Immune-based Therapies Research Articles

Abstract PO1-20-12: CD8+ Tumor Infiltrating Lymphocytes Turn a Cold Tumor Hot in Metastatic Breast Cancer

Abstract Introduction: Turning “cold” tumors “hot” is considered essential for immune-oncology therapies to be effective. Bria-IMT is an allogenic human cancer cell line with antigen presenting cell activity (SV-BR-1-GM) designed to overcome the immune-suppressive tumor microenvironment. However, until now there has not been proof that “cold” tumors can become “hot” with this therapy. Using Zr-89 crefmirlimab berdoxam, a zirconium-89 labelled truncated antibody specific to human CD8α and developed for CD8 ImmunoPET, we image before and after Bria-IMT therapy administration to assess the baseline status as well as changes in CD8 cell presence after initiation of therapy. Here we present the first evidence that cold tumors can become hot on treatment with Bria-IMT combined with an anti-PD-1 checkpoint inhibitor (CPI), showing CD8+ cells increased over baseline using CD8 ImmunoPET. Case: After informed consent, a 61 year-old Hispanic female, enrolled in the ongoing randomized phase 2 Bria-IMT trial in advanced heavily pretreated metastatic breast cancer (MBC) (NCT03328026). Her history included MBC in May 2020, ductal type, grade 3, triple negative breast cancer (TNBC) with 6 prior lines of therapy including a Trop-2-directed antibody-drug conjugate and 6 lines of chemotherapy. Precision medicine testing identified no actionable targets. All prior therapies had progressive disease as their best response. The subject was randomized to start the CPI after 2 cycles of Bria-IMT to “train” the host immune system before proceeding with combination immune-oncology therapy. Baseline testing revealed the subject to be anergic to candida and SV-BR-1-GM inoculation. However, by cycle 3 delayed-type hypersensitivity to SV-BR-1GM developed. Interestingly the subject matched SV-BR-1-GM at 2 HLA loci: DRB3*02:02 and DRB1*11:04 which in previous publications is associated with greater clinical benefit. Tumor markers were stable or decreased slightly including CEA (25% decrease) and CA 15-3 (43% decrease). Circulating Tumor Cells (CTCs) and Cancer Associated Macrophage Like cells (CAMLs) also improved. Standard imaging at baseline showed 3 main sites of disease including a large right breast mass, multiple right axillary lymph nodes and a right lower lobe mass with CD8 ImmunoPET uptake in these areas similar to the blood pool. On the follow-up CT imaging, all of these lesions increased in size with newly appreciated pulmonary nodules. The right lower lobe mass showed increased CD8 ImmunoPET accumulation with an SUV of 5.8 (close to the liver background) as compared to an SUV of 2.2 at baseline. The lesions in the right breast and right axilla remained at blood pool levels. There was an increase in CD8 ImmunoPET uptake in bilateral inguinal lymph nodes reaching an SUV of 4.8 as compared to SUV 2.2 at baseline. In addition, there were non-enlarged lymph nodes in bilateral axillary regions that also showed increased radio-tracer accumulation reaching an SUV of 9.5 as compared to SUV 4.9 at baseline. Conclusion: This subject demonstrated a mixed response of metastatic lesions on CD8 ImmunoPET with encouraging changes in peripheral blood tumor markers and CTCs. The nonspecific nodal localization of CD8 ImmunoPET may indicate a systemic activation of CD8 positive lymphoid cells. This shows the value of CD8 ImmunoPET in identifying lesions that are progressing on treatment versus pseudo progression. It also provides support that the Bria-IMT + CPI combination immune-based therapy can result in an increase of CD8+ tumor infiltrating lymphocytes in breast cancer metastatic sites as well as an increase in lymphoid organs. This advance may aid in triaging patients, adjudicating pseudo-progression and predicting clinical benefit of immune based therapies. Citation Format: Russ Kuker, Frances Valdes-Albini, Giuseppe Del Priore, Aazim Arif, Kristin Schmiedehausen, Carmen Calfa. CD8+ Tumor Infiltrating Lymphocytes Turn a Cold Tumor Hot in Metastatic Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-20-12.

Abstract PO3-05-12: Randomized Phase 2 of Bria-IMT, an Allogenic Human Cell Line with Antigen Presenting Activity, in Heavily Pretreated Metastatic Breast Cancer

