bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 1528: Discovery and preclinical characterization of fratricide-resistant TRuC T-cells targeting CD70
Authors: Ding Jian , Watt Amy , Liu Erica , Adam Zieba , McCarthy Derrick , Gierut Jessica , Schrand Brett , Lofgren Michael , Lajoie Jason , Kenanova Vania , Kiefer-Kwon Philippe , Horton Holly , Gutierrez Dario A. , Hofmeister Robert , Tighe Robert
Published: July 2021

Previously we have described the design and antitumor activity of T cell receptor fusion constructs (TRuC™) that tether an antibody-derived binder to one of the TCR subunits to achieve redirected T cell killing of tumor cells independent of HLA. Different from CAR-T cells, TRuCs are integrated into the full TCR complex and thus harness its full signaling capacity. The cell surface antigen CD70 represents a promising target for cancer immunotherapy for its selective overexpression in various hematological and solid tumor indications. Because the normal tissue expression of CD70 occurs on activated lymphocytes, including activated T cells, fratricide (self-killing) has been recognized as a significant challenge for CD70-targeted T cell therapies. To address this challenge, we discovered a diverse pool of fully human anti-CD70 scFv binders that were used to make TRuC-T cells and then functionally screened for fratricide-resistance in vitro. We successfully identified a CD70-targeted TRuC-T cell candidate that exhibits normal T cell expansion and an improved memory phenotype, clearly differentiating from fratricide-prone candidates, all while maintaining potent cytotoxicity and cytokine production against tumor cells expressing both low and high levels of CD70. In addition, our CD70-targeted TRuC-T cells showed significant anti-tumor efficacy in multiple xenograft mouse models with no evidence of in vivo fratricide. In summary, we have engineered a fratricide-resistant CD70-directed TRuC-T cell therapy that has the potential to treat a wide range of both hematologic and solid cancers.

Citation Format: Jian Ding, Amy Watt, Erica Liu, Zieba Adam, Derrick McCarthy, Jessica Gierut, Brett Schrand, Michael Lofgren, Jason Lajoie, Vania Kenanova, Philippe Kiefer-Kwon, Holly Horton, Dario A. Gutierrez, Robert Hofmeister, Robert Tighe. Discovery and preclinical characterization of fratricide-resistant TRuC T-cells targeting CD70 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1528.
Abstract 1542: A FasL-targeted immunomodulatory fusion protein replaces a pro-death with a costimulatory signal, enhancing T cell function, adoptive cell therapy, and altering the tumor microenvironment
Authors: McMurray Margot , Oda Shannon
Published: July 2021

Improved therapies are urgently needed for several cancers, including acute myeloid leukemia (AML) and pancreatic cancers. Adoptive cell therapy (ACT) with genetically-modified T cells has shown impressive results against B cell malignancies, but limited efficacy in other hematologic and solid tumors. To address this need, we have developed immunomodulatory fusion proteins (IFPs) that combine the ectodomain of an inhibitory receptor with a costimulatory endodomain, providing positive signals exclusively delivered to the T cells concurrently engineered to target tumor-expressed antigens, avoiding the systemic T cell activation seen with immune checkpoint-blocking therapies. We developed an IFP to target Fas ligand (FasL), which is commonly over-expressed in TMEs and induces apoptosis in tumor-infiltrating T cells. We replaced the Fas intracellular tail with the costimulatory, pro-survival 4-1BB signaling domain since both Fas and 4-1BB signal as trimers. After exposure to a murine AML cell line, IFP-transduced murine T cells effectively generated 4-1BB signaling, with metabolic reprogramming, and showed enhanced in vitro proliferation, accumulation and function. IFP T cells resisted exhaustion and effectively eradicated AML, improving survival to 71% in the FBL disseminated AML murine model (vs.11% survival with control T cells). We next engineered T cells with a single-vector that combined the IFP with a tumor-targeted mesothelin-targeted T cell receptor (TCR), for studies with the KPC mouse model of PDA that recapitulates the immunosuppressive characteristics of human disease. TCR/Fas-4-1BB T cells showed increased intratumoral concentration over control TCR-only T cells and increased median survival (65 vs. 37 days, P=0.0042). Human TCR/Fas-4-1BB T cells induced significantly more PDA tumor cell lysis than a dominant negative Fas receptor, supporting the increased benefit of the costimulatory signal. Single-cell RNA sequencing results suggest that IFP-ACT can also improve endogenous antitumor immunity, and Fas-4-1BB primary human T cells showed increased in vitro expansion and cytokine production, relative to TCR-only human T cells. We have now developed a toolbox of IFPs with distinct costimulatory domains and we show that IFPs can substantially improve therapeutic efficacy against liquid and solid tumors, supporting clinical translation.

