Cell Cytotoxic Activity Research Articles

Multifunctional Biomimetic Nanocarriers for Dual-Targeted Immuno-Gene Therapy Against Hepatocellular Carcinoma.

Growing evidences have proved that tumors evade recognition and attack by the immune system through immune escape mechanisms, and PDL1/Pbrm1 genes have a strong correlation with poor response or resistance to immune checkpoint blockade (ICB) therapy. Herein, a multifunctional biomimetic nanocarrier (siRNA-CaP@PD1-NVs) is developed, which can not only enhance the cytotoxic activity of immune cells by blocking PD1/PDL1 axis, but also reduce tumor immune escape via Pbrm1/PDL1 gene silencing, leading to a significant improvement in tumor immunosuppressive microenvironment. Consequently, the nanocarrier promotes DC cell maturation, enhances the infiltration and activity of CD8+ T cells, and forms long-term immune memory, which can effectively inhibit tumor growth or even eliminate tumors, and prevent tumor recurrence and metastasis. Overall, this study presents a powerful strategy for co-delivery of siRNA drugs, immune adjuvant, and immune checkpoint inhibitors, and holds great promise for improving the effectiveness and safety of current immunotherapy regimens.

TLR Agonists Modify NK Cell Activation and Increase Its Cytotoxicity in Acute Lymphoblastic Leukemia.

Natural killer (NK) cells play a crucial role in innate immunity, particularly in combating infections and tumors. However, in hematological cancers, NK cells often exhibit impaired functions. Therefore, it is very important to activate its endosomal Toll-like receptors (TLRs) as a potential strategy to restore its antitumor activity. We stimulated NK cells from the peripheral blood mononuclear cells from children with acute lymphoblastic leukemia and NK cells isolated, and the NK cells were stimulated with specific TLR ligands (Poly I:C, Imiquimod, R848, and ODN2006) and we evaluated changes in IFN-γ, CD107a, NKG2D, NKp44 expression, Granzyme B secretion, cytokine/chemokine release, and cytotoxic activity. Results revealed that Poly I:C and Imiquimod enhanced the activation of both immunoregulatory and cytotoxic NK cells, increasing IFN-γ, CD107a, NKG2D, and NKp44 expression. R848 activated immunoregulatory NK cells, while ODN2006 boosted CD107a, NKp44, NKG2D, and IFN-γ secretion in cytotoxic NK cells. R848 also increased the secretion of seven cytokines/chemokines. Importantly, R848 and ODN 2006 significantly improved cytotoxicity against leukemic cells. Overall, TLR stimulation enhances NK cell activation, suggesting TLR8 (R848) and TLR9 (ODN 2006) ligands as promising candidates for antitumor immunotherapy.

A randomized, double-blind, placebo-controlled study on immune improvement effects of ethanolic extract of Echinacea purpurea (L.) Moench in Korean adults.

Echinacea purpurea (L.) Moench (EP), a medicinal plant native to North America, is now cultivated in various regions including Europe. With increasing popularity of Echinacea in Korea recently, a human clinical trial was conducted to evaluate immune-enhancing efficacy and safety of EP 60% ethanolic extract (EPE) in Koreans. Eighty volunteers were recruited for this randomized, double-blind, placebo-controlled clinical trial. They were randomly divided into two groups and given either a daily dose of 200 mg of EPE or a placebo. All participants underwent testing for Natural Killer (NK) cell cytotoxic activity, serum cytokine levels (IL-2, IL-6, IL-10, IL-12, IFN-γ, TNF-α), Wisconsin Upper Respiratory Symptom Survey-21 (WURSS-21), and Multidimensional Fatigue Scale (MFS) during this study to assess changes in outcomes. After 8 weeks of EPE consumption, a significant increase in NK cell cytotoxic activity compared to the placebo was observed. Additionally, serum cytokine levels of IL-2, IFN-γ, and TNF-α also significantly increased following EPE consumption. However, no significant changes were observed in WURSS-21 and MFS before and after EPE consumption. Throughout the 8-week study period, no adverse reactions were reported in relation to EPE consumption, and there were no clinically significant changes in diagnostic laboratory tests or vital signs in the EPE group. These results indicate that consumption of EPE could lead to immune improvement without any adverse effects. This clinical trial was the first to demonstrate beneficial effects of EPE consumption on immunity in Korean adults.

