NF2-related schwannomatosis (NF2-SWN) is a debilitating condition, characterized by bilateral vestibular schwannomas (VSs) that progressively cause irreversible sensorineural hearing loss. Current management relies on surgery or radiotherapy, while bevacizumab (αVEGF) is used off-label, with variable and often transient efficacy. Effective therapies that durably suppress tumor growth and preserve hearing are urgently needed. Although immune checkpoint inhibitors have transformed cancer treatment, their efficacy in non-malignant tumors such as VS remains unclear. Here, we evaluate combined anti-PD1 (αPD1) and αVEGF therapy in two syngeneic, immune-competent VS models. Combination treatment significantly outperforms either monotherapy, inhibiting tumor growth and preventing hearing loss. Mechanistically, αVEGF enhances αPD1 efficacy by normalizing tumor vasculature, improving drug delivery and immune cell infiltration, and promoting cytotoxicity of T and NK cells via NKG2D upregulation. Combined treatment effectively controls tumor growth that progresses despite anti-VEGF therapy. These findings support αPD1 and αVEGF combination therapy as a promising strategy for NF2-SWN.

PURPOSE:We developed a novel approach to treat newly diagnosed glioblastoma (GBM) using genetically modified gamma-delta (γδ) T cells following the forced upregulation of stress-associated targets on tumor cells. We leveraged the temozolomide (TMZ)-induced activation of the DNA damage response pathway to transiently upregulate the natural killer ligand (NKG2D-L) targets on GBM. Manufactured γδ T cells are engineered to be resistant to alkylating chemotherapies, including TMZ, through insertion of a methylguanine-DNA methyltransferase (MGMT)-expressing lentivector (DeltEx drug-resistant immunotherapy-DRI). METHODS:A total of 23 patients were enrolled, and 13 were treated (62% male; median age 66 years [range, 21-75]; 92% isocitrate dehydrogenase wild type (IDH-WT), 54% MGMT unmethylated, 46% subtotal resection). Cohorts 1, 2, and 3 received 1, 3, or up to 6 doses, respectively (1 × 107 DRI cells/dose), using a Rickham catheter, which was placed into the resection cavity. The DRI cells were dosed in combination with 150 mg/m2 intravenous (IV) TMZ once per day on Day (D) 1 of each maintenance cycle, which was followed by 4 days of oral TMZ. RESULTS:No dose-limiting toxicities were seen nor were any occurrences of cytokine release syndrome (CRS) or neurotoxicity (immune effector cell-associated neurotoxicity syndrome) observed. The median follow-up of patients who received DRI γδ T cells was 15.6 months. For Cohort 1 patients who received a single dose of DRI γδ T cells, the median progression-free survival (mPFS) was 8.0 months; the median PFS was 9.9 months for all patients and 16.1 months for patients who received repeated doses in Cohorts 2 and 3. The median overall survival for all patients was 15.6 months. CONCLUSION:To date, all patients had manageable toxicity with outpatient treatment and a continued encouraging trend in outcomes from repeated investigational treatments with intracranially delivered, longitudinal DRI γδ T cells.

Non-NF2 Schwannomatosis (SWN) is a genetic disorder characterized by multiple non-malignant schwannomas growing on the spine and peripheral nerves. Patients with SWN overwhelmingly present with intractable chronic pain. There are no FDA-approved drugs to halt tumor growth or alleviate pain. Research on SWN is hindered by the lack of clinically relevant models. We established patient-derived SWN cell lines from patients with varying pain levels and developed orthotopic patient-derived xenograft models that reproduce patients' pain responses. We further developed a novel dorsal root ganglia (DRG) imaging model for longitudinal intravital imaging of macrophage infiltration into the DRG and sensory neuron pain response. Leveraging these novel models, we found that Schwannomas grown distantly in the peripheral nerve caused an influx of macrophages into the DRG. These macrophages in the DRG caused pain via overproducing IL-6. Treatment with anti-IL-6 antibody reduced pain but had modest efficacy in tumor control. We identified epidermal growth factor receptor (EGFR) signaling as a key driver of schwannoma growth and an escape mechanism from anti-IL6 treatment. Finally, we found that combining IL-6 and EGFR blockade effectively controlled pain and tumor growth simultaneously in SWN models. In summary, we elucidated the cellular and molecular crosstalk between schwannoma (HMGB1), neuron (CCL2), and macrophage (IL-6) in driving pain, and identified the EGF signaling pathway as a driver of SWN tumor progression, thereby uncovering novel therapeutic targets that may improve clinical management of SWN.