Citation Format: Margot McMurray, Shannon Oda. A FasL-targeted immunomodulatory fusion protein replaces a pro-death with a costimulatory signal, enhancing T cell function, adoptive cell therapy, and altering the tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1542.
Abstract 1544: Generation of ALK CAR-T cells for neuroblastoma therapy
Authors: Bergaggio Elisa , Tai Wei-Tien , Aroldi Andrea , Mota Ineês , Alvarado Diego , Landoni Elisa , Metovic Jasna , Nüesch Manuel , Blasco-Patiño Rafael , Papotti Mauro , Dotti Gianpietro , Chiarle Roberto
Published: July 2021

Neuroblastoma (NB) is the most deadly cancer in children with dismal survival in high-risk patients. The majority of NB express the full length anaplastic lymphoma kinase (ALK) receptor, that typically acts as driver oncogene together with MYCN. In contrast to ALK-driven lung cancer or lymphoma, targeted therapies with ALK tyrosine kinase inhibitors (TKIs), despite encouraging, induce only partial responses in NB. Therefore, additional tools to improve NB treatment are strongly needed. To specifically target NB cells, we developed a series of ALK chimeric antigen receptor (CAR) T constructs from antibodies that recognize both human and mouse ALK. Murine ALK CAR-T cells are able to control the growth of ALK+ leukemia and NB in syngeneic tumor models without detectable toxicity. From the leading candidate, we generated fully humanized ALK CAR-T cells that showed potent in vitro killing activity against a large panel of human NB lines, with activity comparable to GD2 CAR-T cells that are currently in clinical trials for NB patients. Remarkably, ALK CAR-T treatment synergized in vivo with the ALK inhibitor lorlatinib. Mechanistically, lorlatinib not only reduced tumor growth, but enhanced ALK expression on the surface of tumor cells, thereby facilitating ALK CAR-T targeting. Combination of ALK CAR-T cells with lorlatinib resulted in enhanced killing of NB cells and cure or markedly increased survival in mouse models of human metastatic NB even with low ALK expression. These findings support the clinical development of ALK CAR-T cells for NB therapy.

Citation Format: Elisa Bergaggio, Wei-Tien Tai, Andrea Aroldi, Ineês Mota, Diego Alvarado, Elisa Landoni, Jasna Metovic, Manuel Nüesch, Rafael Blasco-Patiño, Mauro Papotti, Gianpietro Dotti, Roberto Chiarle. Generation of ALK CAR-T cells for neuroblastoma therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1544.
Abstract 1557: Intratumoral plasmid IL-12 enhanced the systemic anti-tumor effect of anti-PD-1 antibody in triple-negative breast cancer
Authors: Nagata Hiroshi , Osada Takuya , Crosby Erika J. , Canton David A. , Twitty Chris G. , Lyerly H. Kim
Published: July 2021

Background: Triple-negative breast cancer (TNBC) is an aggressive disease with limited therapeutic options. Although immune checkpoint inhibitors (ICI) have entered the therapeutic landscape in TNBC, their benefits are limited to a minority of patients. We hypothesized the combination of ICI with the intratumoral administration of plasmid IL-12 (tavokinogene telseplasmid; TAVOTM) followed by electroporation could enhance the therapeutic efficacy based on our previous observation of the anti-tumor effect of TAVO in TNBC. The purpose of this study was to clarify the potency of TAVO as an additive local treatment to systemic anti-PD-1 immunotherapy.

Methods: A murine TNBC cell line, E0771, was implanted bilaterally into flanks of female C57BL/6 mice, which were randomized into four groups: control (control plasmid + control antibody), anti-PD-1 (control plasmid + anti-PD-1), Tavo (Tavo + control antibody), and combination (TAVO + anti-PD-1). TAVO or control plasmid (50 µg/injection) was administered into a single tumor followed by electroporation on days 0, 3, and 7, as we previously reported (SITC abstract), while tumors on the other side were left untreated. Anti-PD-1 or control antibody (200 µg/injection) was administered by intraperitoneal injection on days 2, 6, 9, and 13. Tumor volume was measured every other day, and the survival of mice was monitored. The local microenvironment of both treated and untreated tumors and systemic effect on splenocytes were evaluated using flow cytometry and single-cell RNA-sequencing.

Results: The combination of intratumoral administration of TAVO with anti-PD-1 suppressed the tumor growth more effectively compared to the other groups not only in treated local tumors but also in untreated remote tumors. Higher rates of tumor regression and better survival were observed in the combination group. TAVO locally increased effector CD8+ T cells while reducing regulatory T cells in both treated tumors and distant untreated tumors. The systemic expansion of effector CD8+ T cells was also observed in splenocytes.

Conclusions: Intratumoral electroporation of TAVO with anti-PD-1 improved systemic anti-tumor efficacy by modifying the immunosuppressive tumor microenvironment. Clinical studies of this combination treatment in TNBC are underway.

