Antitumor Cytokine Research Articles

Abstract LB339: Transient EZH2 suppression by tazemetostat during in vitro expansion maintains T cell stemness and improves adoptive T cell therapy

Abstract The histone methyltransferase enhancer of zeste homolog 2 (EZH2) plays important roles in T cell differentiation, proliferation and function. Previous studies demonstrated that genetic deletion of EZH2 in CD8+ or total T cells impairs their antiviral and antitumor activity, cytokine production and expansion upon rechallenge. Contrary to the detrimental role of deleting T cell-intrinsic EZH2, here we demonstrate that transient inhibition of EZH2 in T cells prior to the phenotypic onset of exhaustion with a clinically approved inhibitor, Tazemetostat, delays their dysfunctional progression and preserves T cell stemness and polyfunctionality while having no negative impact on cell proliferation. Tazemetostat induces T-cell epigenetic reprogramming and increases the expression of the self-renewal T cell transcription factor TCF1 by reducing its promoter H3K27 methylation preferentially in rapidly dividing T cells. In a murine melanoma model, T cells depleted of EZH2 induce poor tumor control, whereas T cells pretreated with tazemetostat exhibited superior anti-tumor immunity, especially when used in combination with anti-PD-1 blockade after adoptive transfer. Collectively, these data highlight the potential of transient epigenetic reprogramming by EZH2 inhibition to enhance adoptive T cell immunotherapy. Citation Format: Yingqin Hou, Peng Wu. Transient EZH2 suppression by tazemetostat during in vitro expansion maintains T cell stemness and improves adoptive T cell therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB339.

Abstract CT235: RNA-seq molecular subtypes and gene expression signatures in the phase 3 IMpower151 study of 1L bevacizumab + pemetrexed/paclitaxel ± atezolizumab in metastatic NSCLC

Abstract Introduction IMpower151 (NCT04194203) was a phase 3 study to evaluate the efficacy and safety of atezolizumab, bevacizumab, carboplatin, plus paclitaxel or pemetrexed (ABCP) vs BCP, as 1L treatment for metastatic nsqNSCLC. IMpower151 did not meet its primary endpoint of INV-PFS. The objectives of this biomarker analysis were to characterize the molecular subtypes of metastatic nsqNSCLC and to explore the relationship between molecular subtype, predefined gene expression signatures, PD-L1 status and clinical outcomes with ABCP and BCP. Methods RNA sequencing of 250 nsqNSCLC tumor samples from IMpower151 was analyzed in the ACBP (n=123) and BCP (n=127) treatment arms. Non-negative matrix factorization (NMF) was applied to variably expressed genes to define molecular subtypes. Gene expression signatures were defined based on previously published associations with their respective biology. Tumor PD-L1 levels were determined by SP263 immunohistochemistry (Ventana). Results No PD-L1 dependent difference of survival benefit of ABCP compared to BCP was observed at the cutoff of TC 1% or TC 50%. Four molecular subtypes (NMF1-NMF4) were identified based on RNA sequencing. NMF1 (n=78) were immune-depleted and had low tumor proliferation. NMF2 (n=73) were characterized by low level of anti-tumor immune cells, increased expression of stromal signatures and high tumor proliferation. NMF3 (n=65) had the most inflamed transcriptomic profile with high enrichment of immune cells, and increased expression of stromal signatures as well. NMF4 (n=34) had the enrichment of granulocytes, a less inflamed immunophenotype and decreased expression of stromal signatures. The positive rate of PD-L1 expression with TC>=1% was significantly lower in NMF1 compared to other subtypes. None of patients with the four NMF subtypes showed significantly longer PFS or OS with ABCP than BCP. Overall, patients with NMF2 showed numerically shorter PFS and patients with NMF3 showed numerically longer PFS than other subtypes. Gene expression signatures of antitumor cytokines are correlated with survival benefit of ABCP compared to BCP. Patients with high expression level of antitumor cytokines showed substantially improved PFS and OS benefit from ABCP than BCP in both ITT population and EGFR mutation population. Conclusion Four molecular subtypes of nsqNSCLC with different immune-cell and tumor microenvironmental features were characterized. NMF2 may identify a fibrotic and immune-depleted subgroup correlated with worse prognosis. NMF3 may identify an immune-inflamed subgroup correlated with better prognosis. Neither NMF subtypes nor PD-L1 IHC level showed a correlation with survival benefit of ABCP controlled by BCP. The gene expression signature of antitumor cytokines could serve as a potential predictive biomarker for survival benefit of ABCP in metastatic nsqNSCLC including EGFR mutant patients. This finding is based on the exploratory analysis of a single clinical trial with limited sample size. It needs further investigation in other cohorts of tumor tissues and with larger clinical potential in blood samples as well. Citation Format: Caicun Zhou, Charlie Sun, Stacey Huang, Xiaorong Dong, Gongyan Chen, Zhehai Wang, Xianghua Wu, Yu Yao, Yiping Zhang, Ying Cheng, Hongming Pan, Xiaodong Zhang, Jiuwei Cui, Lifeng Wang, Xi Chen, Xiaoling Li, Ziping Wang, Qiming Wang, Jianxing He, Mengzhao Wang, Li Qian, Habib Hamidi, Shanshan Li, Marcus Ballinger, David S. Shames, Minu Srivastava. RNA-seq molecular subtypes and gene expression signatures in the phase 3 IMpower151 study of 1L bevacizumab + pemetrexed/paclitaxel ± atezolizumab in metastatic NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT235.