Abstract Introduction Despite progress in MBC, too many continue to succumb due to treatment resistance or intolerance. SV-BR-1-GM is an allogenic human breast cancer cell line with antigen presenting cell activity designed to overcome the immune-suppressive tumor microenvironment while being acceptable to extensively pretreated contemporary MBC patients. We report interim exploratory analysis of the ongoing RCT of the Bria-IMT regimens. Methods An interim exploratory analysis using preliminary partially available evaluable data of the ongoing prospective, randomized phase 2 (NCT03328026; 2018-present) of Bria-IMT (irradiated SV-BR-1-GM) with a PD-1check point inhibitor (CPI) every 3 weeks (25 patients dosed to date). Both regimens include cyclophosphamide 300 mg/m2 48-72 hours prior to intradermal Bria-IMT (~20 x 106 cells) followed by interferon-alpha at the inoculation sites 2 days later. The control arm used the original sequence with simultaneous start of Bria-IMT and CPI in cycle 1. The experimental arm started CPI in cycle 2 after the 2nd inoculation. Candida skin test was performed before cycle 1 to determine anergy status while delayed-type hypersensitivity skin test (DTH), defined as >5mm erythema & induration, was done at every cycle by intradermal injection of a small test dose of Bria-IMT prior to full dose inoculation. Results Median age: 58 (range 37-81); median prior therapies: 8 lines (range 4-18); 89% were grade 2/3 (n=18); 68% hormone receptor positive; 61% HER2 negative, 33% HER2 low, and 6% HER2 high; 33% triple negative. Overall, 53% of subjects had a clinical benefit as best response by BICR, PI or target lesion measurement. The two treatment arms were similar with a trend showing longer median durations on therapy (mDOT) of 3.7 mo in the experimental delayed CPI arm compared with mDOT = 2.9 for original sequence control arm. 47% of patients were anergic to candida. Among all anergic subjects, the mDOT was 3.5 compared to 2.5 mo for non-anergic patients. However, among anergic subjects, the alternative treatment arm had a lower risk of treatment discontinuation (improved HR) with mDOT of 3.7 compared to the 3.3 mo mDOT of the original treatment. 50% of anergic subjects eventually developed DTH to SV-BR-1-GM. mDOT was 4.0 mo for DTH+ pts vs 3.0 mo for those who did not mount DTH. Median OS was not yet reached; mean OS was higher in non-anergic vs anergic pts. Among those who developed an inoculation site reaction to Bria-IMT, OS was greater than for those who did not. Time on the Bria-IMT regimen exceeded the time on penultimate treatment in 22% of subjects while 33% of subjects with prior CPI use exceeded last therapy. AEs were mild with 28% of subjects (n=7) having > grade 3 events. The most common grade 3+ AE was lipase increase (n=3). One subject with encouraging changes in peripheral blood tumor markers and CTCs completed a PET study using Zr-89 crefmirlimab berdoxam, a zirconium-89 labelled truncated antibody specific to human CD8α (CD8 Immuno-PET) and demonstrated increased uptake in some metastatic lesions and draining lymph nodes. Updated results will be provided at the meeting. Conclusion Sequencing of CPI with Bria-IMT is associated with differential clinical outcome trends but not statistically significant in this interim preliminary exploratory analysis regardless of prior CPI use. Bria-IMT is immunogenic with clinical benefit demonstrated for both treatment schedules among patients with inducible DTH reactions. Patients who develop an immune response to Bria-IMT had an increase in OS compared to those who did not. The nodal localization of CD8+ cells on PET may indicate a systemic activation of CD8 positive lymphoid cells. It also provides support that the Bria-IMT + CPI combination immune-based therapy can result in an increase of CD8+ tumor infiltrating lymphocytes in breast cancer metastatic sites. These preliminary results will be evaluated in the ongoing randomized phase 3 pivotal registrational trial. Citation Format: Carmen Calfa, Chaitali Nangia, Minal Barve, John Knecht, Jarrod Holmes, Kendrith Roland, Ralph Boccia, Frances Valdes-Albini, Zach Gostout, Mingjin Chang, William Williams, Charles Wiseman, Bonnie Guerin, Shaker Dakhil, Giuseppe Del Priore, Saranya Chumsri. Randomized Phase 2 of Bria-IMT, an Allogenic Human Cell Line with Antigen Presenting Activity, in Heavily Pretreated Metastatic Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-05-12.

Inflammation, Autoimmunity and Neurodegenerative Diseases, Therapeutics and Beyond.

Neurodegenerative disease (ND) incidence has recently increased due to improved life expectancy. Alzheimer's (AD) or Parkinson's disease (PD) are the most prevalent NDs. Both diseases are poly genetic, multifactorial and heterogenous. Preventive medicine, a healthy diet, exercise, and controlling comorbidities may delay the onset. After the diseases are diagnosed, therapy is needed to slow progression. Recent studies show that local, peripheral and age-related inflammation accelerates NDs' onset and progression. Patients with autoimmune disorders like inflammatory bowel disease (IBD) could be at higher risk of developing AD or PD. However, no increase in ND incidence has been reported if the patients are adequately diagnosed and treated. Autoantibodies against abnormal tau, β amyloid and α- synuclein have been encountered in AD and PD and may be protective. This discovery led to the proposal of immune-based therapies for AD and PD involving monoclonal antibodies, immunization/ vaccines, pro-inflammatory cytokine inhibition and anti-inflammatory cytokine addition. All the different approaches have been analysed here. Future perspectives on new therapeutic strategies for both disorders are concisely examined.