Rationale: NF2-related schwannomatosis (NF2-SWN) is a progressive neurological disorder with a hallmark of bilateral vestibular schwannomas (VSs), leading to irreversible hearing loss and reduced quality of life. To date, the FDA has not approved any pharmacological therapies for treating VS or hearing loss. While radiotherapy (RT) is the standard treatment for growing VSs, it often exacerbates hearing loss. Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment; however, their efficacy in non-malignant tumors like VS remains largely unexamined. Methods: We used immune-competent VS mouse models to assess the efficacy of combined anti-PD1 (αPD1) and RT treatment, tumor growth, and hearing preservation. Results: We found three significant therapeutic benefits: i) RT induces immunogenic cell death and activates the STING pathway, enhancing αPD1 efficacy and generating long-term immune memory, ii) The combination strategy reduces the required RT dose necessary for effective tumor control, potentially minimizing RT injury to surrounding normal tissues, and iii) RT to peripheral nerve tumor induces a systemic abscopal effect, which enhances αPD-1 efficacy to effectively control intracranial schwannomas without direct irradiation, sparing the cochlea from radiation exposure and avoiding auditory radiation injury. Conclusion: Our findings provide a compelling rationale for deploying ICIs in combination with radiotherapy as a novel treatment approach for patients with VS and NF2-SWN.

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer characterized by activating KRAS mutations and TP53 alterations. TP53 missense mutations lose their wild-type tumor-suppressor function. Here, we studied whether p53 missense mutations have potential gain-of-function oncogenic roles and their impact on cancer-cell-intrinsic gene expression and the tumor immune microenvironment (TME) in PDAC. p53R172H established an immunosuppressive TME and impaired the efficacy of immune checkpoint inhibitors (ICIs) by regulating a distinct set of chemokines. Among these, tumor-specific reduction of Cxcl1, which encodes a chemoattractant for neutrophils, promoted T cell infiltration and decreased tumor growth. Mechanistically, p53R172H occupied the distal enhancers of Cxcl1 and amplified its expression. These enhancers were responsible for Cxcl1 expression and were essential for its immunosuppressive function. Nuclear factor κB (NF-κB) was a critical cofactor required for p53R172H occupancy at these enhancers. Thus, a common mutation in a tumor-suppressor transcription factor appropriates enhancers, thereby stimulating chemokine expression and establishing an immunosuppressive TME that diminishes ICI efficacy in PDAC.

Ependymoma (EPN) is a common form of brain tumor in children, often resistant to available cytotoxic therapies. Molecular profiling studies have led to a better understanding of EPN subtypes and revealed a critical role of oncogenes ZFTA-RELA fusion and EPHB2 in supratentorial ependymoma (ST-EPN). However, the immune system's role in tumor progression and response to therapy remains poorly understood. New treatments for various molecular subtypes of EPN are desperately needed. Using ST-EPN-ZFTA subtype-specific syngeneic mouse models, we found an increased frequency of M2-like tumor-associated macrophages (TAMs), which proportionally increased with tumor size during tumor progression. Transcriptomic profiling of ST-EPN-ZFTA and analysis of a human EPN dataset revealed multiple protein kinases as potential druggable targets. By matching transcriptomic signatures with the target spectrum of FDA-approved drugs, we found that the multikinase inhibitor dasatinib potently inhibited the growth of EPN both in vitro and in vivo, mainly through blocking EPHB2 and ABL1. Treatment with dasatinib reprogrammed the EPN immune microenvironment by polarizing TAMs toward an M1-like phenotype and increasing CD8 T cell activation. Furthermore, dasatinib treatment induced complete regression of established EPN tumors in 78% of the animals and protected survivors against tumor recurrence. Depletion of CD8 cells compromised the durability of EPN responses and reduced overall survival. These data indicate that dasatinib has the potential to be an effective therapy for ST-EPN-ZFTA molecular subgroup of EPN and support further investigation of dasatinib in clinical trials.

