation and activity is of critical importance to unlocking the potential of anti-tumor immune therapy. Thus, we investigated the role of the AhR pathway in M2 macrophages. We found the Aryl Hydrocarbon Receptor (AhR) highly expressed in in vitro polarized human M2 macrophages derived from peripheral blood mononuclear cells. Stimulation of AhR with small molecule agonists TCDD or kynurenine resulted in a significant enhancement of the suppressive activity of M2 macrophages on anti-CD3/CD28 stimulated CD4 T cell proliferation and IFNγ production. Inhibition of AhR using a novel, highly potent and selective AhR inhibitor (IDE-AhRi-1) fully inhibited the suppressive activity of M2 macrophages on T cells. Surprisingly, stimulated CD4 T cells co-cultured with IDE-AhRi-1 exposed M2 macrophages had an enhanced ability to proliferate and produce IFNγ compared with stimulated T cells in the absence of M2 macrophages. This suggests that IDE-AhRi-1 not only inhibits the suppressive mechanisms of M2 macrophages, but also boosts their ability to generate pro-inflammatory responses that enhance T-cell activity. Further studies to elucidate the AhR-driven molecular mechanisms responsible for this activity are underway. To find out whether AhR driven M2 polarization and activity is evident in human cancer, we analyzed TCGA-derived RNA sequencing data from an array of solid tumor indications. In a subset of cancer indications, high AhR activity correlated with key M2 macrophage and immuno-regulatory signature genes. Surprisingly, expression of CYP1B1 also correlated with expression of TDO2 mRNA, but not IDO1 mRNA. These finding establish AhR as a key modulator of M2 macrophages and demonstrate a correlation between AhR activity and tumor associated macrophages in human tumor samples. Furthermore, we demonstrate that IDE-AhRi-1 can potently suppress M2 macrophages and propose IDE-AhRi-1 as a novel approach for potentiating anti-tumor immunity.

Citation Format: Candy Garcia, Hadia Lemar, Christina Galang, James Joseph, Marcos Gonzalez-Lopez, Jeffrey Hager, Michael P. Dillon, Fred J. Aswad. A novel small molecule inhibitor of AhR suppresses the polarization and activity of M2 macrophages [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 3255.
Abstract 3267: Cancer immunotherapy by use of FANA ASO therapy to silence Foxp3, impair Treg function and promote anti-tumor immunity
Authors: Hancock Wayne W. , Wang Liqing , Aishwarya Veenu
Published: August 2019

There is an inverse correlation between tumor and draining lymph node infiltration by Foxp3+CD4+CD25+ Treg cells and clinical outcomes in carcinomas of the breast, liver, stomach, ovary, pancreas, and lung, as well as melanomas and glioblastomas. Tregs suppress tumor responses by host CD8 and CD4 T cells, B cells, NK cells, macrophages and dendritic cells. There are currently no effective ways to target Tregs, since toxins (e.g. IL-2-diptheria toxin) and cyclophosphamide have only transient effects with rebound and may also affect conventional T cells, use of CD25 monoclonal antibodies have confounding effects given IL-2 receptor (CD25) expression by activated T cells, and given the phenomenon of “peripheral” conversion (iTreg development) at the tumor site that can allow Tregs to evade therapy. These problems led us explore use of FANA antisense oligonucleotides (ASO) to suppress expression of Foxp3 mRNA. FANA ASO are highly specific and are taken up by cells without use of any delivery agents, conjugates or formulations, making them attractive compounds for cancer drug development. Various Foxp3 sequence-specific or scrambled FANAs were designed, and fluorescently-labeled FANA tested by addition to Foxp3+ Tregs in vitro; these studies showed successful uptake and both cytoplasmic and nuclear localization. FANAs were further screened by assessing effects on Treg suppressive function, and those resulting in 40-50% reductions were assessed for effects on expression of Foxp3 mRNA (qPCR) and protein (Western blots). We next tested the in vivo efficacy of Foxp3 FANA by intravenous or intraperitoneal injection, either daily or twice/week, of Foxp3 FANA, followed by isolation of Tregs from lymphoid tissues. Selected fluorescently-labeled FANA showed Treg uptake, and unlabeled FANA led to >75% reduction in Foxp3 protein expression (flow cytometry, Western blots), and marked reductions in Treg suppressive function. Lastly, we compared the effects of scrambled vs. specific Foxp3 FANA ASO on TC1 lung tumor growth in syngeneic C57BL/6 mice. Compared with mice receiving scrambled FANA ASO, mice receiving specific Foxp3 FANA ASO showed impaired tumor growth, with 50% showing complete tumor elimination (p<0.0001), and markedly reduced Foxp3+CD4+ Treg infiltration (p<0.01). Our data indicate that FANA oligos can modulate Foxp3 expression and Treg function in vitro and in vivo, such that their use may provide an important new approach to cancer immunotherapy.

