Immune Checkpoint Inhibitor Antibody Research Articles

TROCEPT: An oncolytic virus platform engineered for αvß6 integrin targeted tumor-localised expression of an immune checkpoint inhibitor following intravenous delivery.

e14579 Background: TROCEPT is a novel tumor-selective replicating, oncolytic adenovirus type 5 (Ad5) rationally engineered to remove all natural tissue tropisms. This engineering addresses the main limitation of other viral therapies which infect normal tissues and are rapidly removed by the liver and are therefore limited to local delivery. TROCEPT has been further engineered to specifically bind to αvβ6 integrin which is expressed at high frequency in the majority of epithelial cancers, so that following intravenous delivery the virus targets tumor tissue where it replicates and amplifies. In addition, the TROCEPT platform encodes transgenes which enables in-tumor production of powerful therapeutic drugs. The lead programme, TROCEPT-01, encodes a fully human, full length immune checkpoint inhibitor (ICI) antibody. TROCEPT-01 is currently undergoing IND-enabling studies and is expected to enter First in Human studies in 2024 in multiple solid tumor indications. Methods: Proof of concept studies, both in vitro and in vivo, to demonstrate TROCEPT-01’s tumor selectivity and toxicity profile have been performed. Results: In vitro experiments demonstrate that viral replication, transgene expression and oncolytic cell death following infection with TROCEPT-01 is highly selective for αvβ6 integrin positive tumor cells compared to a panel of normal human primary cells. Intravenous delivery in in vivo SKOV3 ovarian human tumor xenograft mouse models demonstrate virus delivery, replication, and transgene expression in the tumor. In comparison to the parental Ad5 virus, the engineering of TROCEPT-01 leads to more viral delivery to the tumour, less delivery to normal tissue including liver, reduced markers of liver toxicity and reduced inflammatory cytokine release, all of which validate the tumour selectivity and safety profile of the virus. Conclusions: We have demonstrated that TROCEPT engineering enables highly selective tumor targeting and significant tumor exposure following intravenous delivery. TROCEPT-01’s in-tumor selective expression of ICIs enables high local drug concentration in the tumor, potentially reducing systemic toxicity and increasing efficacy. TROCEPT-01 is currently undergoing IND-enabling studies and is expected to enter First in Human studies in 2024 in multiple solid tumor indications.

Abstract 7463: Chromosomal instability elicits anti-tumor immunity in pancreatic cancer

Abstract Chromosomal instability (CIN) is a hallmark of solid cancers and an established driver of disease progression, therapy resistance, metastasis and on the whole poor patient outcome. Pancreatic cancer is particularly devastating, defined by dismal survival rates with many patients presenting with metastatic disease upon diagnosis, and 5-year survival only reaching ~10%. Despite recent efforts to improve prognosis for pancreatic cancer patients with immunotherapies alone and in combination with other therapeutics progress remains limited. Despite CIN’s established role as a driver of disease progression, we have made the paradoxical observation that chromosomally unstable, murine pancreatic cancer cells elicit an anti-tumor immune response. CIN was induced experimentally in a chromosomally stable, metastatic model of pancreatic cancer. Modeling metastatic dissemination by injection of cells into the tail vein of mice led to robust tumor formation in the lungs where CIN-low cells formed many small lesions while CIN-high cells formed fewer but larger tumors. We investigated if the tumors were infiltrated differentially by immune cells by immunofluorescence and found that CIN-high tumors were more readily infiltrated by effector T-cells. This observation motivated us to test immunotherapy response in CIN-low and CIN-high cells. Subcutaneously implanted tumor cells were treated with an immune checkpoint inhibitor and isotype control antibody which revealed that CIN-high cells responded to immunotherapy while CIN-low cells did not. To put forward potential mechanisms explaining CIN-driven anti-tumor immunity, we performed molecular analyses of CIN-low and CIN-high tumors. First, we found that inflammatory pathways were significantly up-regulated in CIN-high tumors compared with CIN-low tumors. These findings were validated by cytokine measurements and RNA in situ hybridization. To dissect inflammatory pathway activation mechanistically, we engineered CIN-high cells using CRISPR/Cas9 that were deficient for key inflammatory cytokines and transcription factors. These experiments suppressed cell-intrinsic and ligand-induced inflammation. Yet, we failed to determine singular cytokine expression as mediator of anti-tumor immunity. To rule out the contribution of ligand-induced inflammation in the tumor microenvironment, we probed immune checkpoint blockade in combination with antibodies blocking inflammatory ligand receptors in CIN-high cells. We found that immune checkpoint blockade was cancer cell-intrinsic and independent of blocking antibodies. In summary, our data implicates CIN as a determinant of therapeutic and genetic anti-tumor immunity in a preclinical model of pancreatic cancer. Citation Format: Daniel Bronder, Roshan K. Sriram, Mercedes Duran, Melody Di Bona, Sarina McElduff, Samuel F. Bakhoum. Chromosomal instability elicits anti-tumor immunity in pancreatic 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 7463.

Immune checkpoint inhibitors and cancer immunotherapy by aptamers: an overview.

