Tumor Growth Delay Research Articles

Scavenger Receptor CD36 in Tumor-Associated Macrophages Promotes Cancer Progression by Dampening Type I Interferon Signaling.

Tumor-associated macrophages (TAMs) are a heterogenous population of myeloid cells that dictate the inflammatory tone of the tumor microenvironment (TME). In this study, we unveiled a mechanism by which scavenger receptor CD36 suppresses TAM inflammatory states. CD36 was upregulated in TAMs and associated with immunosuppressive features, and myeloid-specific deletion of CD36 significantly reduced tumor growth. Moreover, CD36-deficient TAMs acquired inflammatory signatures including elevated type-I interferon (IFN-I) production, mirroring the inverse correlation between CD36 and IFN-I response observed in cancer patients. IFN-I, especially IFNβ, produced by CD36-deficient TAMs directly induced tumor cell quiescence and delayed tumor growth. Mechanistically, CD36 acted as a natural suppressor of IFN-I signaling in macrophages through p38 activation downstream of oxidized lipid signaling. These findings establish CD36 as a critical regulator of TAM function and the tumor inflammatory microenvironment, providing additional rationale for pharmacological inhibition of CD36 to rejuvenate anti-tumor immunity.

Antagonists of CD39 and CD73 potentiate doxycycline repositioning to induce a potent antitumor immune response.

Studies have reported that cellular metabolism at the tumor-immune microenvironment (TiME) serves as a critical checkpoint and perturbs/supports anti-cancer immunity. Extra cellular ATP (eATP) may mediate anti-cancer immune response; however, its catabolism by ectonucleotidase generates immunosuppressive adenosine. In the presented work, we have tried to repurpose doxycycline with or without an antagonist of ectonucleotidase for mitigating ATP metabolism and immunosuppression. In this methodology eATP and adenosine levels were quantified. Bone marrow-derived M1 and M2 polarized macrophages were maintained in tumor mimicking condition (TMC). Total/CD4+Tcells were co-cultured with macrophages to understand the impact of doxycycline and/or antagonist of ectonucleotidase on T cell/subset differentiation. Preclinical efficacy of doxycycline and/or ectonucleotidase antagonist and their synergy was scored in 4 T1-induced breast carcinoma. We found that Doxycycline manipulated macrophage polarization by decreasing the frequency of CD206+M2 macrophages, which resulted in enhanced CD4+ directed CD8+ T cell response. Doxycycline alleviated the expression of CD39 and CD73, rescuing ATP catabolism. Doxycycline delayed tumor growth by enhancing F4/80+ CD86+ M1 macrophages and subsequently anti-tumor Tbet+ CD4+Tcells, attenuating the frequency of FOXP3+ regulatory T cells, which was cooperatively supported by ARL67156 and AMPCP (CD39 and CD73 antagonist).A synergy was observed with ARL67156 and AMPC Pensuring a possibility of using doxycycline alone or in combination with an antagonist of ectonucleotidase to present adenosine-mediated immunosuppression. Subsequently, our finding indicated that prospective usage of doxycycline as a novel metabolic checkpoint blocker (IMB) against ectonucleotidase and may be modified/delivered appropriately as a monotherapy or in combination with antagonists of ectonucleotidases as an IMB.

TMIC-52. DECODING METABOLIC INTERACTIONS IN GLIOBLASTOMA TUMOR MICROENVIRONMENT THROUGH COMPREHENSIVE SPATIAL TRANSCRIPTOMIC AND PROTEOMIC ANALYSIS