Citation Format: Hiroshi Nagata, Takuya Osada, Erika J. Crosby, David A. Canton, Chris G. Twitty, H. Kim Lyerly. Intratumoral plasmid IL-12 enhanced the systemic anti-tumor effect of anti-PD-1 antibody in triple-negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1557.
Abstract 1590: An experimental tumor model resistant to anti-PD-1 is sensitive to local mRNA immunotherapy
Authors: Bernardo Marie , Tolstykh Tatiana , Zhang Yu-an , Bangari Dinesh S. , Cao Hui , Heyl Kerstin A. , Lee Joon Sang , Malkova Natalia , Pollard Jack , Qu Hui , Sun Fangxian , Wiederschain Dmitri , Wagenaar Timothy R.
Published: July 2021

Immune checkpoint blockade elicits durable anti-cancer responses in the clinic, however a large proportion of patients do not benefit from treatment. In an effort to better understand acquired resistance to checkpoint blockade, we generated a mouse tumor model exhibiting in vivo resistance to anti-PD-1 antibody treatment. MC38 tumors acquired resistance to PD-1 blockade following serial in vivo passaging. Lack of sensitivity to PD-1 blockade was not attributed to dysregulation of PD-L1 or β2M expression, as both were expressed at similar levels in parental and resistant cells. Similarly, IFNγ signaling and antigen processing and presentation pathways were functional in both parental and resistant cell lines. RNA-sequencing revealed substantial differences in global gene expression, with tumors resistant to anti-PD-1 displaying a marked reduction in expression of immune-related genes relative to parental MC38 tumors. Indeed, resistant tumors exhibited reduced immune infiltration across multiple cell types, including T and NK cells. Pathway analysis revealed activation of TGFβ and Notch signaling in anti-PD-1 resistant tumors, and activation of these pathways was associated with poorer survival in human cancer patients. While pharmacological inhibition of TGFβ and Notch in combination with PD-1 blockade decelerated tumor growth, local administration of a mixture of mRNAs encoding immune-stimulatory cytokines (IL12sc, GM-CSF, IL15s and IFNα) potently induced regression of resistant tumors and resulted in complete tumor remission. Overall, this study describes a novel anti-PD-1 resistant mouse tumor model and underscores the role of two well-defined signaling pathways in response to immune checkpoint blockade. Furthermore, our data highlights the potential of intratumoral mRNA therapy in overcoming acquired resistance to PD-1 blockade.

Citation Format: Marie Bernardo, Tatiana Tolstykh, Yu-an Zhang, Dinesh S. Bangari, Hui Cao, Kerstin A. Heyl, Joon Sang Lee, Natalia Malkova, Jack Pollard, Hui Qu, Fangxian Sun, Dmitri Wiederschain, Timothy R. Wagenaar. An experimental tumor model resistant to anti-PD-1 is sensitive to local mRNA immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1590.
Abstract 1600: Cancer driver screens identifyregulators of immune checkpoint blockade therapy response
Authors: Zhou Wenrong , Peng Zhengang , Huang Dawei , Long Min , Song Tianyu , Ni Siyuan , Cang Yong
Published: July 2021

Cancer mutations play essential roles in tumor development by promote cell proliferation or immune evasion. However, some recent researches indicate that cancer cells with these mutation burden also expose their vulnerability to immune-based therapies such as checkpoint blockade. Here we performed comprehensive CRISPR knockout library screens in syngeneic mouse models on cancer driver mutation genes. We identified a set of genes including Kmt2d, Arid2, Rhob, Eloc, Ptpn11 and Xpo1, which have high frequency mutation in several human cancer types and their deficiency made tumor cells better respond to anti-PD-1 treatment. Furthermore, some of these deletions were validated to sensitize the tumor cells to cytotoxic T cells by in vitro co-culture with CD8+ T cells. The findings of Kmt2d was in accordance with a recent report for its role as a sensitizing modulator of immune checkpoint blockade from mouse model and patient prediction. These findings provide a new insight for understanding the interaction between the tumor heterogeneity and microenvironment. These results revealed CRISPR in vivo screen as a robust tool for both context and target discovery for tumor immunotherapy.

Citation Format: Wenrong Zhou, Zhengang Peng, Dawei Huang, Min Long, Tianyu Song, Siyuan Ni, Yong Cang. Cancer driver screens identifyregulators of immune checkpoint blockade therapy response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1600.
Abstract 1618: Inhibition of lung tumorigenesis by a novel small molecule CA170 targeting the immune checkpoint protein VISTA
Authors: Pan Jing , Chen Yao , Zhang Qi , Khatun Achia , Palen Katie , Wang Li , Yang Chuanjia , Johnson Bryon D. , Myers Charles R. , Sei Shizuko , Shoemaker Robert H. , Lubet Ronald A. , Wang Yian , Cui Weiguo , You Ming
Published: July 2021

Immunotherapy using monoclonal antibodies to block immune checkpoints is becoming a mainstream therapy for multiple late-stage cancers owing to their efficacy in improving clinical outcomes. However, relatively low response rates and persistent clinical side effects indicate the need for additional strategies to block immune-suppressive pathways. VISTA (V-domain Ig Suppressor of T cell Activation), which is expressed on cells of the myeloid and lymphoid lineages, is an emerging target for cancer immunotherapy. Blocking VISTA activates both innate and adaptive immunity to eradicate tumors in mice. We found that CA170, a novel orally bioavailable tripeptide small molecule antagonist of VISTA and PD-L1/PD-L2, has potent anticancer efficacy on carcinogen-induced mouse lung tumorigenesis. Remarkably, lung tumor development was almost completely suppressed when CA170 was combined with an MHC-II-directed KRAS peptide vaccine. Flow cytometry and single cell RNA sequencing (scRNA-seq) revealed that CA170 increases CD8+ T cell infiltration and effector functions by decreasing the tumor infiltration of myeloid derived suppressor cells (MDSCs) and regulatory T cells (Tregs), while the KRAS vaccine primarily induces expansion of CD4+ effector T cells. Inhibition of VISTA by CA170 has strong efficacy against lung tumorigenesis with broad immunoregulatory functions that influence effector, memory and regulatory T cells, and promotes an adaptive T cell tumor-specific immune response that enhances efficacy of the KRAS vaccine.