Efforts in cancer immunotherapy aim to counteract evasion mechanisms and stimulate the immune system to recognise and attack cancer cells effectively. Combination therapies that target multiple aspects of immune evasion are being investigated to enhance the overall efficacy of cancer immunotherapy. PD-1 (Programmed Cell Death Protein 1), CTLA-4 (Cytotoxic T-Lymphocyte Antigen 4), LAG-3 (Lymphocyte-Activation Gene 3), and TIM-3 (T Cell Immunoglobulin and Mucin Domain-Containing Protein3) are all immune checkpoint receptors that play crucial roles in regulating the immune response and maintaining self-tolerance often exploited by cancer cells to evade immune surveillance. Antibodies targeted against immune checkpoint inhibitors such as anti-PD-1 antibodies (e.g., pembrolizumab, nivolumab), anti-CTLA-4 antibodies (e.g., Ipilimumab), and experimental drugs targeting LAG-3 and TIM-3, aim to block these interactions and unleash the immune system's ability to recognise and destroy cancer cells. The US FDA has approved different categories of immune checkpoint inhibitors that have been utilised successfully in some patients with metastatic melanoma, renal cell carcinoma, head and neck cancers, and non-small lung cancer. Although several immune checkpoint inhibitor antibodies have been developed, they exhibited immune-related adverse effects, resulting in hypophysitis, diabetes, and neurological issues. These adverse effects of antibodies can be reduced by developing aptamer against the target. Aptamers offer several advantages over traditional antibodies, such as improved specificity, reduced immunogenicity, and flexible design for reduced adverse effects that specifically target and block protein-protein or receptor-ligand interactions involved in immune checkpoint pathways. The current study aims to review the function of particular immune checkpoint inhibitors along with developed aptamer-mediated antitumor cytotoxicity in cancer treatment.

Abstract 3159: Next generation immuno-oncology tumor profiling using a biophysics-based biomarker to predict immunotherapy response in early-stage breast cancer

Abstract Background: Immuno-oncology (IO) therapies, such as immune checkpoint inhibitor antibodies, have emerged as promising treatments for early-stage breast cancer (ESBC). Although immunotherapy is standard-of-care for ESBC, the number of benefiting patients remains small, and the therapy itself can prompt severe immune-related adverse events. To date, efforts to identify biomarkers of IO response, such as those targeting the PD-1/PD-L1 signaling axis, have failed to robustly demarcate predictive features that translate across cohorts. Here, we applied an integrative computational approach to develop the IOScope biomarker, which predicts IO response in ESBC. Our method overcomes many of the limitations of invasive, costly, and time-consuming IO response analyses derived from transcriptomics data, and advances beyond the inability of single-site biopsies to account for tumor heterogeneity. Methods: We analyzed single-cell and whole-tissue RNA-seq data from non-IO treated ESBC patients in the I-SPY trials, as well as 23 manually-curated gene expression signatures representing the “hallmarks of cancer”, in order to associate PD-L1 levels with local tumor biology. We then correlated PD-L1 expression to biophysical features derived from patient DCE-MRIs to generate the IOScope biomarker. We quantified IOScope within patient tumors using integrative computational modeling and developed a corresponding IOScope Score. The IOScope biomarker and Score were then applied to data from IO-treated patients in the I-SPY2 clinical trial to assess their performance in predicting pCR in response to IO therapy. We additionally validated IOScope in a virtual clinical trial, comparing pCR rates to empirical data. Results: We validated the IOScope biomarker and the IOScope Score in a small, independent cohort of IO-treated patients (n=17) and correctly predicted pCR response in 15/17 individuals (88.2% accuracy, comprising 10/12 in TNBC and 5/5 in HR+/HER2-). We further applied the IOScope Score in a virtual clinical trial (N = 292) simulating IO administration in IO-naïve cohort (Virtual Tumor Bank, SimBioSys, Inc.). Using this approach, we predicted an increase in pCR rates of 28.5% (TNBC) and 8.9% (HR+/HER2-) with the addition of IO therapy to a standard chemotherapy background. These predicted increases in pCR rate compare favorably to published rates increases produced by IO in both cancer subtypes. Conclusion: The IOScope biomarker and IOScope Score represent a next generation approach using integrative computational and biophysical analysis to assess cancer responsiveness to immunotherapy. This biomarker, predicated on MRI-derived tumor microenvironmental features, allows for immuno-oncology profiling of tumors in a rapid, non-invasive manner and may confer high clinical decision impact to further enable personalized oncologic care. Citation Format: Daniel Cook, John Pfeiffer, Joseph Peterson, Nicole Liadis, Matthew Biancalana, Dorys A. Lopez-Ramos, Tushar Pandey, John Cole, Anuja K. Antony. Next generation immuno-oncology tumor profiling using a biophysics-based biomarker to predict immunotherapy response in early-stage breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3159.