Abstract INTRODUCTION Within the GBM microenvironment, distinct micro-niches arise from independent cancer cell lineages with unique metabolic needs, characterized as Fast Cycling Cells (FCCs) and Slow Cycling Cells (SCCs). FCCs preferentially utilize aerobic glycolysis for energy, whereas treatment-resistant SCCs depend on lipid metabolism. Our study decodes the molecular and spatial heterogeneity within the GBM microenvironment, focusing on the dichotomy of immune infiltrates and the metabolic interactions between SCCs and the immune compartment in human GBM patients. METHODS We performed spatial transcriptomics and proteomics combined with geospatially resolved single-cell neighborhood analysis of IHC-stained GBM tissues using CellProfiler and the SNAQ algorithm that we developed to investigate the specific immune microenvironment of SCCs and FCCs. Holotomography and fluorescence-based time-lapse imaging coupled with flow cytometry were used to study lipid transfer between immune cells and GBM cells. Finally, the effects of pharmacological and genetic targeting of lipid transfer were investigated both in vitro and in vivo. RESULTS Our study establishes a connection between spatial metabolic heterogeneity and immune diversity, highlighting how specific tumor cell lineages correlate with characteristic immune micro-niches. In particular, SCCs exploit the metabolic properties of recruited immunosuppressive myeloid-derived cells, which metabolically support tumor cells by facilitating lipid transport and supporting SCC metabolism. Our results show that inhibiting lipid transfer affect SCCs, remodels the immune microenvironment, delays tumor growth and improves disease outcome. Our study also demonstrates a correlation between predicted sensitivity to lipid-modifying drugs, such as statins, and the SCC phenotype. This correlation could enable stratification and selection of patients most likely to benefit from such treatments. CONCLUSIONS This study establishes critical connections between the TME, cellular metabolism, anti-tumor immunity, and treatment vulnerabilities. Our research provides novel insights into how metabolic exchanges contribute to tumor progression and suggests that targeting metabolic interactions could be an effective therapeutic strategy for GBM.

GPER1 signaling restricts macrophage proliferation and accumulation in human hepatocellular carcinoma

BackgroundSex hormones and their related receptors have been reported to impact the development and progression of tumors. However, their influence on the composition and function of the tumor microenvironment is not well understood. We aimed to investigate the influence of sex disparities on the proliferation and accumulation of macrophages, one of the major components of the tumor microenvironment, in hepatocellular carcinoma (HCC).MethodsImmunohistochemistry was applied to assess the density of immune cells in HCC tissues. The role of sex hormone related signaling in macrophage proliferation was determined by immunofluorescence and flow cytometry. The underlying regulatory mechanisms were examined with both in vitro experiments and murine HCC models.ResultsWe found higher levels of macrophage proliferation and density in tumor tissues from male patients compared to females. The expression of G protein–coupled estrogen receptor 1 (GPER1), a non-classical estrogen receptor, was significantly decreased in proliferating macrophages, and was inversely correlated with macrophage proliferation in HCC tumors. Activation of GPER1 signaling with a selective agonist G-1 suppressed macrophage proliferation by downregulating the MEK/ERK pathway. Additionally, G-1 treatment reduced PD-L1 expression on macrophages and delayed tumor growth in mice. Moreover, patients with a higher percentage of GPER1+ macrophages exhibited longer overall survival and recurrence-free survival compared to those with a lower level.ConclusionsThese findings reveal a novel role of GPER1 signaling in regulating macrophage proliferation and function in HCC tumors and may offer a potential strategy for designing therapies based on understanding sex-related disparities of patients.

Notch1 blockade by a novel, selective anti-Notch1 neutralizing antibody improves immunotherapy efficacy in melanoma by promoting an inflamed TME

BackgroundImmune checkpoint inhibitors (ICI) have dramatically improved the life expectancy of patients with metastatic melanoma. However, about half of the patient population still present resistance to these treatments. We have previously shown Notch1 contributes to a non-inflamed TME in melanoma that reduces the response to ICI. Here, we addressed the therapeutic effects of a novel anti-Notch1 neutralizing antibody we produced, alone and in combination with immune checkpoint inhibition in melanoma models.MethodsAnti-Notch1 was designed to interfere with ligand binding. Mice were immunized with a peptide encompassing EGF-like repeats 11–15 of human Notch1, the minimal required region that allows ligand binding and Notch1 activation. Positive clones were expanded and tested for neutralizing capabilities. Anti-Notch1-NIC was used to determine whether anti-Notch1 was able to reduce Notch1 cleavage; while anti-SNAP23 and BCAT2 were used as downstream Notch1 and Notch2 targets, respectively. K457 human melanoma cells and the YUMM2.1 and 1.7 syngeneic mouse melanoma cells were used. Cell death after anti-Notch1 treatment was determined by trypan blue staining and compared to the effects of the gamma-secretase inhibitor DBZ. 10 mg/kg anti-Notch1 was used for in vivo tumor growth of YUMM2.1 and 1.7 cells. Tumors were measured and processed for flow cytometry using antibodies against major immune cell populations.ResultsAnti-Notch1 selectively inhibited Notch1 but not Notch2; caused significant melanoma cell death in vitro but did not affect normal melanocytes. In vivo, it delayed tumor growth without evident signs of gastro-intestinal toxicities; and importantly promoted an inflamed TME by increasing the cytotoxic CD8+ T cells while reducing the tolerogenic Tregs and MDSCs, resulting in enhanced efficacy of anti-PD-1.ConclusionsAnti-Notch1 safely exerts anti-melanoma effects and improves immune checkpoint inhibitor efficacy. Thus, anti-Notch1 could represent a novel addition to the immunotherapy repertoire for melanoma.