Citation Format: Jing Pan, Yao Chen, Qi Zhang, Achia Khatun, Katie Palen, Li Wang, Chuanjia Yang, Bryon D. Johnson, Charles R. Myers, Shizuko Sei, Robert H. Shoemaker, Ronald A. Lubet, Yian Wang, Weiguo Cui, Ming You. Inhibition of lung tumorigenesis by a novel small molecule CA170 targeting the immune checkpoint protein VISTA [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1618.
Abstract 1619: A prognostic score for advanced non-small cell lung cancer with PD-1/L1 inhibitors
Authors: Yuan Qianyu , Du Mulong , Christiani David
Published: July 2021

Background: Programmed death 1 (PD-1)/programmed death-legend 1(PD-L1) inhibitors have shown clinical benefits for a proportion of advanced lung cancer patients. This study aimed to develop a prognostic store with routinely available variables to identify non-small cell lung cancer (NSCLC) patients who likely benefit from PD-1/L1 inhibitors.

Methods: 412 patients who received PD-1/L1 inhibitors were retrospectively collected from Massachusetts General Hospital (MGH) and Brigham and Women's Hospital (BWH) between Nov 2013 and Jan 2018. Demographic, clinical, and common laboratory tests were collected. Penalized Cox proportional hazard model with group minimax concave penalty (MCP) penalty was applied for variable section and coefficient estimation. Model performance was assessed by calculating area under the receiver operating curves (AUC). A prognostic score was developed to categorize advanced NSCLC patients into good, intermediate and poor groups.

Results: Median PFS was 3.6 (95% CI: 2.9 - 4.3) months, median OS was 18.4 (95% CI: 14.2-24.9) months. A prognostic scoring model incorporating the weighted coefficients of PD-L1 expression level, EGFR mutation status, ECOG performance status, and albumin level was developed. Median PFS were 1.7 (95% CI: 1.5-2.1) vs 3.2 (95% CI: 2.7-6.3) vs 6.2 (95% CI: 4.9-9.7) months for the poor, intermediate and good groups, respectively. Median OS were 8.2 (95% CI: 4.5-14.1) vs 14.9 (95% CI: 11.8-30.0) vs 34.7 (95% CI: 26.2 -NE) months for the poor, intermediate and good groups, respectively.

Conclusions: a prognostic score combining PD-L1 expression level, EGFR mutation status, ECOG performance status, and albumin level may help to identify advanced NSCLC patients who likely benefit from PD-1/L1 inhibitors.

Citation Format: Qianyu Yuan, Mulong Du, David Christiani. A prognostic score for advanced non-small cell lung cancer with PD-1/L1 inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1619.
Abstract 1622: Block-Removed Immunoglobulin Technology (BRITE) to enhance rituximab effector function by counteracting CA125/MUC16-mediated immunosuppression
Authors: Grasso Luigi , Kline J. Bradford , Nicolaides Nicholas C.
Published: July 2021

Rituximab is a CD20-targeting antibody that is the standard-of-care for patients with Non-Hodgkin Lymphoma (NHL) cases. Rituximab's mechanism of action includes complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC) - herein referred to as Humoral Immuno-Oncology (HIO) mechanism. Recent clinical evidence suggest that high serum levels of the tumor-produced MUC16/CA125 protein has a negative impact on the effectiveness of rituximab clinical activity on up to 40% of follicular lymphoma patients. In this study we demonstrate that CA125 binds to rituximab and reduces its tumor cell killing activity. Moreover, we describe the generation of a rituximab variant, named NAV-006, using a proprietary technology called Block-Removed Immunoglobulin Technology (BRITE) that employs randomized amino substitution and high-throughput screening to identify HIO-refractory rituximab variants. Here, we demonstrate that NAV-006 is more refractory to the immunosuppressive effects mediated by CA125 as shown by its reduced CA125 interaction and increased HIO activity. These data warrants further investigation of NAV-006 as a next generation anti-CD20 antibody that could improve upon the efficacy of the parent rituximab in NHL patients with high levels of CA125.

Citation Format: Luigi Grasso, J. Bradford Kline, Nicholas C. Nicolaides. Block-Removed Immunoglobulin Technology (BRITE) to enhance rituximab effector function by counteracting CA125/MUC16-mediated immunosuppression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1622.
Abstract 1634: Siglec-15 knockout inhibits tumor growth in mouse model
Authors: Li Peixue , Yan Guofang , Wang Fuyang , Tang Xuzhen , Lin Qing
Published: July 2021

Several immune checkpoint blockers have been approved for treatment of certain cancers, which benefits a lot of patients with malignancies. However, the overall response rate to the current checkpoint blockers did not exceed 30% in many cases, stressing the importance of developing new immunotherapies. Siglec-15 is reported to be a critical immune suppressor functioning in parellel with PD1/PD-L1 pathway by Lieping Chen's lab in 2019. In order to verify the effect Siglec-15 in immune response against tumor growth, we generated Siglec-15 KO mice with CRISPR/Cas9 mediated genome editing and tested tumor establishment on this mice with syngeneic cell lines with or without human SIGLEC-15 overexpression. Our results showed that Siglec-15 KO inhibits tumor growth and enhances immune response in the tumor infiltrating leukocytes, supporting the role of Siglec-15 as a promising target for development of new immune checkpoint blocker.