Abstract Purpose: Ependymoma (EPN) is a common type of brain tumor in children and is often resistant to available cytotoxic therapies. Molecular profiling studies have led to a better understanding of unique EPN subtypes and revealed a critical role of EPHB2. However, the immune system's role in tumor progression and treatment response remains poorly understood. New treatments for EPN are desperately needed and should be developed in a molecular subtype-specific fashion. Experimental Design: We developed a syngeneic mouse model using subtype-specific EPHB2-driven genetically engineered EPN tumor cells. Druggable targets were identified by matching transcriptomic signatures with the target spectrum of FDA-approved drugs. After identifying dasatinib as a potentially effective agent, we measured the changes in the immune microenvironment during EPN growth and after dasatinib treatment. Results: Transcriptomic profiling of EPHB2-driven EPN and analysis of a human EPN dataset revealed multiple protein kinases as potential druggable targets. We found that the multikinase inhibitor dasatinib potently inhibited the growth of EPN both in vitro and in vivo, mainly through blocking EPHB2 and ABL1 signaling. We found an increased frequency of immunosuppressive M2-like tumor-associated macrophages (TAMs), which proportionally increased with tumor size during tumor progression. However, treatment with dasatinib reprogrammed the EPN immune microenvironment by polarizing the TAMs toward an anti-tumor M1-like phenotype and increasing CD8 T cell activation. Furthermore, dasatinib treatment induced complete regression of established EPN tumors in 78% of the animals and protected survivors against tumor recurrence. Depletion of CD8 T cells compromised the durability of EPN responses and reduced overall survival. Conclusions: These data indicate that dasatinib may be an effective therapy for EPHB2-driven molecular subgroup of EPNs by activating the anti-tumor immune response and support further investigations of dasatinib in clinical trials. Citation Format: Taylor P. Uccello, Jun Ren, Zohreh Amoozgar, Yuhui Zhao, Pin-Ji Lei, William W. Ho, Sylvie Roberge, Peigen Huang, Dan G. Duda, Lei Xu, Rakesh K. Jain. Targeting EPHB2/ABL1 restores anti-tumor immunity in a preclinical model of ependymoma [abstract]. In: Proceedings of the AACR Special Conference on Brain Cancer; 2023 Oct 19-22; Minneapolis, Minnesota. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_1):Abstract nr PR-004.

Abstract Pancreatic ductal Adenocarcinoma (PDAC) is an aggressive malignancy complicated by poor early diagnosis and a lack of response to traditional treatments. It is characterized by a desmoplastic stroma, a lack of infiltration and activation of T cells, and a low mutational burden. The genetic landscape of PDAC is defined by activating KRAS mutations (~90%) and p53 alterations (~70%), but the molecular switches perturbed by these genetic aberrations remain unclear. p53 missense mutations, unlike mutations resulting in the loss of p53, are considered to acquire tumor-supporting functions. But these novel functions remain uncharacterized. The ambiguity in the molecular mechanism of mutant-p53 is further exacerbated by the existence of various types of p53 mutations. The majority of p53 mutations are missense mutations in the DNA binding domain. The repertoire of transcription factors (TFs) it can interact with and the vast regulatory landscape of each TF—composed of gene promoters and distal enhancers—present obstacles in understanding the molecular mechanisms promoting PDAC. In this study, we examined how a common p53 missense mutation in PDAC plays a role in weakening the Immune checkpoint Inhibitors (ICIs) efficacy. Using cells derived from a genetically engineered mouse model (GEMM) of PDAC with activating KRAS mutation (KrasG12D/+) and a p53 missense mutation (p53R172H/-), we found that the PDAC tumorigenesis and resistance to ICIs are dependent on the mutant-p53. We used isogenic p53-null PDAC cells and the restoration of p53R172H in p53-null cells to demonstrate the role of p53R172H in controlling the expression of immunosuppressive chemokine genes such as Cxcl1. p53R172H deletion attenuated PDAC tumor growth, increased the influx of cytotoxic T-cells, and sensitized the tumor to ICIs. The p53R172H-mediated TME reprogramming was replicated by the deletion of the Cxcl1 gene, suggesting the anti-tumorigenic effect of p53R172H was mediated by the Cxcl1 gene. We probed the mechanism of Cxcl1 expression dependence on p53R172H. We found that in conjunction with NF-kB, p53R172H occupies the distal transcription regulatory elements (dTREs) of the Cxcl1 gene harboring NF-kB binding sites. Strikingly, deletion of the Cxcl1 dTREs in PDAC cells recapitulates the phenotypes of p53R172H deletion and Cxcl1 deletion in terms of tumor size, immune landscape of the TME, and ICI responsiveness. Furthermore, we examined the interplay between p53R172H and NF-kB and found that the p53R172H physically interacts with the NF-kB subunit RelA and facilitates its nuclear translocation. Overall, we characterize how a common p53 mutation in PDAC co-opts non-coding regulatory DNA to augment the expression of selective chemokine genes and establishes an immunosuppressive TME to shield the therapeutic benefits of ICIs. Citation Format: Dig B. Mahat, Heena Kumra, Emily Metcalf, Sarah Castro, Kim Nguyen1, Arundeep Singh, William W. Ho, Ivy Chen, Brandon Sullivan, Leon Yim, Enrico Moiso, Vikash Chauhan, Hernandez Moura Silva, Stefani Spranger, Rakesh Jain, Phillip A. Sharp. Mutant-p53 amplifies Cxcl1 expression from distal enhancers blunting immune checkpoint inhibition efficacy in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B087.

