Suppressive Tumor Microenvironment Research Articles

Personalized Nanovaccines Enhance Lymph Node Accumulation and Reprogram the Tumor Microenvironment for Improved Photodynamic Immunotherapy.

Tumor immunotherapy has emerged as an efficacious therapeutic approach that mobilizes the patient's immune system to achieve durable tumor suppression. Here, we design a photodynamic therapy-motivated nanovaccine (Dex-HDL/ALA-Fe3O4) co-delivering 5-aminolevulinic acid and Fe3O4 nanozyme that demonstrate a long-term durable immunotherapy strategy. After vaccination, the nanovaccine exhibits obvious tumor site accumulation, lymph node homing, and specific and memory antitumor immunity evocation. Upon laser irradiation, Dex-HDL/ALA-Fe3O4 effectively generates reactive oxygen species at the tumor site not only to induce the immunogenic cell death-cascade but also to trigger the on-demand release of full types of tumor antigens. Intriguingly, Fe3O4 nanozyme-catalyzed hydrogen peroxide generated oxygen for alleviating tumor hypoxia and modifying the inhibitory tumor microenvironment, thereby exhibiting remarkable potential as a sensitizer. The intravenous administration of nanovaccines in diverse preclinical cancer models has demonstrated remarkable tumor regression and inhibition of postoperative tumor recurrence and metastasis, thereby enabling personalized treatment strategies against highly heterogeneous tumors.

Can magnetic nanoparticles enhance adoptive cell therapy via driving migration of lymphocytes into tumors?

Therapy of malignant tumors still represents a huge problem for healthcare, since these diseases lead to a high rate of disability and premature death of the population. The main problems of adoptive cell therapy for malignant tumors are a low rate of migration of effector lymphocytes into tumors, as well as their low activity in tumors due to suppressive tumor microenvironment. In addition, it should be noted that systemic intravenous administration of a large number of activated lymphocytes may be accompanied by a pronounced cytokine release syndrome, which leads to significant negative side effects, including high temperature, blood clotting disorders, aggression of immune cells against their own tissues, even neurotoxicity. Functional nanomaterials, such as magnetic nanoparticles with various surface modifications (PEG, PEI, DMSA, citrate, etc.) are highly promising agents for targeted delivery of different anti-tumor substances. Magnet-driven enrichment of effector anti-tumor lymphocytes in tumors would highly increase the effectiveness and enhance safety of adoptive lymphocyte therapy. However, different research groups obtained opposing data about the feasibility and efficiency of such approach. Thus, this review is focused on experimental details of the contradicting studies and aims to elucidate the possible reasons of these controversies and the best practices to efficiently target lymphocytes into tumors.

Clinical application of immunogenic cell death inducers in cancer immunotherapy: turning cold tumors hot.

Immunotherapy has emerged as a promising cancer treatment option in recent years. In immune "hot" tumors, characterized by abundant immune cell infiltration, immunotherapy can improve patients' prognosis by activating the function of immune cells. By contrast, immune "cold" tumors are often less sensitive to immunotherapy owing to low immunogenicity of tumor cells, an immune inhibitory tumor microenvironment, and a series of immune-escape mechanisms. Immunogenic cell death (ICD) is a promising cellular process to facilitate the transformation of immune "cold" tumors to immune "hot" tumors by eliciting innate and adaptive immune responses through the release of (or exposure to) damage-related molecular patterns. Accumulating evidence suggests that various traditional therapies can induce ICD, including chemotherapy, targeted therapy, radiotherapy, and photodynamic therapy. In this review, we summarize the biological mechanisms and hallmarks of ICD and introduce some newly discovered and technologically innovative inducers that activate the immune system at the molecular level. Furthermore, we also discuss the clinical applications of combing ICD inducers with cancer immunotherapy. This review will provide valuable insights into the future development of ICD-related combination therapeutics and potential management for "cold" tumors.

Abstract PO2-27-07: The Role of HCMV Infection in Facilitating Brain Metastasis through the Creation of a Suppressive Tumor Microenvironment in Breast Cancer Patients

Abstract Human Cytomegalovirus (HCMV) infection has emerged as a noteworthy factor in breast cancer patients, particularly those experiencing brain metastasis. Despite being prevalent and often asymptomatic, HCMV's contribution to tumor progression remains enigmatic. Notably, a high proportion of breast cancer patients with brain metastasis exhibit HCMV positivity in both primary tumors and metastatic lesions. This study aims to elucidate the influence of HCMV infection on brain metastasis by investigating its impact on the tumor microenvironment. Our findings reveal a distinctive immune suppressive tumor microenvironment in HCMV-positive breast cancer patients. This environment is characterized by impaired NK cell function and an elevated accumulation of TH2 cells. To comprehend the role of HCMV in promoting brain metastasis, we have developed a murine breast tumor model using MCMV, enabling us to mirror the clinical trajectory of tumor progression and metastasis. The integration of a GFP reporter gene into the MCMV genome facilitates the tracking of infected cancer cells. Within this model, we observe a significant increase in brain metastasis coupled with reduced survival rates. Single-cell sequencing analysis uncovers diminished NK cell presence and activation, along with heightened TH2 cell accumulation within the tumor microenvironment—results that parallel the clinical observations in breast cancer patients. GSEA analysis underscores the secretion of inhibitory cytokines by MCMV-infected cancer cells, contrasting with their non-infected counterparts. Collectively, our study reveals that CMV infection contributes to brain metastasis in breast cancer by generating inhibitory cytokines. This hampers the recruitment and proliferation of immune cells within the tumor microenvironment and concurrently impairs the cytotoxic capabilities of NK cells. These insights shed light on the intricate interplay between viral infection and tumor progression, offering potential avenues for therapeutic exploration. Citation Format: Wenjuan Dong, Xin Wang, Kun Han, Akshjot Puri, Amna Irfan, Wei Qian, Liliana Guzman, Roberto Rosato, Jianting Sheng, Hong Zhao, Jenny Chang, Stephen Wong. The Role of HCMV Infection in Facilitating Brain Metastasis through the Creation of a Suppressive Tumor Microenvironment in Breast Cancer Patients [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 PO2-27-07.