Taking a BiTE out of Lymphoma: Bispecific Antibodies in B-Cell Non-Hodgkin Lymphoma

B-cell non-Hodgkin’s lymphoma (NHL) refers to a heterogenous group of diseases, all of which have a wide range of treatment strategies and patient outcomes. There have been multiple novel, immune-based therapies approved in NHL in the last decade, including bispecific antibodies (BsAbs) and chimeric antigen receptor therapy (CAR-T). With a host of new therapies, an important next step will be determining how these therapies should be sequenced in contemporary management strategies. This review seeks to offer a framework for the ways in which BsABs can be incorporated into the current management paradigm for NHL, with special attention paid to diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), and mantle cell lymphoma (MCL).

Laser interstitial thermal therapy for recurrent glioblastomas: a systematic review and meta-analysis.

We aim to investigate the efficacy and safety of laser interstitial thermal therapy (LITT) in treating recurrent glioblastomas (rGBMs). A comprehensive search was conducted in four databases to identify studies published between January 2001 and June 2022 that reported prognosis information of rGBM patients treated with LITT as the primary therapy. The primary outcomes of interest were progression-free survival (PFS) and overall survival (OS) at 6 and 12 months after LITT intervention. Adverse events and complications were also evaluated. Eight eligible non-comparative studies comprising 128 patients were included in the analysis. Seven studies involving 120 patients provided data for the analysis of PFS. The pooled PFS rate at 6 months after LITT was 25% (95% CI 15-37%, I2 = 53%), and at 12 months, it was 9% (95% CI 4-15%, I2 = 24%). OS analysis was performed on 54 patients from six studies, with an OS rate of 92% (95% CI 84-100%, I2 = 0%) at 6 months and 42% (95% CI 13-73%, I2 = 67%) at 12 months after LITT. LITT demonstrates a favorable safety profile with low complication rates and promising tumor control and overall survival rates in patients with rGBMs. Tumor volume and performance status are important factors that may influence the effectiveness of LITT in selected patients. Additionally, the combination of LITT with immune-based therapy holds promise. Further well-designed clinical trials are needed to expand the application of LITT in glioma treatment.

The Role of Autologous Stem Cell Transplantation in the Treatment of Newly Diagnosed Multiple Myeloma: Is It Time to Rethink the Paradigm in the Era of Targeted Therapy?

High-dose melphalan (HDM) plus autologous stem cell transplant (ASCT) remains a standard-of-care treatment approach for eligible patients with newly diagnosed multiple myeloma (NDMM) based on demonstrated superiority in terms of progression-free survival (PFS) versus nontransplant approaches. Very high rates of minimal residual disease (MRD)-negative responses are also being seen with novel triplet and quadruplet induction regimens plus HDM-ASCT. However, recent clinical trials have shown no overall survival benefit with transplant versus nontransplant approaches. Furthermore, HDM is associated with several important downsides, including acute and long-term toxicities, transient decreases in quality of life, the need for hospitalization, an increased mutational burden at relapse, and an elevated risk of second primary malignancies. In this context, given the highly heterogeneous nature of MM in the NDMM patient population, as well as the continued emergence of novel agents and treatment approaches, there is an increasing rationale for considering deferred HDM-ASCT approaches in selected patients. Approaches under investigation include MRD-adapted therapy and the use of novel immune-based therapies as alternatives to HDM-ASCT. Ongoing developments in understanding the pathobiology and prognostic factors in NDMM, plus immune profiling and routine MRD evaluation, will result in novel, HDM-sparing treatment paradigms, enabling further improvement in patient outcomes.

Abstract LB348: Discovery and in vitro efficacy validation of anti-CD39 monoclonal antibody for improving the tumor microenvironment

Abstract In the tumor microenvironment (TME), the accumulation of adenosine inhibits anti-tumor immune responses, thereby reducing the effectiveness of immune-based cancer therapies. CD39 is involved in inducing excessive adenosine production in tumor cells and immune cells, causing an immune-suppressive environment. As a result, cancer cells are able to evade the immune system, and immune cells are impaired in their ability to kill cancer cells. Therefore, the discovery of outstanding antibodies targeting CD39 has great potential for cancer immunotherapy. To this end, we have discovered antibodies that effectively inhibit the hydrolysis of ATP to adenosine.We confirmed the binding affinity of the anti-CD39 mAb to the CD39 antigen. BLI measurements revealed that anti-CD39 mAb had binding kinetics of KD = 9.40 x 10-11 M, which is better than those of comparative antibodies, competitor 1 (2.39x10-10 M) and competitor 2 (2.27x10-9 M). The cell binding affinity of anti-CD39 mAb was evaluated using SK-MEL-28 cells, which endogenously express high levels of surface CD39. The results showed that the anti-CD39 mAb exhibited superior cell binding affinity compared to the two comparative antibodies. Furthermore, anti-CD39 mAb demonstrated greater efficacy in inhibiting ATP hydrolysis by membrane CD39 and soluble CD39 when compared to the comparative antibodies. In vitro functional assays using human PBMCs demonstrated that inhibiting CD39 enhances T cell proliferation. The anti-CD39 mAb showed superior efficacy in promoting proliferation in CD4+ cells compared to the competitor antibody. Similarly, in CD8+ cells, anti-CD39 mAb exhibited more efficacy compared to competitor 1 antibody. In conclusion, our data indicates that anti-CD39 mAb exhibits excellent characteristics, including superior antigen binding affinity, inhibitory efficacy of ATP hydrolysis and promotion of T cell proliferation. In the future, we will validate the efficacy and stability of this antibody in preclinical studies. The use of this antibody is expected to contribute to immune-based cancer therapy by inhibiting the generation of adenosine in the tumor microenvironment. Citation Format: Seonmi Yu, Wanki Park, Jaeho Song, Sooyoung Kim, Bumchan Park. Discovery and in vitro efficacy validation of anti-CD39 monoclonal antibody for improving the tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB348.