Inducing Effect of Corylus avellana on Cytotoxic Activity in Lung and Breast Cancer Cells via Apoptosis

Turkish hazelnut (Corylus avellana L. cv Tombul) is a widely used nut in the chocolate industry and is also rich in polyphenol content, which promises anticancer effects. The anti-cancer and apoptotic effects of hazelnut leaves extracts examined on lung and breast cancer cells. Sulforhodamine B (SRB) and Adenosine 5’- triphosphate (ATP) assays were carried out for cell viability measurement. The mode of cell death was shown morphologically by the double fluorescence staining. Apoptosis was determined by performing caspase-mediated cytokeratin 18 (M30 ELISA) and western blot analysis. PARP, caspase 3, caspase 8, DR4, and GAPHD (Glyceraldehyde-3-phosphate Dehydrogenase) protein bands were visualized as markers of apoptosis. A wound healing test was employed to measure cell migration. Methanol extract of hazelnut leaf exhibited inhibition of cell growth activities in a dose-dependent manner. IC50 values were determined as 32.17 µg/ml in MCF-7, 32.16 µg/ml in MDA-MB-231, 20.40 µg/ml in A549 and 12.04 µg/ml in H1299 cells for ethanol extract while it was determined as 21.08 µg/ml in MCF-7, 40.16 µg/ml in MDA-MB-231, 22.04 µg/ml in A549 and 5.91 µg/ml in H1299 cells in methanol extract. In comparison, methanol leaf extracts were more effective in H1299 cells (IC50 value was 5.91 µg/ml).In comparison, ethanol leaf extracts were more effective in H1299 cells (IC50 value was 9.722 µg/ml). Western blot analysis demonstrated that hazelnut leaf extract treatment of cancer cells led to cell death via apoptosis and inhibited cell migration in lung and breast cancer cell lines. The cytotoxic effects of hazelnut extract on breast and lung cancer cells might be valuable and promising in elucidating cell death mechanisms for the development of new methods in cancer treatment.

Synthesis and cytotoxic evaluation of heterocyclic compounds by vinylic substitution of ketene dithioacetals.

N-heterocyclic compounds are important molecular scaffolds in the search for new drugs, since most drugs contain heterocyclic moieties in their molecular structure, and some of these classes of heterocycles are able to provide ligands for two or more biological targets. Ketene dithioacetals are important building blocks in organic synthesis and are widely used in the synthesis of N-heterocyclic compounds. In this work, we used double vinylic substitution reactions on ketene dithioacetals to synthesize a small library of heterocyclic derivatives and evaluated their cytotoxic activity in breast and ovarian cancer cells, identifying two benzoxazoles with good potency and selectivity. In silico predictions indicate that the two most active derivatives exhibit physicochemical properties within the range of drug-like compounds and showed potential to interact with HDAC8 and ERK1 cancer-related targets.

Turning Waste into Wealth: A Potent Sono-Immune Strategy Based on Microcystis.

Currently, sonodynamic therapy (SDT) has limited therapeutic outcomes and immune responses, highlighting the urgent need for enhanced strategies that can stimulate robust and long-lasting antitumor effects. Microcystis, a notorious microalga, reveals the possibility of mediating SDT owing to the presence of gas vesicles (GVs) and phycocyanin (PC). Herein, a nontoxic strain of Microcystis elabens (labeled Me) is developed as a novel agent for SDT because it generates O2 under red light (RL) illumination, while GVs and PC act as cavitation nuclei and sonosensitizers, respectively. Moreover, algal debris is released after ultrasound (US) irradiation, which primes the Toll-like receptor pathway to initiate a cascade of immune responses. This sono-immune strategy inhibits CT26 colon tumor growth largely by promoting dendritic cell (DC) maturation and cytotoxic T-cell activation. After combination with the immune checkpoint blockade (ICB), the therapeutic outcome is further amplified, accompanied by satisfactory abscopal and immune memory effects; the similar potency is proven in the "cold" 4T1 triple-negative breast tumor. In addition, Me exhibits good biosafety without significant acute or chronic toxicity. Briefly, this study turns waste into wealth by introducing sono-immunotherapy based on Microcystis that achieved encouraging therapeutic effects on cancer, which is expected to be translated into the clinic.

