bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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 (&lt;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 &gt;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

Abstract
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

Abstract
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

Abstract
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

Abstract
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 (&gt;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

Abstract
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

Abstract
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

Abstract
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.