Abstract 4572: 3D-EXpress ex vivo platform using a biorepository of characterized fresh patient tumoroids allows development of rational combinations with drugs targeting DNA damage response and immune checkpoint blockade

Abstract Introduction: Nilogen Oncosystems’ 3D-EXpress platform allows for the detailed characterization offreshly resected patient tumor tissue for inclusion in studies investigating rational combinations of IOtherapeutics. Incorporating data on immune cell composition, tumor cell target expression, mutationalstatus, and HPV infection within tumoroids generated from HNSCC tissues provides tremendous input toidentify candidate tissues for therapeutic testing. The 3D-EXpress platform employed here providesdetailed observations investigating tumor cell viability using confocal microscopy and immune cellactivation indicated by increases in cytokine release. Materials and Methods: 3D tumoroids measuring 150 microns in size were generated from fresh patientHNSCC resection samples collected with proper patient consent and relevant IRB approval. Tumoroidswere never enzymatically dissociated, propagated, or reassembled to maintain the intact tumormicroenvironment (TME). The resulting tumoroids were cryopreserved in the Biorepository, where eachsample had associated patient demographic data, tumor grade, stage, mutational and HPV status inaddition to a detailed tumor immune profile and a FFPE representative sample in TMA format for targetselection. Pooled tumoroids for each patient tumor were treated ex vivo both singly with a selectiveWEE1 inhibitor, AZD1775 and an ATR blocker AZD6738 alone and in combination with a PD-1 immunecheckpoint inhibitor antibody nivolumab for 72h. Results and Summary: To quantify treatment-mediated tumor cell killing we used 3D high-contentconfocal imaging and a proprietary algorithm for data analysis. Additionally, culture supernatantsisolated from treated tumoroids were used for multiplex cytokine detection to monitor changes in theTME upon ex vivo treatment. Responses to treatments were further correlated with the composition ofinnate and adaptive TIL populations within each tumor as assessed by 21-color flow cytometry inaddition to tumor mutational status, HPV infection, smoking status, as well as EGFR and PD-L1expression levels analyzed by multiplex IF on associated TMA slides. Conclusion: These results demonstrate that targeting DNA damage response and immune checkpointblockade may provide a potential combination strategy for the treatment of HNSCC. Furthermore, weshowed that our 3D-EXpress ex vivo tumoroid model provides a unique platform to rapidly assess theefficacy of drugs and drug combinations in fresh patient tumor samples with intact TME. Correlation ofex vivo drug responses with characteristics of each tumor’s immune microenvironment and detailedclinicopathological data may allow to identify clinically relevant biomarkers to enable the most effectivetreatment strategies for individual patients in the clinic. Citation Format: Jared Ehrhart, Seth Currlin, Sharon Camacho, Samantha Hoffman, Angie Rivera, Soner Altiok. 3D-EXpress ex vivo platform using a biorepository of characterized fresh patient tumoroids allows development of rational combinations with drugs targeting DNA damage response and immune checkpoint blockade. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4572.

The Development of STING Agonists and Emerging Results as a Cancer Immunotherapy.

New therapies are needed to potentiate the effects of current immunotherapies and overcome resistance. The stimulator of interferon genes genes (STING) pathway is an innate immune activating cascade that may enhance current cancer immunotherapies. Preclinical data has shown that the addition of a STING agonist enhances the effect of current treatments such as immune checkpoint inhibitor antibodies and radiation therapy. Early phase trials have demonstrated modest efficacy of STING agonists and revealed new mechanistic and technical challenges. STING agonists are a new class of agents that activate the immune response to improve tumor control. A wide range of preclinical experiments, translational data, and ongoing clinical trials support the therapeutic use of STING agonists in patients. Trials to determine optimal drug combinations and novel delivery mechanisms are continuing in development.

Next generation immuno-oncology tumor profiling using a rapid, non-invasive, computational biophysics biomarker in early-stage breast cancer.

Immuno-oncology (IO) therapies targeting the PD-1/PD-L1 axis, such as immune checkpoint inhibitor (ICI) antibodies, have emerged as promising treatments for early-stage breast cancer (ESBC). Despite immunotherapy's clinical significance, the number of benefiting patients remains small, and the therapy can prompt severe immune-related events. Current pathologic and transcriptomic predictions of IO response are limited in terms of accuracy and rely on single-site biopsies, which cannot fully account for tumor heterogeneity. In addition, transcriptomic analyses are costly and time-consuming. We therefore constructed a computational biomarker coupling biophysical simulations and artificial intelligence-based tissue segmentation of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRIs), enabling IO response prediction across the entire tumor. By analyzing both single-cell and whole-tissue RNA-seq data from non-IO-treated ESBC patients, we associated gene expression levels of the PD-1/PD-L1 axis with local tumor biology. PD-L1 expression was then linked to biophysical features derived from DCE-MRIs to generate spatially- and temporally-resolved atlases (virtual tumors) of tumor biology, as well as the TumorIO biomarker of IO response. We quantified TumorIO within patient virtual tumors (n = 63) using integrative modeling to train and develop a corresponding TumorIO Score. We validated the TumorIO biomarker and TumorIO Score in a small, independent cohort of IO-treated patients (n = 17) and correctly predicted pathologic complete response (pCR) in 15/17 individuals (88.2% accuracy), comprising 10/12 in triple negative breast cancer (TNBC) and 5/5 in HR+/HER2- tumors. We applied the TumorIO Score in a virtual clinical trial (n = 292) simulating ICI administration in an IO-naïve cohort that underwent standard chemotherapy. Using this approach, we predicted pCR rates of 67.1% for TNBC and 17.9% for HR+/HER2- tumors with addition of IO therapy; comparing favorably to empiric pCR rates derived from published trials utilizing ICI in both cancer subtypes. The TumorIO biomarker and TumorIO Score represent a next generation approach using integrative biophysical analysis to assess cancer responsiveness to immunotherapy. This computational biomarker performs as well as PD-L1 transcript levels in identifying a patient's likelihood of pCR following anti-PD-1 IO therapy. The TumorIO biomarker allows for rapid IO profiling of tumors and may confer high clinical decision impact to further enable personalized oncologic care.