Abstract 4067: Development of tumor-restricted IL-12 with antigen-dependent expression and localized IL-12 activity

Abstract IL-12 is an immune-stimulatory cytokine that can modulate the tumor microenvironmnent (TME) to enhance the cytotoxic activity of T and NK cells; however, IL-12 expression by T cells caused severe toxicity in a previous clinical trial. Using Outpace’s OutSmart™ technology, we designed a tumor-restricted IL-12 (trIL-12) that is under control of an activation-inducible promoter and auto-inactivates within minutes after secretion. T cells were engineered via lentiviral vectors (LVV) to express wild-type single-chain IL-12 (WT scIL-12) or trIL-12 under the control of an activation-inducible promoter; a second LVV introduces an NY-ESO-1 TCR. Kinetics of IL-12 expression was measured by qPCR and MSD technology; kinetics of IL-12p70 heterodimer half-life was measured using Octet bio-layer interferometry (BLI). T-cell cytotoxicity and cytokine production was evaluated in vitro after repeated stimulation with NY-ESO-1 expressing target cells using Incucyte and MSD. IL-12 activity in bystander cells was measured by detection of IFN-γ using flow cytometry. In vivo T-cell function of trIL-12-engineered NY-ESO-1 TCR T cells was measured in NSG MHCI/II KO mice bearing A375 xenografts. trIL-12 activity in a fully immune-competent mouse model was measured in B6 mice implanted with B16F10 tumor cells engineered to express murine surrogates of trIL-12. Expression of WT scIL-12 under the control of an activation-inducible promoter peaks within 6 hours after activation and produces sufficient IL-12 to improve T-cell function in vitro and in vivo. trIL-12 was created by inclusion of a cleavable linker and elimination of the covalent disulfide bond between the p35 and p40 subunits of IL-12p70, resulting in dissociation of the functional cytokine within 10 minutes post-cleavage. Additional mutations further reduce the IL-12p70 half-life. trIL-12 activates the IL-12-producing T cells, as well as proximal bystander T-cells in direct co-culture, but it does not have the ability to activate distal bystander T-cells separated by Transwell membranes. In xenograft mouse models, trIL-12-expressing T cells have improved proliferation upon antigen recognition and display potent anti-tumor activity and cytokine production without showing systemic IL-12 accumulation. Furthermore, in fully immune competent mice, expression of a murine trIL-12 surrogate by tumor cells led to generation of potent anti-tumor responses without systemic trIL-12 accumulation and reduced systemic IFN-γ. trIL-12-engineered T cells generate potent anti-tumor activity in vitro and in vivo. Unlike WT scIL-12, trIL-12 activity is localized to the region around the producing T cell and systemic IL-12 exposure is not observed in vivo. Collectively, these preclinical data suggest that trIL-12 may enable the development of potent T-cell therapeutics while maintaining an acceptable safety profile. Citation Format: Szu-Han Huang, Thaddeus M. Davenport, Howell F. Moffett, Brian D. Weitzner, Luke Cassereau, Laura E. Baker, Bradley Hammerson, Summer Zhuang, Christine Saechao, Lisa Song, Jade Mimms, David Chian, Candace Sims, Hajime Hiraragi, Marc J. Lajoie, Scott E. Boyken, Bijan Boldajipour. Development of tumor-restricted IL-12 with antigen-dependent expression and localized IL-12 activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4067.

Abstract 15: Massively parallel base-editing screens to map variant effects on anti-tumor hallmarks of primary human T cells and improve cell-based cancer immunotherapies

Abstract Base editing enables precise generation of single nucleotide variants, but large-scale screening in primary human T cells has been limited by low editing efficiency. Here, we developed a high-throughput approach for highly efficient, massively parallel adenine and cytosine base-editor screening in primary human T cells. We performed multiple large-scale pooled screens editing 108 genes with central functions in T cells and whole-gene tiling mutagenesis of selected genes. All screens were functionally read out to capture the effect of variants on hallmarks of T cell anti-tumor immunity, including activation, proliferation, long-term persistence, and cytokine production. We discovered a broad landscape of gain-of-function and loss-of-function mutations and characterized their impact across multiple axes of T cell functions. Among others, we identified gain-of-function mutations in PIK3CD and its regulatory subunit PIK3R1, LCK, AKT1, and loss-of-function mutants of CTLA-4, driving increased T cell polyfunctionality. We validated several of these mutations by probing downstream signaling and functional outputs. To demonstrate the feasibility of using such screen results for improving cell-based cancer immunotherapies, we used human T cells with engineered T cell receptors recognizing specific epitopes in melanoma models. We base-edited these T cells with mutations identified in our screens and demonstrate that these mutations indeed significantly enhance cytotoxic cytokine production and tumor-lytic capacity with minimal off-target activity. Lastly, we also provide proof-of-feasibility for high-efficiency combinatorial base-editing in T cells. This study presents a framework for large-scale base editing screens with multi-dimensional functional readouts in cells that are typically difficult to molecularly engineer in a precise manner. This work also has important therapeutic implications: T cells are the substrate for clinically active cell-based therapies, such as adoptive transfer of tumor-infiltrating lymphocytes (TILs) or chimeric-receptor antigen T (CAR-T) cells. Our screen-informed base editing to achieve an improved T cell product against melanoma exemplifies the therapeutic power of generating synthetic protein variants that improve a wide range of existing and future T cell-based cancer immunotherapies. Citation Format: Zachary Hudson Walsh, Parin Shah, Neeha Kothapalli, Gergo Nikolenyi, Shivem Shah, Giuseppe Leuzzi, Neil Vasan, Mohammed AlQuarishi, Alberto Ciccia, Johannes Melms, Benjamin Izar. Massively parallel base-editing screens to map variant effects on anti-tumor hallmarks of primary human T cells and improve cell-based cancer immunotherapies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 15.