Unconventional human CD61 pairing with CD103 promotes TCR signaling and antigen-specific T cell cytotoxicity

Cancer remains one of the leading causes of mortality worldwide, leading to increased interest in utilizing immunotherapy strategies for better cancer treatments. In the past decade, CD103+ T cells have been associated with better clinical prognosis in patients with cancer. However, the specific immune mechanisms contributing toward CD103-mediated protective immunity remain unclear. Here, we show an unexpected and transient CD61 expression, which is paired with CD103 at the synaptic microclusters of T cells. CD61 colocalization with the T cell antigen receptor further modulates downstream T cell antigen receptor signaling, improving antitumor cytotoxicity and promoting physiological control of tumor growth. Clinically, the presence of CD61+ tumor-infiltrating T lymphocytes is associated with improved clinical outcomes, mediated through enhanced effector functions and phenotype with limited evidence of cellular exhaustion. In conclusion, this study identified an unconventional and transient CD61 expression and pairing with CD103 on human immune cells, which potentiates a new target for immune-based cellular therapies.

Abstract 173: Studying the interaction between macrophages and solid stress in novel models of the tumor immune microenvironment

Abstract Glioblastoma (GBM) is one of the most aggressive forms of cancer, resisting conventional and immune-based therapies and typically killing patients within two years of diagnosis. This is largely due to the immunosuppressive GBM tumor microenvironment (TME), mediated in large part by tumor-resident macrophages. Macrophages’ role as immune regulators, as well as their sheer quantity in brain tumors, makes them attractive therapeutic targets. The GBM TME also features mechanical abnormalities. As a tumor grows, it expands into the surrounding brain, generating compressive solid stress. Macrophages can contribute to up to half of tumor mass and are known to respond to mechanical cues, allowing them to both contribute to and respond to solid stress, but this relationship has not yet been explored experimentally. To isolate the contribution of macrophages on solid stress, we incorporated RAW264.7 murine macrophages into agarose gels with varying stiffnesses. Over time, spheroids form as the cells proliferate. Because cells cannot alter agarose, cell aggregates must generate stress as they grow and displace the surrounding gel matrix. The resulting agarose-embedded spheroids were stained with calcein AM to observe spheroid viability and morphology. Using confocal microscopy and image processing, we obtained the final spheroid geometry and imported it into COMSOL to model the solid stress resulting from spheroid formation. Our initial experiments show that macrophages have distinct growth patterns dependent on the stiffness of their surrounding gel. At larger sizes, the spheroids adopt an ellipsoid shape and generate a distinct stress field compared to spheroidal shapes. To stimulate the solid stress that macrophages experience within a growing mass, we applied a custom weight to macrophages grown on a porous membrane. This applies 0.15 kPa of compressive solid stress, corresponding to the stress measured in murine glioma models. After 24 hours of compression, macrophages upregulate expression of both nitric oxide synthase and arginase-1, canonical M1 and M2 markers, respectively. This indicates that compression causes a more complex phenotype than can be described by the traditional M1/M2 axis, something that has been observed in tumor-associated macrophages. We also found an apparent difference in the fluorescence lifetime of compressed and uncompressed macrophages, indicating that compression alters macrophage metabolism. Both the spheroid and compression culture models are unique in the context of macrophages. This work will elucidate key pathways involved in myeloid “immunomechanics” and inform strategies to target the innate immune system in cancers such as GBM, as well as other immunological diseases. Citation Format: Alice Burchett, Saeed Siri, Hao Chen, Scott Howard, Meenal Datta. Studying the interaction between macrophages and solid stress in novel models of the tumor immune microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 173.

Abstract 5357: The tumor-intrinsic RNA binding protein HuR is essential for anti-tumor immunity in PDAC