Background Bivalent chromatin is an exemplar of epigenetic plasticity. This co-occurrence of active-associated H3K4me3 and inactive-associated H3K27me3 histone modifications on opposite tails of the same nucleosome occurs predominantly at promoters that are poised for future transcriptional upregulation or terminal silencing. We know little of the dynamics, resolution, and regulation of this chromatin state outside of embryonic stem cells where it was first described. This is partly due to the technical challenges distinguishing bone-fide bivalent chromatin, where both marks are on the same nucleosome, from allelic or sample heterogeneity where there is a mix of H3K4me3-only and H3K27me3-only mononucleosomes. Results Here, we present a robust and sensitive method to accurately map bivalent chromatin genome-wide, along with controls, from as little as 2 million cells. We optimized and refined the sequential ChIP protocol which uses two sequential overnight immunoprecipitation reactions to robustly purify nucleosomes that are truly bivalent and contain both H3K4me3 and H3K27me3 modifications. Our method generates high quality genome-wide maps with strong peak enrichment and low background, which can be analyzed using standard bioinformatic packages. Using this method, we detect 8,789 bivalent regions in mouse embryonic stem cells corresponding to 3,918 predominantly CpG rich and developmentally regulated gene promoters. Furthermore, profiling Dppa2/4 knockout mouse embryonic stem cells, which lose both H3K4me3 and H3K27me3 at approximately 10% of bivalent promoters, demonstrated the ability of our method to capture bivalent chromatin dynamics. Conclusions Our optimized sequential reChIP method enables high-resolution genome-wide assessment of bivalent chromatin together with all required controls in as little as 2 million cells. We share a detailed protocol and guidelines that will enable bivalent chromatin landscapes to be generated in a range of cellular contexts, greatly enhancing our understanding of bivalent chromatin and epigenetic plasticity beyond embryonic stem cells.

Background Myeloid cells, unlike other immune cells such as T cells or NK cells, are known residents in the solid tumor microenvironment (TME). In the absence of checkpoints and in proinflammatory conditions, M1 macrophages are known to be capable of direct phagocytosis of tumor cells and can present tumor-associated antigens to the host immune system. However, the immunosuppressive conditions within the TME restrict and limit the anti-tumor response of tumor associated macrophages (TAMs), including their ability to recruit and activate other immune cells against the tumor. Engineered CAR-Monocytes can serve a unique function in cell therapy by bridging a key gap in the treatment of solid tumors. We are developing an autologous engineered CAR-M cell therapy product targeting Glypican-3 to treat hepatocellular carcinoma. The CAR serves as a homing ‘GPS’ signal for trafficking directly to the tumor site, and directs phagocytosis specifically at targeted tumor cells. Our proprietary M83.CAR molecule contains a macrophage-specific costimulatory domain that significantly increases the phagocytosis function of the CAR-M cells. Furthermore, we have demonstrated that the M83.CAR-M cells are not inhibited by the prevalent CD47 ‘do not eat me’ checkpoint, which is known to restrict myeloid function in the TME. Methods Primary hematopoietic stem cells (HSCs) were harvested and engineered to express a CAR molecule by lentivirus transduction generating CAR-HSCs. The CAR-HSCs underwent our proprietary ex-vivo HSC differentiation process to yield CAR-Monocytes. Results Effective phagocytosis of engineered CAR-M cells is central to subsequent mechanisms of actions that can elicit robust anti-tumor immunity against patient-specific neoantigens. However, the first barrier to overcome is effective infiltration of engineered CAR-M into the tumor from the periphery. We have demonstrated that our engineered CAR-Monocyte drug product can successfully home to the targeted tumor specifically, from the periphery. Subsequent in situ differentiation of CAR-monocytes into CAR-macrophages enables robust tumor cell phagocytosis, the central mechanism that results in the following: 1) proinflammatory shift in the TME, 2) recruitment of APCs and immune cells, 3) activation of T-cells against tumor neoantigens. Conclusions The above summarizes a unique outcome of the CAR-M mechanism of action that is not capitulated by CAR-T or CAR-NK cells. Leveraging and further enhancing CAR-M function could lead to the rejection of the tumor and its metastases, particularly in combination with other immune-modulating therapies. Our proprietary HSC-derived CAR-M platform yields a unique product that demonstrates durability and superior function, which we expect to translate to the clinic.