Abstract 6553: Targeting macrophages and regulatory T cells improves response to chemotherapy in high-grade serous ovarian cancer

Abstract Despite the initial response to chemotherapy, most high-grade serous ovarian cancer (HGSOC) patients will suffer disease relapse within two years of diagnosis with no currently successful immunotherapy options.We performed single-cell RNA sequencing (scRNAseq) on omental metastasis from HGSOC patients. Analysis of 64,097 immune cells showed that neoadjuvant chemotherapy (NACT) induced immunosuppressive mechanisms that counteracted its potentially positive effects. We showed that while NACT enhanced phagocytosis and antigen presentation, this was counterbalanced by upregulation of Stabilin1 (STAB1) in eight out of eleven macrophage subpopulations we identified. The NACT associated increase in macrophage STAB1 expression was validated in a separate cohort of eighty HGSOC patients at the protein level. STAB1 is a macrophage scavenger receptor that transports phagocytosed targets to undergo significant lysosomal degradation reducing the efficiency of antigen presentation. In vitro anti-stabilin1 antibody (anti-stab1 ab) -treated macrophages had significantly reduced antigen degradation and higher CD11C expression than isotype-treated ones. Furthermore, T cells co-cultured with anti-stab1 ab -treated macrophages had increased T cell proliferation and killing.We identified thirteen CD4 subpopulations by scRNAseq, five of which were Tregs. We showed that NACT significantly upregulated and activated Tregs. Tregs displayed a shared developmental trajectory with naïve and effector T cells suggesting that those are induced rather than natural Tregs. This was supported by TCR clonal sharing between Tregs and other effector cells. In vitro T cells treated with FOXP3 anti-sense oligonucleotide (ASO), AZD8701, had an anti-tumor cytokine profile and enhanced tumor cell killing. Analysis of 69,781 scRNAseq cells from control and chemotherapy-treated HGSOC syngeneic mouse model showed similar responses. In two HGSOC syngeneic mouse models (HGS2 and 30200), combinations of chemotherapy with anti-stab1 ab and/or Foxp3-ASO significantly increased median survival of mice with established peritoneal disease compared to chemotherapy alone. Bulk RNAseq of tumors treated with anti-stab1 ab were enriched with CXCL9 positive macrophages, while Foxp3-ASO treatment showed significant increase in T helper cell infiltration and activation. Potentially cured long-term survivors (300 days+) were resistant to tumor rechallenge.In a third HGSOC mouse model (60577), in which tumors relapsed after a good initial response to chemotherapy, combinations of chemotherapy with anti-stab1 ab and/or Foxp3-ASO significantly increased the post relapse survival compared to chemotherapy alone.We believe that modulating Tregs and STAB1 could improve response to chemotherapy and can have translational potential as each AZD8701 and a humanized anti-stab1 ab are in phase I clinical trials. Citation Format: Samar Elorbany, Chiara Berlato, Larissa Carnevalli, Simon Barry, Eleni Maniati, Jun Wang, Ranjit Manchanda, Julia Kzhyshkowska, Frances Balkwill. Targeting macrophages and regulatory T cells improves response to chemotherapy in high-grade serous ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6553.

Abstract 3969: Alzheimer's disease-associated amyloid precursor protein improves anti-tumor immunity by inhibiting ceramide-mediated lethal mitophagy and restoring mitochondrial fumarate metabolism in aging T-cells

Abstract The association between Alzheimer’s disease (AD) and lower cancer incidence has been observed in several epidemiological studies without much mechanistic insight. We aimed to understand this cancer resistance mechanism linked to AD and exploit it for broader cancer therapies. A hallmark of AD is the accumulation of amyloid precursor protein (APP) in neuronal mitochondria, inhibiting mitophagy, abrogating the clearance of dysfunctional mitochondria, and contributing to AD pathology. In addition to neurons, mitophagy plays an important role in T-cells, where excessive ceramide-dependent mitophagy in aging T-cells inhibits their energy metabolism and limits their anti-tumor functions. Thus, attenuation of ceramide-dependent mitophagy plays a favorable role in enhancing aging T-cell anti-tumor function. Given that APP is also processed in T-cells, we hypothesized that APP accumulates aberrantly in aging Alzheimer’s T-cells, inhibiting mitophagy and enhancing T-cell anti-tumor activity. Employing techniques of lipidomics, metabolomics, imaging, molecular biology, and genetic models, we show that AD T-cells from a mouse model and human patients are protected against aging-associated ceramide-dependent mitophagy, which enhanced their secretion of inflammatory anti-tumor cytokines. The excessive localization of APP to the T-cell mitochondria, where it inhibits the accumulation of ceramide synthase 6 (CerS6) and C14/C16-ceramides, attenuated the levels of mitophagy and protected the Alzheimer’s T-cells from metabolic defects observed in aging, namely protecting against the exhaustion of fumarate pools. Both in vitro and in vivo re-supplementation of fumarate to aging WT mouse T-cells effectively rescued their viability, cytokine production, and tumor killing capacity both in vitro and in adoptive T-cell transfers to mice with melanoma, functionally mimicking the AD phenotype. The fumarate supplementation also led to a decrease in ceramide-dependent mitophagy in the WT aging T-cells, indicating an interplay between ceramide-dependent mitophagy and fumarate metabolism which contributes to the protection of the anti-tumor function in aging AD T-cells. Moreover, we show that Alzheimer’s mice that express APP in the brain and T-cells, but not AD mice that express APP only in the brain, are protected against the growth of both carcinogen-induced and allografted tumors. Finally, transfer of mitochondria from AD T-cells to aging WT T-cells improved their metabolic fitness and anti-cancer functions. In summary, we show that AD-associated APP improves anti-tumor immunity of aging T-cells by inhibiting ceramide-mediated lethal mitophagy and restoring mitochondrial fumarate metabolism. These data provide a novel mechanism to explain reduced cancer incidences in AD patients. Citation Format: Mohamed Faisal Kassir, Han G. Lee, Natalia Oleinik, Wyatt Wofford, Chase Walton, F. Cansu Atilgan, Paramita Chakraborty, Kubra Calisir, Ozgur Sahin, Shikhar Mehrotra, Besim Ogretmen. Alzheimer's disease-associated amyloid precursor protein improves anti-tumor immunity by inhibiting ceramide-mediated lethal mitophagy and restoring mitochondrial fumarate metabolism in aging T-cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3969.