Antibody-dependent cellular cytotoxicity-null effector developed using mammalian and plant GlycoDelete platform

Cancer therapy using immune checkpoint inhibitor antibodies has markedly shifted the paradigm of cancer treatment. However, methods completely eliminating the effector function of these signal-regulating antibodies is urgently required. The heterogeneity of glycan chains in antibodies limits their use as therapeutic agents due to their variability; thus, the development of uniform glycan chains is necessary. Here, we subjected the anti-programmed cell death protein (PD)-1 antibody nivolumab, a representative immune checkpoint inhibitor, to GlycoDelete (GD) engineering to remove the antibody-dependent cellular cytotoxicity (ADCC) of the antibody, leaving only one glycan in the Fc. Glyco-engineered CHO cells were prepared by overexpressing endo-β-N-acetyl-glucosaminidase (Endo T) in CHO cells, in which N-acetyl-glucosaminyl-transferase I was knocked out using Cas9. GD IgG1 nivolumab and GD IgG4 nivolumab were produced using GD CHO cells, and glycan removal was confirmed using mass spectrometry. Target binding and PD-1 inhibition was not altered; however, ADCC decreased. Furthermore, the IgG4 form, determined to be the most suitable form of GD nivolumab, was produced in a plant GD system. The plant GD nivolumab also reduced ADCC without affecting PD-1 inhibitory function. Thus, CHO and plant GD platforms can be used to improve signal-regulating antibodies by reducing their effector function.

The Blocking vs Depletion Model of Immune Checkpoint Inhibitor Therapy for Cancer

Immune Checkpoint Inhibitor (ICI) therapy is the most exciting development in cancer treatments in recent years. As of the end of 2021, more than a hundred of clinical trials have been carried out by several major drug makers and research hospitals all over the world just to explore the use of ICI antibodies in almost every type of cancer and under various clinical settings. These clinical trials have resulted waves of good news in every year’s major academic conferences and FDA approvals, and now ICI therapy is in the move to take over traditional therapy to become the major player in clinical management of cancer. On the other hand, most of these clinical trials have failed to show clear benefits in most cancer patients, and only few have been reported in public. In real-world clinical setting, ICI antibodies are being massively and sometimes abusively prescribed for almost every desperate situation with clear clinical benefit in only a few (<10%). Yet, the enthusiasm behind ICI therapy is not dampened by the massive clinical failure but has been growing. The reason for the consistent enthusiasm among clinicians and patients is the miracle-like clinical responses seen in some of the responders that even including late-stage hopeless cases. Every clinician wants to repeat this miracle in the next seemingly identical patient, and every patient and their family members want to believe that they are in line for that miracle. But the reality is disheartening in that clinicians do not see the predictable repeat of miracle-like responses in seemingly identical patients and most patients selecting ICI therapy as the last straw in life did not benefit from it, if not hurt by it. What then are the reasons that ICI therapy is so impressive when working and so unpredictable in responses? This review attempts to draw some mechanistic aspects based on our own experiences in ICI therapy and to come up with a different explanation for the unexplained clinical observations. The goal of this review is to alert the clinical field about the danger and irreversible damages that wrongly used ICI antibodies may cause, and at the same time to introduce some preliminary criteria to select proper patient for the benefits and to avoid the harms of ICI therapy.

Abstract 3531: Sensitizing immune unresponsive colorectal cancers to immune checkpoint inhibitors through MAVS overexpression

