Effective Antitumor Immune Response Research Articles

BIBR1532 combined with radiotherapy induces ferroptosis in NSCLC cells and activates cGAS-STING pathway to promote anti-tumor immunity

BackgroundTelomerase, by safeguarding damaged telomeres and bolstering DNA damage repair, has the capacity to heighten the radioresistance of tumour cells. Thus, in turn, can compromise the efficacy of radiotherapy (RT) and radioimmunotherapy. Our previous studies have revealed that the highly selective telomerase inhibitor, BIBR1532, possesses the potential to enhance the radiosensitivity of Non-small cell lung cancer (NSCLC). In this study, we delve further into the impact of BIBR1532 on the immune activation induced by RT and elucidate the underlying mechanisms.MethodsBiological information analyses, immunofluorescence assays, western blot assays, flow cytometry analysis were conducted to elucidate the functions of the combination of BIBR1532 with radiotherapy in NSCLC. Intracellular levels of lipid peroxides, glutathione, malondialdehyde, and Fe2+ were measured as indicators of ferroptosis status. Both in vitro and in vivo studies were conducted to examine the antitumor effects.ResultsOur findings indicate that the confluence of BIBR1532 with RT significantly augments the activation of the cGAS-STING pathway in both in vivo and in vitro settings, thereby fostering an effective anti-tumoral immune response. The effects can be ascribed to two key processes. Firstly, ionizing radiation, in precipitating DNA double-strand breaks (DSBs), prompts the release of tumour-derived double-stranded DNA (dsDNA) into the cytoplasm. Subsequently, BIBR1532 amplifies the activation of antigen-presenting cells by dsDNA post-RT and instigates the cGAS-STING pathway. Secondly, BIBR1532 enhances the ferroptosis response in NSCLC following RT, thereby promoting unrestrained lipid peroxidation and elevated levels of reactive oxygen species (ROS) within tumour cells. This ultimately leads to mitochondrial stress and the release of endogenous mitochondrial DNA (mtDNA) into the cytoplasm, thus facilitating the activation of the STING pathway and the induction of a type I interferon (IFN)-linked adaptive immune response.ConclusionThis study underscores the potential of BIBR1532 as an efficacious and safe radiosensitizer and radioimmunotherapy synergist, providing robust preclinical research evidence for the treatment of NSCLC.

Combined cryoablation and PD-1 inhibitor synergistically enhance antitumor immune responses in Lewis lung adenocarcinoma mice via the PI3K/AKT/mTOR pathway

Cryoablation is a therapeutic modality for lung adenocarcinoma that destroys target tumors using lethal levels of cold, resulting in the release of large amounts of specific antigens that activate immune responses. However, tumor immune checkpoint escape mechanisms prevent these released self-antigens from inducing effective anti-tumor immune responses. To overcome this challenge, we propose the use of immune checkpoint inhibitors to relieve T cell inhibition by immune checkpoints and enhance the anti-tumor immune response mediated by cryoablation. We used bilateral tumor-bearing mouse models and a specific cryoablation instrument to study the efficacy of cryoablation combined with PD-1 inhibitors in Lewis lung adenocarcinoma model mice. We found that cryoablation combined with PD-1 inhibitors significantly inhibited the growth of mouse lung adenocarcinoma, prolonged mouse survival, and enhanced the anti-tumor immune response. Moreover, this combined regimen could synergistically promote the activation and proliferation of T cells via the PI3K/AKT/mTOR pathway. The present study provides a strong theoretical basis for the clinical combination of cryoablation and PD-1 inhibitors.

Improved Immunotherapy Outcomes via Cuproptosis Upregulation of HLA-DRA Expression: Promoting the Aggregation of CD4+ and CD8+T Lymphocytes in Clear Cell Renal Cell Carcinoma.

