anti-PD1 Immunotherapy Research Articles

GZ17-6.02 kills PDX isolates of uveal melanoma.

GZ17-6.02 has undergone phase I evaluation in patients with solid tumors (NCT03775525). The RP2D is 375 mg PO BID, with an uveal melanoma patient exhibiting a 15% reduction in tumor mass for 5 months at this dose. Studies in this manuscript have defined the biology of GZ17-6.02 in PDX isolates of uveal melanoma cells. GZ17-6.02 killed uveal melanoma cells through multiple convergent signals including enhanced ATM-AMPK-mTORC1 activity, inactivation of YAP/TAZ and inactivation of eIF2α. GZ17-6.02 significantly enhanced the expression of BAP1, predictive to reduce metastasis, and reduced the levels of ERBB family RTKs, predicted to reduce growth. GZ17-6.02 interacted with doxorubicin or ERBB family inhibitors to significantly enhance tumor cell killing which was associated with greater levels of autophagosome formation and autophagic flux. Knock down of Beclin1, ATG5 or eIF2α were more protective than knock down of ATM, AMPKα, CD95 or FADD, however, over-expression of FLIP-s provided greater protection compared to knock down of CD95 or FADD. Expression of activated forms of mTOR and STAT3 significantly reduced tumor cell killing. GZ17-6.02 reduced the expression of PD-L1 in uveal melanoma cells to a similar extent as observed in cutaneous melanoma cells whereas it was less effective at enhancing the levels of MHCA. The components of GZ17-6.02 were detected in tumors using a syngeneic tumor model. Our data support future testing GZ17-6.02 in uveal melanoma as a single agent, in combination with ERBB family inhibitors, in combination with cytotoxic drugs, or with an anti-PD1 immunotherapy.

Bevacizumab induces ferroptosis and enhances CD8+ T cell immune activity in liver cancer via modulating HAT1 and increasing IL-9.

Bevacizumab is a recombinant humanized monoclonal immunoglobulin (Ig) G1 antibody of VEGF, and inhibits angiogenesis and tumor growth in hepatocellular carcinoma (HCC). Ferroptosis, a new form of regulated cell death function independently of the apoptotic machinery, has been accepted as an attractive target for pharmacological intervention; the ferroptosis pathway can enhance cell immune activity of anti-PD1 immunotherapy in HCC. In this study we investigated whether and how bevacizumab regulated ferroptosis and immune activity in liver cancer. Firstly, we performed RNA-sequencing in bevacizumab-treated human liver cancer cell line HepG2 cells, and found that bevacizumab significantly altered the expression of a number of genes including VEGF, PI3K, HAT1, SLC7A11 and IL-9 in liver cancer, bevacizumab upregulated 37 ferroptosis-related drivers, and downregulated 17 ferroptosis-related suppressors in particular. We demonstrated that bevacizumab triggered ferroptosis in liver cancer cells by driving VEGF/PI3K/HAT1/SLC7A11 axis. Clinical data confirmed that the expression levels of VEGF were positively associated with those of PI3K, HAT1 and SLC7A11 in HCC tissues. Meanwhile, we found that bevacizumab enhanced immune cell activity in tumor immune-microenvironment. We identified that HAT1 up-regulated miR-143 targeting IL-9 mRNA 3'UTR in liver cancer cells; bevacizumab treatment resulted in the increase of IL-9 levels and its secretion via VEGF/PI3K/HAT1/miR-143/IL-9 axis, which led to the inhibition of tumor growth in vivo through increasing the release of IL-2 and Granzyme B from activated CD8+ T cells. We conclude that in addition to inhibiting angiogenesis, bevacizumab induces ferroptosis and enhances CD8+ T cell immune activity in liver cancer. This study provides new insight into the mechanisms by which bevacizumab synergistically modulates ferroptosis and CD8+ T cell immune activity in liver cancer.

Impact of protein corona and PEGylation on the accumulation and efficacy of lysosome-disrupting lipid nanoparticles in KRAS-mutated cancer

Nanomedicines offer promising approaches for targeted drug delivery to tumor cells but their clinical translation is hindered by limited delivery efficacy in heterogenous clinical tumors. Protein corona adsorbed to the surface of nanoparticles (NPs) would cause opsonization and accelerate blood clearance, posing a significant barrier to effective drug delivery. Polyethylene glycol (PEG) modification is widely employed to prolong the NPs’ circulation time and improve the delivery efficacy. Nevertheless, the clinical efficacy of PEG-based nanomedicines is still debatable. Here, we prepared non-PEGylated lysosomal-disrupting dimeric chloroquine (CQ) lipid nanoparticles (DCLNPs) and PEGylated DCLNPs (PEG-DCLNPs) and systematically studied the impact of PEGylation on DCLNPs’ delivery efficacy in KRAS-mutant (MT) and -wildtype (WT) cancers. We found that the protein corona facilitates KRAS-MT cancer-specific targeted delivery of DCLNPs by exploiting extracellular protein engulfment preference. In contrast, PEGylation hindered delivery and efficacy of DCLNPs. Proteomics analysis highlighted apolipoproteins, particular apolipoprotein E, as key factors promoting the uptake of DCLNPs. Additionally, DCLNPs sensitized immunosuppressive KRAS-MT cancers to anti-PD1 immunotherapy. These results underscore the importance of comprehending the context-dependent role of the protein corona in regulating nanoparticle biodistribution, suggesting that PEGylation may not be suitable across all cancer types.