Abstract 1422: A novel gut microbiota therapeutic approach for enhancing immune checkpoint inhibitor therapy

Abstract Immune checkpoint inhibitor therapy (ICT) has revolutionized cancer care, but up to 50% of patients do not respond to ICT. A host factor implicated in variable ICT response is the gut microbiome: a) germfree/antibiotic-treated mice do not respond to ICT; b) human ICT responders have distinct gut microbiome signatures compared to non-responders; and c) fecal microbiota transplants are safe and potentially effective in cancer patients previously unresponsive to ICT. We have previously established that ICT induces translocation of gut microbiota into secondary lymphoid tissues (particularly the mesenteric lymph nodes) and tumor which is required to enhance extraintestinal anti-tumor immunity (PMID: 36867675). Here, we have developed a novel gut microbiota therapy (GMT) which circumvents the challenges and limitations of conventional microbiome therapies that use live microbes. GMT utilizes specific components derived from commensal gut microbiota identified in our published clinical study (PMID:28923537) that can be administered parenterally (subcutaneous/intravenous) to safely and reproducibly enhance ICT efficacy in multiple preclinical cancer models (B16-F10 with anti-PD-1 and/or CTLA-4, MC38 with or without anti-PD-1, humanized mouse with human melanoma and human anti-PD-1). GMT acts by agonizing the pattern recognition receptors hTLR1/2/6, hNOD2 and hSTING. GMT induces anti-tumor cytokines (IL-12) but does not significantly increase sepsis associated cytokines (IL-6, TNFa) in both human immune cells and in non-human primates. Mechanistically, GMT acts via dendritic cells, and potentially through increased expression of delta-like ligand protein 4 (DLL4), a Notch signaling ligand that activates Notch 1/4 in T cells and promotes Th1 and Th17 differentiation. Current efforts to identify the active components of GMT are underway in which we have used serial liquid-liquid extractions (ethyl acetate followed by water:methanol:chloroform) and subsequent reverse phase chromatography to identify the most active fractions and identification of the bacterial components/constituents within these fractions. Together, these results demonstrate that GMT has the potential to serve as an innate immune adjuvant (akin to vaccine adjuvants) that enhances the effect of immunotherapy for possibly many cancer types. Citation Format: Priscilla Del Valle, Gabriella Nguyen, Yongbin Choi, Parastoo Sabaeifard, Wenng li, Jake Lichterman, Laura Coughlin, Nicole Poulides, Angelica Sanjuan, Andrew Y. Koh. A novel gut microbiota therapeutic approach for enhancing immune checkpoint inhibitor therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1422.

In vitro and vivo anti-tumor activity and mechanisms of the new cryptotanshinone derivative 11 against hepatocellular carcinoma

Global burden of hepatocellular carcinoma (HCC) is increasing. Chemotherapy and immunotherapy are the prevailing options for therapy. Developing new therapeutic strategies for HCC patients is still highly desirable. Recent studies demonstrate that cryptotanshinone is capable of inhibiting tumor growth in HCC and induces antitumor immunity in vitro. In our previous research, we discovered a new cryptotanshinone derivative 11 as an effective immunoregulatory enzyme indoleamine 2, 3-dioxygenase 1 (IDO1) inhibitor. This study aims to evaluate its in vitro and in vivo antitumor activity against hepatocellular carcinoma. 11 displayed robust anti-proliferative activity against HCC cell lines and promoted apoptosis of HCC cell line through the mitochondrial-mediated apoptotic pathway. In H22 tumor-bearing mice models, 11 exhibited significant in vivo anti-tumor activity with different administration routes. And no obvious toxicity was observed. RNA-seq analysis demonstrated the differential expressed genes and alteration of key pathways associated with immune responses after administration of 11. Up-regulation of anti-tumor cytokines and down-regulation of cytokines that promote tumor growth were indicated and further validated. Our study demonstrates that 11 exhibits promising anti-tumor activity both in vitro and in vivo against hepatocellular carcinoma cancer. It is a lead compound for HCC immunotherapy and is worthy for further development.

Abstract 5259: Mechanistic evaluations of the immunological and cell biological effects that distinguish eribulin from other microtubule-targeted chemotherapeutics

Abstract Microtubule-targeted agents (MTAs) are some of the most widely used and effective chemotherapeutics and they continue to find utility as the payloads of antibody-drug conjugates and in combination with targeted agents to improve response, including with immune checkpoint inhibitors. While all MTAs have shared antiproliferative effects, over the last decade it has become increasingly clear that individual drugs of this class have distinct effects on microtubule-dependent signaling and trafficking that are critical for their anticancer efficacy. We and others have demonstrated that eribulin is unique from other MTAs in its ability to promote vascular remodeling, reverse epithelial-to-mesenchymal transition (EMT), and increase immune infiltration into tumors both in animal models and in the clinic. However, the mechanism linking eribulin-mediated microtubule destabilization to these phenotypes, which are associated with improved overall survival of eribulin-treated patients, is unclear. We found that acute eribulin treatment at clinically relevant concentrations promotes the production of antitumor cytokines in both immune and cancer cells and synergizes with direct STING agonists to promote enhanced immune infiltration and improved antitumor efficacy in vivo in both breast and bladder cancer models. This effect was shown to involve activation of natural killer cells and is associated with TBK1-mediated IRF3 phosphorylation, which is regulated downstream of the microtubule associated GTPase GEF-H1. Intriguingly, GEF-H1 release from destabilized microtubules has also been shown to enhance the formation of focal adhesions and promote the differentiation of mesenchymal cells to a more epithelial phenotype. We show that eribulin is indeed sufficient to promote the formation and activation of focal adhesion complexes in mesenchymal triple-negative breast cancer cells, which was not observed when cells were subjected to treatment with microtubule stabilizing chemotherapeutics. Both genetic and pharmacological inhibitors of GEF-H1 were utilized to interrogate the relationship between eribulin-mediated microtubule destabilization and TBK1/IRF3-dependent immunological activation as well as the formation of RhoA-dependent focal adhesions and reversal of EMT-associated phenotypes. Together, our data provide a mechanistic rationale for unique effects of eribulin as compared to other classes of MTAs that could inform on the use of these widely used, but mechanistically underappreciated drugs in a more personalized manner and inform on their rational combination with targeted agents, including immunotherapy. Citation Format: Zaineb Hassouneh, Nancy Wilkinson, Leila Takahashi-Ruiz, Neelam Mukherjee, April L. Risinger. Mechanistic evaluations of the immunological and cell biological effects that distinguish eribulin from other microtubule-targeted chemotherapeutics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5259.