Immunotherapy has shown promising clinical results in clear cell renal cell carcinoma (ccRCC), but low clinical target response rates due to dysfunction of the major histocompatibility complex (MHC) and an inhibitory tumor immune microenvironment (TIME) have largely limited the associated clinical benefits. In the present study, we explored the feasibility of enhancing tumor-specific-MHC-II-HLA-DRA expression, counteracting the TIME's suppressive effects, thereby improving the sensitivity of immune checkpoint inhibitor (ICI) therapy from the standpoint of cuproptosis. Immunohistochemical staining and in vitro experiments validated the expression of HLA-DRA in ccRCC and its positive impact on ICI therapy. Subsequently, we observed that cuproptosis upregulated HLA-DRA expression in a dose-dependent manner, further confirming the link between cuproptosis and HLA-DRA. In vivo experiments showed that cuproptosis increased the sensitivity to ICI treatment, and implementing cuproptosis alongside anti-PD-1 treatment curtailed tumor growth. Mechanistically, cuproptosis upregulates HLA-DRA expression at the transcriptional level in a dose-dependent manner by inducing the production of reactive oxygen species; high levels of HLA-DRA promote the expression of chemokines CCL5, CXCL9, and CXCL10 in the TIME, inhibiting the development of a pro-tumor microenvironment by promoting the infiltration of CD4+T and CD8+T cells, thereby synergizing ICI therapy and exerting anti-tumor effects. Taken together, this work highlights the role of cuproptosis in mediating TIME remodeling and synergistic immunotherapy, providing new evidence that cuproptosis can evoke effective anti-tumor immune responses.

Reversible Chemical Modification of Antibody Effector Function Mitigates Unwanted Systemic Immune Activation.

Antibody effector functions including antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis (ADCP) are mediated through the interaction of the antibody Fc region with Fcγ receptors present on immune cells. Several approaches have been used to modulate antibody Fc-Fcγ interactions with the goal of driving an effective antitumor immune response, including Fc point mutations and glycan modifications. However, robust antibody-Fcγ engagement and immune cell binding of Fc-enhanced antibodies in the periphery can lead to the unwanted induction of systemic cytokine release and other dose-limiting infusion-related reactions. Creating a balance between effective engagement of Fcγ receptors that can induce antitumor activity without incurring systemic immune activation is an ongoing challenge in the field of antibody and immuno-oncology therapeutics. Herein, we describe a method for the reversible chemical modulation of antibody-Fcγ interactions using simple poly(ethylene glycol) (PEG) linkers conjugated to antibody interchain disulfides with maleimide attachments. This method enables dosing of a therapeutic with muted Fcγ engagement that is restored in vivo in a time-dependent manner. The technology was applied to an effector function enhanced agonist CD40 antibody, SEA-CD40, and experiments demonstrate significant reductions in Fc-induced immune activation in vitro and in mice and nonhuman primates despite showing retained efficacy and improved pharmacokinetics compared to the parent antibody. We foresee that this simple, modular system can be rapidly applied to antibodies that suffer from systemic immune activation due to peripheral FcγR binding immediately upon infusion.

Promotion of an Antitumor Immune Program by a Tumor-specific, Complement-activating Antibody.

Tumor-targeting Abs can be used to initiate an antitumor immune program, which appears essential to achieve a long-term durable clinical response to cancer. We previously identified an anti-complement factor H (CFH) autoantibody associated with patients with early-stage non-small cell lung cancer. We cloned from their peripheral B cells an mAb, GT103, that specifically recognizes CFH on tumor cells. Although the underlying mechanisms are not well defined, GT103 targets a conformationally distinct CFH epitope that is created when CFH is associated with tumor cells, kills tumor cells invitro, and has potent antitumor activity invivo. In the effort to better understand how an Ab targeting a tumor epitope can promote an effective antitumor immune response, we used the syngeneic CMT167 lung tumor C57BL/6 mouse model, and we found that murinized GT103 (mGT103) activates complement and enhances antitumor immunity through multiple pathways. It creates a favorable tumor microenvironment by decreasing immunosuppressive regulatory T cells and myeloid-derived suppressor cells, enhances Ag-specific effector T cells, and has an additive antitumor effect with anti-PD-L1 mAb. Furthermore, the immune landscape of tumors from early-stage patients expressing the anti-CFH autoantibody is associated with an immunologically active tumor microenvironment. More broadly, our results using an mAb cloned from autoantibody-expressing B cells provides novel, to our knowledge, mechanistic insights into how a tumor-specific, complement-activating Ab can generate an immune program to kill tumor cells and inhibit tumor growth.

Abstract 3922: Quaking modulates anti-tumor immunity by regulating antigen processing and presentation in dendritic cells