Glioma hexokinase 3 positively correlates with malignancy and macrophage infiltration.

Glioma is the main subtype of primary central nervous system (CNS) tumor with high malignancy and poor prognosis under current therapeutic approaches. Glycolysis and suppressive tumor microenvironment (TME) are key markers of glioma with great importance for aggressive features of glioma and inferior clinical outcomes. Hexokinase 3 (HK3) is an important rate-limiting enzyme in glycolysis, but its function in glioma remains unknown. This study comprehensively assessed the expression distribution and immunological effect of HK3 via pan-cancer analysis based on datasets from Genotype Tissue Expression (GTEx), Cancer Cell Line Encyclopedia (CCLE), and The Cancer Genome Atlas (TCGA). Furthermore, it explored the malignant phenotype and genomic landscape between low-HK3 and high-HK3 expression groups in gliomas from Chinese Glioma Genome Atlas (CGGA) and TCGA. Moreover, data from the TIMER website predicted the relationship between macrophage infiltration and HK3 expression. Also, single-cell sequencing data were used to validate the relationship. For pan-cancer patients, HK3 was expressed in various cancers. The results showed that HK3 was highly expressed in gliomas and positively correlated with tumor-infiltrating immune cells (TIICs), immune checkpoints, immunomodulators, and chemokines. Meanwhile, HK3 expression was highest in normal immune cells and tissues. In gliomas, the expression of HK3 was found to be closely correlated with the malignant clinical characteristics and the infiltration of macrophages. Also, HK3 was proven to be positively associated with macrophage through single-cell sequencing data and immunohistochemistry techniques. Finally, it is predicted that samples with high HK3 expression are often malignant entities and also significant genomic aberrations of driver oncogenes. This is the first comprehensive research to figure out the relationship between HK3 and TME characteristics in gliomas. HK3 is positively associated with macrophage infiltration and can induce the immunosuppressive TME and malignant phenotype of gliomas.

Low ACADM expression predicts poor prognosis and suppressive tumor microenvironment in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) represents a highly frequent renal cancer subtype. However, medium-chain acyl-CoA dehydrogenase (ACADM) encodes an important enzyme responsible for fatty acid β-oxidation (FAO) and its association with prognosis and immunity in cancers has rarely been reported. Therefore, the present work focused on exploring ACADM’s expression and role among ccRCC cases. We used multiple public databases and showed the hypo levels of ACADM protein and mRNA within ccRCC. Additionally, we found that ACADM down-regulation showed a remarkable relation to the advanced stage, high histological grade, as well as dismal prognostic outcome. As suggested by Kaplan–Meier curve analysis, cases showing low ACADM levels displayed shorter overall survival (OS) as well as disease-free survival (DFS). Moreover, according to univariate/multivariate Cox regression, ACADM-mRNA independently predicted the prognosis of ccRCC. In addition, this work conducted immunohistochemistry for validating ACADM protein expression and its prognostic role in ccRCC samples. KEGG and GO analyses revealed significantly enriched genes related to ACADM expression during fatty acid metabolism. The low-ACADM group with more regulatory T-cell infiltration showed higher expression of immune negative regulation genes and higher TIDE scores, which might contribute to poor response to immunotherapies. In conclusion, our results confirmed that downregulated ACADM predicted a poor prognosis for ccRCC and a poor response to immunotherapy. Our results provide important data for developing immunotherapy for ccRCC.

Abstract LB065: Tumor-infiltrating lymphocytes (TIL) engineered with regulatable membrane-bound IL15 (mbIL15) and LIGHT (TNFSF14) show enhanced efficacy in fibroblast-containing cold tumors

Abstract Introduction: Adoptive cellular therapies (ACT) have encountered challenges in solid tumors due in part to the immunosuppressive tumor microenvironment (TME). We have developed OBX-115, TIL engineered to express mbIL15 regulatable using the cytoDRiVE® platform, which allows for TIL expansion, persistence, and anti-tumor efficacy under control of the FDA-approved small-molecule ligand, acetazolamide (ACZ), eliminating the need for co-administration of IL2 (NCT05470283). LIGHT, a tumor necrosis factor family member, interacts with lymphotoxin beta receptor (LTbR) and herpes virus entry mediator (HVEM) found on various TME cell types, including stromal cells such as cancer associated fibroblasts (CAF). In preclinical studies, LIGHT expression within a tumor has been linked to the formation of tertiary lymphoid structures and vascular normalization (Ramachandran Cancer Cell 2023), both associated with better clinical outcomes (Sautès-Fridman Nat Rev Cancer 2019). We hypothesized that engineering TIL with regulatable mbIL15 and LIGHT expression could enhance their efficacy by modifying the TME. Methods: TIL from colorectal (CRC) and head and neck squamous cell carcinoma (HNSCC) were transduced with retroviral vectors to express regulatable mbIL15 and LIGHT. ACZ-induced surface expression of mbIL15 and LIGHT in expanded TIL was examined using flow cytometry. Functional signaling of LIGHT was assessed through co-culture with Jurkat-HVEM-NF-kappaB reporter cells and LTbR+ HUVEC cells. In vitro, engineered TIL were tested in stromal-rich tumor models (CRC and HNSCC) by co-culturing with autologous patient-derived tumor/CAF hybrid spheroids. In vivo, antigen-independent TIL persistence was assessed in NSG mice without exogenous IL2. Syngeneic studies were performed to assess the efficacy of adoptively transferred mbIL15 and LIGHT-engineered Pmel cells (CD8+ T cells transgenic for a gp100-specific T cell receptor) in a subcutaneous cold tumor model (B16-F10). Results: Engineered TIL were successfully expanded without exogenous IL2. ACZ-dependent mbIL15 and LIGHT expression were confirmed, validating co-regulation and functionality in vitro. TIL engineered with mbIL15 and LIGHT displayed significantly increased cytotoxicity against autologous tumor/CAF spheroids compared with TIL expressing mbIL15 alone (p<0.005) in CRC and HNSCC tumor/CAF hybrid models. TIL with mbIL15 and LIGHT expanded in vivo and persisted for ≥42 days without exogenous IL2 support. Moreover, Pmel cells engineered with mbIL15 and LIGHT demonstrated durable anti-tumor efficacy in B16-F10 tumor-bearing mice, which was greater than Pmel cells engineered with mbIL15 alone (p<0.01). Conclusions: These preclinical results suggest that TIL engineered with regulatable mbIL15 and LIGHT using the cytoDRiVE platform have the potential to address the high unmet clinical need in cold tumors with suppressive TME, which are currently not amenable to ACT. Citation Format: Balazs Koscso, Zheng Ao, Carmela Passaro, Nirzari Shah, Ngoc Ly, Patricia Timpug, Bulent A. Aksoy, Dexue Sun, Dan Jun Li, Kerri-Lynn Sheahan, Violet Young, Theresa Ross, Benjamin Primack, Meghan Langley, Jeremy Tchaicha, Dhruv K. Sethi, Jan ter Meulen, Michelle Ols. Tumor-infiltrating lymphocytes (TIL) engineered with regulatable membrane-bound IL15 (mbIL15) and LIGHT (TNFSF14) show enhanced efficacy in fibroblast-containing cold tumors [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 LB065.