Abstract Background: The majority of colorectal carcinomas (CRCs) are insensitive to anti-PD-1/PD-L1 immune checkpoint inhibitor (ICI) antibodies. While there are many causes for ICI insensitivity, recent studies suggest that the suppression of innate immunity through a loss of innate immune adaptor expression could be a root cause of this insensitivity and an important factor in the evolution of tumor immunosuppression. Methods: We interrogated mitochondrial antiviral signaling gene (MAVS) expression through bioinformatics analyses of multiple datasets to validate its suppression in clinical samples. We then engineered MAVS expressing tumor cells and tested its ability to elicit innate and adaptive anti-tumor immunity using both in vitro and in vivo approaches, which we then confirmed using MAVS expressing viral vectors. Finally, we observed that MAVS stimulated PD-L1expression in different types of tumor cells and then assessed the combination of PD-L1 ICI antibodies with MAVS tumor expression in vivo. Results: MAVS was significantly downregulated in CRCs, but its re-expression could stimulate broad cellular interferon-related responses, in both murine and patient-derived CRCs. In vivo, local MAVS expression elicited significant anti-tumor responses in both immune-sensitive and insensitive CRC models, through the stimulation of an interferon responsive axis that elicited tumor antigen-specific adaptive immunity. Critically, we found that tumor-intrinsic MAVS expression triggered systemic adaptive immune responses that enabled abscopal CD8+ T cell cytotoxicity against distant CRCs. As MAVS also induced PD-L1 expression, we further found synergistic anti-tumor responses in combination with anti-PD-L1 ICIs. Conclusion: These data demonstrate that intratumoral MAVS expression results in local and systemic tumor antigen-specific T cell responses, which could be combined with PD-L1 ICI to permit effective anti-tumor immunotherapy in ICI resistant cancers. We are further exploring to overcome the ICI insensitivity of other types of solid tumor, with MAVS-delivery strategies other than viral vectors. Citation Format: Bin-Jin Hwang, Li-Chung Tsao, Chaitanya Acharya, Timothy Trotter, Pankaj Agarwal, Tao Wang, Junping Wei, Xiao-Yi Yang, Gang-jun Lei, Takuya Osada, Herbert Kim Lyerly, Michael A. Morse, Zachary Hartman. Sensitizing immune unresponsive colorectal cancers to immune checkpoint inhibitors through MAVS overexpression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3531.

Abstract 2164: Chromosomal instability as a mediator of anti-tumor immunity in pancreatic cancer

Abstract Chromosomal instability (CIN) is a hallmark of solid cancers and an established driver of dis-ease progression, therapy resistance, metastasis and on the whole poor patient outcome. Pancreatic cancer, in particular, is defined by dismal survival rates with many patients presenting with metastatic disease upon diagnosis and 5-year survival only reaching ~10%. Recent efforts to improve prognosis for pancreatic cancer patients involved immunotherapies alone and in combination with other therapeutics, however, progress remains limited. Despite CIN’s established role as a driver of disease progression, we have made the paradoxical observation that chromosomally unstable, murine pancreatic cancer cells elicit an anti-tumor immune response. CIN was induced in a chromosomally stable, metastatic model using piggyBac mutagenesis to increase chromosome segregation errors and simultaneously express the diphtheria toxin receptor, thymidine kinase, firefly luciferase and blue fluorescence protein transgenes. Modeling metastatic dissemination by injection of cells into the tail vein of mice led to robust tumor formation in the lungs where CINlow cells formed many small lesions while CINhigh cells formed fewer but larger tumors. We investigated if the tumors were infiltrated differentially by immune cells by immunofluorescence and found that CINhigh tumors were more readily infiltrated by effector T-cells. This observation motivated us to test immunotherapy response in CINlow and CINhigh tumors. Subcutaneously implanted tumor cells were treated with an immune checkpoint inhibitor and isotype control antibody which revealed that CINhigh cells responded to immunotherapy while CINlow cells did not. However, this response could easily be explained by the expression of ectopic antigens in CINhigh cells as a result of the piggyBac mutagenesis, therefore, we derived isogenic single cell clones from the CINhigh population and probed chromosome segregation fidelity and anti-tumor immunity in a more controlled system. Indeed, we were able to isolate CINlow and CINhigh subclones and found that these displayed similar lung engraftment to original CINlow and CINhigh cells as demonstrated by in vivo bioluminescence imaging. Importantly, this difference in engraftment efficiency was alleviated in immunocompromised mice supporting our notion that CIN mediates an anti-tumor immune response in this setting. In summary, our data implicates CIN as a determinant of therapeutic and genetic anti-tumor immunity in a preclinical model of pancreatic cancer. The utility of this model is illustrated by the isogenic nature of cells that only differ in CIN levels and their expression of in vitro and in vivo selection markers. Currently, we are determining the mechanistic underpinnings of our observation using a combination of transcriptomics and genetic manipulations by CRISPR/Cas9. Citation Format: Daniel Bronder, Roshan K. Sriram, Samuel F. Bakhoum. Chromosomal instability as a mediator of anti-tumor immunity in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2164.

Imprime PGG Enhances Anti-Tumor Effects of Tumor-Targeting, Anti-Angiogenic, and Immune Checkpoint Inhibitor Antibodies

Imprime PGG (Imprime) is in late-stage clinical development as a combinatorial agent with several therapeutic modalities. Here we present pre-clinical mechanistic data supportive of Imprime, a soluble yeast β-1,3/1,6-glucan pathogen-associated molecular pattern able to prime innate immune cells in a Dectin-1dependent manner. In tumor-free mice, Imprime evoked broad innate immune responses (type I interferon signature, mobilization of myeloid cells, dendritic cell and monocyte/macrophage expression of co-stimulatory ligands like CD86, and activation of natural killer cells). Imprime-mediated activation of myeloid cells also resulted in functional priming of antigen-specific CD8 T cell response. In tumor-bearing mice, Imprime monotherapy further resulted in activation of systemic and tumor infiltrating macrophages and enhanced cytotoxic CD8 T cell trafficking. Imprime enhanced the anti-tumor activity of several combinatorial agents in mouse cancer models; anti-tyrosinase-related protein 1 antibody in B16F10 melanoma experimental lung metastasis model, anti-vascular endothelial growth factor receptor 2 antibody in H1299 and H441 lung cancer, and anti-programmed cell death protein 1 antibody in MC38 colon cancer models. Mechanistically, combining Imprime with these combinatorial therapeutic agents elicited enhanced innate immune activation, supporting immunological synergy. Finally, Imprime treatment induced similar in vitro phenotypic and functional activation of human innate immune cells. Collectively, these data demonstrate Imprime’s potential to orchestrate a broad, yet coordinated, anti-cancer immune response and complement existing cancer immunotherapies.