Abstract Dendritic cells are essential players in anti-tumor immunity. One of their critical roles is to process and present tumor associated antigens to T cells, thereby inducing antigen-specific T cell response. However, cellular factors and molecular pathways regulating antigen processing and presentation by DCs are not fully understood.Here, we revealed a potential regulatory role of a transcriptional co-activator, Quaking (QKI), and its binding partner, PPARδ in antigen processing and presentation by DCs. Consistent with our previous studies in neural stem cells and microglia, we found QKI and PPARδ enhance phagocytosis in DCs by upregulating genes involved in the formation of phagosome and endosomes. QKI- or PPARδ-deficient DCs showed reduced CD8+ T cell priming capacity in vitro. In vivo tumor models suggested DC-specific knocking out of QKI or PPARδ promoted the tumor growth. Furthermore, ablation of QKI or PPARδ in DCs limited the effectiveness of immune checkpoint blockade in multiple tumor models.Together, these revealed a transcriptional regulation of antigen processing and presentation by DCs through QKI and PPARδ. Our data also suggested that perturbing this important function of DC would subvert their anti-tumor activity, highlighting the pivotal role of DCs in an effective anti-tumor immune response. Citation Format: Yating Li, Jian Hu, Cassian Yee. Quaking modulates anti-tumor immunity by regulating antigen processing and presentation in dendritic 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 3922.

Abstract 6537: A novel CCR4 antagonist induces potent anti-tumor response through inhibition of Treg migration into the tumor microenvironment

Abstract Regulatory T cells (Tregs), an immunosuppressive subset of CD4+ T cells, play a vital role in maintaining immune homeostasis by regulating response to self antigens and maintaining tolerance. On the contrary, Tregs infiltrating the tumor microenvironment (TME) impede effective anti-tumor immunity by inhibiting tumor-specific T cell responses and generating a suppressive TME, thus promoting tumor progression. Clinically, Tregs have been proven to play a significant role in resistance to immune checkpoint inhibitors (ICIs) leading to lower response rates. Hence, targeting Tregs would lead to activation of tumor-specific effector T cells and improved long-term anti-tumor immune responses with ICI treatment. CCR4, a chemokine receptor highly expressed on Tregs, spearhead the migration of Tregs and their accumulation in the TME, by responding to the chemokines CCL22 and CCL17 secreted by the inflamed cells in the tumor. CCR4 expression is associated with poor prognosis in various solid tumors. This warrants the therapeutic targeting of CCR4-expressing Tregs to enable effective and durable anti-tumor immune responses. We sought to discover and develop novel small molecule antagonists of CCR4 for use in cancer therapy. Multiple series of CCR4 antagonists were identified by iterative medicinal chemistry efforts and SAR based approach. These compounds were optimized towards attaining required potency, acceptable physicochemical properties, high selectivity and desirable pharmacokinetic profile to achieve anti-tumor activity. Aurigene’s CCR4 antagonists exhibited potent inhibition of CCR4 activity in the reporter-based β-arrestin recruitment assay. This translated well into potent inhibition of CCL22-mediated chemotaxis of CCR4-expressing Tregs in an in vitro cell migration assay. Furthemore, the lead compounds showed desirable drug-like properties and excellent pharmacokinetic exposure in rodents. In an ongoing study in a syngeneic mice tumor model, one of the lead compounds is being evaluated for impact on Treg infiltration, CD8:Treg ratio in the tumor and efficacy. In summary, we have identified novel CCR4 antagonists with desirable drug-like properties that are being evaluated further to identify a clinical candidate. Citation Format: Rashmi Nair, Chandrasekhar Abbineni, Krishna Chaitanya Talluri, Amit A Dhudashiya, Aravind AB, NaveenR Kumar, Ramya R, D Balasubramanyam, Pathur Obanna, Rabin Madhaiyan, DS Samiulla, Girish Daginakatte, Kishore Narayanan, Kavitha Nellore, Shekar Chelur, Susanta Samajdar, Murali Ramachandra. A novel CCR4 antagonist induces potent anti-tumor response through inhibition of Treg migration into the tumor microenvironment [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 6537.

Abstract 1365: INB03: a new immune checkpoint inhibitor that reprograms macrophage polarization, boosts ADCP and reverts T-cell exhaustion markers