Blocking senescence and tolerogenic function of dendritic cells induced by γδ Treg cells enhances tumor-specific immunity for cancer immunotherapy

BackgroundRegulatory T (Treg) cells are a key component in maintaining the suppressive tumor microenvironment and immune suppression in different types of cancers. A precise understanding of the molecular mechanisms used...

Abstract 2699: Application of whole genome loss of function CRISPR screen in primary natural killer cells

Abstract Natural killer cells (NKs) are cytotoxic lymphocytes of the innate immune system, operating against infections and cancer. NKs act in an antigen independent manner, preventing graft versus host disease in allogeneic settings. NKs can be isolated from healthy donors, activated, expanded and safely administered to cancer patients. Although NKs are highly cytotoxic against cancer cells in vitro, they lose viability and functionality in the suppressive tumor microenvironment (TME). Until recently, viral transduction of primary NKs was considered a technical hurdle. The latest progress using Baboon Lentiviral (BaLV) pseudotyping substantially increased transduction rates and facilitated the use of chimeric antigen receptor (CAR) NKs for cancer immunotherapies. Due to this challenge, most genetic manipulations were performed in single genes with limited capabilities. Large-scale functional manipulation of NKs using CRISPR-cas9 editing was not implemented, leaving a gap in our understanding of NK suppression. We generated a whole genome library of 55,548 guide RNAs (gdRNAs, 4 per gene), targeting 13,749 genes that were determined to be expressed in NKs and 138 (10%) olfactory receptor genes that are not expressed in NKs as control gdRNAs. The gdRNA plasmid was optimized based on our CAR-NK backbone, to express the gdRNA scaffold under U6 promotor and GFP under EF1α promotor. The library plasmids were sequenced and their gaussian distribution was verified, with high representation of all the different gdRNAs. Primary NKs were isolated from 3 healthy donors and transduced at 25% transduction rates using our optimized BaLV system. After a week expansion in vitro, NKs were electroporated with protein cas9-RFP using the maxCyte electroporator. RFP levels at 6 hours after electroporation were at least 80%. The cells were profiled after electroporation for cytotoxicity and for functionality against the K562 target cell line. IFNγ production and degranulation (CD107a) were similar before and after electroporation. Genomic DNA was extracted from the transduced NKs and the gdRNA barcodes were amplified by PCR and sequenced. The distribution of the gdRNA barcodes after sequencing exhibited high representation of almost all gdRNAs, with minimal loss of gdRNAs. Several gene knockouts were identified as important for survival/proliferation of NKs and are being validated using single gdRNAs in vitro and in vivo. NK cell immunotherapy is a promising approach for cancer treatment. Although recent clinical trials with CAR-NK present exciting results, many solid tumors do not benefit from NK immunotherapies due to the inactivation of NKs in the immune-suppressive TME. Here, we successfully implemented an unbiased genome wide loss-of-function CRISPR screen as an effective and informative method to identify novel candidates for NK cell suppression. Citation Format: Michal Sheffer, Isabel E. Kaplan, Eden Bobilev, Yasmin Z. Abdulhamid, Rizwan Romee. Application of whole genome loss of function CRISPR screen in primary natural killer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2699.

Abstract 7042: Enhancing TCR T cell function in solid tumors through in vivo combinatorial screens and single-cell analysis

Abstract The therapeutic potential of T cell therapies for treating solid tumors can be limited by intrinsic T cell exhaustion mechanisms and the suppressive tumor microenvironment. To better understand these challenges and identify genetic perturbations to enhance T cell functions, we developed in vivo exhaustion models and performed pooled CRISPR/Cas9-based screens with detailed characterization of T cell states through single cell RNA-sequencing (scRNA-seq). In vivo Xenograft exhaustion models were developed in the format of T cell receptor (TCR) T cells, with tumor cell lines expressing TCR-specific antigen (NY-ESO-1) respectively. Individual perturbations were introduced into T cells via non-viral editing and pooled before transferred into mice with established tumors of various sizes that provided continuous antigen exposure to drive exhaustion, while providing sufficient number of T cells from tumor and spleen tissues for scRNA-seq. The pooled CRISPR in vivo screens in human TCR T cells enabled us to evaluate T cell phenotypes resulting from gain-of-function, loss-of-function, or combinations of these modifications across a wide array of target genes. We identified known and previously uncharacterized combinatorial perturbations that were enriched or depleted and were associated with distinct transcriptional phenotypes over the course of chronic stimulation. This approach allows us to bridge the gaps in our understanding of how T cells can be reprogrammed to overcome exhaustion and function more effectively in the challenging environment of solid tumors. Citation Format: Dina Polyak, Jessica Fuhriman, Josephine Susanto, Allyson Merrell, Mandi Simon, Catherine Oh, Andrew Cordazo, David DeTomasso, Carla Tocchini, Vibhavari Sail, Eric Cui, Jeff Milush, Levi Gray-Rupp, Brendan Galvin, Christopher Murriel, Grace Zheng, Angela C. Boroughs, Pratiksha Thakore, Soyoung Oh, Jake Freimer, Bob Chen, Celine Eidenschenk, Emily Wheeler, Jacob Levine, Jan-Christian Huetter, Jill Schartner, Katie Geiger-Schuller, Orit Rozenblatt-Rosen, Sascha Rutz, Ira Mellman, W. Nicholas Haining. Enhancing TCR T cell function in solid tumors through in vivo combinatorial screens and single-cell analysis [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 7042.