The True Mechanisms Behind Immune Checkpoint Inhibitor Therapy for Cancer

Immune Checkpoint Inhibitor (ICI) therapy is the most exciting development in cancer treatments in recent years. As of the end of 2021, more than a hundred of clinical trials have been carried out by several major drug makers and research hospitals all over the world just to explore the use of ICI antibodies in almost every type of cancer and under various clinical settings. These clinical trials have resulted waves of good news in every year’s major academic conferences and FDA approvals, and now ICI therapy is in the move to take over traditional therapy to become the major player in clinical management of cancer. On the other hand, most of these clinical trials have failed to show clear benefits in most cancer patients, and only few have been reported in public. In real-world clinical setting, ICI antibodies are being massively and sometimes abusively prescribed for almost every desperate situation with clear clinical benefit in only a few (<10%). Yet, the enthusiasm behind ICI therapy is not dampened by the massive clinical failure but has been growing. The reason for the consistent enthusiasm among clinicians and patients is the miracle-like clinical responses seen in some of the responders that even including late-stage hopeless cases. Every clinician wants to repeat this miracle in the next seemingly identical patient, and every patient and their family members want to believe that they are in line for that miracle. But the reality is disheartening in that clinicians do not see the predictable repeat of miracle-like responses in seemingly identical patients and most patients selecting ICI therapy as the last straw in life did not benefit from it, if not hurt by it. What then are the reasons that ICI therapy is so impressive when working and so unpredictable in responses? This review attempts to draw some mechanistic aspects based on our own experiences in ICI therapy and to come up with a different explanation for the unexplained clinical observations. The goal of this review is to alert the clinical field about the danger and irreversible damages that wrongly used ICI antibodies may cause, and at the same time to introduce some preliminary criteria to select proper patient for the benefits and to avoid the harms of ICI therapy.

Radical benefits and harms associated with immune checkpoint inhibitor therapy in cancer and the true mechanisms behind

Immune Checkpoint Inhibitor (ICI) therapy is the most exciting development in cancer treatments in recent years. As of the end of 2021, more than a hundred of clinical trials have been carried out by several major drug makers and research hospitals all over the world just to explore the use of ICI antibodies in almost every type of cancer and under various clinical settings. These clinical trials have resulted waves of good news in every year’s major academic conferences and FDA approvals, and now ICI therapy is in the move to take over traditional therapy to become the major player in clinical management of cancer. On the other hand, most of these clinical trials have failed to show clear benefits in most cancer patients, and only few have been reported in public. In real-world clinical setting, ICI antibodies are being massively and sometimes abusively prescribed for almost every desperate situation with clear clinical benefit in only a few (<10%). Yet, the enthusiasm behind ICI therapy is not dampened by the massive clinical failure but has been growing. The reason for the consistent enthusiasm among clinicians and patients is the miracle-like clinical responses seen in some of the responders that even including late-stage hopeless cases. Every clinician wants to repeat this miracle in the next seemingly identical patient, and every patient and their family members want to believe that they are in line for that miracle. But the reality is disheartening in that clinicians do not see the predictable repeat of miracle-like responses in seemingly identical patients and most patients selecting ICI therapy as the last straw in life did not benefit from it, if not hurt by it. What then are the reasons that ICI therapy is so impressive when working and so unpredictable in responses? This review attempts to draw some mechanistic aspects based on our own experiences in ICI therapy and to come up with a different explanation for the unexplained clinical observations. The goal of this review is to alert the clinical field about the danger and irreversible damages that wrongly used ICI antibodies may cause, and at the same time to introduce some preliminary criteria to select proper patient for the benefits and to avoid the harms of ICI therapy

Sensitizing immune unresponsive colorectal cancers to immune checkpoint inhibitors through MAVS overexpression

BackgroundThe majority of colorectal carcinomas (CRCs) are insensitive to programmed death protein-1/programmed death-ligand 1 (anti-PD-1/PD-L1) immune checkpoint inhibitor (ICI) antibodies. While there are many causes for ICI insensitivity, recent studies...

Effect of Atezolizumab plus Bevacizumab in Patients with Hepatocellular Carcinoma Harboring CTNNB1 Mutation in Early Clinical Experience.