Latent-Transforming Growth Factor β-Binding Protein 1/Transforming Growth Factor β1 Complex Drives Antitumoral Effects upon ERK5 Targeting in Melanoma

Melanoma is the deadliest skin cancer, with a poor prognosis in advanced stages. Available treatments have improved the survival, although long-term benefits are still unsatisfactory. The mitogen-activated protein kinase ERK5 promotes melanoma growth, and ERK5 inhibition determines cellular senescence and the senescence-associated secretory phenotype. Here, latent-transforming growth factor β-binding protein 1 (LTBP1) mRNA was found to be upregulated in A375 and SK-Mel-5 BRAFV600E melanoma cells after ERK5 inhibition. In keeping with a key role of LTBP1 in regulating transforming growth factor β (TGF-β), TGF-β1 protein levels were increased in lysates and conditioned media of ERK5-knock down (KD) cells, and were reduced upon LTBP1 KD. Both LTBP1 and TGF-β1 proteins were increased in melanoma xenografts in mice treated with the ERK5 inhibitor XMD8-92. Moreover, treatment with conditioned media from ERK5-KD melanoma cells reduced cell proliferation and invasiveness, and TGF-β1-neutralizing antibodies impaired these effects. In silico datasets revealed that higher expression levels of both LTBP1 and TGFB1 mRNA are associated with better overall survival of melanoma patients, and that increased LTBP1 or TGF-β1 expression proved a beneficial role in patients treated with anti-PD1 immunotherapy, making unlikely a possible immunosuppressive role of LTBP1/TGF-β1 upon ERK5 inhibition. This study, therefore, identifies additional desirable effects of ERK5 targeting, providing evidence of an ERK5-dependent tumor suppressive role of TGF-β in melanoma.

Chronic intermittent hypoxia alters CD8+ expression in the bone marrow of C57BL/6 mice

Cytotoxic CD8+ cells are critical in anticancer immune response and have become prevalent in immunotherapies over the past decade. Anti-LAG3/anti-PD1 combined immunotherapies increase the number of CD8+ cells. Moderate to severe sleep apnea increases the risk of cancer-related mortality. Chronic intermittent hypoxia, a feature of sleep apnea, decreases the percentage of perforin-expressing CD8+ cells, impairing cytotoxicity. Our objective is to determine the distribution of Prf1(perforin), LAG3(lymphocyte-activation gene 3), and PDCD1(programmed cell death 1) in C57BL/6 mice exposed to chronic intermittent hypoxia (CIH). We hypothesize that Prf1, PDCD1, and LAG3 will be expressed on three discrete clusters with a higher expression of LAG3 and PDCD1 and lower expression of Prf1 between C57BL/6 mice exposed to chronic intermittent hypoxia and normoxia. Bone marrow from the femur of C57BL/6 mice exposed to chronic intermittent hypoxia or normoxia was harvested. Bone marrow mononuclear cells were isolated, RNA was extracted, and single-cell RNA sequencing was performed. Loupe browser was used to re-cluster and quantify expression for genes of interest. Prf1 and PDCD1 are expressed in CD3+CD8−CD4− cluster and LAG3 is expressed in CD3−CD8+CD4+ cluster. LAG3 and Prf1 are present among the top ten genes, while PDCD1 is not in those clusters. Further analysis of the top ten genes of CD3+CD8−CD4− has demonstrated they are a group of natural killer cells. Contradictory to our expectation, Prf1 and PDCD1 are present in CD3+CD8−CD4− cluster while LAG3 is present in CD3−CD8+CD4+ cluster. Further analysis is necessary to determine the underlying mechanisms causing these changes. 5R01CA244271-02. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

PD1 blockade improves survival and CD8+ cytotoxic capacity, without increasing inflammation, during normal microbial experience in old mice.

By 2030, individuals 65 years of age or older will make up approximately 20% of the world's population1. Older individuals are at the highest risk for mortality from infections, largely due to the pro-inflammatory, dysfunctional immune response, which is collectively known as immunosenescence2. During aging, CD8+ T cells acquire an exhausted phenotype, including increased expression of inhibitory receptors, such as programmed cell death 1 (PD1), a decline in effector function and elevated expression of inflammatory factors3-7. PD1 reduces T cell receptor activity via SHP2-dependent dephosphorylation of multiple pathways; accordingly, inhibiting PD1 activity through monoclonal antibodies increases CD8+ T cell effector response in young mice8-11. Attempts to improve CD8+ T cell responses by blocking inhibitory receptors are attractive; however, they can lead to adverse immune events due to overamplification of T cell receptor signaling and T cell activation12,13. Here we investigated the effect of monoclonal anti-PD1 immunotherapy during normal microbial experience, otherwise known as exposure to dirty mice, to determine whether it either improves exhausted CD8+ T cell responses in old mice or leads to a heightened inflammatory response and increased mortality.