Abstract 6755: NKT activation enhanced the therapeutic efficacy of neoantigen vaccine in hepatocellular carcinoma

Abstract One sentence introduction: This study indicated the potential of combinational therapy of neoantigen vaccine and iNKT activator α-GalCer in Hepatocellular carcinoma. Hepatocellular carcinoma (HCC) is a leading cause of death around the world. Current immune checkpoint blockade therapies only show effectiveness in some cancer patients, so there is an urgent need for more effective immunotherapy strategies. One alternative is the use of neoantigen-based cancer vaccines, which target tumor-specific antigens (neoantigens) on cancer cells and induce strong T-cell responses. Advances in technology now allow for precise identification of tumor neoantigens using bioinformatic analysis or mass spectrometry. While cancer vaccines have demonstrated strong anti-tumor immune responses and therapeutic effectiveness in some cancer types, their success in HCC remains limited. A contributing factor is the suppressive tumor microenvironment (TME) found in advanced HCC. Some studies suggest that combining neoantigen vaccines with anti-PD1/PD-L1 therapies can significantly enhance HCC treatment outcomes. Overcoming the suppressive immune microenvironment is crucial in cancer treatment, and reactivating intratumoral immunity is essential. In our study, we developed an HCC cancer vaccine using transcriptome sequencing and bioinformatics analysis. Our ELISpot assay results showed that this vaccine induced strong tumor-specific immune responses and significantly inhibited tumor growth in early-stage orthotopic HCC mouse models when administered five days after tumor inoculation. However, the effectiveness decreased in advanced tumors when administered ten days after tumor inoculation. We also discovered a significant relationship between the therapeutic effectiveness of the neoantigen vaccine and the activation of intratumoral NKT cells in HCC. Our study suggested that the type-I NKT cell activator, α-Galactosylceramide (α-GalCer), significantly improved the therapeutic outcomes of the cancer neoantigen vaccine in advanced orthotopic HCC mouse models. In some cases, tumors were almost completely eliminated. This indicates the potential of combining iNKT activators with neoantigen vaccines for HCC treatment. To further understand the role of NKT cells in HCC's TME, we plan to investigate intratumoral NKT cell subtypes following neoantigen vaccine therapy. Additionally, we will develop a new delivery system to deliver type I NKT cell activators and type II NKT inhibitors to tumor sites, aiming to reactivate the suppressive TME in HCC after neoantigen vaccine therapy. Citation Format: Renhao Li, Jing-Chu Hu, Li Rong, Yangfan Wu, Yige He, Jiandong Huang. NKT activation enhanced the therapeutic efficacy of neoantigen vaccine 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 6755.

Abstract 3996: Secreted cytokine-αPDL1 fusion proteins improve solid tumor chimeric antigen receptor (CAR) T-cell therapy

Abstract Background: Success of Chimeric Antigen Receptor (CAR) T cells therapy for solid tumors are limited by the suppressive solid tumor microenvironment (TME), T cell exhaustion, lack of persistence, and poor trafficking to tumors. Strategies to improve this include therapeutic combinations, such as checkpoint inhibition (CPI) or cytokine support. However, CPI therapy has largely failed because of refractory and resistant tumors and cytokine administration can lead to lethal toxicities. To this end, we propose that enabling CAR T cells to secrete bi-functional fusion proteins consisting of cytokine modifiers (ie: IL12, IL15, or TGFβ-trap) combined with checkpoint inhibition (αPDL1 scFv) can provide tumor PDL1 sequestered cytokine activity and local tumor-immune modulation to boost solid tumor CAR T cell efficacy, enhance CPI impacts, and safely improve durable outcomes. Methods: Mouse T cells dual transduced to express surface CAR targeting prostate or ovarian solid tumors in addition to secretable cytokine fused to an αPDL1 scFv were generated. In vitro, the PDL1 blockade capacity and tumor-surface cytokine presentation of supernatants from dual transduced CAR T cells was assessed on PDL1 induced tumor cells. Further, secreted fusion protein transduced CAR T cells were assessed for function, phenotype, and cytokine release in a repetitive tumor rechallenge assay. In vivo, mouse CAR T cells dual transduced with fusion proteins and appropriate controls were assessed for anti-tumor efficacy, survival kinetics, and toxicity in immunocompetent solid tumor mouse models of prostate cancer and intraperitoneal disseminated ovarian cancer. Results: CAR T cells were shown to be successfully dual transduced, and secreted αPDL1-cytokine fusion proteins exhibiting functional PDL1 binding characteristics in vitro. CAR T cells engineered with αPDL1-IL12 fusion protein had greater anti-tumor activity and CAR specific expansion compared to other tested fusion proteins in in vitro co-culture assays. In a syngeneic prostate tumor model, mice receiving CAR T cells with αPDL1-IL12 fusion T cells out competed other cytokine fusion combinations. In a syngeneic ovarian tumor model we safely achieved 100% curative response rate with CAR secreting αPDL1-IL12 fusion in contrast to CAR with αPDL1mutIL12 control along with tumor regional PDL1 blockade on myeloid subsets within the TME. Conclusions: Our findings suggest that CAR T cells engineered to secrete αPD-L1-IL12 fusion protein show improved tumor control, less systemic toxicity, and enhanced expansion which promotes eradication of disease in two independent in vivo tumor models with two unique solid tumor CAR targets. We believe this strategy has the potential to improve solid tumor CAR T-cell efficacy and enhance durable innate immune responses. Citation Format: Lea Christian, John P. Murad, Lupita Lopez, Anthony Park, Jason Yang, Eric Lee, Candi Trac, Stephen Forman, Saul J. Priceman. Secreted cytokine-αPDL1 fusion proteins improve solid tumor chimeric antigen receptor (CAR) T-cell therapy [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 3996.