Abstract Immunotherapies have shown limited effectiveness in pancreatic ductal adenocarcinoma (PDAC), despite having success in other cancers. The RNA-binding protein HuR is known to play a critical role in the oncogenesis of PDAC by regulating key mRNA transcripts. Our lab has shown that tumor-intrinsic HuR is overexpressed in PDAC and regulates the tumor microenvironment composition, altering multiple tumor cytokines to release. Thus, we hypothesized that HuR plays a role in immune evasion of PDAC. We disrupted the locus encoding HuR (Elavl1) using CRISPR Cas9 in Kras-p53 mutant-driven (KPC) murine PDAC to assess its function in tumor immune evasion. Here, we report that HuR, a known pro-survival factor for PDAC, has a role in tumor immune evasion by suppressing T cell infiltration and T cell activation. Specifically, HuR-knockout (KO) KPC tumors grew slower compared to KPC wildtype (WT) tumors in an orthotopically implanted model (p-value < 0.0001), even though human PDAC cell lines with HuR-WT and HuR-KO grew at the same rate in NRG mice (in an immune-compromised environment). Accordingly, HuR-KO tumors had more T cell infiltration and activated T cells compared to HuR-WT tumors (p-value = 0.0047). Importantly, T cell depletion (both CD4+ and CD8+) partially rescued the size of HuR-KO tumors. Next, we rescued the expression of HuR in the HuR-KO cell line, and the re-expression partially rescued the tumor size in vivo. This observation validates a HuR-mediated dependent mechanism. Collectively, these data support the hypothesis that HuR suppresses T cell activation and prevents T cells from infiltrating into the PDAC microenvironment, leading to PDAC immune evasion. Ongoing experiments will transduce KPC cell lines with ovalbumin (OVA) antigen, which will selectively activate CD8+ OT-I T cells through their transgenic TCR, to measure the ability of KPC HuR-WT or HuR-KO OVA cells in directly activating CD8+ OT-I T cells. We will also investigate HuR's impact on immune cells' cytokine release and how that will impact the cytotoxicity of T cells. These findings support the ongoing concept that HuR plays an important pro-survival role in PDAC in vivo, and targeting strategies against HuR being developed (e.g., siHuR nano-therapies and small molecule inhibitors) could potentially enhance PDAC sensitivity to immune-based anti-cancer therapies, such as checkpoint blockade and T cell transfer. Citation Format: Yifei Guo, Jennifer M. Finan, Alexandra Q. Bartlett, Jonathan R. Brody, Robert Eil. The tumor-intrinsic RNA binding protein HuR is essential for anti-tumor immunity in PDAC [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 5357.

Abstract 2367: STING agonist ADU-S100 improves the antitumor response of CLDN18.2/CD3 BiTEs by enhancing stem-like tumor-reactive CD8+ T cells in pancreatic adenocarcinoma

Abstract Background: Immunotherapy with CLDN18.2/CD3 BiTEs (bispecific T-cell engagers) has shown clinical activity in pancreatic adenocarcinoma. However, only few patients benefit from the treatment, and most responders develop acquired resistance. STING agonists may promote the development of stem-like central memory CD8+ T cells and enhance antitumor responses. This study aimed to investigate the synergistic effect and related mechanism of STING agonist plus CLDN18.2/CD3 BiTEs regimen. Methods: Single-cell RNA sequencing and flow cytometry were used to examine the tumor immune landscape in humanized PDX mouse models. By qPCR, western blot and flow cytometry, an orthotopic transplantation mouse model of pancreatic cancer and an in vitro tumor-PBMC coculture system were established to reveal the potential molecular mechanism of STING agonist ADU-S100 in optimizing the effects of CLDN18.2/CD3 BiTEs (IBI389). Results: In PDAC organoids, IBI389 induced potent, specific cytotoxicity, the CLDN18.2 BiTEs significantly engaged human CD3+ T cells with tumor cells in an organoid-PBMC coculture system in vitro, resulting in the formation of the immunological synapse (IS). IBI389 monotherapy significantly suppressed tumor growth and improved survival in vivo in hCD3e C57BL/6 and humanized hCD34+ PDX mouse models. Further, single-cell RNA sequencing and flow cytometry analysis revealed that the intertumoral TCF1+PD-1+ stem-like T cells and STING signaling activity of T cells were enriched in the early stage of tumor development and sharply decreased in the late stage during CLDN18.2 BiTEs administration. Furthermore, we discovered that the STING agonist ADU-S100 could significantly induce the enrichment of TCF1+PD-1+ stem-like CD8+ T cells in vitro and in vivo, increasing IBI389’s therapeutic effects. Furthermore, humanized PDX mice that were given the combination of IBI389 and ADU-S100 and survived after complete tumor rejection were rechallenged with PDX tumors. Humanized PDX tumors and hCD3e KPC orthotopic tumors from mice treated with the combination contained increased numbers of TCF1+PD-1+ stem-like CD8+ T cells, CD4+CD127+ memory T cells, CD8+CD127+ memory T cells, and fewer numbers of CD4+PD-1+Tim-3+ exhausted T cells, CD8+PD-1+Tim-3+ exhausted T cells and CD4+CD25+ Treg cells. Conclusions: Pancreatic tumors appear to evade immune response by inducing immune-suppressive tumor microenvironment development. In mice, the combination of STING agonist ADU-S100 and CLDN18.2 BiTEs increased the proportion of memory and stem-like CD4+ and CD8+ T cells while decreasing the proportion of regulatory and exhausted T cells in pancreatic tumors, eradicating all detectable tumors. This data may be utilized to formulate immune-based combination therapies for PDAC. Citation Format: Tianxing Zhou, Jingrui Yan, Bin Wang, Yongjie Xie, Chao Yang, Jun Yu, Jihui Hao. STING agonist ADU-S100 improves the antitumor response of CLDN18.2/CD3 BiTEs by enhancing stem-like tumor-reactive CD8+ T cells in pancreatic 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 2367.