T cell exhaustion has emerged as a major hurdle that impedes the clinical translation of stimulator of interferon genes (STING) agonists. It is crucial to explore innovative strategies to rejuvenate exhausted T cells and potentiate the antitumor efficacy. Here, we propose an approach utilizing MSA-2 as a STING agonist, along with nanoparticle-mediated delivery of mRNA encoding interleukin-12 (IL-12) to restore the function of T cells. We developed a lipid nanoparticle (DMT7-IL12 LNP) that encapsulated IL12 mRNA. Our findings convincingly demonstrated that the combination of MSA-2 and DMT7-IL12 LNP can effectively reverse the exhausted T cell phenotype, as evidenced by the enhanced secretion of cytokines, such as tumor necrosis factor alpha, interferon gamma, and Granzyme B, coupled with reduced levels of inhibitory molecules such as T cell immunoglobulin and mucin domain-3 and programmed cell death protein-1 on CD8+ T cells. Furthermore, this approach led to improved survival and tumor regression without causing any systemic toxicity in melanoma and lung metastasis models. These findings suggest that mRNA encoding IL-12 in conjunction with STING agonists has the potential to confer superior clinical outcomes, representing a promising advancement in cancer immunotherapy.

Abstract Background: Immune checkpoint blockers (ICBs) have revolutionized cancer treatment, but they are often associated with severe immune related adverse events (irAEs). These severe irAEs are more often seen in patients with obesity or concomitantly treated with cytotoxic therapies. Methods: We aimed to understand the mechanisms of ICB-induced irAEs, in the context of obesity and ICB/chemotherapy combinations. We developed a mouse model of cardiac irAEs, which is the most fatal type of irAE in ICB-treated cancer patients, with clinically relevant features: (i) an ICB-resistant cancer (pancreatic ductal adenocarcinoma or PDAC), (ii) obesity induced with high-fat diets, and (iii) a combination treatment of ICB (α-PD1 + α-CTLA4) and chemotherapy (FOLFIRINOX). Results: Our FDA and single institution retrospective analyses indicate that patients treated with ICB had greater relative risk of developing myocarditis as compared to other anti-cancer therapies. Mice with orthotopic PDAC and obesity developed irAEs after treatment with ICB and chemotherapy as compared to chow diet. These irAEs recapitulated those observed in patients with cancer and obesity, including cardiac dysfunction consistent with myocarditis, cardiac fibrosis, and increased circulating levels of interleukin-1 beta (IL-1b). IL-1β blockade prevented myocarditis and reduced cardiac fibrosis after immunotherapy. Importantly, IL-1β blockade also enhanced the anti-tumor effects of ICB + FOLFIRINOX combination therapy, and increased mouse survival. Conclusions: We developed a translationally relevant 'triple hit' mouse model and discovered that IL-1β mediates ICB-induced cardiotoxicity. In addition, we found that IL-1β blockers, which are already used in the clinic for cardiology indications, both reduce adverse events and simultaneously enhance the antitumor effects triggered by immunotherapy. Citation Format: Nilesh P. Talele, Heena Kumra, Igor L. Gomes-Santos, Sylvie Roberge, William W. Ho, Patrick Andersson, Sampurna Chatterjee, Marie Siwicki, Dan G. Duda, Mikael J. Pittet, Dai Fukumura, Rakesh K. Jain. IL-1 blockade prevents cardiac toxicity and improves immunotherapy efficacy in mouse models of pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B025.