Abstract 2376: Mitazalimab, a potent CD40 agonist in combination with FOLFIRINOX demonstrates changes consistent with increased immune activation in TME and peripheral blood in a preclinical pancreatic cancer tumor model

Abstract Mitazalimab is a human CD40 FcγR-conditional agonistic IgG1 antibody developed for cancer immunotherapy. Immune-excluded tumors, such as pancreatic ductal adenocarcinoma (PDAC), are defined by low infiltration of immune cells. In PDAC, effector CD8+ T cells are excluded from the tumor by its desmoplastic stroma which surrounds cancer cell islets and hosts immunosuppressive macrophages. CD40 is expressed on key myeloid cell populations and targeting this receptor has a two-fold mode of action. First, mitazalimab activates macrophages, skewing them towards a tumoricidal phenotype that can potentially reverse the suppressive tumor microenvironment found in PDAC and sensitizes the tumor for chemotherapy by stromal degradation. Second, mitazalimab activates antigen-presenting cells, resulting in priming and expansion of tumor-specific T cells with the potential to generate an effective immune response that could provide immunological memory resulting in long term benefits to patients. Mitazalimab is currently being investigated in a phase 2 study in patients with metastatic PDAC (OPTIMIZE-1) in combination with modified FOLFIRINOX (NCT04888312). The treatment starts with a dose of mitazalimab administered one week prior to chemotherapy in the first cycle to leverage the mode of action and increase the efficacy of the combination therapy. Interim results of the study demonstrated encouraging anti-tumor activity with good durability of responses. To study the changes induced by mitazalimab and FOLFIRINOX in the tumor microenvironment, we evaluated the combination in human CD40 transgenic mice using the KPCY pancreatic tumor model. Tumor, tumor draining lymph nodes, blood and spleen were analyzed for changes in the immune compartment using multiplex assays at different time points. The results showed distinct immunophenotypical changes induced by mitazalimab, FOLFIRINOX and the combination. The combination of mitazalimab and FOLFIRINOX resulted in an increased tumoricidal immune profile, including a marked increase in effector CD8+ T cells compared to the individual therapies. Overall, these preclinical data support the chosen dosing regimen of mitazalimab and modified FOLFIRINOX in the OPTIMIZE-1study and underline the synergistic potential of this combination for an improved antitumor response. Citation Format: Karin Enell Smith, David Gomez Jimenez, Mia Thagesson, Anneli Nilsson, Yago Pico de Coaña, Sumeet Ambarkhane, Peter Ellmark. Mitazalimab, a potent CD40 agonist in combination with FOLFIRINOX demonstrates changes consistent with increased immune activation in TME and peripheral blood in a preclinical pancreatic cancer tumor model [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 2376.

Abstract 4012: SOT302: Dual expression of exogenous glutamine oxaloacetate transaminase (GOT2) and TP53-induced glycolysis and apoptosis regulator (TIGAR) enhance CAR T cell activity in preclinical solid tumor models

Abstract Background: Despite success in hematological malignancies, CAR T therapy has had limited efficacy against solid tumors. The suppressive tumor microenvironment limits CAR T activity through various mechanisms including competition for available nutrients and chronic stimulation resulting in reduced effector functions or T cell exhaustion. CAR T cells with enhanced metabolic fitness or more durable memory phenotype could potentially improve the clinical outcome in solid tumors. GOT2 plays an important role in mitochondrial function and maintenance of redox homeostasis. We have previously demonstrated enhancement of CAR T cells overexpressing GOT2. TIGAR is an enzyme known to promote antioxidative activites and reduce reactive oxygen species and has a role in protecting against apoptosis. Here we tested SOT302 CAR T cells expressing both GOT2 and TIGAR in preclinical solid tumor models. Results: Expression of GOT2 and TIGAR transgenes were confirmed by qRT-PCR and western blot. Activity of GOT2 and TIGAR were confirmed by measuring aminotransferase activity (AST) and glutathione production, respectively. Compared to control CAR T cells, SOT302 is enriched for CD8+ Tscm cells and has a higher percentage functional, non-senescent (CD28+CD57-) cells. SOT302 has similar cytokine expression and cytotoxicity in standard co-culture assays compared to controls. SOT302 cells were chronically stimulated with plate-bound antigen every 3-4 days for 4 rounds. SOT302 had greater expansion of cells and were less exhausted and had better cytolytic capacity compared to controls. SOT302 cells were then evaluated in tumor xenograft mouse models. Consistent with our previous findings, CAR T cells expressing the single GOT2 transgene were more efficacious compared to CAR T cells alone. Expression of the single TIGAR transgene had no apparent benefit over CAR alone, however SOT302 cells expressing both GOT2 and TIGAR had superior anti-tumor activity compared to CAR alone and CAR+GOT2. No overt toxicity or significant body weight loss was observed. Ex vivo analyses to measure peripheral expansion, tumor infiltration and exhaustion were also performed. Preliminary findings indicate that SOT302 has better peripheral expansion compared to CAR alone and similar expansion compared to CAR+GOT2 controls. SOT302 cells had better tumor infiltration compared to both the CAR alone and CAR+GOT2 cells. Tumor infiltrating SOT302 cells also exhibited lower levels of exhaustion compared to CAR alone or CAR+GOT2 controls. Summary: SOT302 cells express exogenous GOT2 and TIGAR transgenes and have superior anti-tumor activity in preclinical solid tumor models. These data suggest that SOT302 may be a promising candidate for patients with solid tumor cancers. Citation Format: Emily Kuiper, Samyabrata Bhaduri, Daniel Garafola, Kshitij Sharma, Jennifer Coccia, Kathleen Whiteman, Amy Jensen-Smith. SOT302: Dual expression of exogenous glutamine oxaloacetate transaminase (GOT2) and TP53-induced glycolysis and apoptosis regulator (TIGAR) enhance CAR T cell activity in preclinical solid tumor models [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 4012.