Divergent Cellular Expression Patterns of PD-L1 and PD-L2 Proteins in Breast Cancer.

PD-L1 immunohistochemistry (IHC) has become an established method for predicting cancer response to targeted anti-PD1 immunotherapies, including breast cancer (BC). The alternative PD-1 ligand, PD-L2, remains understudied but may be a complementary predictive marker. Prospective analysis of 32 breast cancers revealed divergent expression patterns of PD-L1 and PD-L2. PD-L1-positivity was higher in immune cells than in cancer cells (median = 5.0% vs. 0.0%; p = 0.001), whereas PD-L2-positivity was higher in cancer cells than immune cells (median = 30% vs. 5.0%; p = 0.001). Percent positivity of PD-L1 and PD-L2 were not correlated, neither in cancer cells nor immune cells. Based on a cut-point of ≥1% positivity, ER+ tumors (n = 23) were frequently PD-L2-positive (73.9%), whereas only 40.9% were PD-L1-positive. These data suggest differential control of cellular PD-L1 and PD-L2 expression in BC and a potential role for PD-L2 IHC as a complementary marker to PD-L1 to improve selection of aggressive ER+ BC that may benefit from anti-PD-1 therapy.

HSPA4 upregulation induces immune evasion via ALKBH5/CD58 axis in gastric cancer

IntroductionGastric cancer (GC) is one of the leading causes of cancer-related death worldwide. Recently, targeted therapies including PD1 (programmed cell death 1) antibodies have been used in advanced GC patients. However, identifying new biomarker for immunotherapy is still urgently needed. The objective of this study is to unveil the immune evasion mechanism of GC cells and identify new biomarkers for immune checkpoint blockade therapy in patients with GC.MethodsCoimmunoprecipitation and meRIP were performed to investigate the mechanism of immune evasion of GC cells. Cocuture system was established to evaluate the cytotoxicity of cocultured CD8+ T cells. The clinical significance of HSPA4 upregulation was analyzed by multiplex fluorescent immunohistochemistry staining in GC tumor tissues.ResultsHistone acetylation causes HSPA4 upregulation in GC tumor tissues. HSPA4 upregulation increases the protein stability of m6A demethylase ALKBH5. ALKBH5 decreases CD58 in GC cells through m6A methylation regulation. The cytotoxicity of CD8+ T cells are impaired and PD1/PDL1 axis is activated when CD8+ T cells are cocultured with HSPA4 overexpressed GC cells. HSPA4 upregulation is associated with worse 5-year overall survival of GC patients receiving only surgery. It is an independent prognosis factor for worse survival of GC patients. In GC patients receiving the combined chemotherapy with anti-PD1 immunotherapy, HSPA4 upregulation is observed in responders compared with non-responders.ConclusionHSPA4 upregulation causes the decrease of CD58 in GC cells via HSPA4/ALKBH5/CD58 axis, followed by PD1/PDL1 activation and impairment of CD8+ T cell’s cytotoxicity, finally induces immune evasion of GC cells. HSPA4 upregulation is associated with worse overall survival of GC patients with only surgery. Meanwhile, HSPA4 upregulation predicts for better response in GC patients receiving the combined immunotherapy.

Адъювантная таргетная терапия и анти-PD-1-иммунотерапия у пациентов с меланомой кожи III стадии с мутацией в гене BRAF. Данные реальной клинической практики

Targeted therapy and anti-PD1 immunotherapy are standard of adjuvant stage III (or equivalent stage III) melanoma treatment. Both treatments significantly improve relapse-free survival compared with placebo and ipilimumab. The impact of adjuvant immunotherapy on overall survival remains unclear. Targeted therapy improved 3-year overall survival, but data didn’t reach statistical significance. There is still a lack of direct comparison in randomized trials between targeted therapy and immunotherapy. Data limited to a few retrospective studies. We conducted a single-center observational retrospective study comparing two adjuvant treatment options in BRAF-mutated high-risk melanoma patients who were treated or consulted at the N.N. Blokhin National Medical Research Center of Oncology.