Atezolizumab plus bevacizumab (ATZ/BV) treatment is a combined immunotherapy consisting of immune checkpoint inhibitor (ICI) and anti-vascular endothelial growth factor monoclonal antibody, which has brought a major paradigm shift in the treatment of unresectable hepatocellular carcinoma (HCC). Gain-of-function mutation of CTNNB1 contributes to resistance of ICI monotherapy through the framework of non-T-cell-inflamed tumor microenvironment. However, whether CTNNB1 mutation renders resistance to ATZ/BV similar to ICI monotherapy remains to be elucidated. In this study, a liquid biopsy sample in plasma of 33 patients with HCC treated with ATZ/BV was subjected to droplet digital PCR for detecting hotspot mutations at the exon 3 of CTNNB1 locus. A total of eight patients (24.2%) exhibited at least one CTNNB1 mutation. The objective response rate (ORR) in patients with wild-type (WT) and mutant (MT) CTNNB1 was 8.0% and 12.5%, respectively, and the disease control rate (DCR) was 68.0% and 87.5%, respectively. No significant difference in both ORR and DCR has been observed between the two groups. The median progression-free survival in patients with WT and MT CTNNB1 was 6.6 and 7.6 months, respectively (not statistically significant). Similarly, no significant difference in overall survival has been observed between patients with WT and MT CTNNB1 (13.6 vs. 12.3 months). In conclusion, the treatment effect of ATZ/BV in patients with HCC with MT CTNNB1 was comparable to those patients with WT CTNNB1. These results implicate that BV added to ATZ might improve immunosuppressive tumor microenvironment caused by CTNNB1 mutation.

Immune Therapies for Myelodysplastic Syndromes and Acute Myeloid Leukemia.

Simple SummaryMyelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) are bone marrow cancers that have a poor prognosis. They have traditionally been treated with chemotherapy with limited success, and stem cell transplant, which many patients are too frail to receive. Perturbations in the immune system play a role in the development of MDS and AML. Recently, there has been progress in understanding how the immune system can be harnessed to treat these cancers. Effective immune therapies for MDS and AML have been developed at a rapid pace, including novel immune checkpoint inhibitor antibodies, bispecific T-cell-engaging antibodies, antibody drug conjugates, vaccine therapies, and cellular therapeutics including chimeric antigen receptor T-cells and natural killer cells. This review article highlights advances in this field for the practicing clinician to aid in understanding new developments for treating patients with MDS and AML.Myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) are hematologic malignancies arising from the bone marrow. Despite recent advances in treating these diseases, patients with higher-risk MDS and AML continue to have a poor prognosis with limited survival. It has long been recognized that there is an immune component to the pathogenesis of MDS and AML, but until recently, immune therapies have played a limited role in treating these diseases. Immune suppressive therapy exhibits durable clinical responses in selected patients with MDS, but the question of which patients are most suitable for this treatment remains unclear. Over the past decade, there has been remarkable progress in identifying genomic features of MDS and AML, which has led to an improved discernment of the molecular pathogenesis of these diseases. An improved understanding of immune and inflammatory molecular mechanisms of MDS and AML have also recently revealed novel therapeutic targets. Emerging treatments for MDS and AML include monoclonal antibodies such as immune checkpoint inhibitors, bispecific T-cell-engaging antibodies, antibody drug conjugates, vaccine therapies, and cellular therapeutics including chimeric antigen receptor T-cells and NK cells. In this review, we provide an overview of the current understanding of immune dysregulation in MDS and AML and an update on novel immune therapies for these bone marrow malignancies.

Immuno‐Reactive Cancer Organoid Models to Examine Microbiome Metabolite Effects on Immune Checkpoint Blockade Efficacy

Introduction As the number of available immunotherapies for solid tumors increase, their prevalence in the clinic continues to rise as well. While the results are promising, a sizable percentage of patients are non-responders to all types of immunotherapy. Yet, there has been limited number of in vitro models to assess tumor immune-reactivity and enable directed study of the mechanisms of immunotherapy resistance in solid tumors. The goal of this project is develop a model in which we could validate cancer cell killing due to immune cell action in an easily modifiable environment. Towards that, we created 3D tumor tissue constructs (organoids) containing cancer cells paired with cytotoxic T-cells to model immunotherapy efficacy. Our choice of immune checkpoint inhibitor antibodies were a paired course of PD-1 and CTLA-4, which are used extensively in the clinic, or anti-CD47. Upon validation of our organoid model, they could address specific mechanisms behind certain tumor microenvironment elements, such as bacterial metabolites, on immunotherapy efficacy. Methods We created extracellular matrix like 3D structures using collagen/hyaluronic acid-based hydrogels into which tumor cell were mixed, along with T-cells. The cancer cells incorporated were either freshly-isolated CT-26 colon adenocarcinoma cells, 4T1 breast cancer cells, or cultured CT-26 cells. The T-cells were either derived from murine lymph nodes or were isolated from the murine tumor infiltrating mononuclear cell population. Organoids were treated with microbial metabolites and their response to therapeutic equivalent doses of anti- PD-1, CTLA-4 and CD47 antibodies was examined using cell viability assays, flow cytometry, RT-qPCR, and immunohistochemistry (IHC) staining. Results The results show that in our immune cell supplemented tumor organoid models the immune checkpoint inhibitor regimens stimulated internally localizing T-cells and inducing T-cell-mediated tumor cell killing. Checkpoint inhibitor treated samples showed proportionally greater loss of viability when compared to untreated controls (p<0.01). The results were corroborated by IHC, showing increased numbers of CD-4+ T-cells and cytotoxic proteins such as granzyme B in the stimulated samples. RT-qPCR results show an increase in key proteins for immune function when both immunotherapy and bacterial metabolites are administered simultaneously. Conclusion: We have created an ex-vivo immune-reactive tumor organoid model for studying immunotherapy. This model will allow us to modulate facets of the tumor cell component in the organoid system including cancer type and grade, tumor cell mutations, biochemical signals, and physical properties of the microenvironment. We can then observe the impacts of these changes on immunotherapy efficacy in order to identify factors that could be targeted to improve immunotherapy efficacy. In this study, we have focused on the effects of bacterial metabolites on immunotherapy efficacy. Preliminary data suggest that there may be a connection between these microbial factors and tumor sensitivity to immunotherapy.