Non‐Natural MUC1 Glycopeptide Homogeneous Cancer Vaccine with Enhanced Immunogenicity and Therapeutic Activity

AbstractGlycopeptides derived from the glycoprotein mucin‐1 (MUC1) have shown potential as tumor‐associated antigens for cancer vaccine development. However, their low immunogenicity and non‐selective conjugation to carriers present significant challenges for the clinical efficacy of MUC1‐based vaccines. Here, we introduce a novel vaccine candidate based on a structure‐guided design of an artificial antigen derived from MUC1 glycopeptide. This engineered antigen contains two non‐natural amino acids and has an α‐S‐glycosidic bond, where sulfur replaces the conventional oxygen atom linking the peptide backbone to the sugar N‐acetylgalactosamine. The glycopeptide is then specifically conjugated to the immunogenic protein carrier CRM197 (Cross‐Reactive Material 197), a protein approved for human use. Conjugation involves selective reduction and re‐bridging of a disulfide in CRM197, allowing the attachment of a single copy of MUC1. This strategy results in a chemically defined vaccine while maintaining both the structural integrity and immunogenicity of the protein carrier. The vaccine elicits a robust Th1‐like immune response in mice and generates antibodies capable of recognizing human cancer cells expressing tumor‐associated MUC1. When tested in mouse models of colon adenocarcinoma and pancreatic cancer, the vaccine is effective both as a prophylactic and therapeutic use, significantly delaying tumor growth. In therapeutic applications, improved outcomes were observed when the vaccine was combined with an anti‐programmed cell death protein 1 (anti‐PD‐1) checkpoint inhibitor. Our strategy reduces batch‐to‐batch variability and enhances both immunogenicity and therapeutic potential. This site‐specific approach disputes a prevailing dogma where glycoconjugate vaccines require multivalent display of antigens.

In situ endoscopic photodynamic therapy combined with immature DC vaccination induces a robust T cell response against peritoneal carcinomatosis.

Immunogenic cell death (ICD) and ferroptosis have recently emerged as key factors in the anticancer immune response. Among the treatments able to induce ICD and the associated release of danger signals is photodynamic therapy (PDT). Ferroptosis for its part results from lipid peroxidation and is induced by CD8+ T cells to kill nearby cancer cells on IFN-γ production. We aimed to combine the two concepts, that is, to evaluate whether the strong pro-oxidant effects of PDT may promote ferroptosis and antigen release and to develop a procedure for in situ PDT to prepare the soil for highly endocytotic immature dendritic cell (iDC) adoptive transfer. This approach was implemented for managing peritoneal carcinomatosis, a lesion often associated with poor outcomes. We used three-dimensional (3D) heterotypic spheroids made of cancer cells, exposed them to a white light-activated OR141 photosensitizer (PS), and subsequently complexified them by adding iDC and naive lymphocytes. We next used a model of mouse peritoneal carcinomatosis and administered PDT using laparoscopy to locally induce photoactivation using the endoscope light. The immune response following adoptive transfer of iDC was tracked both in vivo and ex vivo using isolated immune cells from in situ vaccinated mice. Cancer cells undergoing PDT-induced cell death significantly increased ICD markers and the infiltration of iDCs in spheroids, relying on ferroptosis. These actions induced the sequential activation of CD8+ and CD4+ T cells as revealed by a significant spheroid 3D structure deterioration and, remarkably, were not recapitulated by conventional ferroptosis inducer RSL3. Using LED light from an endoscope for in situ photoactivation of PS enabled us to apply the vaccination modality in mice with peritoneal tumors. Consecutive intraperitoneal injection of iDCs resulted in delayed tumor growth, increased survival rates, and prevented tumor relapse on rechallenge. CD8+ T cell response was supported by depletion experiments, nodal detection of early activated T cells, and ex vivo T cell-induced cytotoxicity toward spheroids. The combination of in situ PDT locally delivered by an endoscope light and iDC administration induces a durable memory immune response against peritoneal carcinomatosis thereby opening new perspectives for the treatment of a life-threatening condition.

Fibrolytic vaccination against ADAM12 reduces desmoplasia in preclinical pancreatic adenocarcinomas.