Abstract 454: microRNAs role in innate immunosenescence during anti-PD1 immunotherapy

Abstract Checkpoint inhibitors have achieved durable responses and long-lasting immunologic memory in cancer patients. However, the initial and acquired resistance remains an unsolved problem. It’s urgent to learn the molecular mechanisms causing resistance. microRNAs (miRNAs) are short transcripts that regulate many pathophysiological processes. Here, we investigated the miRNAs expression changes after GVAX combined with monoclonal PD-1 antibody treatment in the murine melanoma B16F10 tumors and identified microRNAs down-regulated in responsive tumors. Deletion of this family member in three different syngeneic mouse tumors did not affect their in vitro nor in vivo proliferation but sensitized anti-PD1 immunotherapy. The miRNA deletion with anti-PD1 therapy increased total CD45+ leukocyte infiltration with all types of hematopoietic cells except macrophages. Both tumor bulk RNA sequencing and single-cell RNA sequencing revealed activated innate sensing genes especially for pathogen recognition and phagosome formation. Importantly, we found specific miRNA-deletion effects rely on tumor resident macrophage, IFN-γ release in the tumor microenvironment (TME) and the miRNA regulating machinery protein Argonaut2 (Ago2). Notably, the miRNA expression status of melanoma patients correlates with the survival and innate immune sensing gene expression. Our results suggest that this family of miRNAs participate in initial resistance by escaping innate immunosurveillance. Deletion of the miRNA may turn immune “cold” tumors to “hot” tumors, providing potential therapeutic targets to overcome resistance in melanoma, colorectal, triple-negative breast cancer and possibly other cancers. Citation Format: Zhouting Zhu, Tariq M. Rana. microRNAs role in innate immunosenescence during anti-PD1 immunotherapy [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 454.

Abstract 4997: Auranofin enhances the efficacy of anti-PD1 immunotherapy

Abstract Anti-PD-1 immunotherapy brings hope for the treatment of malignant tumors, but its overall response rate is low. Therefore, how to sensitize anti-PD-1 therapy to make more patients benefit from immunotherapy is an urgent clinical demand. PKCι, a classical oncogene that affects cell proliferation and differentiation, has recently been found to be involved in the recruitment of immunosuppressive cells MDSCs and Tregs, which leads to anti-PD1 immunotherapy resistance. Our study is consistent with previously reported results that interfering with PKCι expression in tumor cells significantly enhances the anti-tumor effect of anti-PD1 therapy. Immunological mechanistic analyses demonstrated that the inhibition of PKCι expression significantly reduced the infiltration of tumor-associated macrophages (TAMs) rather than MDSCs or Tregs. Further studies revealed that PKCι enhanced the expression of macrophage chemokine CCL7 by promoting the formation of the YAP1/TEAD transcriptional complex. Interference in vitro and pharmacological inhibition of PKCι in tumor cells both significantly reduced CCL7 expression and TAMs invasion. Auranofin is a commonly used anti-inflammatory agent in clinical practice, which has been recently found that it directly induces tumor death by modulating the cellular redox system in tumor cells and remodels the tumor immunosuppressive microenvironment by specifically inhibiting PKCι expression. The results of our study showed that the anti-tumor effect of Auranofin combined with anti-PD1 therapy was superior to that of monotherapy in lung adenocarcinoma. Auranofin exerted synergistic anti-tumor effects with anti-PD1 immunotherapy by inhibiting the expression of PKCι-YAP1/TEAD-CCL7, reducing the recruitment of TAMs, and promoting the infiltration of effector CD8+ T cells. In summary, Auranofin is a potent candidate for sensitizing anti-PD-1 immunotherapy, reversing immunotherapy blunting by remodeling TIME, which provides new ideas and theoretical basis for immunotherapy of sensitizing malignant tumors. Citation Format: Zichen Zhao, Shichuan Hu, Yan Zhang. Auranofin enhances the efficacy of anti-PD1 immunotherapy [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 4997.

Abstract 1416: Resolvins enhance immunotherapy to induce Fanconi anemia tumor regression via inflammation resolution