Abstract 2899: Combined inhibition of RAF, MEK and FAK increases PDAC responsiveness to cytotoxic- and immune therapy

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy with poor response rate to therapy. An immune suppressive tumor microenvironment (TME) and oncogenic mutations in KRAS have been implicated as drivers of resistance to both conventional and immune therapies. As such, targeting RAS/MAPK signaling is an attractive strategy. However, RAS/MAPK inhibition has not yet shown clinical efficacy for PDAC, likely due to rapid acquisition of resistance in PDAC cells. Tumor intrinsic mechanisms of resistance to RAS/MAPK have been studied, however, the unique PDAC TME may also be a key driver in resistance. Previous studies have shown that FAK inhibition can reprogram the PDAC TME and delay PDAC progression in animal models. Herein, we found that long-term FAK inhibitor treatment led to hyperactivation of the RAS/MAPK pathway in both genetically engineered mouse models and in post-treatment PDAC tissues from FAK inhibitor clinical trials. Concomitant inhibition of both FAK (VS-4718) and RAF/MEK (avutometinib) signaling dramatically suppressed tumor growth, leading to increased survival across multiple PDAC mouse models. The mechanisms of synergy include both changes in tumor-intrinsic signaling and modulation of tumor/stroma interactions that drive avutometinib resistance. In the TME, we found that cancer associated fibroblasts (CAFs) can impair the downregulation of cMyc by RAF/MEK inhibition in PDAC cells. This resulted in de-novo resistance to RAF/MEK inhibition in fibrotic conditions. By contrast, FAK inhibitors reprogramed CAFs to suppress the production of key growth factors, including FGF1, that drove resistance to RAF/MEK inhibition. While combined FAK and RAF/MEK inhibition only led to disease stasis, the addition of chemotherapy to the combination led to tumor regression and improved long-term survival in PDAC mouse models. Analysis of tumor immunity showed that the combination of FAK and RAF/MEK inhibition improved anti-tumor immunity and improved priming of T cell responses, which was further improved with the addition of chemotherapy. These findings led to testing of FAK (defactinib) plus RAF/MEK (avutometinib) inhibition in combination with gemcitabine and nab-paclitaxel in advanced front-line pancreatic cancer patients (RAMP 205; NCT05669482). Finally, we tested whether addition of immunotherapy could enhance the efficacy of FAKi + RAF/MEKi + chemotherapy and found that addition of either PD-1 or CTLA4/PD-1 blockade led to long term disease control in PDAC animal models. Together, these studies identified FAK inhibition as a novel approach to overcome both tumor intrinsic and stromal-derived resistance to RAS/MAPK inhibition and showed that this combination can be exploited to increase the efficacy of cytotoxic and immunotherapy approaches. Citation Format: Xiuting Liu, John Baer, Brett Knolhoff, Graham Hogg, Faiz Ahmad, Silvia Coma, Jonathan Pachter, Kian Lim, David DeNardo. Combined inhibition of RAF, MEK and FAK increases PDAC responsiveness to cytotoxic- and immune therapy [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 2899.

Abstract 7465: Leukemia inhibitory factor creates an immune suppressive tumor microenvironment and fosters tumor growth in KRAS-driven pancreatic ductal adenocarcinoma

Abstract Immune checkpoint blockade revolutionized cancer treatments by activating anti-tumor immunity. Pancreatic ductal adenocarcinoma (PDA) patients have not benefited from these advances due to an immune suppressive tumor microenvironment. Identifying PDA cell-encoded factors that drive immune evasion is necessary to unlock new immunologically active treatment options in PDA. We have recently demonstrated that the cytokine Leukemia inhibitory factor (LIF) is highly upregulated in PDA compared to the normal healthy pancreas. LIF is known for its immune suppressive qualities, but data on LIF in PDA is currently limited. We generated a conditional Lif flox (L) allele and crossed it into the well-established KrasLSL-G12D/+, Trp53flox/flox, Pdx1-Cre (KPC) mouse model. LKPC mice (n=29) had longer overall survival (69 days) than control KPC mice (n=29) (59 days), (p<0.05). LKPC mice harbored significantly smaller tumors with an average tumor weight of 0.6g compared to KPC control animals with an average tumor weight of 1.0g (p<0.005). Immunohistochemical evaluation of tumor proliferation measured by Ki-67 positivity in LKPC and KPC tumors at endpoint showed comparable results. Tumor-derived cell lines from KPC and LKPC mice showed no growth differences in vitro nor when reimplanted subcutaneously (sc) in immunodeficient mice. In contrast, we observed a significant decrease in tumor growth and weight in LKPC sc tumors (p<0.05) compared to the KPC sc tumors in syngeneic mice. LKPC sc tumors had significantly fewer neutrophils and more macrophages, particularly MHC II-high macrophages, known for their anti-tumor qualities when compared to KPC sc tumors using flow cytometry. A trend towards more CD8+ T-cells in sc LKPC tumors was also observed. Our genetically engineered mouse model confirmed this finding by immunohistochemical evaluation of tumors at endpoint, which demonstrated a significant increase of CD8+ T-cells in the LKPC animals compared to the KPC controls. In summary, we find that cancer-cell-expressed LIF augments tumor growth and shortens overall survival by changing the immune tumor microenvironment, nominating leukemia inhibitory factor depletion as a promising therapeutic immune target in KRAS-driven pancreatic cancer. Citation Format: Lisa Miller-Phillips, Imene Boukhalfa Hanafi, Alexis J. Combes, Shabana Bano, Lisiena Hysenaj, Jeroen P. Roose, Adam Olshen, Ashley Kiemen, Sarah Umetsu, Man-Tzu Wang, Eric A. Collisson. Leukemia inhibitory factor creates an immune suppressive tumor microenvironment and fosters tumor growth in KRAS-driven pancreatic ductal 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 7465.