A hallmark feature of pancreatic ductal adenocarcinoma (PDAC) is massive intratumoral fibrosis, designated as desmoplasia. Desmoplasia is characterized by the expansion of cancer-associated fibroblasts (CAFs) and a massive increase in extracellular matrix (ECM). During fibrogenesis, distinct genes become reactivated specifically in fibroblasts, e.g., the disintegrin metalloprotease, ADAM12. Previous studies have shown that immunotherapeutic ablation of ADAM12+ cells reduces fibrosis in various organs. In preclinical mouse models of PDAC, we observe ADAM12 expression in CAFs as well as in tumor cells but not in healthy mouse pancreas. Therefore, we tested prophylactic and therapeutic vaccination against ADAM12 in murine PDAC and observed delayed tumor growth along with a reduction in CAFs and tumor desmoplasia. This is furthermore associated with vascular normalization and alleviated tumor hypoxia. The ADAM12 vaccine induces a redistribution of CD8+ T cells within the tumor and cytotoxic responses against ADAM12+ cells. In summary, vaccination against the endogenous fibroblast target ADAM12 effectively depletes CAFs, reduces desmoplasia and delays the growth of murine PDACs. These results provide proof-of-principle for the development of vaccination-based immunotherapies to treat tumor desmoplasia.

Combining Vascular Targeting Agents with Radiation: An Effective Anti-Tumor Treatment but Associated with Radiation-Induced Systemic Toxicity

This study investigated the effect of combining radiation with an angiogenesis inhibitor and vascular disrupting agent on tumor response and systemic toxicity. CDF1 mice with 200 mm3 foot implanted C3H mammary carcinomas were treated with TNP-470 (100 mg/kg every second day for 2 weeks; s.c.) and combretastatin A-4 phosphate (CA4P; 1 × 250 mg/kg, i.p.). Radiation (230-kV X-rays) was locally administered to tumors of restrained non-anesthetized mice. Response was tumor growth delay and change in mouse body weight. Radiation induced changes in serum levels of 10 cytokines up to 72-h after irradiation were measured using a Luminex assay. The results showed that TNP-470 (100 mg/kg × 7) or CA4P (250 mg/kg × 1) significantly (Student’s t-test; p < 0.05) inhibited tumor growth; the greatest effect when these two drugs were combined. TNP-470 and CA4P, alone or together, also significantly enhanced tumor response to radiation. No systemic toxicity occurred with drugs administered alone or in combination, but toxicity was observed when TNP-470 was combined with radiation. Serum cytokine levels only showed a significant transient increase in IL-6 1-h after irradiating. In conclusion, combining different acting vascular targeting agents with radiation increased anti-tumor activity. However, this benefit may sometimes be associated with a radiation-induced inflammatory response increasing systemic toxicity.

Abstract PR-07: Optimally designed mRNA vaccine encoding tumor-specific antigens identified in a colorectal cancer model leads to complete tumor rejection in mice

Abstract mRNA vaccines can be designed to encode multiple epitopes of choice, which is a crucial advantage when aiming to include a broad coverage immune response. Upon translation, the cell machinery must process the vaccine-encoded poly-epitope protein to release individual peptides. This processing step is key in inducing an immune response toward selected epitopes, as efficient processing yields a higher amount of peptide available for MHC-I presentation. The efficiency of peptide processing is greatly influenced by the peptide surrounding context (i.e. the flanking amino acids in N-and C-terminal). Aberrantly expressed tumor-specific antigens (aeTSAs) are MHC-I-associated peptides (MAPs) resulting from cancer-specific epigenetic changes and splicing aberrations. In contrast to TSAs derived from mutated protein-coding exons, aeTSAs are highly shared by different tumors. Moreover, unlike commonly used tumor-associated antigens (TAAs), they are not expressed by normal healthy cells, which is pivotal for inducing strong CD8+ T cell responses. The present study aimed to determine whether RNA vaccines encoding aeTSAs would elicit protective anti-tumor responses against a colorectal cancer cell line model (MC38). We hypothesized that multiepitope mRNA vaccine efficacy would be improved if the mRNA construct was composed of minimal epitopes (here, cancer antigens) bordered by optimal (rather than natural) flanking sequences. Thus, we designed 2 vaccine constructs encoding 5 aeTSAs identified by mass spectrometry in MC38 tumor cells. The 2 constructs differ in the identity of the amino acids flanking the antigens (natural vs. substituted antigen flanking sequences). Mice were injected subcutaneously with MC38 cells on Day 0. Three mRNA vaccine doses were administered intravenously one week apart, starting at Day 4. Vaccination with our improved mRNA vaccine design showed a clear therapeutic effect. As opposed to the natural flanking sequences design resulting in delayed tumor growth, vaccination with the substituted flanking sequences design led to the complete elimination of tumors and the survival of all mice. Elispot and dextramer stainings revealed that at least 3 of the 5 MC38 aeTSAs were immunogenic and that the amplitude of antigen-specific CD8+ T cell responses was significantly higher in mice vaccinated with the substituted flanking sequences design. Our results confirm our hypothesis that highly proficient flanking regions have intrinsic benefits that can be carried over to different antigens. From a translational perspective, our work provides new insights into the therapeutic potential of optimally designed aeTSA-encoding mRNA vaccines for treating cancers. Citation Format: Marie-Pierre Hardy, Krystel Vincent, Gabriel Ouellet-Lavallée, Chantal Durette, Isabelle Caron, Joel Lanoix, Mathieu Courcelles, Jean-Philippe Laverdure, Pierre Thibault, Claude Perreault. Optimally designed mRNA vaccine encoding tumor-specific antigens identified in a colorectal cancer model leads to complete tumor rejection in mice [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2024 Oct 18-21; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2024;12(10 Suppl):Abstract nr PR-07.

