bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 2657: Sphingosine-1-phosphate receptor 1 signalling modulates macrophage recruitment to diffuse large B cell lymphomas and the phagocytosis of rituximab-opsonized tumor cells
Authors: Perry Tracey Adams , Lupino Lauren , Vrzalikova Katerina , Masand Navta , Kearns Pamela R. , Murray Paul G.
Published: September 2020

Diffuse large B cell lymphoma (DLBCL) is the most common form of non-Hodgkin lymphoma. Currently, approximately 40% of DLBCL patients treated with standard of care therapies, which include a combination of immunotherapy (rituximab; R) and chemotherapy (CHOP), will have disease that is refractory or will relapse. Tumor-associated macrophages can phagocytose opsonised DLBCL tumor cells and are therefore centrally important in determining therapeutic outcomes for patients treated with R-CHOP. Recent data from our lab and from others suggests that the modulation of sphingosine-1-phosphate (S1P) signalling may therapeutically benefit some patients with this tumor. Here, we have investigated the effects of S1P on macrophage functions relevant to DLBCL. We show that S1P signalling through the major receptor, S1P-receptor 1 (S1PR1), suppresses the phagocytosis of rituximab-opsonized DLBCL cells. However, we also show that chemotherapy potently induces monocyte recruitment to DLBCL tumors in vivo and that S1PR1 is a primary mediator of monocyte migration both in vitro and in vivo. According to our data, S1PR1 signalling inhibitors could improve the therapeutic efficacy of rituximab-based therapies for DLBCL patients. However, our data suggests that these drugs should be given only after chemotherapy and before rituximab administration so as to maximize the S1P-mediated recruitment of therapeutic macrophages to the tumor site.

Citation Format: Tracey Adams Perry, Lauren Lupino, Katerina Vrzalikova, Navta Masand, Pamela R. Kearns, Paul G. Murray. Sphingosine-1-phosphate receptor 1 signalling modulates macrophage recruitment to diffuse large B cell lymphomas and the phagocytosis of rituximab-opsonized tumor cells [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 2657.
Abstract 2675: Single-CellRNA-Seq reveals the transcriptional landscape of the immune microenvironment in chemical induced liver cancer
Authors: He Jian
Published: September 2020

The immune cell types as well as their numbers and activities in the tumor microenvironment (TME) may contribute to tumor progression, metastasis, prognosis and clinical response to cancer immunotherapies. Hepatocellular Carcinoma (HCC) is a type of highly heterogeneous solid tumor, causing high morbidity and mortality in the world, especially in China, however, the immune microenvironment of HCC has not been well-defined so far. In the present work, we first employed single-cell RNA sequencing on diethylnitrosamine (DEN)-induced mouse HCC model to depict the changing landscape of the immune cell composition, lineages and functional activities in TME during tumorigenesis, showing the distinct immune features in precancerous and cancerous lesions. The data indicated that the tumor-associated immune changes appeared early in pathological progression and the specific subsets of T and B cells were preferentially enriched in TME of HCC. We identified the signature genes for these specific cell subsets, and then mapped them onto the HCC RNA-seq dataset of human The Cancer Genome Atlas (TCGA) database. We found a cluster of naïve B cells characterized by high expression of CD38 was associated with better prognosis of human HCC. In addition, the inter-cellular interaction map was established based on the receptor-ligand bonding at single cell resolution. Taken together, this study will be helpful to the comprehensive understanding of dynamic immune microenvironment and cellular networks, especial naïve B cells, during HCC pathogenesis, which could provide a novel insight into the therapeutics for the HCC.

Citation Format: Jian He. Single-CellRNA-Seq reveals the transcriptional landscape of the immune microenvironment in chemical induced liver 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 2675.
Abstract 2677: Sequential same slide multiplex immunofluorescence and H&E staining for combined phenotypic and morphologic characterization of formalin-fixed paraffin-embedded tissue sections
Authors: Patel Katir K. , Bares Amanda , Manesse Mael , Burton Mark , Phillips Bonnie , Lillard Kate , Hellebust Anne , Duplessis Melinda , Teplitz Kyla , George Tad
Published: September 2020

Multiplex immunofluorescence (mIF) has become an established method for characterizing the tumor immune microenvironment. Currently, hematoxylin and eosin (H&E) staining is typically performed on a serial tissue section to provide morphologic context for the mIF data. Serial sections do not represent identical cell populations, however, and are not always possible to obtain when the amount of available tissue is limited. Consequently, a method to examine the same tissue section by both fluorescence and brightfield imaging would be advantageous. Here we present a streamlined method and system for serial mIF and H&E staining on a single tissue slide for a comprehensive analysis to support high-throughput tissue immunophenotyping. The UltiMapper I/O PD-L1 kit was used for multiplex immunofluorescence staining of CD8, CD68, PD-L1, and pan-Cytokeratin in formalin-fixed, paraffin-embedded (FFPE) samples from human tonsil and primary tumor biopsies using the Leica Biosystems BOND RX autostainer. Stained tissues were imaged in five spectrally distinct fluorescence channels (DAPI, FITC, TRITC, Cy5, Cy7) on the RareCyte CyteFinder II HT Instrument. Slides were de-coverslipped and stained with H&E, then imaged with brightfield using the CyteFinder II HT instrument. To segment the tumor and stroma tissue regions, a HALO AI classifier was created. Fluorescence images were analyzed using the HALO Highplex FL module to identify CD8+ cytotoxic T-cells, CD68+ macrophages, CD68+/PD-L1+ immuno-suppressive macrophages, pan-CK+ tumor cells, and pan-CK+/PD-L1+ immune-evading tumor cells within the tumor and stromal regions identified by the H&E stain. This novel combination of fluorescence and brightfield analysis enables deep phenotyping of immune cells as well as assessment of cellular morphology and tumor architecture in the same tissue section.