Abstract 2359: New insights into targeting the CD200R1 pathway in T and NK cells using 23ME-00610 as a single agent or in combination

Abstract 23ME-00610 is a monoclonal antibody that is being evaluated as a single agent in a Phase 1/2a clinical trial for advanced solid malignancies (NCT05199272). It binds with high affinity (KD < 0.1 nM) to CD200R1, a promising immune-oncology (IO) target identified by surveying the 23andMe genetic and health survey database. CD200R1 is an inhibitory receptor that when bound to its ligand CD200, reduces pro-inflammatory cytokine production, and leads to an immunosuppressive tumor environment. To gain further insight into the mechanism of action of 23ME-00610 and its potential for combination therapy, we profiled CD200R1 and other immune inhibitory receptors in human dissociated solid tumor samples using spectral flow cytometry. CD200R1 was broadly expressed across tumor-infiltrating immune cells, including T cells and NK cells, cytotoxic cell types with known antitumor functions. Notably, CD200R1 expression pattern was differentiated from PD-1, which is mostly restricted to T cells, indicating differences in patient populations that could potentially benefit from anti-CD200R1 and anti-PD-1 treatments. The ligand, CD200 was broadly expressed, including on tumor cells and endothelial cells. The differential expression profiles of CD200R1 and PD-1 on immune cells, along with CD200 expression on endothelial cells, suggest that combining 23ME-00610 with other clinically validated immunomodulatory agents could enhance antitumor responses. Follow-up experiments were conducted to validate and extend these findings. In an in vitro assay with cancer patient-derived PBMCs, 23ME-00610 promoted higher production of IFNγ, a key functional antitumor cytokine, compared to anti-PD-1 in 9 of 10 donors. Subsequent attempts were made to pinpoint immune cells responsible for 23ME-00610's anti-tumor activity. 23ME-00610 reversed CD200-mediated suppression of chronically stimulated primary T cells and CD200-mediated inhibition of NK cell degranulation, suggesting that 23ME-00610 can mediate tumor cell killing through at least two different cell types. To test the potential of 23ME-00610 to combine with anti-PD-1 to enhance T cell function, an artificial antigen-presenting cell (aAPC) line overexpressing PD-L1 and CD200 was co-cultured with chronically stimulated primary human T cells. Anti-PD-1 and 23ME-00610 each independently enhanced IFNy secretion levels compared to isotype control, yet their combination resulted in a more than additive effect. Taken together, these data demonstrate that 23ME-00610 can enhance both NK and T cell antitumor effector functions, and 23ME-00610 could synergize with anti-PD-1 to further increase the activity of T cells against cancer cells. The results of this study provide evidence that 23ME-00610 could expand IO treatment options for patients with advanced solid malignancies as a single agent or in combination with other anti-tumor therapeutics. Citation Format: Mithra R. Kumar, Shiteng Duan, Shruti Yadav, Abigail Jarret, Zhonghao Yan, Jill Fenaux, Martin Kinisu, Zuoan Yi, Mauro Poggio, Patrick Collins, Antony Symons, Lorena Riol Blanco, Maike Schmidt, Sophia Majeed, Anh Diep, Clarissa Lee. New insights into targeting the CD200R1 pathway in T and NK cells using 23ME-00610 as a single agent or in combination [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2359.

Advancing immunotherapy in triple negative breast Cancer: A novel multimodal theranostic nanoplatform integrating synergetic ferroptosis and photothermal therapy

Triple negative breast cancer (TNBC) is a subtype of breast cancer with high invasiveness and the worst prognosis. Immunotherapy has demonstrated significant potential in its treatment. However, the response rate remains unsatisfactory. In this work, we prepared multifunctional theranostic nanoplatforms (P-R@P/U-V) with synergetic ferroptosis and photothermal therapy (PTT) in improving TNBC tumor microenvironment for improving local treatment in situ, and synergistic anti-programmed cell death-ligand 1 (PD-L1) immunotherapy to prevent distant metastasis. With P-R@P/U-V, real-time monitoring of the specific distribution in tumors is possible due to the greatly improved ultrasound imaging (US), photoacoustic imaging (PAI), and magnetic resonance imaging (MRI) capabilities. Moreover, P-R@P/U-V has excellent photothermal conversion ability. Whereas PTT killed TNBC cells after laser irradiation, the liquid–gas phase transition not only improved US but also triggered controllable release of RSL3 in situ, enhancing ferroptosis of TNBC cells. Besides, the release of tumor-associated antigens (TAAs) increased via PTT and ferroptosis, strongly stimulating T cell activation, dendritic cell maturation, and anti-tumor cytokine secretion. The lung metastases of TNBC were significantly inhibited following the combined use of P-R@P/U-V and PD-L1 inhibitors. The multimodal and multifunctional nanoplatforms demonstrated excellent effects in early diagnosis and synergistic treatment of TNBC. This represents a novel strategy based on local treatment for additional enhanced anti-PD-L1 immunotherapy, with high clinical application prospects.

Tumor-Microenvironment-Activatable Nanoparticle Mediating Immunogene Therapy and M2 Macrophage-Targeted Inhibitor for Synergistic Cancer Immunotherapy.