Abstract Fanconi anemia (FA) is a disorder characterized by early-onset solid tumors unresponsive to chemotherapy and radiation. Unresolved inflammation is a hallmark of FA, the mechanisms underlying the initiation and resolution of inflammation in FA are poorly characterized. We hypothesized that FA tumor progression is controlled by dysregulated resolution metabolomes and a systemic pro-inflammatory eicosanoid storm of inflammation-initiating mediators. Using a novel transplantable murine FA tumor model, we show that Fancc-/- HNSCC (head and neck squamous cell carcinoma) progression disrupts the resolution of inflammation via an imbalance between specialized pro-resolving lipid mediators (SPMs) and eicosanoids. Fancc-/- tumor-bearing mice exhibited an increase in eicosanoids, including leukotriene B4 (LTB4) and thromboxane B2 (TXB2) in the spleen and a 113% increase in prostaglandin E metabolite (PGEM), a marker of PGE2 production, in the plasma compared to non-tumor-bearing (NT) mice. Fancc-/- tumor-bearing mice exhibited a loss in the SPM/LTB4 ratio including RvD1/LTB4, RvD2/LTB4, and MaR1/LTB4, compared to NT mice. Given the activity of immune checkpoint blockade in mismatch repair deficient tumors including head and neck cancers, immunotherapy may be relevant to FA-induced cancers. Importantly, the number of absolute T cells and CD4+ T cell function is preserved in individuals with FA. We combined stimulation of the resolution of inflammation (i.e., treatment with RvDs) with immunotherapy in a new transplantable murine FA tumor model. While treatment with RvD4, RvD5, or anti-PD1 immunotherapy alone delayed tumor growth compared to control at treatment day 20, the tumors did escape monotherapy by treatment day 30. Remarkably, RvD4 or RvD5 combined with anti-PD1 immunotherapy induced sustained Fancc-/- tumor regression. Moreover, RvD4 and/or anti-PD1 immunotherapy inhibited orthotopic Fancc-/- tumor growth compared to control. Resolvins and immune checkpoint blockade synergistically induced Fancc-/- tumor regression via macrophage phagocytosis of apoptotic debris, counter-regulation of pro-angiogenic cytokines, and inhibition of angiogenesis. Triggering Receptor Expressed on Myeloid cells-2 (TREM2)-antagonism combined with resolvins and immunotherapy restored SPM/eicosanoid ratios in Fancc−/- tumor-bearing mice to pre-cancer levels. SPMs and eicosanoids provide potential early biomarkers and biological targets in FA-induced cancer progression. Stimulating the resolution of inflammation via pro-resolution lipid mediators to enhance immunotherapy is a novel host-centric therapeutic approach to prevent FA-induced cancer progression via debris clearance and cytokine suppression. These results provide evidence for targeting the resolution of inflammation via resolvins to enhance immunotherapy to prevent and/or reverse FA-induced cancer progression. Citation Format: Katherine Quinlivan, Haixia Yang, Diane R. Bielenberg, Susanne I. Wells, Charles N. Serhan, Dipak Panigrahy. Resolvins enhance immunotherapy to induce Fanconi anemia tumor regression via inflammation resolution [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 1416.

Abstract 674: Novel anti-cancer small molecule targeting the protein regulator of cytokinesis pathway

Abstract Aberrant migration and proliferation of cancer cells are the hallmark of metastatic tumors. Protein Regulator of Cytokinesis 1 (PRC1) is a scaffold protein that regulates metabolic pathways of cancer cell proliferation, survival, and metastasis. BKT300 is a small molecule (MW 399.33, C22H25NO6), that selectively inhibits the migration and survival of hematological and solid cancer cells. BKT300 inhibits, at high affinity, both actin and microtubule formation and organization leading to G2/M cell cycle arrest, mitotic catastrophe, and apoptosis through the caspase 3 pathway. These effects are selective to cancer cells and were not observed on normal cells. BKT300 was found to arrest PRC1 in a phosphorylated form at position T481, down regulates the expression of CDC25C and up regulate p21. Suppression of PRC1 using SiRNA ablation inhibited BKT300 induced apoptosis on several tumor cell lines and inhibited the effect of BKT300 on G2M cell cycle arrest. Furthermore, using Biacore SPR, microscale thermophoresis (MST), and ELISA assays we were able to demonstrate the direct binding of BKT300 to PRC1. Beyond its single agent activity, BKT300 was shown to synergize with standard of care (SoC) treatments, including anti PD-1 immunotherapy, BCL-2 inhibitor (Ventoclax), topoisomerase I inhibitor (Irinotecan) topoisomerase II inhibitor (Doxorubicin), anti-metabolite Fluorouracil (5-FU) and alkylating agent (Temozolomide). BKT300 has a remarkable safety profile when administered at high doses to mice rats, minipigs and non-human primates. Treatment with BKT300 showed almost no effects on hematopoiesis and biochemistry in doses far higher than the affective ones. The in-vivo activity of BKT300 was demonstrated in multiple Xenograft, Syngeneic and PDX models in mice. In-vivo treatment with BKT300 resulted in preventive (small tumors) as well as therapeutic (large tumors) activity in triple negative breast cancer (TNBC) xenograft, MDA-MB-453 and MDA-MB-468 models leading to over then 70%-90% reduction in tumor size following one to two treatments cycles. Similar results were obtained using PDX models derived from patients with Colon, Ovarian and Pancreatic cancer. BKT300 is a novel, first in class, targeted anti-cancer treatment that inhibits the activity of the scaffold protein PRC1. BKT300 is expected to provide a new treatment option to, the high unmet medical need of, advanced difficult to treat cancers, specifically ones that overexpress PRC1 and CDC25C. Citation Format: Amnon Peled, Michal Abraham, Hanna Wald, Rakefet Rosenfeld, Orly Eizenberg, Arnon Aharon. Novel anti-cancer small molecule targeting the protein regulator of cytokinesis pathway [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 674.