Citation Format: Katir K. Patel, Amanda Bares, Mael Manesse, Mark Burton, Bonnie Phillips, Kate Lillard, Anne Hellebust, Melinda Duplessis, Kyla Teplitz, Tad George. Sequential same slide multiplex immunofluorescence and H&E staining for combined phenotypic and morphologic characterization of formalin-fixed paraffin-embedded tissue sections [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 2677.
Abstract 2766: Potassium channel expression in cervical cancer models
Authors: Ramírez Ana , Chávez-López María de Guadalupe , Vera Eunice , de la Garza Jaime , Gariglio Patricio , Camacho Javier
Published: September 2020

Introduction. Cervical cancer is a public health problem in developing countries, and the fourth leading cause of cancer death in women worldwide. Most human cervical cancer cases are associated with high-risk human papillomavirus (HR-HPV) infection, but different cofactors including long-term use of oral contraceptives and multiple pregnancies increase the risk for cervical cancer in HPV-positive women. Ion channel expression and/or function differ between healthy and tumor cells. This alteration confers proliferation, progression, and survival advantages to tumor cells, making ion channels promising targets for cancer therapy and diagnosis. Here, we studied the mRNA expression of two potassium channels in human keratinocytes stably transfected with either E6 or both E6/E7 oncogenes of HPV16, and in a K14E7 transgenic mouse model of cervical cancer. These mice express the HPV16-E7 oncogene and develop cervical cancer after 6 months of treatment with 17β-estradiol (E2).

Methods. Human normal keratinocytes and keratinocytes transfected with either E6 or E6/E7 oncogenes of HPV16 were cultured. In addition, we used the K14E7-transgenic mice-cervical cancer model; some animals were treated with E2. Continuous-release pellets delivering daily 0.05 mg of E2 were implanted into 4–6-week old female mice for either 3 months to produce low-grade cervical dysplasia or 6 months to produce cervical cancer. Total RNA extraction and subsequent quantification by qPCR of Kv3.4 and KCa3.1 mRNA channel levels were performed both from cultured cells and the mice cervical tissue.

Results. Significantly higher KV3.4 and KCa3.1 channel mRNA expression was observed in keratinocytes transfected with either the E6 or E6/E7 HPV oncogenes in comparison with normal keratinocytes. In the cervical cancer mouse model, E2 treatment for 6 months increased the mRNA levels of KV3.4 and KCa3.1 channels both in the transgenic and the non-transgenic mice in comparison with the rest of the groups. The highest mRNA relative expression was observed for the KV3.4 channels in the transgenic mice displaying cervical cancer (K14E7+E2 group).

Conclusion. KV3.4 channel expression may serve as a cervical cancer biomarker.

This work was partially supported by Conacyt grant A1-S-9783.

Citation Format: Ana Ramírez, María de Guadalupe Chávez-López, Eunice Vera, Jaime de la Garza, Patricio Gariglio, Javier Camacho. Potassium channel expression in cervical cancer models [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 2766.
Abstract 2838: Peritoneal immune evasion can be overcome with STING agonist treatment in peritoneal carcinomatosis of colon cancer
Authors: Yang Hannah , Lee Seung Jun , Lee Yu Seong , Lee Won Suk , Kong So Jung , Kang Beodeul , Chon Hong Jae , Kim Chan
Published: September 2020

Introduction: Peritoneal immune system plays an important role during the peritoneal dissemination of colon cancers. Therefore, tumor-induced T cell anergy in peritoneal cavity could lead to immune evasion and the progression of peritoneal carcinomatosis. Here, we aimed to reverse the immune evasion in peritoneal cavity and effectively suppress the peritoneal carcinomatosis of colon cancer by STING-based immunotherapy.

Methods: We established an animal model of peritoneal carcinomatosis by intraperitoneal injection of MC38 colon cancer cells to C57BL/6 mice. Temporal changes in peritoneal immune microenvironment during peritoneal tumor dissemination were first characterized by analyzing tumor nodules, malignant ascites, and peritoneum lavage by flow cytometry. Then, tumor-bearing mice were treated with either STING agonist (ADU-S100), and/or anti-PD-1 antibody. Tumor burden and the volume of ascites were assessed after the treatment. The tumors were analyzed with flow cytometric, histologic, and RNA sequencing analyses.