Abstract Trastuzumab resistance is an important clinical issue in HER2+ breast cancer (BC), and few actionable targets are available. We demonstrated that soluble TNF (sTNF) upregulates mucin 4 (MUC4) expression, which shields trastuzumab epitope on HER2 hindering its therapeutic effect, and that sTNF blockade with INB03 decreases MUC4 expression which, together with trastuzumab, triggers an effective antitumor immune response based on antitumoral macrophage-NK cell collaboration. Because immune checkpoint molecules (ICP) and T cell exhaustion foster tumor immune escape, we addressed whether INB03 could modulate macrophage polarization, T cell exhaustion, and ICP expression in both populations to boost an antitumor immune response. For in vitro assays, human monocytes and T cells were isolated from buffy coats and enriched with specific RosetteSep. Macrophages (Mϕ) were differentiated for 6 days with M-CSF (10 ng/ml) to M0, and polarized for 48h to the M1-like subtype with LPS (50 ng/ml)+IFNγ (20 ng/ml), or to the M2-like subtype with IL-4 (20 ng/ml)+IL-10 (20 ng/ml). Then, INB03 was added (10 μg/ml) for 96h with corresponding cytokines to already-polarized Mϕ to test its ability to revert polarization. Also, Mϕ antibody-dependent cellular phagocytosis (ADCP) against human HER2+ breast cancer cell line JIMT-1 was assessed. T cells were activated with CD3/CD28 beads and cultured for 7 or 14 days. INB03 was added at those times for 48h to test its ability to modulate ICP and exhaustion markers. For in vivo assays, tumor-free mice or bearing the HER2+ C4HD tumor were treated with vehicle or INB03 (10 mg/kg, i.p.) for 21 days. Polarization, exhaustion and ICP markers were studied in Mϕ and T cells from spleen and tumor. Adding INB03 to already-polarized human Mϕ enhanced polarization towards M1-like (CD86+CD206−). Polarized Mϕ exposed to INB03 showed decreased PD1 and PDL-1 expression. Also, the expression of ADCP-inhibitory markers B7H4 and SIRPα was diminished when INB03 was present. These Mϕ exhibited increased ADCP against JIMT-1 cells treated with INB03, which showed downregulation of the inhibitory signal CD47. Murine Mϕ from tumor-bearing mice treated with INB03 showed increased polarization to the M1-like phenotype. Human CD8+ T cells showed decreased expression of PD1, PD-L1, LAG3, TIM3 and TIGIT. However, only TIM3 and PD1 were downregulated in murine CD8+ T cells of tumor-bearing mice treated with INB03. In all, sTNF blockade skews Mϕ to the M1-like phenotype and reprograms already-polarized pro-tumoral M2-like Mϕ to antitumoral ones. INB03 can tailor the tumor microenvironment by promoting Mϕ ADCP against tumor cells and by acting as an ICP inhibitor for CD8+ T cells, possibly relieving their exhaustion. HER2+MUC4+ BC patients could benefit from the administration of INB03 to boost targeted therapy efficacy and overcome tumor-induced macrophage and T-cell immune escape. Citation Format: Sofia Bruni, Maria F. Mercogliano, Roxana Schillaci. INB03: a new immune checkpoint inhibitor that reprograms macrophage polarization, boosts ADCP and reverts T-cell exhaustion markers [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 1365.

Abstract 5378: Spatially resolved human leukocyte antigen (HLA) expression correlates with motif neoepitope expression and durable response to immune checkpoint blockade (ICB) in non-small cell lung cancer (NSCLC)

Abstract Background: We previously showed electrostatic interactions enhance binding between “motif” neoepitopes and HLA and predict advanced NSCLC ICB benefit, suggesting optimal neoantigen presentation drives effective anti-tumor immune response (Cummings 2020). However, not all cases with motif neoepitopes exhibit favorable ICB outcomes. Methods: As proof-of-concept, participants from our published NSCLC ICB cohort with available pre-treatment archival tissue were selected based on HLA supertype B44, predicted motif neoepitopes, and best response of progressive disease (PD) vs partial/complete response (PR/CR). Whole exome sequencing, HLA typing and neoepitope prediction were previously performed (Cummings 2020). GeoMx slides were prepared, hybridized with RNA probes and stained with antibodies to cytokeratin (CK), nuclear material and CD45 per manufacture instructions (Geiss 2008). Antibody to CD8 (Novus) was optimized at 1:50 dilution. Twelve regions of interest (ROI) were selected per sample including the following compartments: CK+CD8+, CK+CD8-, CK-CD8+ and CK-CD8- (negative control). Each ROI included ~150 nuclei selected using GeoMx Digital Spatial Profiler. Sequencing was performed on Illumina Novaseq 6000 (50bpx2) demultiplexed using Illumina Bcl2fastq v2.19.1.403. Raw reads were normalized and compared using paired student’s T-tests with Tukey’s correction via R v4.1. Neoepitope (non/motif) comparisons used matched numbers per sample selected by highest expression. Results: Seven participants (3 PD, 3 PR, 1 CR) were included, each exhibiting 1-7 motif neoepitopes without HLA loss of heterozygosity. 84 ROI included 24 CK+CD8+, 24 CK+CD8-, 24 CK-CD8+ and 12 CK-CD8- with at least one ROI per category per participant. PD samples had fewer CD8+ ROI (12 vs 36) and lower CXCL9 (p=0.011) and CD274 (p=0.014). HLA-A/B/C expression followed a gradient with highest expression in CK+CD8+ ROI with limited detection in CK-CD8- ROI. Among HLA, HLA-B had highest median expression (A: 226, B: 650, C: 202; p<0.001). In CK+ ROI, motif neoepitope expression was detectable for all participants but not statistically different from non-motif expression (p=0.23). HLA-A/B/C all exhibited lower expression in PD CK+ ROI (p<0.001). Conclusion: HLA expression may modify prediction of clinically meaningful neoepitopes and response to ICB. Validation in a larger, prospective cohort is planned. Citation Format: Lucas Goldman, Sarah Gorbatov, Collin Shen, Alexa Berezowitz, Edward Garon, Amy Lauren Cummings. Spatially resolved human leukocyte antigen (HLA) expression correlates with motif neoepitope expression and durable response to immune checkpoint blockade (ICB) in non-small cell lung cancer (NSCLC) [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 5378.