Abstract 2703: Targeting STING pathway as a therapeutic strategy against β-catenin driven immune escape and resistance to anti-PD1 therapy in hepatocellular carcinoma

Abstract β-catenin mutation occurs in around 40% of hepatocellular carcinoma(HCC); yet no precision therapies are available to treat this tumor subset. Immune checkpoint inhibitors (ICIs) are now widely used for the treatment of patients with advanced HCC. Unfortunately, preliminary evidence showed that β-catenin mutation drives resistance to anti-PD1 immunotherapy in HCC. In this study, we studied the molecular mechanisms underlying β-catenin mutation during HCC pathogenesis to develop novel therapeutics targeting β-Catenin-driven HCC. Firstly, three HCC cohorts were examined, including 70 untreated, 20 treated patients with nivolumab, and patients from a public TCGA database. By single-cell RNA sequencing analysis, we identified that anti-PD-1 treatment displayed effectiveness with the increase of CD27+CD8+ T-cell infiltration, correlating to improved prognosis with longer progression-free survival (PFS) and OS. Importantly, multiplex IHC staining showed that β-catenin activation is associated with significantly reduced CD8+CD27+ T cell infiltration in tumors (n=70), demonstrating that β-catenin promoted immune escape and resistance to anti-PD-1 treatment involved defective cytotoxic T-cell activity. Subsequently, we found that the interaction of β-Catenin with sirtuin 1 (SIRT1) mediated suppression of IRF3/IRF7 activity, resulting in inhibition of Type I interferon (IFN-I) production. However, by CRISPRi screening, we found that disruption of β-catenin-SIRT1 interaction via STING caused persistent high-level IFN-I response which increased the transcription of T-cell costimulatory molecule CD27 via IL10/STAT3/BATF signaling on infiltrated CD8+ T cells. This effect was also confirmed in the STING null mice, emphasizing that STING signaling is a therapeutic target to overcome β-catenin driven immune escape. Further, using hydrodynamic tail-vein injection murine HCC models, we found that the STING agonist inhibited β-catenin-SIRT1 activity, restored IFN signaling to rescue T-cell cytotoxic capacities, and enhanced the anti-PD-1 therapy efficacy. In conclusion, we demonstrated that STING reprogrammed β-Catenin mutated the HCC tumor microenvironment and a combination of STING and anti-PD-1 treatment represents an effective novel therapeutic strategy for HCC patients with β-Catenin mutation. Citation Format: Qingmei Zhang, Jiacheng Bi, Oscar Wai-Ho Yeung, Tao Ding, Wing-Lim Chan, Yueqin Zhu, Jiang Liu, Kevin Tak-Pan Ng, Kwan Man. Targeting STING pathway as a therapeutic strategy against β-catenin driven immune escape and resistance to anti-PD1 therapy in hepatocellular carcinoma [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 2703.

Abstract 3916: TNG260, a small molecule CoREST inhibitor, sensitizes STK11-mutant NSCLC to anti-PD1 immunotherapy

Abstract Loss of function (LOF) of the serine-threonine kinase STK11/LKB1, which has been reported in ~15% of non-small cell lung cancer (NSCLC), drives resistance to immune checkpoint therapies such as PD1. In vivo CRISPR screens in tumor-bearing immune competent mice identified the Corepressor of Repressor Element 1 Silencing Transcription (CoREST) complex as a synthetic lethal immune evasion target for STK11- mutant tumors. Here, we demonstrate that TNG260, a small molecule drug specifically targeting the CoREST complex, can sensitize STK11 mutant lung cancers to anti-PD1 immunotherapy. Combination treatment with TNG260 and anti-PD1 arrested KRAS/STK11 mutant NSCLC tumor growth with no major toxicity observed, as confirmed in both allograft and genetically engineered mouse models (GEMMs) of STK11 mutant NSCLC. Further transcriptional analysis via bulk RNA-seq revealed that treatment of KRAS/STK11 mutant lung tumors with TNG260 promotes genes related to inflammatory responses and suppresses genes related to cell cycle and mitotic checkpoint(s). This phenotype was not observed in STK11 wildtype KRAS/P53 mutant lung tumors. Furthermore, combinational treatment of TNG260 with PD1 antibody showed increased macrophages, neutrophils and dendritic cells signatures in vivo. Our data suggests that epigenetic reprogramming via TNG260 sensitizes STK11 mutant NSCLC tumors to anti- PD1 treatment via targeting of the CoREST complex. This work identifies new vulnerabilities in STK11 LOF cancers that can be exploited therapeutically. TNG260 is currently being investigated in combination with pembrolizumab for the treatment of STK11-mutant cancer (NCT05887492), including NSCLC. Citation Format: Ayushi Patel, Soumyadip Sahu, Ke Geng, Salman Punekar, Janaye Stephens, Jiehui Deng, Ting Chen, Leanne Ahronian, Minjie Zhang, Jannik Andersen, Brian Haines, Kwok-Kin Wong. TNG260, a small molecule CoREST inhibitor, sensitizes STK11-mutant NSCLC to anti-PD1 immunotherapy [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 3916.