Natural killer cells in cancer immunotherapy.

Natural killer (NK) cells, as innate lymphocytes, possess cytotoxic capabilities and engage target cells through a repertoire of activating and inhibitory receptors. Particularly, natural killer group 2, member D (NKG2D) receptor on NK cells recognizes stress-induced ligands-the MHC class I chain-related molecules A and B (MICA/B) presented on tumor cells and is key to trigger the cytolytic response of NK cells. However, tumors have developed sophisticated strategies to evade NK cell surveillance, which lead to failure of tumor immunotherapy. In this paper, we summarized these immune escaping strategies, including the downregulation of ligands for activating receptors, upregulation of ligands for inhibitory receptors, secretion of immunosuppressive compounds, and the development of apoptosis resistance. Then, we focus on recent advancements in NK cell immune therapies, which include engaging activating NK cell receptors, upregulating NKG2D ligand MICA/B expression, blocking inhibitory NK cell receptors, adoptive NK cell therapy, chimeric antigen receptor (CAR)-engineered NK cells (CAR-NK), and NKG2D CAR-T cells, especially several vaccines targeting MICA/B. This review will inspire the research in NK cell biology in tumor and provide significant hope for improving cancer treatment outcomes by harnessing the potent cytotoxic activity of NK cells.

PLGA and PDMS-based in situ forming implants loaded with rosuvastatin and copper-selenium nanoparticles: a promising dual-effect formulation with augmented antimicrobial and cytotoxic activity in breast cancer cells.

Breast cancer is among the most prevalent tumors worldwide. In this study, in-situ forming implants (ISFIs) containing rosuvastatin calcium were prepared using three types of poly (D, L-lactic-co-glycolic acid) (PLGA), namely, PLGA 50/50 with ester terminal and PLGA 75/25 with ester or acid terminal. Additionally, polydimethylsiloxane (PDMS) was added in concentrations of 0, 10, 20, and 30% w/v to accelerate matrix formation. The prepared ISFIs were characterized for their rheological behaviors, rate of matrix formation, and in-vitro drug release. All the prepared formulations revealed a Newtonian flow with a matrix formation rate between 0.017 and 0.059mm/min. Generally, increasing the concentration of PDMS increased the matrix formation rate. The prepared implants' release efficiency values ranged between 46.39 and 89.75%. The ISFI containing PLGA 50/50 with 30% PDMS was selected for further testing, as it has the highest matrix formation rate and a promising release efficiency value. Copper-selenium nanoparticles were prepared with two different particle sizes (560 and 383nm for CS1 and CS2, respectively) and loaded into the selected formulation to enhance its anticancer activity. The unloaded and loaded implants with rosuvastatin and copper-selenium nanoparticles were evaluated for their antibacterial activity, against Gram-positive and negative microorganisms, and anticancer efficacy, against MCF-7 and MDA-MB-231 cell lines. The results confirmed the potency of rosuvastatin calcium against cancer cells and the synergistic effect when loaded with smaller particle sizes of copper-selenium nanoparticles. This formulation holds a considerable potential for efficient breast cancer therapy.

AFNT-211: A phase 1 study of autologous CD4+ and CD8+ T cells engineered to express a high avidity HLA-A*11:01-restricted, KRAS G12V-specific, transgenic TCR, a CD8α/β coreceptor, and a FAS41BB switch receptor in patients with advanced/metastatic solid tumors.