Results: The intraperitoneal inoculation of MC38 colon cancer cells led to dramatic immune cell changes in peritoneal cavity. While the number of myeloid-derived suppressor cells (MDSCs) were markedly increased, the number of CD8+ T cells and dendritic cells gradually decreased after initial influx in the peritoneal cavity. Treatment with STING agonist remarkably suppressed the growth of peritoneal seeding nodules (75%). Moreover, normalization and reduction of peritoneal tumor blood vessels resulted in an overt decrease in malignant ascites (85%) in the peritoneal cavity after STING agonist treatment. In addition, the number of dendritic cells and CD8+ T cells had markedly increased, but that of MDSCs was decreased in the peritoneal cavity. Moreover, the number of IFN-gamma-secreting cytotoxic T cells were increased in tumor nodules and peritoneal cavity after STING agonist treatment. Finally, the combination immunotherapy of STING agonist and anti-PD1 antibody induced stronger adaptive immunity against peritoneal carcinomatosis than monotherapy and showed potent anti-cancer activity with reduced ascites formation.

Conclusion: STING immunotherapy can normalize peritoneal tumor vasculature and immune system, and synergize with immune checkpoint blockade to control peritoneal carcinomatosis of colon cancer.

Citation Format: Hannah Yang, Seung Jun Lee, Yu Seong Lee, Won Suk Lee, So Jung Kong, Beodeul Kang, Hong Jae Chon, Chan Kim. Peritoneal immune evasion can be overcome with STING agonist treatment in peritoneal carcinomatosis of colon 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 2838.
Abstract 2840: Development of a model of dihomo-gamma-linolenic acid interference with platelet promotion of ovarian cancer
Authors: Isingizwe Zitha Redempta , Benbrook Doris M.
Published: September 2020

Background: Cancer is the second leading cause of deaths worldwide after cardiovascular diseases. A commonality between cancer and cardiovascular diseases is disregulation of platelets. Platelets and cancer are known to promote each other in a feedforward mechanism that is poorly understood. A long chain polyunsaturated fatty acids dihomo-gamma-linolenic acid (DGLA) was shown to reduce cardiovascular events in a platelet dependent manner while the exact mechanism of DGLA-mediated cancer cells death is yet to be explored.

Objectives: The objective of our study was to develop an experimental model to study interventions that could disrupt the cancer/platelets loop.

Methods: The effects of a range of DGLA concentrations on platelet aggregation and growth of high grade serous ovarian cancer cell lines (OVCAR3, MesOV, OVSAHO), normal human fallopian tube secretory epithelial cells (hFTSECs) primary culture and an immortalized hFTSEC cultures were determined with an MTT assay. Cocultures were used to evaluate effects of platelets on ovarian cancer cell line spheroid formation and size and effects of ovarian cancer cells and hFTSECs on platelet aggregation. Results: The minimal cytotoxic DGLA concentrations for cancer and normal epithelial cells were above physiologically-achievable concentrations, and the half maximal inhibitory concentrations (IC50's) were similar across epithelial cell types with the IC50's for hFTSEC primary culture (261 µM) and immortalized culture (206 µM) falling within the range of cancer cell IC50's (153-275 µM). DGLA inhibited platelet aggregation at concentrations ≥250 µM. Platelets increased cancer spheroid sizes in a concentration-dependent manner and cancer cells, but not hFTSECs, induced platelet aggregation in cocultures.

Conclusions: Our model incorporates both platelet effects on cancer cells and cancer cell effects on platelets. Physiologically-achievable DGLA concentrations that affect platelet aggregation without affecting epithelial cells were identified. Minimal doses of DGLA needed to cause cytotoxicity against cancer and normal cells are above levels that are physiologically achievable. Future studies will utilize DGLA doses that can interfere with platelet aggregation without directly causing cytotoxicity to cancer or healthy cells. This experimental model will allow study of DGLA's potential for interfering with platelet promotion of ovarian cancer in the absence of direct effects of DGLA on cancer cells. Funded by NCI R01 CA196200

Citation Format: Zitha Redempta Isingizwe, Doris M. Benbrook. Development of a model of dihomo-gamma-linolenic acid interference with platelet promotion of 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 2840.
Abstract 2862: Cetuximab-Triptolide conjugate suppresses growth of EGFR-overexpressing lung cancers through targeting RNA polymerase II
Authors: Zhang Keqiang , Ma Yuelong , Guo Yuming , Sun Ting , Wu Jun , Horne David , Raz Dan
Published: September 2020

Triptolide (TPL), a natural compound isolated from a traditional Chinese medicine Thunder God Vine, exhibits strong anticancer activities; however, its clinical use is limited by low water-solubility and high systemic toxicity. To overcome these disadvantages, we developed a novel antibody drug conjugate (ADC) to specifically delivered TPL to cancer cells overexpressing EGFR which is frequently found in many types of human cancers including 70% of non-small cell lung cancers (NSCLC). The ADC is made by conjugation of TPL to Cetuximab, a clinically available anti-EGFR monoclonal antibody, via lysine residues of the antibody. Biochemical analysis showed that the average of drug-to-antibody ratio (DAR) of Cet-TPL is about 5, and the conjugation has little effect on the solubility and binding affinity of Cetuximab. The antitumor efficacy and toxicity of Cet-TPL were assessed and compared to that of TPL, Cetuximab, and a combination of these two. And the results demonstrated that Cet-TPL drastically suppresses in vitro proliferation and in vivo growth of these EGFR-overexpressing cancers including A549 and H1299 NSCLC cell lines, and two NSCLC patient-derived xenografts (PDXs); and SCC6 head-neck cancer cell line, while it did not significantly inhibit the proliferation and growth of NSCLC H520 that barely expresses EGFR. Furthermore, immunofluorescent analysis revealed that Cet-TPL is effectively transported into lysosomes of cancer cells that overexpress EGFR proteins, spared cells that don't express EGFR. Similar to TPL, which inhibits RNA polymerase II (Pol II) mediated transcription, Cet-TPL can also effectively target Pol II and significantly induce apoptosis in these EGFR-overexpressing cancers. Compared to Triptolide, Cetuximab, or their combinations, Cet-TPL displays higher target-specific cytotoxicity against EGFR-expressed cancers and much lower in vivo systematic toxicity. In addition, Cet-TPL efficiently suppresses activated EGFR pathway in SCC6 cancer cells. Taken together, Cet-TPL represents a potent targeted therapeutic agent against EGFR-overexpressing NSCLC and other cancers.