Abstract A030: CD4 neoantigen mRNA vaccine enhances endogenous CD8 responses and tumor control

Abstract CD4 T cells have long been known to be critical for priming CD8 T cells, a process referred to as CD4 T cell help. Recent data have suggested that CD4 help may be delivered at the surface of conventional type 1 dendritic cells (cDC1s), which can efficiently present antigens (Ag) on both MHC class I and class II molecules. However, the actual mechanisms underlying CD4 T cell help remain poorly characterized. We sought to understand how anti-tumor T cell responses are generated in the context of mRNA vaccines, which have been shown to elicit protective CD4 and/or CD8 T cells. For this purpose, we compared two mRNA-Lipoplex (mRNA-LPX) vaccines that express a single MHC-II-restricted Ag either tumor-specific (neoAg) or tumor-irrelevant. mRNA-LPX is injected intravenously and taken up predominantly by cDCs in the spleen.As expected, both vaccines elicited systemic CD4 T cell responses. However, only the anti-tumor CD4 T cell response elicited the accumulation of tumor-infiltrating CD8 lymphocytes (CD8 TILs) that led to tumor regression in a CD8-dependant manner. Single cell RNA-sequencing revealed higher expression of effector molecules and genes associated with stem-like progenitor T cell states in CD8 TILs following neoAg vaccine. In contrast, inhibitory molecules were down-regulated in CD8 TILs from neoAg-vaccinated mice.We next characterized the role of cDCs in the response to the vaccines. We found that both mRNA-LPX vaccines induced better maturation of cDC1s than cDC2s in the spleen. Surprisingly, priming of CD4 T cells was dependent on cDC1s, rather than cDC2s. cDC1s were also required for neoAg CD4 vaccine-induced CD8 TIL accumulation and for vaccine efficacy. We investigated whether neoAg-specific CD4 T cells were i) sufficient to enhance anti-tumor CD8 responses and ii) needed to maintain effector CD8 TIL activity in situ. Using adoptive cell transfer (ACT) into the tumor, we found that the transfer of neoAg-specific CD4 T cells alone significantly delayed tumor growth, suggesting an increased CD8 TIL activity. Interestingly, while the transfer of CD8 TILs alone was insufficient to control tumors; ACT of both CD4 and CD8 T cells was required for efficient tumor rejection. cDC1s were required for the efficacy of both, the ACT of CD4 T cells alone and the CD4 and CD8 ACT combination. Taken together, our data suggest a novel mechanism whereby immunizing with exogenous CD4 T cell epitopes can produce tumor immunity by generating endogenous CD8 responses. These results emphasize the importance of cDC1s for both, eliciting tumor-specific CD4 T cells in the setting of mRNA-LPX vaccine expressing a single MHC-II-restricted Ag and improving in situ anti-tumor CD8 responses and tumor control. We are currently investigating the mechanisms and location of the MHC-II-restricted neoAg dependent-cDC1 help using both in vivo and cell culture approaches.This model provides fundamental insight for the development of cancer vaccines and highlights the need of tumor-specific CD4 T cells and mature tumor-Ag loaded cDC1s. Citation Format: Camille-Charlotte Balanca, Aude-Hélène Capietto, Catherine Carbone, Alan Gutierrez, Yajun Chestnut, Ellen Duong, Aditya Anand, Anthony Antonelli, Jeanne Cheung, Shiuh Luoh, Ariane Nissembaum, Keiko Hokeness, Sara Wichner, Emily Freund, Vincent Javinal, Romain Bouziat, Joshua Gober, Adel ElSohly, Jon Linehan, Ugur Sahin, Lélia Delamarre, Ira Mellman. CD4 neoantigen mRNA vaccine enhances endogenous CD8 responses and tumor control [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2024 Oct 18-21; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2024;12(10 Suppl):Abstract nr A030.