Abstract BACKGROUND Ependymoma (EPN) is a childhood brain cancer that is often resistant to cytotoxic therapies. Molecular profiling has led to a better understanding of unique EPN subtypes and revealed a critical role of EPHB2 in driving disease. With this in mind, new treatments for EPN are desperately needed and should be developed in a molecular subtype-specific fashion. METHODS We developed a syngeneic mouse model of EPHB2-driven genetically engineered EPN tumor cells. We performed transcriptomic profiling and analysis of EPHB2-driven murine EPN tumors and human EPN datasets to reveal multiple protein kinases as potential druggable targets. After identifying the tyrosine kinase inhibitor, Dasatinib, as a potentially effective FDA-approved agent, we measured changes in the murine microenvironment during EPN growth and after Dasatinib treatment. RESULTS We determined that Dasatinib inhibited the growth of EPN both in vitro and in vivo, through blocking EPHB2 and ABL1 signaling. Furthermore, we identified an increased frequency of immunosuppressive M2-like tumor- associated macrophages (TAMs), which proportionally increased with tumor size during tumor progression. However, treatment with Dasatinib reprogrammed the EPN immune microenvironment by polarizing TAMs toward an anti-tumor M1-like phenotype and increasing CD8 T cell activation. In addition, Dasatinib treatment induced complete regression of established EPN tumors in 78% of the animals and protected survivors against tumor recurrence. Depletion of CD8 T cells compromised the durability of response and reduced overall survival. CONCLUSION In conclusion, these data indicate that Dasatinib may be an effective therapy for EPHB2-driven molecular subgroup of EPN by activating the anti-tumor immune response and support further investigation of Dasatinib in clinical trials.

The ischemic stroke is a major global health concern, with high mortality and disability rates. Unfortunately, there is a dearth of effective clinical interventions for managing poststroke neuroinflammation and blood-brain barrier (BBB) disruption that are crucial for the brain injury evolving and neurological deficits. By leveraging the pathological progression of an ischemic stroke, we developed an M2 microglia-targeting lipid nanoparticle (termed MLNP) approach that can selectively deliver mRNA encoding phenotype-switching interleukin-10 (mIL-10) to the ischemic brain, creating a beneficial feedback loop that drives microglial polarization toward the protective M2 phenotypes and augments the homing of mIL-10-loaded MLNPs (mIL-10@MLNPs) to ischemic regions. In a transient middle cerebral artery occlusion (MCAO) mouse model of an ischemic stroke, our findings demonstrate that intravenously injected mIL-10@MLNPs induce IL-10 production and enhance the M2 polarization of microglia. The resulting positive loop reinforces the resolution of neuroinflammation, restores the impaired BBB, and prevents neuronal apoptosis after stroke. Using a permanent distal MCAO mouse model of an ischemic stroke, the neuroprotective effects of mIL-10@MLNPs have been further validated by the attenuation of the sensorimotor and cognitive neurological deficits. Furthermore, the developed mRNA-based targeted therapy has great potential to extend the therapeutic time window at least up to 72 h poststroke. This study depicts a simple and versatile LNP platform for selective delivery of mRNA therapeutics to cerebral lesions, showcasing a promising approach for addressing an ischemic stroke and associated brain conditions.

Tumor-draining lymph nodes (TDLNs) are important for tumor antigen–specific T cell generation and effective anticancer immune responses. However, TDLNs are often the primary site of metastasis, causing immune suppression and worse outcomes. Through cross-species single-cell RNA-Seq analysis, we identified features defining cancer cell heterogeneity, plasticity, and immune evasion during breast cancer progression and lymph node metastasis (LNM). A subset of cancer cells in the lymph nodes exhibited elevated MHC class II (MHC-II) gene expression in both mice and humans. MHC-II+ cancer cells lacked costimulatory molecule expression, leading to regulatory T cell (Treg) expansion and fewer CD4+ effector T cells in TDLNs. Genetic knockout of MHC-II reduced LNM and Treg expansion, while overexpression of the MHC-II transactivator, Ciita, worsened LNM and caused excessive Treg expansion. These findings demonstrate that cancer cell MHC-II expression promotes metastasis and immune evasion in TDLNs.