Citation Format: Keqiang Zhang, Yuelong Ma, Yuming Guo, Ting Sun, Jun Wu, David Horne, Dan Raz. Cetuximab-Triptolide conjugate suppresses growth of EGFR-overexpressing lung cancers through targeting RNA polymerase II [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 2862.
Abstract 287: A nuclear cAMP microdomain suppresses tumor growth by Hippo Pathway inactivation
Authors: Drozdz Marek M. , Doane Ashley , Desman Garrett , Wang Jenny , Reilly Michael , Aguirre Kelsey , Kane Elsbeth , Wolchok Jedd , Merghoub Taha , Elemento Olivier , Piskounova Elena , Zippin Jonathan
Published: September 2020

Cyclic AMP can both promote and suppress tumor growth; however, how this single second messenger can simultaneously have such disparate effects on cancer remains largely undefined. It is well appreciated that cAMP does not diffuse within a cell but is made in microdomains, which consist of a unique adenylyl cyclase, one or more phosphodiesterases, and cAMP effector proteins, but the role of specific cAMP microdomains in cancer is unclear. Examination of human tissue biopsies revealed that the nuclear cAMP microdomain, defined by the soluble adenylyl cyclase (sAC), is upregulated early in tumorigenesis, but is lost with melanoma invasion and metastasis. Further, we showed that loss of sAC led to the transformation of melanocytes and reintroduction of sAC, only into the nucleus, was sufficient to block tumorigenesis in vitro and in mice. Neither mitochondrial, nor cytoplasmic cAMP microdomains affected tumor cell growth. Activation of nuclear sAC led to significant changes in chromatin accessibility suggesting that this cAMP microdomain regulates numerous transcription factors. Specifically, activation of nuclear sAC led to reduced chromatin accessibility for the TEAD and SMAD family of transcription factors, the key effectors of the Hippo Pathway. Consistent with those data, nuclear sAC suppressed TEAD-dependent pro-cancer gene expression profiles (e.g., MYC) by inhibiting YAP, one of the main oncoproteins in this signaling cascade. Moreover, we showed that nuclear cAMP evokes the same YAP-dependent inhibition of the Hippo Pathway in a variety of cancers, suggesting tumor suppression by nuclear sAC is not limited to melanoma. These studies reveal that a cAMP microdomain wholly contained within the nucleus is a pivotal a tumor suppressor that acts via Hippo Pathway inactivation.

Citation Format: Marek M. Drozdz, Ashley Doane, Garrett Desman, Jenny Wang, Michael Reilly, Kelsey Aguirre, Elsbeth Kane, Jedd Wolchok, Taha Merghoub, Olivier Elemento, Elena Piskounova, Jonathan Zippin. A nuclear cAMP microdomain suppresses tumor growth by Hippo Pathway inactivation [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 287.
Abstract 2891: Targeting breast cancer stem cells with anti-EMP2 immunotoxins delivering granzyme b
Authors: Mohamedali Khalid A. , Su-yin Kok , Cheung Lawrence H. , Dhawan Naina , Rosenblum Michael G. , Wadehra Madhuri
Published: September 2020

Despite new therapies, breast cancer remains one of the leading causes of cancer-related death in women worldwide. Part of the issue remains the inability of these therapies to target cancer stem cells (CSCs). These cells show unique resistance to chemotherapy and have enhanced capacity for self-renewal. Recently, our group has shown that Epithelial membrane protein-2, or EMP2, is expressed on CSCs defined by increased aldehyde dehydrogenase activity (ALDH+). Clinical data supports the role of EMP2 in advanced breast cancer as increased expression of the protein is observed in metastatic lesions compared to primary tumors and its expression is enhanced in chemotherapy resistant tumors. In parallel, EMP2 expression correlated with enhanced mammosphere formation, an accepted surrogate for cells with enriched stem cell capacity. We have recently developed a novel IgG1 monoclonal antibody to EMP2, which has been shown to reduce tumor load. As the antibody-antigen complex rapidly internalizes, we hypothesized that its anti-tumor effects could be enhanced through the creation of a fusion protein. Granzyme B (GrB) is a serine protease that plays a critical role in the body's defense against viral infection and tumor development by initiating the apoptotic cascade via both caspase-dependent and -independent mechanisms. We developed novel fusion proteins composed of the anti-EMP2 backbone as the targeting moiety and granzyme B as the cytotoxic payload. Our initial design comprised of the active GrB fused to the IgG heavy chain (Fc) domain containing 2 single-chain antibodies against EMP2, a format that results in a longer plasma retention time. This new construct showed high and specific affinity for EMP2 (10−10M) using both flow cytometry and ELISA based formats. Moreover, treatment with these agents induced cell death to EMP2 positive cells, including those characterized by high ALDEFLUOR activity. Preclinical assessment of the anti-EMP2 immunotoxins showed no acute toxicity and acceptable plasma retention. Preliminary results using a 4T1 model system produced a significant reduction in tumor burden. Our results suggest that continued development of these agents may be successful at targeting advanced disease.