Citation Format: Wayne W. Hancock, Liqing Wang, Veenu Aishwarya. Cancer immunotherapy by use of FANA ASO therapy to silence Foxp3, impair Treg function and promote anti-tumor immunity [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 3267.
Abstract 3292: Prevalence and socio-behavioral determinants of psychological distress among cancer patients and survivors in the United States, 2010-2015
Authors: Singh Gopal K. , Liu Lihua , Chai Audrey L. , Ung Alexander , Allender Michelle
Published: August 2019

Background: Cancer patients face many unique physical and mental health challenges that directly affect their cancer outcome and quality of life. As cancer treatment improves, the prevalence of long-term cancer survivors increases. However, the psychological well-being of cancer survivors has been largely understudied, which may lead to missed opportunities to improve cancer survivorship.

Methods: Using 2010-2015 National Health Interview Surveys (N=194,757), we examined the prevalence of psychological distress among 17,657 adult cancer patients and survivors and identified the socio-demographic and behavioral correlates in the United States. Differentials in serious psychological distress (SPD, defined by a 6-item scale) and factor-based psychological distress scores (a composite index with a mean of 100 to measure levels of psychological distress) were analyzed by multivariate linear and logistic regression models.

Results: The prevalence of SPD among cancer patients was 4.7% (95% CI: 4.2, 5.1), compared with 3.3% (95% CI: 3.1, 3.4) for the general population without a cancer history or diagnosis. The SPD prevalence was significantly higher among patients diagnosed with stomach, ovarian, cervical, and uterine cancers than the non-cancer population (age-adjusted odds ratio: 3.2, 3.1, 2.9, 2.7, respectively). Patients diagnosed with lung, colorectal, and thyroid cancer also reported significantly higher levels of psychological distress. SPD prevalence and distress index scores were substantially higher among American Indian/Alaska Native, Hispanic, and non-Hispanic (NH) Black cancer patients, compared with NH whites with cancer. Prevalence and levels of psychological distress were significantly greater among cancer patients with low education and income levels, non-professional occupations, unmarried status, functional limitation, and among smokers and physically inactive patients.

Conclusions: Our findings underscore the importance of addressing the psychological well-being of cancer patients and survivors, particularly among the high-risk groups, in order to achieve the best treatment outcome and quality of life among the increasing number of cancer survivors.

Citation Format: Gopal K. Singh, Lihua Liu, Audrey L. Chai, Alexander Ung, Michelle Allender. Prevalence and socio-behavioral determinants of psychological distress among cancer patients and survivors in the United States, 2010-2015 [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 3292.
Abstract 3346: The role of insurance on mammogram adherence among Latina ethnicity and citizenship status
Authors: Johnson Roman B. , Bae Sejong
Published: August 2019

Introduction: Cancer screening researchers have long observed that Latinas are less likely to be mammogram adherent, but little is understood how this varies by citizenship status.

Methods: Logistic regression analysis. The sample size was weighed according to CDC specifications. There were 1002 latina women in the sample. The 2016 National Health Interview Survey was utilized.

Results: Compared to naturalized Latina women, both U.S. citizen and non-citizen Latina women are less likely to be mammogram adherent (p<0.05). Insurance status attenuated the relationship between Latina ethnicity and mammogram adherence. For those who have a private insurance and other insurance, they were significantly more likely to be mammogram adherence (p<0.05).

Findings: Cancer screening researchers benefit from disaggregating Latina ethnicity by citizenship status to develop more tailored interventions regarding mammogram adherence in this population. This study points to the need for policy makers to advocate for Latina populations impacted by insurance coverage disparities.

Citation Format: Roman B. Johnson, Sejong Bae. The role of insurance on mammogram adherence among Latina ethnicity and citizenship status [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 3346.