Virus-Like Particle-Drug Conjugates Induce Protective, Long-lasting Adaptive Antitumor Immunity in the Absence of Specifically Targeted Tumor Antigens.

This study examined the ability of a papillomavirus-like particle drug conjugate, belzupacap sarotalocan (AU-011), to eradicate subcutaneous tumors after intravenous injection and to subsequently elicit long-term antitumor immunity in the TC-1 syngeneic murine tumor model. Upon in vitro activation with near-infrared light (NIR), AU-011-mediated cell killing was proimmunogenic in nature, resulting in the release of damage-associated molecular patterns such as DNA, ATP, and HMGB-1, activation of caspase-1, and surface relocalization of calreticulin and HSP70 on killed tumor cells. A single in vivo administration of AU-011 followed by NIR caused rapid cell death, leading to long-term tumor regression in ∼50% of all animals. Within hours of treatment, calreticulin surface expression, caspase-1 activation, and depletion of immunosuppressive leukocytes were observed in tumors. Combination of AU-011 with immune-checkpoint inhibitor antibodies, anti-CTLA-4 or anti-PD-1, improved therapeutic efficacy, resulting in 70% to 100% complete response rate that was durable 100 days after treatment, with 50% to 80% of those animals displaying protection from secondary tumor rechallenge. Depletion of CD4+ or CD8+ T cells, either at the time of AU-011 treatment or secondary tumor rechallenge of tumor-free mice, indicated that both cell populations are vital to AU-011's ability to eradicate primary tumors and induce long-lasting antitumor protection. Tumor-specific CD8+ T-cell responses could be observed in circulating peripheral blood mononuclear cells within 3 weeks of AU-011 treatment. These data, taken together, support the conclusion that AU-011 has a direct cytotoxic effect on tumor cells and induces long-term antitumor immunity, and this activity is enhanced when combined with checkpoint inhibitor antibodies.

MiRNAs and lncRNAs as Novel Therapeutic Targets to Improve Cancer Immunotherapy.

Simple SummaryCancer onset and progression are promoted by high deregulation of the immune system. Recently, major advances in molecular and clinical cancer immunology have been achieved, offering new agents for the treatment of common tumors, often with astonishing benefits in terms of prolonged survival and even cure. Unfortunately, most tumors are still resistant to current immune therapy approaches, and basic knowledge of the resistance mechanisms is eagerly awaited. We focused our attention on noncoding RNAs, a class of RNA that regulates many biological processes by targeting selectively crucial molecular pathways and that, recently, had their role in cancer cell immune escape and modulation of the tumor microenvironment identified, suggesting their function as promising immunotherapeutic targets. In this scenario, we point out that noncoding RNAs are progressively emerging as immunoregulators, and we depict the current information on the complex network involving the immune system and noncoding RNAs and the promising therapeutic options under investigation. Novel opportunities are emerging from noncoding-RNAs for the treatment of immune-refractory tumors.Immunotherapy is presently one of the most promising areas of investigation and development for the treatment of cancer. While immune checkpoint-blocking monoclonal antibodies and chimeric antigen receptor (CAR) T-cell-based therapy have recently provided in some cases valuable therapeutic options, the goal of cure has not yet been achieved for most malignancies and more efforts are urgently needed. Noncoding RNAs (ncRNA), including microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), regulate several biological processes via selective targeting of crucial molecular signaling pathways. Recently, the key roles of miRNA and lncRNAs as regulators of the immune-response in cancer have progressively emerged, since they may act (i) by shaping the intrinsic tumor cell and microenvironment (TME) properties; (ii) by regulating angiogenesis, immune-escape, epithelial-to-mesenchymal transition, invasion, and drug resistance; and (iii) by acting as potential biomarkers for prognostic assessment and prediction of response to immunotherapy. In this review, we provide an overview on the role of ncRNAs in modulating the immune response and the TME. We discuss the potential use of ncRNAs as potential biomarkers or as targets for development or clinical translation of new therapeutics. Finally, we discuss the potential combinatory approaches based on ncRNA targeting agents and tumor immune-checkpoint inhibitor antibodies or CAR-T for the experimental treatment of human cancer.