Research supported, in part, by NCI R21 CA234642 and the Clayton Foundation for Research.

Citation Format: Khalid A. Mohamedali, Kok Su-yin, Lawrence H. Cheung, Naina Dhawan, Michael G. Rosenblum, Madhuri Wadehra. Targeting breast cancer stem cells with anti-EMP2 immunotoxins delivering granzyme b [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 2891.
Abstract 290: Development and characterization of antibodies specific for the SS18-SSX fusion protein in synovial sarcoma
Authors: Desilets Curtis , Chen Fang , Comeau Christopher , Costa Katrina , Crosby Katherine , Ferrante Michelle , Grange Christopher , Patrikas Maggie , McBride Matthew , Baranov Esther , Hornick Jason , Kadoch Cigall
Published: September 2020

Synovial sarcoma (SS) is a soft tissue cancer characterized by the fusion of the SS18 gene, which encodes for a subunit of the BAF ATP-dependent chromatin remodeling complex, with either SSX1, SSX2, or SSX4 genes. The resulting SS18-SSX fusion protein is incorporated into the BAF complex, where it evicts wild-type SMARCB1 (BAF47) and retargets the complex to polycomb-repressed chromatin domains, thus activating oncogenic gene expression to drive tumor progression. Traditional means of diagnosis of SS include immunohistochemical staining, including that for the biomarker TLE1, but TLE1 is not overexpressed in all tumors and cases ultimately need to be confirmed by either FISH or PCR assays to detect the SS18-SSX fusion. We have developed the first highly specific, recombinant monoclonal antibodies for the detection of SS18-SSX fusion proteins by immunohistochemistry and for the capture of SS18-SSX-containing BAF complexes in cells, with downstream utility in biochemistry and genomics-centered approaches such as ChIP-seq. The E9 × 9V clone directly targets the highly conserved fusion breakpoint, while the E5A2C clone detects the C-terminus of the SSX protein family and is capable of recognizing alternative breakpoints. Taken together, our data show that these antibodies can accurately and reproducibly detect the SS18-SSX fusion protein in SS cells and tissues.

Citation Format: Curtis Desilets, Fang Chen, Christopher Comeau, Katrina Costa, Katherine Crosby, Michelle Ferrante, Christopher Grange, Maggie Patrikas, Matthew McBride, Esther Baranov, Jason Hornick, Cigall Kadoch. Development and characterization of antibodies specific for the SS18-SSX fusion protein in synovial sarcoma [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 290.
Abstract 2906: SGN-B6A: A new MMAE ADC targeting integrin beta-6 in multiple carcinoma indications
Authors: Lyon Robert P. , Schmitt Michael W. , Jonas Mechthild , Franz Christopher E. , Trueblood Esther S. , Yumul Roma , Westendorf Lori , Ryan Maureen C.
Published: September 2020

The integrins are a large family of cell surface receptors with diverse roles in cellular adhesion, motility, and cytokinesis. Functional integrins exist as heterodimers consisting of single alpha and beta chains. Within this family, integrin beta-6 (which dimerizes exclusively with isoform alpha-v) is of particular note for its role in cancer. Integrin beta-6 is overexpressed in numerous solid tumors and multiple investigators have noted its expression as a negative prognostic indicator in diverse cancers including colorectal, non-small cell lung, gastric, and cervical. SGN-B6A is an antibody-drug conjugate (ADC) targeting integrin beta-6 to deliver the clinically validated payload monomethyl auristatin E (MMAE). The antibody component of SGN-B6A is specific for integrin beta-6 and does not bind other alpha-v family members. In preclinical studies, this ADC has demonstrated activity in vivo in models derived from pancreatic, pharyngeal, and bladder carcinomas spanning a range of antigen expression levels at doses of 1 or 3 mg/kg given weekly for three doses. In exploratory toxicology studies in cynomolgus monkeys, doses of up to 5 mg/kg weekly for three doses or 6 mg/kg every 3 weeks for two doses were tolerated. Hematologic toxicities typical of MMAE ADCs were dose limiting and no evidence of target-mediated toxicity was observed. A Phase I first-in-human study is planned to evaluate the safety and antitumor activity of SGN-B6A in a variety of solid tumors known to express integrin beta-6.