Immunotherapy has achieved prominent clinical efficacy in combating cancer and has recently become a mainstream treatment strategy. However, achieving broad efficacy with a single modality is challenging, and the heterogeneity of the tumor microenvironment (TME) restricts the accuracy and effectiveness of immunotherapy strategies for tumors. Herein, a TME-responsive targeted nanoparticle to enhance antitumor immunity and reverse immune escape by codelivering interleukin-12 (IL-12) expressing gene and colony-stimulating factor-1 receptor (CSF-1R) inhibitor PLX3397 (PLX) is presented. The introduction of disulfide bonds and cyclo(Arg-Gly-Asp-d-Phe-Lys) (cRGD) peptides conferred reduction reactivity and tumor targeting to the nanoparticles, respectively. It is hypothesized that activating host immunity by the local expression of IL-12, while modulating the tumor-associated macrophages (TAM) function through blocking CSF-1/CSF-1R signaling, could constitute a feasible approach for cancer immunotherapy. The fabricated functional nanoparticle successfully ameliorated the TME by stimulating the proliferation and activation of T lymphocytes, promoting the repolarization of TAMs, reducing myeloid-derived suppressor cells (MDSCs), and promoting the maturation of dendritic cells (DC) as well as the secretion of antitumor cytokines, which efficiently suppressed tumor growth and metastasis. Finally, substantial changes in the TME were deciphered by single-cell analysis including infiltration of different cells, transcriptional states, secretory signaling and cell-cell communications. These findings provide a promising combinatorial immunotherapy strategy through immunomodulatory nanoparticles.

Acellular scaffold-based approach for in situ genetic engineering of host T-cells in solid tumor immunotherapy

BackgroundTargeted T-cell therapy has emerged as a promising strategy for the treatment of hematological malignancies. However, its application to solid tumors presents significant challenges due to the limited accessibility and heterogeneity. Localized delivery of tumor-specific T-cells using biomaterials has shown promise, however, procedures required for genetic modification and generation of a sufficient number of tumor-specific T-cells ex vivo remain major obstacles due to cost and time constraints.MethodsPolyethylene glycol (PEG)-based three-dimensional (3D) scaffolds were developed and conjugated with positively charged poly-L-lysine (PLL) using carbamide chemistry for efficient loading of lentiviruses (LVs) carrying tumor antigen-specific T-cell receptors (TCRs). The physical and biological properties of the scaffold were extensively characterized. Further, the scaffold loaded with OVA-TCR LVs was implanted in B16F10 cells expressing ovalbumin (B16-OVA) tumor model to evaluate the anti-tumor response and the presence of transduced T-cells.ResultsOur findings demonstrate that the scaffolds do not induce any systemic inflammation upon subcutaneous implantation and effectively recruit T-cells to the site. In B16-OVA melanoma tumor-bearing mice, the scaffolds efficiently transduce host T-cells with OVA-specific TCRs. These genetically modified T-cells exhibit homing capability towards the tumor and secondary lymphoid organs, resulting in a significant reduction of tumor size and systemic increase in anti-tumor cytokines. Immune cell profiling revealed a significantly high percentage of transduced T-cells and a notable reduction in suppressor immune cells within the tumors of mice implanted with these scaffolds.ConclusionOur scaffold-based T-cell therapy presents an innovative in situ localized approach for programming T-cells to target solid tumors. This approach offers a viable alternative to in vitro manipulation of T-cells, circumventing the need for large-scale in vitro generation and culture of tumor-specific T-cells. It offers an off-the-shelf alternative that facilitates the use of host cells instead of allogeneic cells, thereby, overcoming a major hurdle.

Radiation immunodynamics in patients with glioblastoma receiving chemoradiation.

This is a prospective, rigorous inquiry into the systemic immune effects of standard adjuvant chemoradiotherapy, for WHO grade 4, glioblastoma. The purpose is to identify peripheral immunologic effects never yet reported in key immune populations, including myeloid-derived suppressor cells, which are critical to the immune suppressive environment of glioblastoma. We hypothesize that harmful immune-supportive white blood cells, myeloid derived suppressor cells, expand in response to conventionally fractionated radiotherapy with concurrent temozolomide, essentially promoting systemic immunity similar what is seen in chronic diseases like diabetes and heart disease. 16 patients were enrolled in a single-institution, observational, immune surveillance study where peripheral blood was collected and interrogated by flow cytometry and RNAseq. Tumor tissue from baseline assessment was analyzed with spatial proteomics to link peripheral blood findings to baseline tissue characteristics. We identified an increase in myeloid-derived suppressor cells during the final week of a six-week treatment of chemoradiotherapy in peripheral blood of patients that were not alive at two years after diagnosis compared to those who were living. This was also associated with a decrease in CD8+ T lymphocytes that produced IFNγ, the potent anti-tumor cytokine. These data suggest that, as in chronic inflammatory disease, systemic immunity is impaired following delivery of adjuvant chemoradiotherapy. Finally, baseline investigation of myeloid cells within tumor tissue did not differ between survival groups, indicating immune surveillance of peripheral blood during adjuvant therapy may be a critical missing link to educate our understanding of the immune effects of standard of care therapy for glioblastoma.

Immune Modulation of Innate and Adaptive Responses Restores Immune Surveillance and Establishes Antitumor Immunologic Memory.

Current immunotherapies have proven effective in strengthening antitumor immune responses, but constant opposing signals from tumor cells and the surrounding microenvironment eventually lead to immune escape. We hypothesized that in situ release of antigens and regulation of both the innate and adaptive arms of the immune system would provide a robust and long-term antitumor effect by creating immunologic memory against tumors. To achieve this, we developed CARG-2020, a genetically modified virus-like vesicle (VLV) that is a self-amplifying RNA with oncolytic capacity and encodes immune regulatory genes. CARG-2020 carries three immune modulators: (i) the pleiotropic antitumor cytokine IL12, in which the subunits (p35 and p40) are tethered together; (ii) the extracellular domain (ECD) of the protumor IL17RA, which serves as a dominant-negative antagonist; and (iii) a shRNA targeting PD-L1. Using a mouse model of ovarian cancer, we demonstrated the oncolytic effect and immune-modulatory capacities of CARG-2020. By enhancing IL12 and blocking IL17 and PD-L1, CARG-2020 successfully reactivated immune surveillance by promoting M1, instead of M2, macrophage differentiation, inhibiting MDSC expansion and establishing a potent CD8+ T cell-mediated antitumoral response. Furthermore, we demonstrated that this therapeutic approach provided tumor-specific and long-term protection against the establishment of new tumors. Our results provide a rationale for the further development of this platform as a therapeutic modality for ovarian cancer patients to enhance antitumor responses and prevent a recurrence.