Multi-dimensional characterization of apoptosis in the tumor microenvironment and therapeutic relevance in melanoma.

Melanoma is widely utilized as a prominent model for the development of immunotherapy, thought an inadequate immune response can occur. Moreover, the development of apoptosis-related therapies and combinations with other therapeutic strategies is impeded by the limited understanding of apoptosis's role within diverse tumor immune microenvironments (TMEs). Here, we constructed an apoptosis-related tumor microenvironment signature (ATM) and employ multi-dimensional analysis to understand the roles of apoptosis in tumor microenvironment. We further assessed the clinical applications of ATM in nine independent cohorts, and anticipated the impact of ATM on cellular drug response in cultured cells. Our ATM model exhibits robust performance in survival prediction in multiple melanoma cohorts. Different ATM groups exhibited distinct molecular signatures and biological processes. The low ATM group exhibited significant enrichment in B cell activation-related pathways. What's more, plasma cells showed the lowest ATM score, highlighting their role as pivotal contributors in the ATM model. Mechanistically, the analysis of the interplay between plasma cells and other immune cells elucidated their crucial role in orchestrating an effective anti-tumor immune response. Significantly, the ATM signature exhibited associations with therapeutic efficacy of immune checkpoint blockade and the drug sensitivity of various agents, including FDA-approved and clinically utilized drugs targeting the VEGF signaling pathway. Finally, ATM was associated with tertiary lymphoid structures (TLS), exhibiting stronger patient stratification ability compared to classical "hot tumors". Our findings indicate that ATM is a prognostic factor and is associated with the immune response and drug sensitivity in melanoma.

Oncolytic vaccinia virus immunotherapy antagonizes image-guided radiotherapy in mouse mammary tumor models.

Ionizing radiation (IR) and oncolytic viruses are both used to treat cancer, and the effectiveness of both agents depends upon stimulating an immune response against the tumor. In this study we tested whether combining image guided ionizing radiation (IG-IR) with an oncolytic vaccinia virus (VACV) could yield a better therapeutic response than either treatment alone. ΔF4LΔJ2R VACV grew well on irradiated human and mouse breast cancer cells, and the virus can be combined with 4 or 8 Gy of IR to kill cells in an additive or weakly synergistic manner. To test efficacy in vivo we used immune competent mice bearing orthotopic TUBO mammary tumors. IG-IR worked well with 10 Gy producing 80% complete responses, but this was halved when the tumors were treated with VACV starting 2 days after IG-IR. VACV monotherapy was ineffective in this model. The antagonism was time dependent as waiting for 21 days after IG-IR eliminated the inhibitory effect but without yielding any further benefits over IR alone. In irradiated tumors, VACV replication was also lower, suggesting that irradiation created an environment that did not support infection as well in vivo as in vitro. A study of how four different treatment regimens affected the immune composition of the tumor microenvironment showed that treating irradiated tumors with VACV altered the immunological profiles in tumors exposed to IR or VACV alone. We detected more PD-1 and PD-L1 expression in tumors exposed to IR+VACV but adding an αPD-1 antibody to the protocol did not change the way VACV interferes with IG-IR therapy. VACV encodes many immunosuppressive gene products that may interfere with the ability of radiotherapy to induce an effective anti-tumor immune response through the release of danger-associated molecular patterns. These data suggest that infecting irradiated tumors with VACV, too soon after exposure, may interfere in the innate and linked adaptive immune responses that are triggered by radiotherapy to achieve a beneficial impact.

Strategies for Overcoming Immune Evasion in Bladder Cancer.