Citation Format: Robert P. Lyon, Michael W. Schmitt, Mechthild Jonas, Christopher E. Franz, Esther S. Trueblood, Roma Yumul, Lori Westendorf, Maureen C. Ryan. SGN-B6A: A new MMAE ADC targeting integrin beta-6 in multiple carcinoma indications [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 2906.
Abstract 3010: VKNG 1 reverses multidrug resistance by inhibiting ABCG2 mediated drug transport in vitro and in vivo
Authors: Narayanan Silpa , Gujarati Nehaben A. , Teng Qiuxu , Wang Jingquan , Cai Chao-Yun , Yang Yuqi , Chintalapati Anirudh Jaganna , Korlipara Vijaya L. , Chen Zhe-Sheng
Published: September 2020

The emergence of multidrug resistance (MDR) to chemotherapeutic drugs continues to be a major problem in the treatment of cancer. Drug resistance, either intrinsic or extrinsic is responsible for the recurrence of cancer related deaths. Understanding the drug resistant mechanisms of cancer is necessary for developing an effective treatment. ATP-binding cassette transporters are the integral transmembrane proteins which play a role in the expulsion of chemotherapeutic drugs, make the MDR more complicated. Breast cancer resistance protein (BCRP/ABCG2) is one among the MDR transporters with a wide range of substrates and overexpressed in various kinds of cancers like breast, colon, ovarian and lung cancers. An analysis of various new compounds leads to the

discovery of VKNG-1 that selectively inhibits ABCG2 transporter and reverses the resistance to chemotherapeutic drugs both in vitro and in vivo. VKNG-1 selectively causes the ABCG2 inhibition and sensitizes the ABCG2 overexpressing resistant cells to the substrate anti-cancer drugs. The mechanism of action of VKNG-1 is its ability to prevent the efflux function of ABCG2 and thereby increases the intracellular accumulation of substrate drugs. In addition, there was a decrease in the expression of ABCG2 at both mRNA and protein level, but the protein translocation did not happen in the presence of VKNG-1. The induced-fit docking studies suggest the existence of strong interactions between VKNG-1and BCRP protein. In addition, VKNG-1 maintains the anti-cancer effect of irinotecan in ABCG2 overexpressing tumor xenografts and combination of VKNG-1 and irinotecan greatly inhibited the growth of S1-M1-80 resistant tumors. These results suggest that potent and selective action of VKNG-1 makes it as a promising treatment option in overcoming drug resistance in cancer.

Citation Format: Silpa Narayanan, Nehaben A. Gujarati, Qiuxu Teng, Jingquan Wang, Chao-Yun Cai, Yuqi Yang, Anirudh Jaganna Chintalapati, Vijaya L. Korlipara, Zhe-Sheng Chen. VKNG 1 reverses multidrug resistance by inhibiting ABCG2 mediated drug transport in vitro and in vivo [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 3010.
Abstract 3030: Different pharmacodynamic profiles of ERK1/2 inhibition can elicit comparable anti-tumor activity
Authors: Hindley Christopher , Bevan Luke , Braithwaite Hannah , Courtin Aurélie , Fazal Lynsey , Ferraldeschi Roberta , Martins Vanessa , Muench Sandra , Wallis Nicola , Wilsher Nicola , Lyons John , Munck Joanne
Published: September 2020

The MAPK pathway is frequently dysregulated in cancer, resulting in constitutive phosphorylation and activation of its downstream signaling node ERK1/2 (ERK). The direct targeting of activated ERK is being explored in several phase I clinical trials. A good understanding of the relationship between inhibition of pathway activity and inhibition of tumor growth allows dose scheduling in the clinic to maximise response to an inhibitor. We have recently described the development of a novel, potent and selective small molecule inhibitor of both ERK activity and phosphorylation using fragment-based drug discovery. Using this inhibitor as a tool compound, we explored the relationship between duration of ERK inhibition and inhibition of tumor growth. We examined the in vivo activity of our ERK inhibitor in a Colo205 xenograft model. Inhibition of the ERK pathway was monitored by measuring phosphorylation of a direct substrate of ERK, RSK90 (pRSK), and phosphorylated ERK itself (pERK) to determine pharmacodynamic profiles. We observed that pathway inhibition was consistent with the pharmacokinetic profile of the ERK inhibitor and that the duration of pathway inhibition was primarily determined by dosing frequency rather than the total dose of ERK inhibitor. High, single doses (50 or 40 mg/kg) of ERK inhibitor produce strong maximal pathway inhibition at 2 h post dose (pRSK levels 8% of control levels for a single dose of 40 mg/kg) but pRSK levels have returned to levels close to control values by 12 h post dose. In contrast, 3x equally spaced doses of 20 mg/kg have a lower maximal pathway inhibition at 2 h post dose (pRSK levels 29% of control) but extend pathway inhibition beyond 12 h (pRSK levels 21% of control at 14 h). Despite these two different pharmacodynamic profiles, we observed comparable tumor growth inhibition following daily dosing either at 1 × 50 mg/kg (maximal tumor growth inhibition of 21%) or 3 × 20 mg/kg (maximal tumor growth inhibition of 15%). These data suggest that a short duration of ERK inhibition rather than constant suppression can be sufficient to provide anti-tumor activity. This may allow flexibility in clinical dosing schedules to improve tolerability without a loss in efficacy.