CD94 deficiency or blockade unleashes the anti-tumor immunity in mice and humanized murine models

NKG2 family members have emerged as promising targets in tumor immunotherapy. CD94 can dimerize with both inhibitory and activating NKG2 proteins, while the overall effect and value of targeting CD94 on anti-tumor immunity are unclear. Here, it is shown that the expression of CD94 is upregulated on tumor-infiltrating natural killer (NK) cells and CD8+ T cells, and is related to their exhausted characteristics. Tumor-bearing CD94 knockout (CD94-KO) mice exhibit delayed tumor growth, decreased lung metastases, and prolonged survival. Single cell RNA-seq reveal a remodeled tumor microenvironment in CD94-KO mice, with a reduction in immunosuppressive cells and an increase in anti-tumor immune cells. Moreover, NK cells and CD8+ T cells become proliferative and strongly tumoricidal in CD94-KO mice, thus contributing to the tumor inhibition effect of CD94 deficiency. Treatment with a humanized anti-CD94 blocking antibody (h15C10) alone, in tumor-bearing humanized mouse, delays tumor progression, and improves the therapeutic efficacy of PD-L1 blockade through combination therapy. Our study indicates that CD94 may work as a candidate target in checkpoint immunotherapy.

Enhancing Intrapleural Hyperthermic Chemotherapy for Lung Cancer: Insights from 3D and PDX Models

Background/Objectives: Malignant pleural effusion (MPE) in lung cancer indicates systemically disseminated advanced lung cancer and is associated with poor survival. Intrapleural hyperthermic chemotherapy (IPHC) is a promising treatment for MPE; however, its biological basis is not fully understood. IPHC can enhance anticancer drug efficacy, particularly in drug-resistant cancers. This study investigated the effects of hyperthermia on cisplatin cytotoxicity in lung cancer cell lines, patient-derived tumor cells, and a patient-derived xenograft (PDX) model. Methods: Lung cancer cell lines (A549 and H2170) and patient-derived tumor cells were cultured in 2D/3D systems and treated with cisplatin under varying temperatures (37 °C, 43 °C, and 45 °C) and exposure times (5, 15, and 30 min). Antiproliferative effects were evaluated using LDH and CCK-8 assays. Optimal conditions identified in cell culture experiments were validated using a PDX model; tumor growth inhibition, delay, and protein expression were analyzed post-treatment. Results: Hyperthermia significantly enhanced the antitumor efficacy of cisplatin at 43 °C and 45 °C, with comparable effects under 15 and 30 min exposure. In the PDX model, IPHC showed increased tumor inhibition and necrosis and delayed tumor regrowth, particularly at higher cisplatin doses. Protein expression analysis revealed that hyperthermia decreased EGFR expression and increased levels of apoptosis-related proteins, including cleaved PARP and caspase-3. Conclusions: IPHC with cisplatin demonstrated enhanced antitumor efficacy in vitro models, particularly in drug-resistant lung cancer, indicating its potential as a valuable adjunct to existing treatment regimens for lung cancer and for improving patient outcomes in advanced lung cancer with MPE or pleural metastasis.

Preclinical evaluation of 225Ac-labeled minigastrin analog DOTA-CCK-66 for Targeted Alpha Therapy.