Citation Format: Peixue Li, Guofang Yan, Fuyang Wang, Xuzhen Tang, Qing Lin. Siglec-15 knockout inhibits tumor growth in mouse model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1634.
Abstract 1644: Targeting type I IFN-regulated secretory profiles to overcome acquired anti-PD-L1 resistance
Authors: Shi Yuhao , Dolan Melissa , Mastri Michalis , Hill James W. , Eng Kevin , Ebos John M.
Published: July 2021

Therapeutic inhibition of PD-L1 has led to durable benefits for many cancer patients; however, acquired resistance is common. Dysregulated type I and II interferon (IFN) signalling on tumor cells can contribute to resistance via altered expression of IFN stimulated genes (ISGs) leading to immune-suppression and tumor promotion. In this study, we examined the role of type I IFN signaling following acquired resistance to PD-L1 blockade using an EMT6 mouse breast orthotopic tumor model that was initially responsive to treatment, but that later relapsed. Following selection of PD-L1 drug resistant (PDR) tumor cells, transcriptomic and proteomic analysis was used to identify a unique signature of secreted proteins associated with IFN signaling that was then validated using published preclinical and clinical datasets. Using genetic and therapeutic approaches to block PD-L1 in vitro, we found PDR secretory signatures to be enhanced after type I IFN stimulation. In vivo, inhibition of specific ISGs (IL-6) or ISG regulators (IFNAR1) led to enhanced anti-tumor effects in PDR models, compared to parental controls. Together, these results identify a secretory profile associated with acquired resistance to PD-L1 blockade that may be modulated, in part, by a tumor-intrinsic PD-L1/IFN signaling crosstalk and suggest that selective targeting of secreted ISGs may provide benefit for patients after anti-PD-L1 treatment failure.

Citation Format: Yuhao Shi, Melissa Dolan, Michalis Mastri, James W. Hill, Kevin Eng, John M. Ebos. Targeting type I IFN-regulated secretory profiles to overcome acquired anti-PD-L1 resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1644.
Abstract 1654: Myeloid-dominated spontaneous tumor models as the tool for the evaluation of immune modulators
Authors: Zhai Xianzhi , Yang Yuying , Zhao Haoxia , Jiang Jingjing , Tang Xuzhen , Ji Qunsheng
Published: July 2021

BACKGROUND:Myeloid cells, such as TAMs and MDSCs and their correlation with solid tumor progression have been widely recognized. As researchers are turning their interests to explore myeloid related tumor models, spontaneous tumor models, which represent a natural development/progression of tumor under certain immune microenvironment, would be a valuable tool for such studies. Some traditional targeted drugs have been re-evaluated for their immune effects, for example, CDK inhibitors can trigger anti-tumor immunity beyond its cell cycle regulation. Methods:In prior studies we have identified two myeloid-dominant spontaneous tumor models, APCmin and MMTV-PyMT, which represented a myeloid-enriched(especially for gMDSCs) and low T cell infiltrated microenvironment compared to the congenic mice. Immune modulators including checkpoint inhibitors (aCTLA-4),NSAID (Celecoxib) and CDK4/6 inhibitor(Palbociclib) were applied to evaluate their efficacy to the two models and their influences on the immune microenvironment. RESULTS:As a result, CDK inhibitor Palbociclib showed a better curative effect on MMTV-PyMT model compared to aCTLA-4. It seems when aCTLA-4 only up-regulated T cell level, CDK inhibitor can both increase the tumor infiltrating T cells as well as decrease Treg and myeloid, which explain its good response on this myeloid-dominated model. In APCmin model, Celecoxib reduce adenomas and alleviate the anemia symptoms with its significant immune benefit: the increase of lymphocyte infiltration and the reversal of myeloid cell elevation. SUMMARY:In summary, APCmin and MMTV-PyMT can be used as good tool models for the evaluation of myeloid-related immune modulators.

Citation Format: Xianzhi Zhai, Yuying Yang, Haoxia Zhao, Jingjing Jiang, Xuzhen Tang, Qunsheng Ji. Myeloid-dominated spontaneous tumor models as the tool for the evaluation of immune modulators [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1654.
Abstract 166: Real world genomic data supports combined use of SHP-2 and PD-1/PD-L1 inhibitors in solid tumors
Authors: Toral Keller
Published: July 2021