Abstract 2466: tRNA-derived fragments as immunotherapy response targets in head and neck squamous cell carcinoma

Abstract Background: Despite significant advances in immunotherapy-based treatment options for Head and Neck Squamous Cell Carcinoma (HNSCC), patient prognosis and survival remains poor. To enhance response to immune-based therapies, specific targeting of immunomodulatory pathways has been investigated through co-stimulatory gene targets, the microbiome, and more. An emerging biomolecule is Transfer RNAs (tRNAs), which are a class of RNAs that transport amino acids from the cytoplasm to ribosomes, and synthesize new proteins encoded by mRNA transcripts. tRNA-derived fragments (tRFs) are a category of cleaved, mature tRNA that participate in post-transcriptional regulation and have been implicated in the modulation of cancer and other immune-associated diseases. While tRFs are primarily implicated in diagnostic signatures for various cancers, few studies have investigated their role in modulating the immunotherapy-based response in HNSCC. In this study, we characterized the role of tRFs in modulating immunotherapy gene targets pertinent to HNSCC. Methods: We extracted tRF read counts from MINTbase 2.0 for 455 primary HNSCC tumor samples and 44 adjacent normals. Differential expression analysis was first performed to identify tRFs implicated in HNSCC tumors, with respect to adjacent normal tissue. Next, these tRFs were associated with immunotherapy target genes and response markers with Spearman’s correlation. Further characterization of these tRFs was performed by correlating their abundance to infiltrating immune cells, pathway enrichment of immunotherapy targets, and clinical variables. Results: Significant differential expression of tRFs were found between HNSCC primary tumor samples and adjacent normal tissue, including 7 tRFs (FDR < 0.05, |log fold change| > 0.5). All were enriched in normal samples. AlaCGC5tRF appeared to be an important regulator of immunotherapy target genes through increased co-expression of PTPN11, STAT3, and PTEN (p-value < 0.05, R > 0) and decreased co-expression of CD58 and TNFRSF14 (p-value < 0.05, R < 0). Immune Checkpoint Inhibitor (ICI) genes were significantly correlated with several tRFs. Among several pertinent tRF markers, AlaCGC5tRF was strongly associated with negatively correlated with infiltrating activated NK cells naïve CD4 T cells (p-value < 0.05, R < 0). Conclusion: Our study is the most comprehensive to date to characterize the role of tRF elements in modulating HNSCC immunotherapy targets. We found several potential tRF biomarkers that may be indicative of enhanced immunotherapy treatment susceptibility, including AlaCGC5tRF and ArgTCT3tRf. Further studies are needed to investigate how these tRFs may be targeted alongside immunotherapies to enhance response to treatment. Citation Format: Rishabh Yalamarty, Daniel John, Annie Do, Tianyi Chen, Megan Ngo, Pranava Gande, Matthew Uzelac, Wei Tse Li, Weg M. Ongkeko. tRNA-derived fragments as immunotherapy response targets in head and neck squamous cell 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 2466.

Rintatolimod in Advanced Pancreatic Cancer enhances Anti-Tumor Immunity through Dendritic Cell-Mediated T Cell Responses.

Amid the need for new approaches to improve survival in pancreatic ductal adenocarcinoma (PDAC), immune-based therapies have garnered interest. Rintatolimod, a toll-like receptor 3 (TLR-3) agonist, is a potential candidate due to its dual impact on restraining PDAC cell functions and boosting the anti-tumor immune response. This study investigates the effect of TLR-3 activation through rintatolimod on the peripheral immune landscape of advanced PDAC patients. Paired blood samples of 30 patients with advanced PDAC, collected at baseline and after 12 rintatolimod intravenous infusions, underwent comprehensive transcriptomic NanoString and proteomic flow cytometry profiling. The impact of rintatolimod and immunological factors on survival outcomes was assessed through univariate Cox proportional hazards models. Rintatolimod treatment enhances peripheral immune activity at the transcriptomic and proteomic levels, particularly involving type 1 conventional dendritic cells (cDC1s) and T cells. Post-rintatolimod, the increased peripheral abundance of BTLA+XCR1+ cDC1s and CD4+SELL+ T cells correlated with improved clinical outcomes. Patients with stable disease exhibited pronounced DC and T cell activation gene overexpression. Notably, the expression of immune checkpoints PD-L1 and PD-L2 decreased post-rintatolimod across all patients. However, those with progressive disease showed increased expression of genes encoding IDO1 and PD-1. This study presents compelling evidence of the immune-stimulatory properties linked to TLR-3 activation through rintatolimod. Rintatolimod may break immunological tolerance by enhancing anti-tumor immunity through DC-mediated Th-cell responses. Furthermore, our findings lay the groundwork for investigating the potential synergy between TLR-3 activation and immune checkpoint inhibitor therapy to improve therapeutic outcomes.

Myeloid cells as potential targets for immunotherapy in pediatric gliomas.