Abstract 6522: Epigenetic modulation decreases myeloid suppression to improve response to immune checkpoint inhibition in breast cancer

Abstract Immune checkpoint inhibitors (ICIs) promote a durable anti-tumor immune response. Unfortunately, many patients with breast cancer are thought to be intrinsically resistant. One potential mechanism of resistance is a myeloid suppressed tumor microenvironment (TME). Targeting myeloid suppression is under investigation as a therapeutic strategy to sensitize tumors to ICI. In our trial, NCI-9844, we demonstrated that the combination of the epigenetic modulator, entinostat with ICIs—nivolumab (anti-PD-1) + ipilimumab (anti-CTLA-4), leads to a 25% objective response rate in patients with advanced breast cancer. Work in our preclinical models showed entinostat decreases suppressive function by myeloid derived suppressor cells (MDSCs). We hypothesized that entinostat decreases intra-tumoral MDSC suppression via the STAT3/AP-1 axis and drives cellular shifts within the TME to improve response to ICI. Here, we examined expression of upstream, downstream, and interacting factors within the STAT3 pathway in MDSCs treated with entinostat. Macro-dissected lung metastases from entinostat treated NeuN mice revealed differential gene expression of AP-1 subunits JunB and FOSL1 in MDSCs identified by single cell RNA sequencing (scRNAseq). Western blot of isolated intratumoral MDSCs from lung metastases revealed decreased STAT3 phosphorylation upon entinostat treatment. In an entinostat treated MDSC-like cell line, J774M, JunB phosphorylation and FOSL1 were both decreased. scRNAseq also revealed decreased gene expression of STAT3 upstream receptors IL4RA and IFNGR1 and increased expression of STAT3 negative regulator SOCS3. Chromatin immunoprecipitation sequencing is planned to further narrow the molecular mechanism of action. Cell-cell communication analysis of scRNAseq data was performed to evaluate the contribution of entinostat treated macrophages, dendritic cells (DCs), and natural killer (NK) cells on MDSC function. We observed increased frequency of DC populations (classic DC2s and Ccr7 DCs). Following combined treatment with entinostat + ICIs, we also found increased DC to T cell signaling strength for receptor-ligand pairs involved in T cell activation, including Tnfsf9__Tnfrsf9, Cd70_Cd27, H2-dmb2_Cd4, and Cd80_Cd28. Analysis of macrophage-T cell interactions revealed a synergistic decrease in signaling associated with immunosuppression after combined treatment, such as Cd80_Ctla4, Tnf_Tnfrsf1b, and Entpd1_Adora2a. Suppressive function of treated sub-populations of macrophages is planned to determine functional effect of findings. Finally, we are using imaging mass cytometry and bulk RNA sequencing to evaluate proposed mechanisms in patient specimens (NCI-9844). The goal of this work is to identify the molecular and cellular mechanisms driving myeloid suppression of the TME thereby identifying potential therapeutic targets. Citation Format: Aaron G. Baugh, Edgar Gonzalez, Jesse Kreger, Yingtong Liu, Batul Al-Zubeidy, Ludmila Danilova, Sarah M. Shin, Valerie H. Narumi, Sofi Castanon, Julie Jang, Elana J. Fertig, Ashley Cimino-Mathews, Elizabeth M. Jaffee, Vered Stearns, Roisin M. Connolly, Won Jin Ho, Adam MacLean, Evanthia T. Roussos Torres. Epigenetic modulation decreases myeloid suppression to improve response to immune checkpoint inhibition in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6522.

Prostate fibroblasts and prostate cancer associated fibroblasts exhibit different metabolic, matrix degradation and PD-L1 expression responses to hypoxia.

Fibroblasts are versatile cells that play a major role in wound healing by synthesizing and remodeling the extracellular matrix (ECM). In cancers, fibroblasts play an expanded role in tumor progression and dissemination, immunosuppression, and metabolic support of cancer cells. In prostate cancer (PCa), fibroblasts have been shown to induce growth and increase metastatic potential. To further understand differences in the functions of human PCa associated fibroblasts (PCAFs) compared to normal prostate fibroblasts (PFs), we investigated the metabolic profile and ECM degradation characteristics of PFs and PCAFs using a magnetic resonance imaging and spectroscopy compatible intact cell perfusion assay. To further understand how PFs and PCAFs respond to hypoxic tumor microenvironments that are often observed in PCa, we characterized the effects of hypoxia on PF and PCAF metabolism, invasion and PD-L1 expression. We found that under normoxia, PCAFs displayed decreased ECM degradation compared to PFs. Under hypoxia, ECM degradation by PFs increased, whereas PCAFs exhibited decreased ECM degradation. Under both normoxia and hypoxia, PCAFs and PFs showed significantly different metabolic profiles. PD-L1 expression was intrinsically higher in PCAFs compared to PFs. Under hypoxia, PD-L1 expression increased in PCAFs but not in PFs. Our data suggest that PCAFs may not directly induce ECM degradation to assist in tumor dissemination, but may instead create an immune suppressive tumor microenvironment that further increases under hypoxic conditions. Our data identify the intrinsic metabolic, ECM degradation and PD-L1 expression differences between PCAFs and PFs under normoxia and hypoxia that may provide novel targets in PCa treatment.