Abstract 6596: BRMS1 downregulation alters the tumor microenvironment and induces immunotherapy resistance in lung adenocarcinoma

Abstract Background: Lung cancer is the leading cause of cancer-related deaths globally. During cancer progression, tumor cells interact with tumor-infiltrating immune cells (TIICs) creating an immunosuppressive microenvironment. Therefore, it is essential to delineate the communication dynamics between cancer cells and TIICs to identify novel pathways for therapeutic targeting. BRMS1 is a metastasis suppressor gene that is frequently downregulated in lung adenocarcinoma (LUAD). We, and others, have shown that loss of BRMS1 results in increased distant metastatic disease. Given the strong correlation between immune suppression, metastasis, and immunotherapy resistance we sought to elucidate if BRMS1 contributes to these processes. Specifically, we hypothesized that loss of BRMS1 in LUAD cells influences the immune cell composition, shaping an immunosuppressive microenvironment and decreasing tumor response to immunotherapy. Methods: To experimentally address our hypothesis, we generated KrasG12D P53fl/fl Brms1−/− mice inducing spontaneous tumors with Ad-Cre intratracheal inoculation. RNA-seq scRNA-seq on Brms1+/+ and Brms1−/− tumors, coupled with cell type annotations using mMCP-counter and DCATS were used to identify diverse TIIC subsets. To validate our observation, we performed immunofluorescence and flow cytometry to assess the number of TIICs. To explore the impact of Brms1 loss on the efficacy of anti-PD1 immunotherapy, a syngeneic CMT167 mouse model with BRMS1KD cells implanted in the flank was treated with an anti-PD1 antibody. Results: Differential gene expression analysis of RNA-seq data revealed a reduction in CCL9, CCL24, CLEC1B, PYCARD and other proinflammatory molecules in Brms1−/− tumors. Gene ontology and GSEA highlighted a diminished immune response signature in Brms1−/- tumors. In contrast, hallmark gene sets like IFNγ response, IL6 signaling, and inflammation are highly enriched in Brms1+/+ tumors. mMCP-counter suggested a decrease in CD8+ T cells in Brms1−/- tumors. Likewise, scRNA-seq data confirmed a significant decrease in cytotoxic CD8+ T cells in the Brms1−/− mice. Immunofluorescence and flow cytometric analysis showed a reduction in cytotoxic CD8+ T cells with low proliferative potential (Ki67+) in the Brms1−/− mice. Postmortem on our syngeneic mouse tumors after a 30-day anti-PD1 antibody treatment revealed a significantly larger mean tumor size in the BRMS1KD group compared to the WT group (942.4 mm³ vs. 184 mm³; p<0.023). Immunophenotyping on these tumors using flow cytometry also demonstrated reduced cytotoxic CD8+ T cells in the KD group post-treatment. Conclusion: Our data suggest that reduced BRMS1 expression in LUAD alters CD8+ T cell composition and primary tumor response to immunotherapy. Implications of our findings underscore the potential of BRMS1 as a therapeutic target in the context of immunotherapy-resistant LUAD. Citation Format: Manendra B. Lankadasari, Yuan Liu, Brooke Mastrogiacomo, Yingjie Zhu, Elizabeth G. Dunne, Cameron N. Fick, Choudhary Harsha, Jorge S. Reis-Filho, David R. Jones. BRMS1 downregulation alters the tumor microenvironment and induces immunotherapy resistance in lung adenocarcinoma [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 6596.

High-Throughput Antigen Microarray Identifies Longitudinal Prognostic Autoantibody for Chemoimmunotherapy in Advanced Non-Small Cell Lung Cancer

Chemoimmunotherapy has evolved as a standard treatment for advanced non-small cell lung cancer (aNSCLC). However, inevitable drug resistance has limited its efficacy, highlighting the urgent need for biomarkers of chemoimmunotherapy. A three-phase strategy to discover, verify, and validate longitudinal predictive autoantibodies (AAbs) for aNSCLC before and after chemoimmunotherapy was employed. A total of 528 plasma samples from 267 aNSCLC patients before and after anti-PD1 immunotherapy were collected, plus 30 independent formalin-fixed paraffin-embedded samples. Candidate AAbs were firstly selected using a HuProt high-density microarray containing 21,000 proteins in the discovery phase, followed by validation using an aNSCLC-focused microarray. Longitudinal predictive AAbs were chosen for ELISA based on responders versus non-responders comparison and progression-free survival (PFS) survival analysis. Prognostic markers were also validated using immunohistochemistry and publicly available immunotherapy datasets. We identified and validated a panel of two AAbs (MAX and DHX29) as pre-treatment biomarkers and another panel of two AAbs (MAX and TAPBP) as on-treatment predictive markers in aNSCLC patients undergoing chemoimmunotherapy. All three AAbs exhibited a positive correlation with early responses and PFS (p < 0.05). The kinetics of MAX AAb showed an increasing trend in responders (p < 0.05) and a tendency to initially increase and then decrease in non-responders (p < 0.05). Importantly, MAX protein and mRNA levels effectively discriminated PFS (p < 0.05) in aNSCLC patients treated with immunotherapy. Our results present a longitudinal analysis of changes in prognostic AAbs in aNSCLC patients undergoing chemoimmunotherapy.