Pediatric high-grade glioma (pHGG) including pediatric glioblastoma (pGBM) are highly aggressive pediatric central nervous system (CNS) malignancies. pGBM comprises approximately 3% of all pediatric CNS malignancies and has a 5-year survival rate of approximately 20%. Surgical resection and chemoradiation are often the standard of care for pGBM and pHGG, however, even with these interventions, survival for children diagnosed with pGBM and pHGG remains poor. Due to shortcomings associated with the standard of care, many efforts have been made to create novel immunotherapeutic approaches targeted to these malignancies. These efforts include the use of vaccines, cell-based therapies, and immune-checkpoint inhibitors. However, it is believed that in many pediatric glioma patients an immunosuppressive tumor microenvironment (TME) possess barriers that limit the efficacy of immune-based therapies. One of these barriers includes the presence of immunosuppressive myeloid cells. In this review we will discuss the various types of myeloid cells present in the glioma TME, including macrophages and microglia, myeloid-derived suppressor cells, and dendritic cells, as well as the specific mechanisms these cells can employ to enable immunosuppression. Finally, we will highlight therapeutic strategies targeted to these cells that are aimed at impeding myeloid-cell derived immunosuppression.

Prostaglandin E2 in the Tumor Microenvironment, a Convoluted Affair Mediated by EP Receptors 2 and 4.

The involvement of the prostaglandin E2 (PGE2) system in cancer progression has long been recognized. PGE2 functions as an autocrine and paracrine signaling molecule with pleiotropic effects in the human body. High levels of intratumoral PGE2 and overexpression of the key metabolic enzymes of PGE2 have been observed and suggested to contribute to tumor progression. This has been claimed for different types of solid tumors, including, but not limited to, lung, breast, and colon cancer. PGE2 has direct effects on tumor cells and angiogenesis that are known to promote tumor development. However, one of the main mechanisms behind PGE2 driving cancerogenesis is currently thought to be anchored in suppressed antitumor immunity, thus providing possible therapeutic targets to be used in cancer immunotherapies. EP2 and EP4, two receptors for PGE2, are emerging as being the most relevant for this purpose. This review aims to summarize the known roles of PGE2 in the immune system and its functions within the tumor microenvironment. SIGNIFICANCE STATEMENT: Prostaglandin E2 (PGE2) has long been known to be a signaling molecule in cancer. Its presence in tumors has been repeatedly associated with disease progression. Elucidation of its effects on immunological components of the tumor microenvironment has highlighted the potential of PGE2 receptor antagonists in cancer treatment, particularly in combination with immune checkpoint inhibitor therapeutics. Adjuvant treatment could increase the response rates and the efficacy of immune-based therapies.

Targeting tumor-infiltrating tregs for improved antitumor responses.

Immunotherapies have revolutionized the landscape of cancer treatment. Regulatory T cells (Tregs), as crucial components of the tumor immune environment, has great therapeutic potential. However, nonspecific inhibition of Tregs in therapies may not lead to enhanced antitumor responses, but could also trigger autoimmune reactions in patients, resulting in intolerable treatment side effects. Hence, the precision targeting and inhibition of tumor-infiltrating Tregs is of paramount importance. In this overview, we summarize the characteristics and subpopulations of Tregs within tumor microenvironment and their inhibitory mechanisms in antitumor responses. Furthermore, we discuss the current major strategies targeting regulatory T cells, weighing their advantages and limitations, and summarize representative clinical trials targeting Tregs in cancer treatment. We believe that developing therapies that specifically target and suppress tumor-infiltrating Tregs holds great promise for advancing immune-based therapies.

Unlocking melanoma Suppression: Insights from Plasma-Induced potent miRNAs through PI3K-AKT-ZEB1 axis

IntroductionMelanoma is a rare but highly malignant form of skin cancer. Although recent targeted and immune-based therapies have improved survival rates by 10–15%, effective melanoma treatment remains challenging. Therefore, novel, combinatorial therapy options such as non-thermal atmospheric pressure plasma (NTP) are being investigated to inhibit and prevent chemoresistance. Although several studies have reported the apoptotic and inhibitory effects of reactive oxygen species produced by NTP in the context of melanoma, the intricate molecular network that determines the role of microRNAs (miRNAs) in regulating NTP-mediated cell death remains unexplored. ObjectivesThis study aimed to explore the molecular mechanisms and miRNA networks regulated by NTP-induced oxidative stress in melanoma cells. MethodsMelanoma cells were exposed to NTP and then subjected to high-throughput miRNA sequencing to identify NTP-regulated miRNAs. Various biological processes and underlying molecular mechanisms were assessed using Alamar Blue, propidium iodide (PI) uptake, cell migration, and clonogenic assays followed by qRT-PCR and flow cytometry. ResultsNTP exposure for 3 min was sufficient to modulate the expression of several miRNAs, inhibiting cell growth. Persistent NTP exposure for 5 min increased differential miRNA regulation, PI uptake, and the expression of genes involved in cell cycle arrest and death. qPCR confirmed that miR-200b-3p and miR-215-5p upregulation contributed to decreased cell viability and migration. Mechanistically, inhibiting miR-200b-3p and miR-215-5p in SK-2 cells enhancedZEB1, PI3K, and AKT expression, increasing cell proliferation and viability. ConclusionThis study demonstrated that NTP exposure for 5 min results in the differential regulation of miRNAs related to the PI3K-AKT-ZEB1 axis and cell cycle dysregulation to facilitate melanoma suppression.