Treatment studies were performed (3 groups, n = 5, AR42J tumor-bearing 394-NOD SCID mice). Control group animals were injected with [68Ga]Ga-DOTA-CCK-66 (1.1MBq, PET/CT imaging), while treatment group animals received a single dose of either [177Lu]Lu-DOTA-CCK-66 (37MBq, radioligand therapy (RLT)) or [225Ac]Ac-DOTA-CCK-66 (37kBq, TAT). All animals' tumor volume and body weight were monitored twice a week until end-point criteria were reached. Blood samples were evaluated (VetScan VS2, Abaxis) once mice were sacrificed. Upon treatment, an initial decline in tumor volume, followed by a significantly delayed tumor growth of treated cohorts, was observed. Mean survival of 177Lu- as well as 225Ac-treated animals was increased by 3- (37 ± 3 d) and 4.5-fold (54 ± 6d), respectively, when compared to non-treated animals (12 ± 3d). Blood sample analysis did not indicate toxic side effects to the liver, kidney, or stomach upon 177Lu and 225Ac-treatment. We demonstrated a substantial therapeutic efficacy of 177Lu- and 225Ac-labeled DOTA-CCK-66. As expected, treatment with the latter resulted in the highest mean survival rates. These results indicate a high therapeutic potential of 225Ac-labeled DOTA-CCK-66 for TAT in MTC patient management.

Silmitasertib in Combination With Cabozantinib Impairs Liver Cancer Cell Cycle Progression, Induces Apoptosis, and Delays Tumor Growth in a Preclinical Model.

The rising incidence of hepatocellular carcinoma (HCC) is a global problem. Several approved treatments, including immune therapy and multi-tyrosine kinase inhibitors, are used for treatment, although the results are not optimum. There is an unmet need to develop highly effective chemotherapies for HCC. Targeting multiple pathways to attack cancer cells is beneficial. Cabozantinib is an orally available bioactive multikinase inhibitor and has a modest effect on HCC treatment. Silmitasertib is an orally bioavailable, potent CK2 inhibitor with a direct role in DNA damage repair and is in clinical trials for other cancers. In this study, we planned to repurpose these existing drugs on HCC treatment. We observed a stronger antiproliferative effect of these two combined drugs on HCC cells generated from different etiologies as compared to the single treatment. Global RNA-seq analyses revealed a decrease in the expression of G2/M cell cycle transition genes in HCC cells following combination treatment, suggesting G2 phase cell arrest. We observed G2/M cell cycle phase arrest in HCC cells upon combination treatment compared to the single-treated or vehicle-treated control cells. The downregulation of CCNA2 and CDC25C following combination therapy further supported the observation. Subsequent analyses demonstrated that combination treatment inhibited 70 kDa ribosomal protein S6 kinase (p70S6K) phosphorylation, and increased Bim expression. Apoptosis of HCC cells were accompanied by increased poly (ADP-ribose) polymerase cleavage and caspase-9 activation. Next, we observed that a combination therapy significantly delayed the progression of HCC xenograft growth as compared to vehicle control. Together, our results suggested combining cabozantinib and silmitasertib would be a promising treatment option for HCC.

Neudesin regulates dendritic cell function and antitumor CD8+ T cell immunity

Dendritic cells (DCs) are essential for antitumor T-cell responses to immune checkpoint inhibitor therapies. We have previously reported that the secreted protein neudesin suppresses DC function. In contrast, neudesin has been found to be abundantly expressed in human cancers. In this study, we evaluated the role of neudesin in cancer immunity. Cancer-related database analysis revealed that patients with melanoma with low neudesin expression exhibited increased infiltration of DCs and CD8+ T cells and improved outcomes of checkpoint inhibitor therapy. In mouse tumor models, neudesin deficiency delayed tumor growth and increased the proportions of Type 1 conventional DCs (cDC1s) and tumor antigen-specific CD8+ T cells in tumors and tumor-infiltrating lymph nodes. Neudesin-deficient antitumor cDC1 vaccine enhanced the systemic immunity more effectively than the wild-type cDC1 vaccine. Overall, our findings highlight the importance of neudesin in cancer immunity, providing a novel target for immunotherapy.

Redefining FLASH Radiation Therapy: The Impact of Mean Dose Rate and Dose Per Pulse in the Gastrointestinal Tract