Green Nanotechnology of Yucca filamentosa- Phytochemicals-Functionalized Gold Nanoparticles-Antitumor Efficacy Against Prostate and Breast Cancers.

We report an innovative green nanotechnology utilizing an electron-rich cocktail of phytochemicals from Yucca filamentosa L. to synthesize biocompatible gold nanoparticles without the use of any external chemical reducing agents and evaluate their anti-cancer activity. Yucca filamentosa L. extract, containing a cocktail of phytochemicals, was prepared, and used to transform gold salt into Y. filamentosa phytochemicals encapsulated gold nanoparticles (YF-AuNPs). Additionally, gum arabic stabilized YF-AuNPs (GAYF-AuNPs) were also prepared to enhance the in vitro/in vivo stability. Anticancer activity was evaluated against prostate (PC-3) and breast (MDAMB-231) cancer cell lines. Targeting abilities of gold nanoparticles were tested using pro-tumor macrophage cell lines. Comprehensive characterization of new nanomedicine agents YF-AuNPs and GAYF-AuNPs revealed spherical, and monodisperse AuNPs with moderate zeta potentials (-19 and -20 mV, respectively), indicating in vitro/in vivo stability. The core size of YF-AuNPs (14 ± 5 nm) and GAYF-AuNPs (10 ± 5 nm) is suitable for optimal penetration into tumor cells through both enhanced permeability and retention (EPR) effect as well as through the receptor mediated endocytosis. Notably, YF-AuNPs exhibited potent anticancer activity against prostate (PC-3) and breast tumors (MDAMB-231) by inducing early and late apoptotic stages. Moreover, YF-AuNPs resulted in elevated levels of anti-tumor cytokines (TNF-α and IL-12) and reduced levels of pro-tumor cytokines (IL-6 and IL-10), provide compelling evidence on the immunomodulatory property of YF-AuNPs. Overall, these Y. filamentosa phytochemicals functionalized nano-Ayurvedic medicine agents demonstrated selective toxicity to cancer cells while sparing normal cells. Most notably, to our knowledge, this is the first study that shows YF-AuNP's targeting efficacy toward pro-tumor macrophage cell lines, suggesting an immunomodulatory pathway for cancer treatment. This work introduces a novel avenue for herbal and nano-Ayurvedic approaches to human cancer treatment, mediated through selective efficacy and immunomodulatory potential.

Engineered Macrophages Tune Intratumoral Cytokines through Precisely Controlled Self-Pyroptosis to Enhance Bladder Cancer Immunotherapy.

Engineered macrophages are a promising tool for drug delivery and immunotherapy in cancer treatment. However, simultaneous targeted enrichment and controllable immunological activation of these macrophages at the tumor site remains challenging. As a solution, macrophages loaded with an advanced nanoparticle encapsulating CpG-conjugated magnetic nanoclusters (MNC) with indocyanine green (ICG) and nigericin (NIG) (MNC-ICG-NIG@SiO2 (MINS)), utilizing Se─Se bond-modified SiO2, are designed and applied in bladder cancer, which is typically managed surgically, followed by Bacillus Calmette-Guerin (BCG) adjuvant instillation therapy. Upon intravenous administration, BCG-mediated tumor-localized inflammation leads to targeted accumulation of MINS@MΦ. MINS@MΦ accumulates within the tumor tissue and is immunologically activated through laser irradiation, leading to ICG-mediated generation of reactive oxygen species, Se─Se bond cleavage, and subsequent NIG release to induce self-pyroptosis. Consequently, MINS@MΦ releases Fe2+ ions and CpG, thus promoting the M1 polarization of tumor-associated macrophages and secretion of appropriate antitumor cytokines. However, without intervention, MINS@MΦ undergoes apoptosis in the bloodstream after 48h without eliciting any immune response. Therefore, this innovative approach optimizes and enhances the efficacy of BCG immunotherapy by precisely modulating the cytokines for effective bladder cancer treatment without inducing a systemic inflammatory response.

TMIC-67. GLIOBLASTOMA AUGMENTS SYSTEMIC IMMUNUNOSUPPRESSION UPON LOSS OF TESTOSTERONE VIA ALTERATION OF GLUCOCORTICOIDS PRODUCTION

Abstract While sex differences in incidence, genetics, and immune changes are established in glioblastoma (GBM), the specific contribution of sex hormones to these differences has not been fully explored. Testosterone has been shown to have a pro-tumorigenic effect on human and mouse GBM tumor cells. However, the systemic effect of testosterone in an immune competent model has not been tested. To test this, we performed castration or sham surgery on C57BL/6 male mice, followed by intracranial implantation of syngeneic glioma cells. Surprisingly, castrated mice exhibited more aggressive tumor growth compared to sham surgery controls, and this castration-induced aggressiveness could be reversed by administering exogenous testosterone. This finding was further confirmed by chemically blocking androgen receptor signaling using enzalutamide. We observed a significant increase in adrenocorticotropic hormone (ACTH) levels in the serum from castrated mice compared to the sham group after tumor implantation. Additionally, mass spectrometry analysis detected elevated levels of circulating glucocorticoids in castrated mice, and pharmacological blockade of glucocorticoid receptor using mifepristone reversed the shorted survival in castrated mice, but not in sham control. Flow analysis revealed decreased production of anti-tumor cytokines such as IFN-γ and TNF-α in CD4+ and CD8+ T cells from tumors and lymph nodes in castrated mice, suggesting systemic immunosuppression in these animals. Indeed, castration of immune-compromised mice, specifically NSG and RAG1KO strains, did not result in reduced survival. Moreover, when GBM cells were subcutaneously implanted into the flank, tumor growth in castrated mice was decelerated compared to sham controls. We also observed significantly lower ACTH levels in the flank tumor model compared to the brain tumor model, indicating a brain-specific effect of steroid hormones on tumor control. Taken together, these findings demonstrate that testosterone regulates T cell function through glucocorticoids, ultimately affecting GBM growth in a site-specific manner.