The identification of novel therapies, new strategies for combination of therapies, and repurposing of drugs approved for other indications are all important for continued progress in the fight against lung cancers. Antibodies that target immune checkpoints can unmask an immunologically hot tumor from the immune system of a patient. However, despite accounts of significant tumor regression resulting from these medications, most patients do not respond. In this study, we sought to use protein expression and RNA sequencing data from The Cancer Genome Atlas and two smaller studies deposited onto the Gene Expression Omnibus (GEO) to advance our hypothesis that inhibition of SHP-2, a tyrosine phosphatase, will improve the activity of immune checkpoint inhibitors (ICI) that target PD-1 or PD-L1 in lung cancers. We first collected protein expression data from the The Cancer Proteome Atlas (TCPA) to study the association of SHP-2 and PD-L1 expression in lung adenocarcinomas. RNA sequencing data was collected from the same subjects through the NCI Genetic Data Commons and evaluated for expression of the PTPN11 (SHP-2) and CD274 (PD-L1) genes. We then analyzed RNA sequencing data from a series of melanoma patients who were either treatment naïve or resistant to ICI therapy. PTPN11 and CD274 expression was compared between groups. Finally, we analyzed gene expression and drug response data collected from 21 non-small cell lung cancer (NSCLC) patients for PTPN11 and CD274 expression. From the three studies, we hypothesize that the activity of SHP-2, rather than the expression, likely controls the expression of PD-L1 as only a weak relationship between PTPN11 and CD274 expression in either lung adenocarcinomas or melanomas was observed. Lastly, the expression of CD274, not PTPN11, correlates with response to ICI in NSCLC.

Citation Format: Keller Toral. Real world genomic data supports combined use of SHP-2 and PD-1/PD-L1 inhibitors in solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 166.
Abstract 1681: Correlation of BRCA1/2 mutations with response to immune checkpoint inhibitors in colorectal cancer
Authors: Jia Dong-Dong , Niu Yanling , Ma Tonghui , Shi Min
Published: July 2021

Background: BRCA1 and BRCA2 are involved in homologous recombination (HR) DNA repair. They have been found to promote both tumor initiation and progression. BRCA1/2 mutations lead to genomic instability and higher tumor mutation burden (TMB). Therefore, we hypothesized that BRCA1/2 mutations may be a predictor of immune checkpoint inhibitors (ICIs) efficacy. In the present work, we explored the correlation of BRCA1/2 mutations with TMB, high microsatellite instability (MSI-H), PD-L1 expression, tumor-infiltrating lymphocytes (TILs), and ICIs efficacy in colorectal cancer.

Methods: A total of 509 Chinese colorectal cancer patients were enrolled from January 2017 to January 2020 in our center. Targeted next-generation sequencing and PD-L1 immunohistochemistry (22C3 antibody) were performed in the tissues from patients. TCGA colorectal cancer cohort was used for characterizing TILs with CIBERSORT. The ICIs treatment cohort from the Memorial Sloan Kettering Cancer Center (MSKCC) was selected to analyze the association of BRCA1/2 mutations with ICIs efficacy.

Results: In our cohort, the mutational frequency of BRCA1/2 genes was 9.04%. The median TMB was significantly higher in the BRCA1/2 mutations (Mut) group compared to the wild type (WT) group (52.4 vs 5.7 muts/Mb, P < 0.0001). About 41.30% of patients have MSI-H in the Mut group, while 3.67% of patients display MSI-H in the WT group (P < 0.0001). There was no association of BRCA1/2 mutations with PD-L1 expression (P = 0.172). In TCGA cohort, BRCA1/2 mutations can down-regulate regulatory T (T reg) cells (P = 0.0176) and up-regulate T follicular helper cells (P = 0.0042) and macrophages M1 (P <0.0001). In MSKCC cohort, patients in the Mut group had significantly longer median overall survival after ICIs therapy (34 vs 13 months, HR: 0.37 [95%CI: 0.19-0.72], P = 0.0234).

Conclusions: Our data indicated that BRCA1/2 mutations are associated with increased TMB and MSI-H, but not with PD-L1 expression. And BRCA1/2 mutations can regulate TILs. Furthermore, BRCA1/2 mutations are associated with better response to ICIs, suggesting that they may be a useful predictor for ICIs efficacy in colorectal cancer.

Citation Format: Dong-Dong Jia, Yanling Niu, Tonghui Ma, Min Shi. Correlation of BRCA1/2 mutations with response to immune checkpoint inhibitors in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1681.
Abstract 1694: Validation of GVHD in humanized mouse model for preclinical efficacy screen
Authors: Liu Menglin , Cai Yingying , Xu Na , Zhang Ya , Xie Rou , Jia Lijun , Lin Qing
Published: July 2021

Bone marrow transplantation has been successfully and widely used to treat diseases such as leukemia and lymphoma. However, the complication Graft vs Host Disease (GVHD) is a serious hindrance in patients' outcome. Immunosuppressant such as Cyclosporine A has been used to decrease the GVHD occurrence, but the associated side-effect such as transplant rejection and opportunistic infection outweigh its benefit. Therefore, new medication to suppress GVHD without severe toxicity is urgently in need now. To build better preclinical platform for drug efficacy evaluation in GVHD, we have validated the GVHD model in both mouse host and humanized mouse host. We collected bone marrow cells and splenocyte from C57BL/6J (H-2d) mice and transplant to irradiated BALB/c (H-2b) mice to induce GVHD. In humanized model, we injected humanized NPI mice (NOD-Prkdcscid-Il2rgem1lDMO with CD34+ hematopoeitc stem cells (HSCs) reconstitution) with PBMCs from MHCII mismatched donors to trigger GVHD occurrence. In both models, we observed the typical clinical symptoms such as hollow back, inactiveness, body weight loss in transplanted mice. Humanized mice with transplantation start to die in 2 weeks. In the endpoint, we used FACS to analyze the cell population change in whole blood, spleen and lymph nodes, and found histological changes in GI tract and skin. Thus, this model is suitable to screen potential human-specific antibodies or new small molecules. We are also going to explore extra parameters to characterize the disease progression.