Citation Format: Christopher Hindley, Luke Bevan, Hannah Braithwaite, Aurélie Courtin, Lynsey Fazal, Roberta Ferraldeschi, Vanessa Martins, Sandra Muench, Nicola Wallis, Nicola Wilsher, John Lyons, Joanne Munck. Different pharmacodynamic profiles of ERK1/2 inhibition can elicit comparable anti-tumor activity [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 3030.
Abstract 3196: Analysis of taxane drug target engagement of microtubules in circulating tumor cells from metastatic castration resistant prostate cancer patients treated with CRLX301, a nanoparticle of docetaxel
Authors: Mukhtar Eiman , Worroll Daniel , Galletti Giuseppe , Schuster Shelly , Piha-Paul Sarina A. , Giannakakou Paraskevi
Published: September 2020

We reviewed the radiographic response of three patients with metastatic castration-resistant prostate cancer (mCRPC) treated with CRLX301, a docetaxel nanoparticle. For these three patients, we isolated and analyzed circulating tumor cells (CTC) to explore microtubule (MT) drug-target engagement (MT-DTE) as a biomarker of response to treatment. We quantitatively assessed the MT cytoskeleton in CTCs from pre- and post-treatment patient samples as a potential read-out of CRLX301 activity. We isolated CTCs using negative CD45+ depletion and subjected them to multiplex confocal microscopy using our established protocol. CTCs were identified as CD45-/CK+/DAPI+ cells and MT-DTE was determined using our developed, semi-high-throughput, high-content imaging algorithm to quantify MT bundling in CTCs across multiple time points, from baseline to on-treatment to disease progression. We collected CTCs at seven time points from three mCRPC patients. Clinical response was evaluated by RECIST v.1.1 criteria in those patients with measurable disease. Of the three patients who received CRLX301, one experienced partial response and two patients were unevaluable per RECIST given bone only disease, however showed stable disease clinically per bone scans. MT-DTE across all time points revealed that, early time points within four and 24 hours of drug administration exhibited the highest levels of drug engagement as compared to baseline but did not discriminate the responding patient from the patients with stable disease. However, the limited sample size makes this an observation that warrants validation in a larger cohort of patients. We observed that the CTCs collected one week after the first or second dose of CRLX301 treatment in the responding patient had numerically higher levels of MT-DTE as compared to the other two patients. MT-DTE can be detected and analyzed quantitatively in CTCs by tubulin immunofluorescence. The clinical utility of the 1-week CTC DTE should be tested and validated in future clinical trials involving nanoparticle formulations of taxanes or taxanes in general.

Citation Format: Eiman Mukhtar, Daniel Worroll, Giuseppe Galletti, Shelly Schuster, Sarina A. Piha-Paul, Paraskevi Giannakakou. Analysis of taxane drug target engagement of microtubules in circulating tumor cells from metastatic castration resistant prostate cancer patients treated with CRLX301, a nanoparticle of docetaxel [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 3196.
Abstract 3213: DIAS, the COSMIC data integration and annotation system
Authors: Boutselakis Charalampos , Kok Chai , Harsha Bhavana , Bindal Nidhi , Wang Shicai , Yong Siew-Yit , Cole Charlotte , Sondka Zbyslaw , Forbes Simon
Published: September 2020

COSMIC, the catalog of somatic mutations in cancer (https://cancer.sanger.ac.uk/) is the leading and most comprehensive global genetic resource for the exploration of somatic variation across all forms of human cancer. Since the initial inception of COSMIC 15 years ago, cancer genetics have seen substantial changes. Maintaining interoperability between COSMIC and various bioinformatics resources across the globe is a non-trivial task. Resources update at different intervals and as information is interdependent is difficult to keep synchronized. Standardization and adherence to FAIR principles have fueled the development of COSMIC DIAS (Data Integration and Annotation System).For all variants where the genomic location is known, DIAS using the ensembl VEP (Variant Effect Predictor) has ensured the re-annotation of all COSMIC variants, for all available genes and transcripts to a specific ensembl version, independently and for both the GRCh37 and GRCh38 assemblies. From release v90 we have created new stable cosmic genomic identifiers (COSV) for all simple nucleotide variants which point to the corresponding locations on the reference genome. A flip mechanism has been developed that maps the same COSV identifier to both GRCh37 and GRCh38 assemblies, easily searchable from the COSMIC website. The legacy COSM and COSN identifiers have been mapped to the COSV genomic identifiers for backwards compatibility. Additionally, where redundant variants have been identified, these were merged and website redirection has been implemented. Standardized variant annotations have been utilized that adhere to the most recent HGVS recommendations on genomic, transcriptomic and proteomic syntaxes.The cross-references between COSMIC genes and other widely-used databases, such as HGNC, RefSeq, UniProt and CCDS, have been updated and kept up-to-date.Curated cross references between COSMIC phenotypes, NCI terminologies and EFO codes are also available.All the information stored in COSMIC is easily accessible by the website where users are able to explore cancer genomics in high resolution, with the various views available in downloadable formats with a simple click (https://cancer.sanger.ac.uk/cosmic/download).The DIAS system, minimized redundancy of variants, and enhanced the interoperability of COSMIC with other variation resources enabling more precise analysis and easier integration with in-house systems for our users.