The understanding of how varying radiation beam parameter settings affect the induction and magnitude of the FLASH effect remains limited. We sought to systematically evaluate how the magnitude of radiation-induced gastrointestinal toxicity depends on the interplay between mean dose rate (MDR) and dose per pulse (DPP). C57BL/6J mice received total abdominal irradiation (TAI, 11-14 Gy single fraction) through either conventional (CONV) irradiation (low-DPP and low MDR, CONV) or through various combinations of DPP and MDR up to ultra-high-dose-rate beam conditions. DPPs ranging from 1 to 6 Gy were evaluated, while the total dose and MDR (>100 Gy/s) were kept constant; the effects of MDR were evaluated for the range of 0.3 to 1440 Gy/s, while the total dose and DPP were kept constant. Radiation-induced gastrointestinal toxicity was quantified in nontumor-bearing mice through the regenerating crypt assay and survival assessment. Tumor response was evaluated through tumor growth delay. Within each tested total dose using a constant MDR (>100 Gy/s), increasing DPP led to an increase in sparing (an increase in the number of regenerating crypts), with a more prominent effect seen at 12- and 14-Gy TAI. Interestingly, at DPPs of >4 Gy, a similar level of crypt sparing was demonstrated irrespective of the MDR used (from 0.3 to 1440 Gy/s). At a fixed high-DPP of 4.7 Gy, survival was equivalently improved relative to CONV irrespective of MDR. However, at a lower DPP of 0.93 Gy, an MDR of 104 Gy/s produced a greater survival effect compared with 0.3 Gy/s. We also confirmed that high-DPP, regardless of MDR, produced the same magnitude of tumor growth delay relative to CONV using a clinically relevant melanoma mouse model. This study demonstrates the strong influence that the beam parameter settings have on the magnitude of the FLASH effect. Both high-DPP and ultra-high-dose-rate appeared independently sufficient to produce FLASH sparing of gastrointestinal toxicity while isoeffective tumor response was maintained across all conditions.

A-264 Enhanced Phototherapeutic Efficacy Through Microbial Modulation in Cutaneous T-Cell Lymphoma delays tumour growth and increases survival in the murine EL4 model

A-264 Enhanced Phototherapeutic Efficacy Through Microbial Modulation in Cutaneous T-Cell Lymphoma delays tumour growth and increases survival in the murine EL4 model

Enhancing the potency of anti-P32-active targeted PEGylated liposomal doxorubicin using various spacers: In silico, in vitro and in vivo studies

Even though nanoliposomal drug delivery systems are superior to conventional drug delivery methods, studies indicate that they may deliver small quantities of drugs through passive targeting. Specific peptides are used to decorate the surface of the liposomes for active targeting of tumors. Among these, CGKRK is the tumor homing peptide to target p32 protein on the surface of endothelial and tumor cells. In the present study, serine-glycine (SG) and glycine-glycine-glycine (GGG) spacer were added to CGKRK, an anti-P32 peptide and in silico molecular docking studies were conducted. PEGylated liposomal doxorubicin (PLD) was then surface modified with these peptides. All liposomal formulations had the sizes between 96 and 110 nm, negative zeta potentials and there were spherical in shape. The release of the doxorubicin (Dox) followed the same pattern for all formulations during 24 h. The cytotoxic effects of the formulations during 1, 3 and 6 h of the incubation, indicated the time-dependent cytotoxicity of formulations, while the PLD-CGGGKRK was the most potent. Apoptosis and antiangiogenic assays were also demonstrated the ability of PLD-CGGGKRK in inducing apoptosis and decreasing vessels densities. The in vivo anti-tumor study demonstrated the efficacy of CGGGKRK surface-modified PLDs in delaying tumor growth and increasing the median survival. Our findings indicated that the GGG spacer could improve the efficacy of anti-P32 peptide, CGKRK, in targeting breast cancer tumor models in mice and merit further investigation.

ICOS limits memory-like properties and function of exhausted PD-1 + CD8 T cells.

During persistent antigen stimulation, PD-1 + CD8 T cells are maintained by progenitor exhausted PD-1 + TCF-1 + CD8 T cells (Tpex). Tpex respond to PD-1 blockade, and regulation of Tpex differentiation into more functional Tex is of major interest for cancer immunotherapies. Tpex express high levels of Inducible Costimulator (ICOS), but the role of ICOS for PD-1 + CD8 T cell responses has not been addressed. In chronic infection, ICOS-deficiency increased both number and quality of virus-specific CD8 T cells, with accumulation of effector-like Tex due to enhanced survival. Mechanistically, loss of ICOS signaling potentiated FoxO1 activity and memory-like features of Tpex. In mice with established chronic infection, ICOS-Ligand blockade resulted in expansion of effector-like Tex and reduction in viral load. In a mouse model of hepatocellular carcinoma, ICOS inhibition improved cytokine production by tumor-specific PD-1 + CD8 T cells and delayed tumor growth. Overall, we show that ICOS limits CD8 T cell responses during chronic antigen exposure.