Citation Format: Menglin Liu, Yingying Cai, Na Xu, Ya Zhang, Rou Xie, Lijun Jia, Qing Lin. Validation of GVHD in humanized mouse model for preclinical efficacy screen [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1694.
Abstract 1708: Improving genotype specific chemotherapy response in ovarian cancer via cGAS-STING pathway activation
Authors: Shakfa Noor , Lightbody Elizabeth , Li Deyang , Wilson-Sanchez Juliette , Conseil Gwenaelle , Afriyie-Asante Afrakoma , Chenard Stephen , Hamade Ali , Koti Madhuri
Published: July 2021

High grade serous ovarian carcinoma (HGSC) is the most lethal gynecologic malignancy with high rates of chemotherapy resistance and poor outcomes. Our previous studies have demonstrated the variable tumor immune microenvironment states that associate with platinum chemotherapy response. We further showed the significance of the interferon (IFN) induced chemokine CXCL10 as a key mediator of tumor infiltrating immune cell recruitment. Using the ID8-Trp53−/− murine model of HGSC, we demonstrated the potential of Stimulator of Interferon Genes (STING) pathway activation in enhancing response of HGSC tumors to carboplatin chemotherapy and sensitizing them to immune checkpoint blockade therapy through a heightened type 1 IFN (IFN1) response. CXCL10 production via IFN1 is also governed by genes that regulate cellular DNA damage repair pathways. Evolving evidence indicates a role of BRCA1 and PTEN genes in mediating cellular IFN1 responses. Losses in the function of these genes is widely prevalent in a large proportion of HGSC tumors, where tumors with BRCA1 mutations (~25% of HGSC cases) have higher CD8+ T cell infiltration in contrast to those with loss of PTEN (~10% of cases). We hypothesized that HGSC tumors with loss of PTEN expression can be rendered susceptible to immune mediated killing via activating the STING pathway. Tumors generated from ID8-Trp53−/−; Brca1−/− cells and those from ID8-Trp53−/−; Pten−/− cells in C57BL6 mice showed significant immunologic differences through local and systemic immune profiling. The addition of STING agonist treatment significantly increased chemosensitivity and improved overall response in mice implanted with ID8-Trp53−/−; Pten−/− cells compared to those treated with carboplatin alone, altering immune responses. This study is foundational to inform rational combinations of STING pathway activating therapies in HGSC, augmenting responses to existing chemotherapy regimens and prolonging survival rates in patients.

Citation Format: Noor Shakfa, Elizabeth Lightbody, Deyang Li, Juliette Wilson-Sanchez, Gwenaelle Conseil, Afrakoma Afriyie-Asante, Stephen Chenard, Ali Hamade, Madhuri Koti. Improving genotype specific chemotherapy response in ovarian cancer via cGAS-STING pathway activation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1708.
Abstract 1718: Tumor eradicated by an effective in situ vaccine based on a TLR agonist and an agonistic anti-OX40 antibody
Authors: Chu Yanhong , Liu Qin , Liu Baorui
Published: July 2021

As cancers are antigenic, numerous efforts have been devoted to harnessing the exquisite specificity of the immune system to destruct tumors over the past two decades. In this study, we have employed a practical approach called in situ vaccination without the need to previously identify and isolate antigen targets. Intratumoral injection of a TLR7 ligand R837 and an agonistic anti-OX40 antibody showed impressive synergistic anti-tumor effects. R837 upregulated the expression of OX40 on CD4+ T cells in the treated tumor. Then, anti-OX40 antibody triggered systemic tumor-specific T cell responses, with one-fold increase of effector memory T cells properties and stronger toxicity of lymphocytes in spleen. Remarkably, both the injected tumor and the noninjected tumor in the distant lesion of the mice were eliminated after vaccination. IL-1α is a pro-inflammatory cytokine, however IL-10 is an important anti-inflammatory cytokine that plays a central role as a negative immune regulator. In the tumor microenvironment, we found that the level of IL-1α increased and IL-10 decreased after vaccination. From RNA-seq analysis, many immune-related pathways in the tumor microenvironment were activated after vaccination, such as TNF signaling pathway, NOD-like receptor signaling pathway, C-type lectin receptor signaling pathway, Toll-like receptor signaling pathway and so on. This in situ vaccine based on two low doses of immunoomdulators caused little harm to normal organs and provided long-term protection against the same syngeneic tumor rechallenge. It could be applied to various types of late stage solid tumors and worthy of further clinical research.