Tumors intricately shape a highly immunosuppressive microenvironment, hampering effective antitumor immune responses through diverse mechanisms. Consequently, achieving optimal efficacy in cancer immunotherapy necessitates the reorganization of the tumor microenvironment and restoration of immune responses. Bladder cancer, ranking as the second most prevalent malignant tumor of the urinary tract, presents a formidable challenge. Immunotherapeutic interventions including intravesical BCG and immune checkpoint inhibitors such as atezolizumab, avelumab, and pembrolizumab have been implemented. However, a substantial unmet need persists as a majority of bladder cancer patients across all stages do not respond adequately to immunotherapy. Bladder cancer establishes a microenvironment that can actively hinder an efficient anti-tumor immune response. A deeper understanding of immune evasion mechanisms in bladder cancer will aid in suppressing recurrence and identifying viable therapeutic targets. This review seeks to elucidate mechanisms of immune evasion specific to bladder cancer and explore novel pathways and molecular targets that might circumvent resistance to immunotherapy.

Prognostic biomarker CPEB3 and its associations with immune infiltration in clear cell renal cell carcinoma.

The role and underlying mechanism of cytoplasmic polyadenylation element binding protein 3 (CPEB3) in clear cell renal cell carcinoma [ccRCC progression remain poorly characterized. The present study was designed to evaluate the role of CPEB3 in ccRCC and its clinical associations. The overall response rate of first-line therapies (ICIs combined with VEGFR-TKIs or ICI combination) for ccRCC] is 42.0-59.3%, so a number of patients with ccRCC do not benefit from these therapies. To avoid immunosurveillance and immune killing, tumor cells decrease immunogenicity and recruit immunosuppressive cells such as regulatory T cells (Tregs). Tregs inhibit the development of anti-tumor immunity, thereby hindering immune surveillance of cancer and preventing effective anti-tumor immune response in tumor-bearing hosts. The present study analyzed clinical specimens from patients ccRCC and then examined the role of CPEB3 in ccRCC via bioinformatics analysis. CPEB3 expression was significantly reduced in ccRCC compared with normal tissue and low CPEB3 expression was associated with poor overall survival. Moreover, CPEB3 expression was an independent predictor of survival. CPEB3 expression was positively associated with immune biomarkers [CD274, programmed cell death 1 ligand 2, Hepatitis a virus cellular receptor 2, Chemokine (C-X-C motif) ligand (CXCL)9, CXCL10, Inducible T cell costimulatory, CD40, CD80 and CD38] that improve the outcome of anti-tumor immune responses. CPEB3 expression in ccRCC also affected the status of 24 types of infiltrating immune cell, of which Tregs were the most significantly negatively correlated cell type. CPEB3 may serve as a prognostic biomarker in ccRCC and its mechanism may be related to the regulation of Tregs.

Neoadjuvant CD40 Agonism Remodels the Tumor Immune Microenvironment in Locally Advanced Esophageal/Gastroesophageal Junction Cancer.

Sotigalimab is an agonistic anti-CD40 mAb that can modulate antitumor immune responses. In a phase II clinical trial of sotigalimab combined with neoadjuvant chemoradiation (CRT) in locally advanced esophageal/gastroesophageal junction (E/GEJ) cancer with the primary outcome of efficacy as measured by pathologic complete response (pCR) rate, the combination induced pCR in 38% of treated patients. We investigated the mechanism of action of sotigalimab in samples obtained from this clinical trial. Tumor biopsies and peripheral blood samples were collected at baseline, following an initial dose of sotigalimab, and at the time of surgery after CRT completion from six patients. High dimensional single-cell techniques were used, including combined single-cell RNA-sequencing and proteomics (CITEseq) and multiplexed ion beam imaging, to analyze immune responses. Sotigalimab dramatically remodeled the immune compartment in the periphery and within the tumor microenvironment (TME), increasing expression of molecules related to antigen processing and presentation and altering metabolic pathways in myeloid cells. Concomitant with these changes in myeloid cells, sotigalimab treatment primed new T cell clonotypes and increased the density and activation of T cells with enhanced cytotoxic function. Sotigalimab treatment also induced a decrease in the frequency of Tregs in the TME. These findings indicate that a single dose of sotigalimab leads to enhanced antigen presentation that can activate T cells and induce new T cell clones. This restructuring of the TME provides elements which are critical to the development of effective antitumor immune responses and improved clinical outcomes.

Glutamine antagonist DRP-104 in combination with durvalumab in patients with advanced fibrolamellar carcinoma (FLC) following progression on prior anti-PD(L)1 therapy.