Supplemental Figures 1-11 and Supplementary table.

SummaryTumor-draining lymph nodes are critical sites for generating tumor antigen-specific T cells and are associated with durable immune responses. However, lymph nodes are often the first site of metastasis and lymph node metastases portend worse outcomes. Through cross-species single cell gene expression analysis of breast cancer progression and metastasis to lymph nodes, we uncovered features that define the heterogeneity, plasticity, and immune evasion of cancer cells. Notably, a subpopulation of metastatic cancer cells in the lymph node were marked by high levels of MHC class II (MHC-II) gene expression both in mice and humans. Mechanistically, the IFN-γ and JAK/STAT signaling pathways mediate MHC-II expression in cancer cells. Ablation of IFNGR1/2 or CIITA, the transactivator of MHC-II, in cancer cells prevented tumor progression. Interestingly, MHC-II+ cancer cells lacked co-stimulatory molecule expression, engendered the expansion of regulatory T cells and blunted CD4+ effector T cells in the tumor-draining lymph nodes and favor tumor progression. Overall, our data suggests that cancer cell plasticity during breast cancer progression and metastasis to lymph nodes endows metastatic cells with the ability to avoid immune surveillance. These data provide the basis for new opportunities to therapeutically stimulate anti-cancer immune responses against local and systemic metastases.