TPS8650 Background: Activating mutations in KRAS (including KRAS G12V) are well-described oncogenic drivers in solid tumors. Patients with KRAS driver mutations have a poor prognosis, and most KRAS-mutated cancers lack effective therapies. T cell receptor (TCR)-T cell therapies targeting mutant KRAS have demonstrated proof of concept in the clinic, but duration of response remains a challenge. AFNT-211 represents a novel strategy to address the immunosuppressive tumor microenvironment and improve response rate and duration in solid tumors. AFNT-211 autologous CD4+ and CD8+ T cells are engineered to express a high avidity HLA-A*11:01-restricted, KRAS G12V-specific, transgenic TCR; the wildtype CD8α/β coreceptor; and a FAS-41BB switch receptor. The intended mechanism of action is recognition and elimination of KRAS G12V-mutated tumor cells by AFNT-211. AFNT-211 is designed to enhance anti-tumor activity via the following mechanisms of action as shown in preclinical models: (1) the CD8α/β coreceptor enables MHC-I– restricted TCR recognition of the KRAS G12V target by CD4+ T cells; (2) engaging CD4+ helper T cell responses drives enhanced CD8+ T cell cytotoxic activity and prevents T cell exhaustion; (3) the FAS-41BB chimeric switch receptor drives increased T cell activity, circumventing native FAS apoptotic signaling. Methods: This ongoing Phase 1, first-in-human, multicenter, open-label study of AFNT-211 (1) evaluates safety/tolerability, (2) determines the optimal biological dose (OBD) and recommended Phase 2 dose (RP2D), and (3) assesses preliminary antitumor activity. The study consists of 2 parts: dose escalation and dose expansion. Dose escalation is guided by the Bayesian optimal interval Phase 1/2 (BOIN12) design to determine the OBD. The BOIN12 design quantifies the desirability of a dose in terms of toxicity-efficacy tradeoff and adaptively allocates patients to the dose with the highest estimated desirability. The RP2D will be selected based on the BOIN12 design and the totality of benefit/risk assessment. Patients enrolling in dose expansion will be treated at the OBD/RP2D in indication-specific cohorts. This study is conducted in patients aged ≥ 18 years who are HLA-A*11:01-positive with advanced/metastatic solid tumors harboring a KRAS G12V mutation, and intolerance of/progression on at least 1 prior systemic therapy. Patients undergo leukapheresis to collect T cells for the manufacturing of AFNT-211 and receive lymphodepleting chemotherapy prior to AFNT-211 infusion. This is followed by a 28-day dose-limiting toxicity observation period (dose escalation only) and a post-treatment follow-up period for 24 months/ until disease progression. The study is open for recruitment in the United States. Clinical trial information: NCT06105021 .

A phase 1/1b, first-in-human, multi-part study of DF6215, an engineered IL-2Rα-active agonist, to investigate the safety, tolerability, pharmacokinetics, and biological and clinical activity in patients with advanced solid tumors.