TPS573 Background: Fibrolamellar carcinoma (FLC) is a rare, aggressive form of primary liver cancer predominantly affecting children and young adults under the age of 30. There is no established standard therapy and most patients with advanced disease succumb to their illness with a median prognosis of only 12 months. A chimeric transcript between DNAJB1 and PRKACA, which encodes the catalytic subunit of protein kinase A (PKA), was identified as a signature genomic event in FLC. However, pharmacological inhibition of PKAc for FLC with traditional small molecule inhibitors has been infeasible due to unacceptable on-target toxicity. Preclinical work from our laboratory and others has revealed that the DNAJB1- PRKACA fusion results in a metabolic rewiring of the tumor characterized by glutamine dependence. This glutamine dependence also creates a nutrient-depleted tumor immune microenvironment (TiME) enriched in immunosuppressive metabolites (e.g., ammonia, acidosis) that prohibits an effective antitumor immune response. Through this trial, we will test the hypothesis that glutamine antagonism in FLC reverses resistance to immune checkpoint inhibitor (ICI) therapy through modulating the TiME. Methods: We are conducting a single-arm phase 1b/2 clinical trial of glutamine antagonist DRP-104 in combination with durvalumab in children (age ≥ 12) and adults with advanced FLC who have progressed on prior anti-PD(L)1 therapy. Patients will receive DRP-104 (145 mg s.c. twice weekly) in combination with a fixed dose of durvalumab (1500 mg i.v. every 28 days). The primary clinical endpoints are safety and objective response rate (ORR), defined as the percentage of patients achieving a complete response (CR) or partial response (PR) based on the Response Evaluation Criteria in Solid Tumors (RECIST 1.1). Secondary objectives include progression free survival (PFS), overall survival (OS), and immunological correlates. Key eligibility criteria include histologically confirmed FLC that is metastatic or unresectable; demonstrated radiographic progression on at least one line of prior anti-PD(L)1 therapy; Age ≥ 12 years; ECOG performance status of ≤2; measurable disease according to RECIST 1.1; and adequate end organ function. Patients will undergo fresh core tumor biopsy pre-treatment and at approximately week 4. Biopsies will be used to prepare paraffin embedded and flash-frozen samples. Research bloodwork will be collected prior to dosing at baseline, prior to dosing on cycles 2-5, and every 3 months thereafter to be processed for PBMC isolation. This study has been registered under NCT06027086 and is expected to begin enrollment in December 2023. Clinical trial information: NCT06027086 .

A novel intranasal peptide vaccine inhibits non-small cell lung cancer with KRAS mutation.

KRAS mutations occur commonly in the lung and can lead to the development of non-small cell lung cancer (NSCLC). While the mutated KRAS protein is a neoantigen, it usually does not generate an effective anti-tumor immune response on mucosal/epithelial surfaces. Despite this, mutated KRAS remains a potential target for immunotherapy since immune targeting of this protein in animal models has been effective at eliminating tumor cells. We attempted to develop a KRAS vaccine using mutated and wild-type KRAS peptides in combination with a nanoemulsion (NE) adjuvant. The efficacy of this approach was tested in an inducible mutant KRAS-mouse lung tumor model. Animals were immunized intranasally using NE with KRAS peptides. These animals had decreased CD4+FoxP3+ T cells in both lymph nodes and spleen. Immunized animals also showed higher IFN-γ and IL-17a levels to mutated KRAS that were produced by CD8+ T cells and enhancement in KRAS-specific Th1 and Th17 responses that persisted for 3 months after the last vaccination. Importantly, the immunized animals had significantly decreased tumor incidence compared to control animals. In conclusion, a mucosal approach to KRAS vaccination demonstrated the ability to induce local KRAS-specific immune responses in the lung and resulted in reduced tumor incidence.