Background FLX475 (tivumecirnon) is a selective CCR4 antagonist designed to block the recruitment of immunosuppressive regulatory T cells (Treg) into the tumor microenvironment. The FLX475-02 trial (NCT03674567) is a phase 1/2 study of FLX475 as monotherapy and in combination with pembrolizumab in subjects with advanced cancer. Early encouraging data on the biologic effects, safety and antitumor activity of FLX475 have previously been presented.1–4 We now present the results from the completed Phase 2 cohort of combination therapy in subjects with non-small cell lung cancer (NSCLC) not previously treated with checkpoint inhibitor (CPI-naive). Methods Subjects with CPI-naïve, locally advanced or metastatic NSCLC received FLX475 100 mg orally once daily with pembrolizumab (200 mg IV Q3 weeks). The primary study objectives were safety and tolerability, and antitumor activity. The primary efficacy endpoint was objective response rate (ORR), based on RECIST 1.1 criteria. Additional efficacy endpoints included progression-free survival (PFS). Data cutoff was 31Aug2023. Results Of the 35 subjects with relevant NSCLC histologies evaluable for response, median follow-up was 192 days (9 – 660 days) and median lines of prior therapy was 1 (0–5). As previously described,3 the only adverse event determined to be specifically related to FLX475 treatment was asymptomatic and reversible QT prolongation (managed by dose reduction). Across all the subjects evaluable for response regardless of PD-L1 status (n=35), confirmed partial response (cPR) was observed in 9 (ORR: 26%). Amongst the subgroup of subjects whose tumors expressed PD-L1 (tumor proportion score [TPS] ≥1%) (n=20), cPR was observed in 7 (ORR: 35%), with an ORR of 31% (5/16) and 50% (2/4) in subjects with tumors expressing low and high levels of PD-L1 (TPS 1-49% or ≥50%), respectively. As of the data cutoff, the PD-L1 TPS ≥ 1% subgroup had a median PFS of 6.3 months with 8 subjects still on treatment. Conclusions FLX475, an oral CCR4 antagonist, has previously demonstrated clear monotherapy and encouraging combination activity with pembrolizumab.2 3 In this completed Phase 2 cohort of subjects with CPI-naïve NSCLC, FLX475 in combination with pembrolizumab was shown to be well tolerated and has demonstrated encouraging clinical activity compared to pembrolizumab monotherapy in PD-L1+ NSCLC (based on historical results) – in both subjects with low (TPS 1-49%) and those with high (TPS ≥50%) PD-L1 expression – supporting the continued development of this combination therapy for NSCLC. Acknowledgements Thank you to the patients who have participated in the study, and to their families and caregivers. Over 30 sites in the United States, Australia, South Korea, Taiwan, Thailand, and Hong Kong have participated in this study. Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA has provided pembrolizumab for the study. Trial Registration ClinicalTrials.gov Identifier: NCT03674567 References van Marle S, van Hoogdalem E-J, Johnson D, Okal A, Kassner, P, Wustrow D, Ho W. Pharmacokinetics, pharmacodynamics, and safety of FLX475, an orally-available, potent, and selective small-molecule antagonist of CCR4, in healthy volunteers. Journal for ImmunoTherapy of Cancer. 2018;6(Suppl 1):P484. Rhee P, Oh D-Y, Ryu M, Hwang J-E, Cho J, Zang D, Oh S, Lee J, Lee K-W, Rha S, Shim B, Ho W, Kim T, Baek E, Baek S, Chisamore M. A phase 2 study to assess the safety, efficacy of FLX475 combined with pembrolizumab in patients with advanced or metastatic gastric cancer. Journal for ImmunoTherapy of Cancer. 2022;10:0658. Lin C-C, Kim T, Desai P, Lee K, Feng Y-H, Ngamphaiboon N, Kim S-B, Yang M-H, Muzaffar J, Chmielowski B, Swiecicki P, Bowyer S, Brahmer J, Chisamore M, Goyal R, Nasrah N, Ho W, Cho B. Phase 1/2 study of the oral CCR4 antagonist, FLX475, as monotherapy and in combination with pembrolizumab in advanced cancer. Annals of Oncology. 2022;16(suppl_1):100104. Brockstedt D, Grant A, Adamik J, Trujillo D, Goyal R, Ho W, Ikeda S, Zhu Q, Anders R, Sabouri M, Kassner P. Clinical and biological activity of FLX475, an oral CCR4 antagonist, in advanced cancer. J Clin Oncol. 2023;41(16_suppl):2625. Ethics Approval All patients provided informed consent prior to inclusion in the study, and the protocol was approved by local institutional review boards for each clinical site. IRB Name/Approval no. or ID: Advarra/20132; BSD/IRB18-1199, Columbia Research HRPO/IRB-AAAS7290; JHM/IRB00188614/CIR00077638; Mary Crowley IRB/19-06; Medical School IRB/HUM00160818; Office of Human Subject Protection/2019-0139; Office for Human Research Studies/19-282; Univ. of Louisville IRB/19.0698; UCKA HRPP/IRB#18-001513; WCG®/20181802; Asan Medical Center IRB/S2019-0624-0001; Austin Health HREC/52407/Austin-2019; Belberry HREC/2018-08-671; CREC/CPA-CREC 044/2019; CMMC IRB/10806-002; CBNUH IRB/2019-03-010-001; Chulalongkorn Univ. IRB/1148/2019; Inje Univ. BPIRB/2021-05-020; IRB of the Univ. of Hong Kong/Hosp. Authority HK West Cluster/UW 19-394, UW 21-299; Joint Chinese Univ. of Hong Kong CREC/2019.342-T; NCKUH IRB/AB-CR-108-021; NTUH EC/201905048MSB; SMC IRB/2021-04-156-001; SNU Bundang Hosp. IRB/B-2108/703-401; SNUH IRB/H-1903-158-1023; Ulsan Univ. Hosp. IRB/UUH 2019-05-012, Yonsei Univ./4-2019-0520 and Severance Hosp. IRB/4-2019-0520. Consent Written informed consent was obtained from the patient for publication of this abstract and any accompanying images. A copy of the written consent is available for review by the Editor of this journal.

Kirsten rat sarcoma (KRAS) is the most commonly mutated oncogene in lung cancers. Gene therapy is emerging as a promising cancer treatment modality; however, the systemic administration of gene therapy has been limited by inefficient delivery to the lungs and systemic toxicity. Herein, we report a noninvasive aerosol inhalation nanoparticle (NP) system, termed "siKRAS@GCLPP NPs," to treat KRAS-mutant non-small-cell lung cancer (NSCLC). The self-assembled siKRAS@GCLPP NPs are capable of maintaining structural integrity during nebulization, with preferential distribution within the tumor-bearing lung. Inhalable siKRAS@GCLPP NPs show not only significant tumor-targeting capability but also enhanced antitumor activity in an orthotopic mouse model of human KRAS-mutant NSCLC. The nebulized delivery of siKRAS@GCLPP NPs demonstrates potent knockdown of mutated KRAS in tumor-bearing lungs without causing any observable adverse effects, exhibiting a better biosafety profile than the systemic delivery approach. The results present a promising inhaled gene therapy approach for the treatment of KRAS-mutant NSCLC and other respiratory diseases.

Genes differentially expressed in ACEi alone treated group compared to control group