TPS2704 Background: IL-2 is a pleiotropic cytokine that stimulates strong anti-tumor responses by promoting expansion and activation of cytotoxic tumor-infiltrating immune cells including CD8 + T cells and NK cells (1). Aldesleukin is an approved rhIL-2; however, it has clinical limitations due to short half-life, requirement for 5 days of hospitalization per cycle, and high toxicity [eg, cytokine-related toxicity, capillary leak syndrome (CLS)] that limits its use [aldesleukin USPI]. DF6215 is a modified monovalent human IL-2 that binds to the IL2R. Preclinically, DF6215 administration results in sustained and modulated IL-2 pharmacology, leading to protracted pharmacodynamic (PD) effects and enhanced anti-tumor activity without observation of CLS in murine and primate toxicology studies. In response to the limitations of previous IL-2 therapeutics, DF6215 was designed as an IL-2Rα-active agonist with increased IL-2Rβγ stimulation to improve the benefit-to-risk ratio of historic IL-2 drugs. An additional design element is a prolonged elimination half-life due to Fc fusion, allowing for less frequent dosing. Methods: This is a first-in-human, open-label, multipart, Phase 1/1b clinical trial to characterize the initial safety, tolerability, pharmacokinetics, and preliminary efficacy of DF6215 in patients with advanced solid tumors. The Phase 1 dose escalation (DE) starting dose is 10 ug/kg IV every 2 weeks (up to 42 subjects expected to be enrolled), and the Safety/PK/PD will be explored at doses already characterized as safe in dose escalation and potentially efficacious (max of 40 subjects). Phase 1b includes an efficacy expansion (EE) cohort in subjects with advanced melanoma who have received prior anti-PD-1 agents and, if the tumor harbors a BRAF-activating mutation, a BRAF inhibitor. Key inclusion criteria include ≥ 18 years of age; ECOG PS of 0 or 1; adequate organ function, and locally advanced or metastatic solid tumors for which standard therapy options have been exhausted; and availability of baseline tumor biopsy. Primary objectives include determination of the MTD of DF6215 in DE and demonstration of clinical activity of DF6215 in the EE. Secondary objectives include assessment of safety and tolerability, pharmacokinetics, and immunogenicity of DF6215. This study plans to enroll up to 102 subjects across ~30 global centers in the US, European, and the Asia/Pacific regions, and is currently open to enrollment. 1. Arenas-Ramirez N, et al. 2015. Trends Immunol. Clinical trial information: NCT06108479 .

IL-27-engineered CAR.19-NK-92 cells exhibit enhanced therapeutic efficacy

Chimeric antigen receptor (CAR) engineering of natural killer (NK) cells has shown promising results in early-phase clinical studies. However, advancing CAR-NK cell therapeutic efficacy is imperative. In this study, we investigated the impact of a fourth-generation CD19-targeted CAR (CAR.19) coexpressing IL-27 on NK-92 cells. We observed a significant improvement in NK-92 cell proliferation and cytotoxicity activity against B-cell cancer cell lines, both in vitro and in a xenograft mouse B-cell lymphoma model. Our systematic transcriptome analysis of the activated NK-92 CAR variants further supports the potential of IL-27 in fourth-generation CARs to overcome limitations of NK cell-based targeted tumor therapies by providing essential growth and activation signals. Integrating IL-27 into CAR-NK cells emerges as a promising strategy to enhance their therapeutic potential and elicit robust responses against cancer cells. These findings contribute substantially to the mounting evidence supporting the potential of fourth-generation CAR engineering in advancing NK cell-based immunotherapies.

Isolation of flavonoids from Tagetes patula(French Marigold) flowers: Cytotoxic and oxidant activity in human cervical carcinoma cells

Tagetes patula, known as French Marigold, belongs to the family Asteraceae. Human papillomavirus infection is considered one of the causes of cervical cancer. This study assessedthe cytotoxic activity and intracellular oxidative capacity of compounds isolated from extract of T. patulaflowers as anti-cancer cervical agents. Fraction F6 of n-butanol extract was subjected to column chromatography and HPLC-ESI-MS. The isolated compounds of T. patulawere used to examine cytotoxic activity and the production of total reactive oxygen species in SiHa and HeLa cells; the cells were also characterized using scanning electron microscopy. Patulitrin was cytotoxic to SiHa and HeLa cells. An increase in ROS production was observed at different times of treatment of cells with patuletin and patulitrin. Scanning electron microscopy showed morphological changes in SiHa and HeLa cells. Thus, compounds isolated from T. patulahave great treatment potential against cervical cancer.