Citation Format: Charalampos Boutselakis, Chai Kok, Bhavana Harsha, Nidhi Bindal, Shicai Wang, Siew-Yit Yong, Charlotte Cole, Zbyslaw Sondka, Simon Forbes. DIAS, the COSMIC data integration and annotation system [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 3213.
Abstract 3217: An integrated web server for multi-omics data deconvolution
Authors: Lu Xiaoyu , Dang Pengtao , Tu Szu-Wei , Chang Wennan , Wan Changlin , Zhang Chi , Cao Sha
Published: September 2020

Tissue data deconvolution has been broadly utilized to characterize the variation of cell components and their relative abundance in cancer tumor microenvironment. Numerous deconvolution methods have been developed with different mathematical and biological considerations. Our previous studies have derived a rigorous mathematical condition for a less biased deconvolution. We have demonstrated a cell type can be reliably inferred from an omics data only of the cell type is with distinct signature genes, i.e., the cell type specific expression signature of the selected marker genes of all cell types are orthogonal or at least non-positively associated with each other, which is named as strong or weak “identifiable” conditions. Our analysis suggests the identifiability of a certain cell type is mostly determined by the significance of its gene markers, which is data set and tissue microenvironment dependent. However, such data set specificity has been commonly ignored in existing methods.

In this study, we developed a comprehensive web server, namely ISMD (an Integrated web Server for Multi-omics data Deconvolution), to recommend a best deconvolution method and optimize the gene markers and cell types in analyzing a specific data set. The server solved to two fundamental challenges in the practical application of deconvolution methods, namely (1) method selection and (2) parameter optimization. Specifically, ISMD utilized a semi-supervised approach for method recommendation and parameter optimization, which first evaluate the species, sample size, and tissue type of a given data set and test the low rank structure of commonly used cell type specific markers for cell type and signature gene selection. ISMD can handle the blood, normal, inflammatory, and cancer tissue, and central nervous and hematopoietic systems of human and mouse. The semi-supervised knowledge transfer encoded in ISMD enables its application to multi-omics data including general transcriptomics, ATAC-seq and DNA-methylation data. The method has been validated by using a large collection of tissue samples. A user friend web-server has been released through https://github.com/xiaoyulu95/ISMD. We anticipate ISMD can help to increase the specificity and rigorousness in the application of tissue deconvolution methods, to bring more insights of the role of different cell types and their interactions and stimulate the discovery of new therapeutic targets in a tumor micro-environment.

Citation Format: Xiaoyu Lu, Pengtao Dang, Szu-Wei Tu, Wennan Chang, Changlin Wan, Chi Zhang, Sha Cao. An integrated web server for multi-omics data deconvolution [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 3217.
Abstract 3272: Is PD-L1 expression a decision-making biomarker for immunotherapy: a meta-analysis and cross-sectional study
Authors: Wang Zhijie , Duan Jianchun , Cui Longgang , Cai Shangli , Wang Jie
Published: September 2020

Background: PD-L1 expression has been approved by FDA as a diagnosis for anti-PD-(L)1 therapy in several types of cancer, however, there were still discrepancies of the predictive value of PD-L1 expression. Here we aimed to systematically assess the value of PD-L1 expression in determining cancer patients who should be offered anti-PD-(L)1 therapy and to characterize PD-L1 expression in Chinese cancer population.

Methods: Cochrane library, PubMed and Embase databases were systematically searched to include relevant studies published between January 2000 and June 2019. We also reviewed the reports from all major conference proceedings. All randomized controlled trials investigating anti-PD-(L)1 efficacy in solid tumors were initially included if overall survival (OS) data were stratified by PD-L1 expression. Differences in OS benefits between PD-L1-positive and PD-L1-negative patients were analyzed. Effect size derived from each study was pooled using a random-effects model. Data regarding PD-L1 expression in Chinese patients were obtained from a CAP-accredited and CLIA-certified laboratory.

Results: Twenty-five RCTs involving 14,471 patients were included. OS benefit was observed in patients with either positive (HR=0.68 [0.63-0.73], P<0.00001) or negative (HR=0.86 [0.78-0.95], P=0.003) PD-L1 expression, though significant longer OS was achieved in patients that are PD-L1 positive (P interaction=0.0001). Superior PFS were observed in patients with positive PD-L1 expression (HR=0.69 [0.57-0.82]) while not with negative PD-L1 expression (HR=1.00 [0.85-1.19]). PD-L1-positive patients exhibited significantly improved ORR than those who tested negative for PD-L1 when treated with immunotherapy (OR=0.50 [0.39-0.65], P<0.00001), while no differences were observed among patients given SOC (OR=1.02 [0.86-1.21], P=0.81). Analysis of Chinese patients PD-L1 status revealed that thymoma and small cell lung cancer expressed the highest and the lowest levels of PD-L1, respectively.

Conclusion: PD-L1 expression alone is not determinative in patient selection for anti-PD-(L)1 treatment. Multiple modality biomarkers should be considered for cancer patients especially for those with PD-L1-negative tumors.

Citation Format: Zhijie Wang, Jianchun Duan, Longgang Cui, Shangli Cai, Jie Wang. Is PD-L1 expression a decision-making biomarker for immunotherapy: a meta-analysis and cross-sectional study [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 3272.