WTAP-induced N6-methyladenosine of PD-L1 blocked T-cell-mediated antitumor activity under hypoxia in colorectal cancer.

N6-Methyladenosine (m6A) is a important process regulating gene expression post-transcriptionally. Programmed death ligand 1 (PD-L1) is a major immune inhibitive checkpoint that facilitates immune evasion and is expressed in tumor cells. In this research we discovered that Wilms' tumor 1-associated protein (WTAP) degradation caused by ubiquitin-mediated cleavage in cancer cells (colorectal cancer, CRC) under hypoxia was inhibited by Pumilio homolog 1 (PUM1) directly bound to WTAP. WTAP enhanced PD-L1 expression in a way that was m6A-dependent. m6A "reader," Insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) identified methylated PD-L1 transcripts and subsequently fixed its mRNA. Additionally, we found that T-cell proliferation and its cancer cell-killing effects were prevented by overexpression of WTAP invitro and invivo. Overexpression prevented T cells from proliferating and killing CRC by maintaining the expression of PD-L1. Further evidence supporting the WTAP-PD-L1 regulatory axis was found in human CRC and organoid tissues. Tumors with high WTAP levels appeared more responsive to anti-PD1 immunotherapy, when analyzing samples from patients undergoing treatment. Overall, our findings demonstrated a novel PD-L1 regulatory mechanism by WTAP-induced mRNA epigenetic regulation and the possible application of targeting WTAP as immunotherapy for tumor hypoxia.

Blood platelet RNA profiles do not enable for nivolumab response prediction at baseline in patients with non-small cell lung cancer.

Anti-PD-(L)1 immunotherapy has emerged as a promising treatment approach for non-small cell lung cancer (NSCLC), though the response rates remain low. Pre-treatment response prediction may improve patient allocation for immunotherapy. Blood platelets act as active immune-like cells, thereby constraining T-cell activity, propagating cancer metastasis, and adjusting their spliced mRNA content. We investigated whether platelet RNA profiles before start of nivolumab anti-PD1 immunotherapy may predict treatment responses. We performed RNA-sequencing of platelet RNA samples isolated from stage III-IV NSCLC patients before treatment with nivolumab. Treatment response was scored by the RECIST-criteria. Data were analyzed using a predefined thromboSeq analysis including a particle-swarm-enhanced support vector machine (PSO/SVM) classification algorithm. We collected and processed a 286-samples cohort, separated into a training/evaluation and validation series and subjected those to training of the PSO/SVM-classification algorithm. We observed only low classification accuracy in the 107-samples validation series (area under the curve (AUC) training series: 0.73 (95% -CI: 0.63-0.84, n = 88 samples), AUC evaluation series: 0.64 (95% -CI: 0.51-0.76, n = 91 samples), AUC validation series: 0.58 (95% -CI: 0.45-0.70, n = 107 samples)), employing a five-RNAs biomarker panel. We concluded that platelet RNA may have minimally discriminative capacity for anti-PD1 nivolumab response prediction, with which the current methodology is insufficient for diagnostic application.

Identification of the transcriptomic alterations of resistance to immune checkpoint inhibitors in melanoma

Although immunotherapeutics like immune checkpoint inhibitor (ICI) therapy have greatly improved survival rates, death rates of melanoma still remain high. One of the reasons for this is that the solid tumor microenvironment creates obstacles for the effectiveness of anti-PD1 immunotherapy in patients. Therefore, it is crucial to identify potential biomarkers that could be used in combination therapy with anti-PD1 to modify the tumor microenvironment and enhance response to treatment. In this study, we examined clinical and tumor transcriptional sequencing data from 91 patients who received anti-PD1/anti-CTLA4 therapy. Through both bulk RNA sequencing analysis and single-cell RNA-sequencing (scRNA-seq), we discovered that 8 key pathways were upregulated in patients who responded well to the therapy. Interestingly, these pathways were found in myeloid and T cell populations, indicating their significant role in response to anti-PD1/anti-CTLA4 therapy. Among these pathways, genes such as IRF1, IRF2, C1, and C3 emerged as potential biomarkers that could potentially enhance the effectiveness of ICIs therapy. Further clinical research is required to validate the impact of these genes. The novelty of this study lies in the combination of bulk RNA sequencing and single RNA sequencing methods, which allowed us to uncover distinct differences in the transcriptomic landscape of solid tumors, particularly melanoma.