CTIM-41. ONCOLYTIC IMMUNOTHERAPY LINKS IMMUNOACTIVATION TO SUBJECT SURVIVAL IN PHASE I TRIAL OF RECURRENT GLIOBLASTOMA

Abstract A “first-in-human” phase 1 trial of intralesional injection of CAN-3110, an immunotherapeutic oncolytic based on herpes simplex virus 1 (HSV1), was conducted in 41 subjects with recurrent high-grade glioma (rHGG). The impact of CAN-3110 on the tumor immune microenvironment was assessed using immunohistochemistry, multiplexed immunofluorescence, TCR-beta DNA sequencing, and bulk RNA sequencing of paired pre- and post-treatment samples. These analyses were combined with patient features to identify potential biomarkers of therapy response in rHGG. In IDH wild type recurrent glioblastoma (IDHwt rGBM) patients, post-treatment survival times were positively associated with positive pre-treatment HSV1 serology after controlling for additional covariates such as tumor volume, age, gender, CAN-3110 dose, etc. (HR = 0.16, p < 0.001, n = 32, CoxPH). Positive HSV1 serology was also significantly associated with clearance of CAN-3110 from injected tumors. Interestingly, increased intratumoral CD8 and CD4 T cell numbers following treatment were positively associated with prolonged survival in HSV1 seropositive patients (p = 0.017 and 0.026, respectively), but not when analyses were conducted including HSV1 seronegative patients. Likewise, post-treatment immune expression signatures (such as for antitumor cytokines, T cell traffic, etc.) were more strongly associated with prolonged survival for HSV1 seropositive patients than for seronegative patients, and most assessed immune signatures only became associated with survival after CAN-3110 treatment. Extended survival was also associated with increased TCR-beta diversity following therapy in both the tumor and in PBMCs. Combined with a lack of observed dose-limiting toxicities and a median post-treatment survival of 14.2 months (95% CI: 9.5-15.7) in IDHwt rGBM patients with positive HSV1 serology, these data provide evidence that intralesional CAN-3110 treatment can instigate immune activation in a traditionally immunologically cold tumor and that this immune activation may influence survival time—particularly when patients have had prior exposure to HSV1. (clinicaltrials.gov NCT03152318).

Multiplex Prime Editing and PASSIGE TM for Non-Viral Generation of an Allogeneic CAR-T Cell Product

While CAR-T cell therapy represents a major advance in personalized immunotherapy, the autologous nature of commercially available CAR-T products have delayed its broad application beyond a subset of hematological malignancies. In particular, manufacturing autologous CAR-T therapies is costly and time-consuming, and success relies on the fitness of a patient's cells. An allogeneic off-the-shelf CAR-T product could overcome these cell quality and quantity issues and could be accessed on-demand. However, a successful allogeneic CAR-T product will require multiplex gene knockout in addition to stable CAR integration to prevent graft-versus-host disease (GvHD) and graft rejection by the patient's immune system. Strategies for the delivery and expression of CAR transgenes include semi-random integration using lentivirus or transposons, which risk unintended gene disruption or activation. Targeted integration can be achieved using nucleases in combination with a template for homology-directed repair (HDR), but efficiency of this approach is generally low and there are risks associated with the induction of double-strand breaks (DSBs), including p53 activation and chromothripsis. This is further complicated in a situation where multiplex editing is required, as multiple DSBs can lead to gross chromosomal rearrangements. Alternatively, base editors have been used for targeted gene disruption without the induction of DSBs via single nucleotide conversion to disrupt a splice site or introduce a single premature stop (pmSTOP) codon. However, this approach is limited to transition mutations and cannot be used to integrate large genetic cargo, which is required to generate CAR-T cells. Prime Editing (PE) can be used for precise and programmable gene disruption via multiple strategies, including introduction of multiple pmSTOP codons, splice site disruption, frameshift mutations, or deletion of large segments of regulatory or coding sequence. Further, Prime-Assisted Site-Specific Integrase Gene Editing (PASSIGE) can be used to precisely and flexibly integrate large genetic cargo at a specific locus. Together, PE-mediated gene knock out and PASSIGE can be tailored to generate a more broadly applicable, potentially safer, and more effective CAR-T cell product. To evaluate the efficacy of an all-PE non-viral approach to allogeneic CAR-T cell generation, PASSIGE and PE mediated gene knockout were used to generate CD19-CAR-T cells. Multiplex PE precisely disrupted expression of the endogenous T cell receptor alpha constant ( TRAC) and beta-2-microglobulin ( B2M) loci in over 90% of human T cells. Co-delivery of a non-viral DNA donor template with PASSIGE editing components resulted in targeted integration of a 3.5 kb CD19-CAR transgene expression cassette at the TRAC locus in over 60% of the T cells, with no observed impact on T cell viability, phenotype, or functionality. CD19 CAR-T cells generated using PASSIGE show potent anti-tumor activity and cytokine production in response to CD19 + tumor cell lines in vitro and in vivo. The PASSIGE-generated CD19 CAR-T cells reduce tumor burden and prolong survival of mice bearing CD19 + tumors. These results show that a PE platform can be used to generate multiplex edited CAR-T cells without the need for viral vectors and without causing DSBs. This modular, one-step, non-viral delivery Prime Editing platform expands the applicability of T cell therapies for the treatment of tumors and immune diseases.