Intracranial Hypertension Associated With Poly-Cranio-Radicular-Neuropathies: A Case Report and Review of the Literature.

We present the case of a gentleman who developed rapidly progressive vision loss, ophthalmo-paresis, and flaccid quadriparesis in the context of severe intracranial hypertension. We reviewed the available cases in the literature to increase awareness of this rare clinical entity.Case Report:A 36-year-old man developed rapidly progressive vision loss, ophthalmo-paresis, and flaccid quadriparesis. He had an extensive workup, only notable for severe intracranial hypertension, >55cm of H2O. No inflammatory features were present, and the patient responded to CSF diversion. Few similar cases are available in the literature, but all show markedly elevated intracranial pressure associated with extensive neuroaxis dysfunction. Similarly, these patients improved with CSF diversion but did not appear to respond to immune-based therapies. We term this extensive neuroaxis dysfunction intracranial hypertension associated with poly-cranio-radicular-neuropathy (IHP) and distinguish it from similar immune-mediated clinical presentations. Clinicians should be aware of the different etiologies of this potentially devastating clinical presentation to inform appropriate and timely treatment.

Taming the cytokine storm: small molecule inhibitors targeting IL-6/IL-6α receptor.

Given the increasing effectiveness of immune-based therapies, management of their associated toxicities is of utmost importance. Cytokine release syndrome (CRS), characterized by elevated levels of cytokine, poses a significant challenge following the administration of antibodies and CAR-T cell therapies. CRS also contributes to multiple organ dysfunction in severe viral infections, notably in COVID-19. Given the pivotal role of IL-6 cytokine in initiating CRS, it has been considered a most potential therapeutic target to mitigate hyperactivated immune responses. While monoclonal antibodies of IL-6 show promise in mitigating cytokine storm, concerns about immunotoxicity persist, and small molecule IL-6 antagonists remain unavailable. The present study employed sophisticated computational techniques to identify potential hit compounds as IL-6 inhibitors, with the aim of inhibiting IL-6/IL-6R protein-protein interactions. Through ligand-based pharmacophore mapping and shape similarity in combination with docking-based screening, we identified nine hit compounds with diverse chemical scaffolds as potential binders of IL-6. Further, the MD simulation of 300 ns of five virtual hits in a complex with IL-6 was employed to study the dynamic behavior. To provide a more precise prediction, binding free energy was also estimated. The identified compounds persistently interacted with the residues lining the binding site of the IL-6 protein. These compounds displayed low binding energy during MMPBSA calculations, substantiating their strong association with IL-6. This study suggests promising scaffolds as potential inhibitors of IL-6/IL-6R protein-protein interactions and provides direction for lead optimization.

Comprehensive Analysis of the Immunosuppressive Function of Regulatory T Cells in Human Hepatocellular Carcinoma Tissues.

Immune-based therapies are commonly employed to combat hepatocellular carcinoma (HCC). However, the presence of immune-regulating elements, especially regulatory T cells (Tregs), can dramatically impact the treatment efficacy. A deeper examination of the immune-regulation mechanisms linked to these inhibitory factors and their impact on HCC patient outcomes is warranted. We employed multicolor fluorescence immunohistochemistry (mIHC) to stain Foxp3, cytokeratin, and nuclei on an HCC tissue microarray (TMA). Leveraging liver cancer transcriptome data from TCGA, we built a prognostic model focused on Treg-associated gene sets and represented it with a nomogram. We then sourced liver cancer single-cell RNA sequencing data (GSE140228) from the GEO database, selectively focusing on Treg subsets, and conducted further analyses, including cell-to-cell communication and pseudo-time trajectory examination. Our mIHC results revealed a more substantial presence of Foxp3+Tregs in HCC samples than in adjacent normal tissue samples (P < .001). An increased presence of Foxp3+Tregs in HCC samples correlated with unfavorable patient outcomes (HR = 1.722, 95% CI:1.023-2.899, P = .041). The multi-factorial prognosis model we built from TCGA liver cancer data highlighted Tregs as a standalone risk determinant for predicting outcomes (HR = 3.84, 95% CI:2.52-5.83, P < .001). Re-analyzing the scRNA-seq dataset (GSE140228) showcased distinctive gene expression patterns in Tregs from varying tissues. Interactions between Tregs and other CD4+T cell types were predominantly governed by the CXCL13/CXCR3 signaling pathway. Communication pathways between Tregs and macrophages primarily involved MIF-CD74/CXCR4, LGALS9/CD45, and PTPRC/MRC1. Additionally, macrophages could influence Tregs via HLA-class II and CD4 interactions. An elevated presence of Tregs in HCC samples correlated with negative patient outcomes. Elucidating the interplay between Tregs and other immune cells in HCC could provide insights into the modulatory role of Tregs within HCC tissues.