Citation Format: Yanhong Chu, Qin Liu, Baorui Liu. Tumor eradicated by an effective in situ vaccine based on a TLR agonist and an agonistic anti-OX40 antibody [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1718.
Abstract 172: Computational analysis of the NEK family of proteins reveals unique structural features and interactions with other cancer-related proteins
Authors: Silva Andriele , Singh Shaneen
Published: July 2021

The human Never In Mitosis A-like kinase (NEK) protein family consists of serine/threonine kinases that are implicated in the assembly of the mitotic spindle, regulation of the disjunction of the centrosome, and the functioning of the primary cilium. Protein kinases that regulate the centrosome cycle are often abnormally controlled in tumor cells, as are NEK family members. NEK2 was first identified in pediatric solid tumors and also has elevated expression levels in breast, pancreatic and colorectal cancer. NEK1, NEK3, and NEK5 are highly expressed in thyroid tumors, NEK8 is overexpressed in primary human breast tumors, and NEK11's expression is upregulated in early-stage colorectal cancers. To effectively exploit NEKs as drug targets, it is critical to understand their structure-function relationships to help elucidate their mechanism of action. However, structural information for most NEKs and the range and breadth of their interactions with other proteins are still widely unknown. In this study, we use an integrated computational approach which includes the prediction of the 3D structure using homology modeling, threading, and ab initio techniques, the biophysical/biochemical characterization of the theoretical models, followed by in silico protein-protein predictions and docking analysis to present a comprehensive computational analysis of all eleven NEK proteins. Our results reveal unique structural features in some of NEK family members, such as the armadillo (ARM)-like fold in NEK10 and RCC1 repeats found in NEK8 and NEK9. In addition, we present detailed investigations of four predicted protein-protein interaction scenarios involving NEK1, NEK7, NEK8, and NEK9 using docking analysis. This analysis lends support to new, previously unreported interactions of these NEKs with other cancer-related proteins i.e., TNF alpha with NEK7, GEF2 with NEK9, LRRK2 with NEK1, and ARA9 with NEK8. The details of the residues involved in the interaction interfaces from our proposed interaction scenarios provide valuable data for designing rational experiments to validate these interactions. Overall, this study uncovers novel and intriguing information about the NEK protein family, unique protein-protein interaction predictions, and lays the groundwork for elucidating their molecular mechanism as well as for investigating their potential as therapeutic targets.

Citation Format: Andriele Silva, Shaneen Singh. Computational analysis of the NEK family of proteins reveals unique structural features and interactions with other cancer-related proteins [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 172.
Abstract 1725: Short-term administration of high dose mIL-2/CD25 fusion protein elicits CD8+ T cell-driven anti-tumor immunity and memory
Authors: LaPorte Kathryn , Hernandez Rosmely , Malek Thomas
Published: July 2021

Recombinant IL-2 (rIL-2) promotes the differentiation, proliferation, and survival of antigen-activated T cells and induces potent anti-tumor activity. High dose (HD) rIL-2 broadly targets T effector (Teff) and NK cells. However, rIL-2 cancer therapy requires long-term infusions of high doses due to its short half-life and is associated with severe toxicities which limit efficacy. To circumvent these limitations, our lab has developed and is testing a new IL-2-based biologic, mIL-2/CD25, which can be used at high doses to promote anti-tumor immunity. mIL-2/CD25 is a fusion protein (FP) composed of mouse IL-2 fused to the mouse CD25 extracellular domain via a non-cleavable glycine-serine linker with selectivity toward the high affinity IL-2R. This FP has a much longer half-life (16 hr) than rIL-2 (15 min). At a low dose, mIL-2/CD25 selectively expands Tregs, but at a HD, Teff cells are also engaged. These properties allow for HD FP to readily expand activated endogenous tumor-reactive Teff cells, but not memory-phenotypic CD8+ T cells and NK cells. In the current study, we tested the extent short-term HD FP therapy activated tumor-reactive Teff cells to elicit efficacious anti-tumor immunity responses despite Treg stimulation. HD FP prolonged survival in mice bearing B16.F10 melanoma, MC-38 colon adenocarcinoma, or CT26 colon carcinoma. In the CT26 model, a significant increase in both the number and the frequency of CD8+ T cells was detected in the tumor microenvironment (TME) of treated mice. FP-dependent Treg expansion was observed in secondary lymphoid tissues but not the TME. This therapeutic approach, therefore, led to a higher CD8+ Teff to Treg ratio specifically in the TME. After FP treatment, CD8+ T cells isolated from the TME expressed lower levels of TOX, PD-1, and LAG-3, suggesting that they were less exhausted. T cell depletion studies using anti-CD8 revealed that CD8+ T cells are the major driver of the FP-induced anti-tumor response. Rechallenge of animals that had previously cleared CT26 due to FP treatment led to successful tumor rejection, showing that the FP supported anti-tumor memory. These findings demonstrate that mIL-2/CD25 amplifies recently activated tumor-reactive CD8+ Teff cells to generate efficacious anti-tumor responses that limit Treg-dependent negative regulation in the TME and lead to anti-tumor memory.

Citation Format: Kathryn LaPorte, Rosmely Hernandez, Thomas Malek. Short-term administration of high dose mIL-2/CD25 fusion protein elicits CD8+ T cell-driven anti-tumor immunity and memory [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1725.