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

Abstract Regulatory T cells (Tregs), an immunosuppressive subset of CD4+ T cells, play a vital role in maintaining immune homeostasis by regulating response to self antigens and maintaining tolerance. On the contrary, Tregs infiltrating the tumor microenvironment (TME) impede effective anti-tumor immunity by inhibiting tumor-specific T cell responses and generating a suppressive TME, thus promoting tumor progression. Clinically, Tregs have been proven to play a significant role in resistance to immune checkpoint inhibitors (ICIs) leading to lower response rates. Hence, targeting Tregs would lead to activation of tumor-specific effector T cells and improved long-term anti-tumor immune responses with ICI treatment. CCR4, a chemokine receptor highly expressed on Tregs, spearhead the migration of Tregs and their accumulation in the TME, by responding to the chemokines CCL22 and CCL17 secreted by the inflamed cells in the tumor. CCR4 expression is associated with poor prognosis in various solid tumors. This warrants the therapeutic targeting of CCR4-expressing Tregs to enable effective and durable anti-tumor immune responses. We sought to discover and develop novel small molecule antagonists of CCR4 for use in cancer therapy. Multiple series of CCR4 antagonists were identified by iterative medicinal chemistry efforts and SAR based approach. These compounds were optimized towards attaining required potency, acceptable physicochemical properties, high selectivity and desirable pharmacokinetic profile to achieve anti-tumor activity. Aurigene’s CCR4 antagonists exhibited potent inhibition of CCR4 activity in the reporter-based β-arrestin recruitment assay. This translated well into potent inhibition of CCL22-mediated chemotaxis of CCR4-expressing Tregs in an in vitro cell migration assay. Furthemore, the lead compounds showed desirable drug-like properties and excellent pharmacokinetic exposure in rodents. In an ongoing study in a syngeneic mice tumor model, one of the lead compounds is being evaluated for impact on Treg infiltration, CD8:Treg ratio in the tumor and efficacy. In summary, we have identified novel CCR4 antagonists with desirable drug-like properties that are being evaluated further to identify a clinical candidate. Citation Format: Rashmi Nair, Chandrasekhar Abbineni, Krishna Chaitanya Talluri, Amit A Dhudashiya, Aravind AB, NaveenR Kumar, Ramya R, D Balasubramanyam, Pathur Obanna, Rabin Madhaiyan, DS Samiulla, Girish Daginakatte, Kishore Narayanan, Kavitha Nellore, Shekar Chelur, Susanta Samajdar, Murali Ramachandra. A novel CCR4 antagonist induces potent anti-tumor response through inhibition of Treg migration into the tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6537.

Abstract 6349: 2MW4991, a novel ADCC-enhanced integrin αvβ8 blocker, exhibits high anti-tumor potency and was well tolerated in cynomolgus monkeys

Abstract Background: The three highly structurally related TGF-β isoforms (TGF-β1, TGF-β2, and TGF-β3) exert greatly different effects on cancer and immune cells under various physiological conditions. Efforts to target the TGF-β pathway have been hampered by systemic toxicity or limited efficacy due to challenges associated with the global inhibition of TGF-βs. Recently, TGF-β1 was proven to be a critical player in generating an immunosuppressive tumor microenvironment (TME). TGF-β1 is expressed as an inactive latent form (L-TGF-β1) and activated upon binding to integrins, and integrin αvβ8 is a key activator of TGF-β1 in TME. Here, an ADCC-enhanced αvβ8 blocking antibody, 2MW4991, was developed to specifically inhibit TGF-β1-mediated signaling for the treatment of αvβ8-expressing cancers. Methods: Binding ability, specificity, and affinity of antibodies were measured by Flow cytometry and Biacore T200. A blocking assay was performed using U251MG cells and TGF-β signaling reporter cells. Jurkat/h FcγRIIIa reporter system was used to assess the ADCC activity of 2MW4991. Mouse syngeneic tumor models were used to characterize the in vivo anti-tumor efficacy. A repeat dose administration study was performed in cynomolgus monkeys to evaluate the pharmacokinetic and toxicity profiles of 2MW4991. Results: ScRNA-seq analysis of kidney renal clear cell carcinoma (KIRC) and head and neck squamous cell carcinoma (HNSCC) clinical samples revealed that αvβ8 highly expresses in tumor and some myeloid-derived cells, suggesting the development of ADCC-enhanced αvβ8 blocking antibodies for the treatment of αvβ8-expressing cancers. 2MW4991 showed sub-nanomolar binding affinity and high specificity to αvβ8, with no cross-reactivity to other integrins. 2MW4991 could effectively block TGF-β1 release in a GARP/L-TGF-β1/αvβ8 reporter system. In an immune-excluded EMT6 syngeneic model, 2MW4991 promoted substantial tumor regression and reversed immune suppressive TME by significantly increasing tumor infiltration of CD8+ T and innate immune cells. As expected, TGF-β1 blockade significantly increased the sensitivity of anti-PD-1 therapy in a combination study. Furthermore, 2MW4991 displayed potent anti-tumor efficacy in the human αvβ8 knock-in syngeneic model mimicking αvβ8 expression in human cancers. In a repeat dose administration NHP study, 2MW4991 showed a good pharmacokinetic profile and was well tolerated at a high dose of 100 mg/kg, accompanied by significantly declined pharmacodynamic biomarker TGF-β1 in peripheral blood. Conclusion: Integrin αvβ8 is a main activator of TGF-β1 in the TME and overexpressed in some cancer types. 2MW4991 demonstrated potent anti-tumor activity by unleashing the immune cells suppressed by TGF-β1 in TME and Fc-mediated immune functions. These compelling preclinical results support further evaluation of 2MW4991 in clinical trials. Citation Format: Cuicui Guo, Zhen Han, Xiaowei Cen, Hai Wu, Jinchao Zhang, Xun Gui. 2MW4991, a novel ADCC-enhanced integrin αvβ8 blocker, exhibits high anti-tumor potency and was well tolerated in cynomolgus monkeys [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 6349.