Radiotherapy and blockade of immune checkpoints in treatment of cancer patients

Background. Immunotherapy, which aims to use immune defense mechanisms to fight cancer, is a new area of anticancer treatment. A major breakthrough in tumor immunotherapy was the discovery of immune checkpoint proteins, which act as powerful suppressors of the immune system. Humanized monoclonal antibodies, which target these proteins, have proven to be clinically effective in patients with different types of cancer. However, the majority of patients do not respond to checkpoint inhibitor therapy, which necessitates the use of combination strategies to overcome resistance to immunotherapy. In recent years, the combination of radiotherapy and immune checkpoint inhibitors has attracted considerable attention and has been widely studied in preclinical and clinical trials. Much attention is given to the optimization of combined treatment regimens. However, the optimal radiation dose, fractionation scheme, radiation volumes, and radiation sequence in checkpoint inhibitor treatment still remain unclear. Purpose – to analyze and summarize data from preclinical and clinical trials aimed at solving problems related to the choice of optimal doses, fractionation, radiation volume, and sequencing of checkpoint inhibitor immunotherapy and radiotherapy. Materials and methods. For data search, we used Cochrane library and databases (Pubmed, Scopus, Google Scholar). The results of the studies published over the period from 2008 to 2023 were analyzed. Results and discussion. The evidence of the rationality of combining radiotherapy and checkpoint inhibitors in the treatment of cancer patients is shown. The data on the effects of radiation dose and fractionation on antitumor immune responses were analyzed. The results of works that deal with the search for the optimal sequence of radiotherapy and immune checkpoint inhibitors and the selection of the irradiation volume necessary for the generation of an effective systemic antitumor immune response are considered. Conclusions. Combined treatment with radiation therapy and immune checkpoint inhibitors is a promising strategy for patients with metastatic tumors. Preclinical and clinical data indicate that different radiation regimens can cause different effects on antitumor immunity. Further studies of doses and fractionation regimens of radiation therapy, irradiation volume, and the optimal time for each component of combination therapy are needed to determine the conditions for maximizing the immune response. The obtained results will help optimize the combination treatment regimens and wider implementation of such treatment in clinical practice.

T cell-mediated curation and restructuring of tumor tissue coordinates an effective immune response

Antigen-specific Tcells traffic to, are influenced by, and create unique cellular microenvironments. Here we characterize these microenvironments over time with multiplexed imaging in a melanoma model of adoptive Tcell therapy and human patients with melanoma treated with checkpoint inhibitor therapy. Multicellular neighborhood analysis reveals dynamic immune cell infiltration and inflamed tumor cell neighborhoods associated with CD8+ Tcells. Tcell-focused analysis indicates Tcells are found along a continuum of neighborhoods that reflect the progressive steps coordinating the anti-tumor immune response. More effective anti-tumor immune responses are characterized by inflamed tumor-T cell neighborhoods, flanked by dense immune infiltration neighborhoods. Conversely, ineffective Tcell therapies express anti-inflammatory cytokines, resulting in regulatory neighborhoods, spatially disrupting productive Tcell-immune and -tumor interactions. Our study provides in situ mechanistic insights into temporal tumor microenvironment changes, cell interactions critical for response, and spatial correlates of immunotherapy outcomes, informing cellular therapy evaluation and engineering.

Abstract A030: Blood-based screening panel for lung cancer based on clonal hematopoietic mutations in tumor infiltrating immune cells

Abstract Early detection can significantly reduce mortality due to lung cancer. However, the high cost of the currently approved screening protocol has limited its uptake. Presented here is a blood-based screening panel based on clonal hematopoietic mutations. Mutations in tumor cells that inhibit immune destruction have been extensively studied. However, mutations in immune cells that may prevent an effective anti-tumor immune response remain relatively unstudied. Animal model studies suggest that clonal hematopoietic mutations in tumor infiltrating immune cells can modulate cancer progression, representing potential predictive biomarkers. The goal of this study was to determine if the clonal expansion of these mutations in blood samples could predict the occurrence of lung cancer. We identified a set of 98 potentially pathogenic clonal hematopoietic mutations in tumor infiltrating immune cells. A logistic regression machine learning model based on these mutations correctly classified lung cancer and non-cancer blood samples with 94.12% sensitivity (95% Confidence Interval: 92.20-96.04%) and 85.96% specificity (95% Confidence Interval: 82.98-88.95%) in a test set of 578 lung cancer and 545 non-cancer samples from 18 different cohorts. More importantly, 89.98% of the cancer cases were unambiguously predicted with probability of cancer >0.90 and 74.86% of the non-cancer cases with probability of cancer <0.10. These results suggest that it may be possible to develop an accurate blood-based lung cancer screening panel. Unlike most other “liquid biopsies” currently under development, the assay presented here is based on standard sequencing protocols and uses a relatively small number of rationally selected mutations as predictors. Citation Format: Ramu Anandakrishnan, Ryan Shahidi, Andrew Dai, Veneeth Antony. Blood-based screening panel for lung cancer based on clonal hematopoietic mutations in tumor infiltrating immune cells [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr A030.

Intratumoral delivery of a Tim-3 antibody-encoding oncolytic adenovirus engages an effective antitumor immune response in liver cancer

Intratumoral delivery of a Tim-3 antibody-encoding oncolytic adenovirus engages an effective antitumor immune response in liver cancer