In situ analysis of CCR8+ regulatory T cells in lung cancer: suppression of GzmB+ CD8+ T cells and prognostic marker implications

BackgroundCCR8-expressing regulatory T cells (Tregs) are selectively localized within tumors and have gained attention as potent suppressors of anti-tumor immunity. This study focused on CCR8+ Tregs and their interaction with CD8+ T cells in the tumor microenvironment of human lung cancer. We evaluated their spatial distribution impact on CD8+ T cell effector function, specifically granzyme B (GzmB) expression, and clinical outcomes.MethodsA total of 81 patients with lung squamous cell carcinoma (LSCC) who underwent radical surgical resection without preoperative treatment were enrolled. Histological analyses were performed, utilizing an automated image analysis system for double-stained immunohistochemistry assays of CCR8/Foxp3 and GzmB/CD8. We investigated the association of CCR8+ Tregs and GzmB+ CD8+ T cells in tumor tissues and further evaluated the prognostic impact of their distribution profiles.ResultsHistological evaluation using the region of interest (ROI) protocol showed that GzmB expression levels in CD8+ T cells were decreased in areas with high infiltration of CCR8+ Tregs, suggesting a suppressive effect of CCR8+ Tregs on T cell cytotoxicity in the local tumor microenvironment. Analysis of the association with clinical outcomes showed that patients with more CCR8+ Tregs and lower GzmB expression, represented by a low GzmB/CCR8 ratio, had worse progression-free survival.ConclusionsOur data suggest that local CCR8+ Treg accumulation is associated with reduced CD8+ T cell cytotoxic activity and poor prognosis in LSCC patients, highlighting the biological role and clinical significance of CCR8+ Tregs in the tumor microenvironment. The GzmB/CCR8 ratio may be a useful prognostic factor for future clinical applications in LSCC.

T cell activation and deficits in T regulatory cells are associated with major depressive disorder and severity of depression

Major depressive disorder (MDD) is associated with T cell activation, but no studies have examined the combined effects of T cell activation and deficits in T regulatory (Treg) cells on the severity of acute phase MDD. Using flow cytometry, we determined the percentage and median fluorescence intensity of CD69, CD71, CD40L, and HLADR-bearing CD3+, CD4+, and CD8+ cells, and cannabinoid type 1 receptor (CB1), CD152 and GARP (glycoprotein A repetitions predominant)-bearing CD25+ FoxP3 T regulatory (Treg) cells in 30 MDD patients and 20 healthy controls in unstimulated and stimulated (anti-CD3/CD28) conditions. Based on cytokine levels, we assessed M1 macrophage, T helper (Th)-1 cell, immune-inflammatory response system (IRS), T cell growth, and neurotoxicity immune profiles. We found that the immune profiles (including IRS and neurotoxicity) were significantly predicted by decreased numbers of CD152 or GARP-bearing CD25+ FoxP3 cells or CD152 and GARP expression in combination with increases in activated T cells (especially CD8+ CD40L+ percentage and expression). MDD patients showed significantly increased numbers of CD3+ CD71+, CD3+ CD40L+, CD4+ CD71+, CD4+ CD40L+, CD4+ HLADR+, and CD8+ HLADR+ T cells, increased CD3+ CD71+, CD4+ CD71+ and CD4+ HLADR+ expression, and lowered CD25+ FoxP3 expression and CD25+ FoxP+ CB1+ numbers as compared with controls. The Hamilton Depression Rating Scale score was strongly predicted (between 30 and 40% of its variance) by a lower number of CB1 or GARP-bearing Treg cells and one or more activated T cell subtypes (especially CD8+ CD40L+). In conclusion, increased T helper and cytotoxic cell activation along with decreased Treg homeostatic defenses are important parts of MDD that lead to enhanced immune responses and, as a result, neuroimmunotoxicity.

LL37 Microspheres Loaded on Activated Carbon-chitosan Hydrogel: Anti-bacterial and Anti-toxin Wound Dressing for Chronic Wound Infections.

Antimicrobial peptide LL37 is a promising antibacterial candidate due to its potent antimicrobial activity with no known bacterial resistance. However, intrinsically LL37 is susceptible to degradation in wound fluids limits its effectiveness. Bacterial toxins which are released after cell lysis are found to hinder wound healing. To address these challenges, encapsulating LL37 in microspheres (MS) and loading the MS onto activated carbon (AC)-chitosan (CS) hydrogel. This advanced wound dressing not only protects LL37 from degradation but also targets bacterial toxins, aiding in the healing of chronic wound infections. First, LL37 MS and LL37-AC-CS hydrogel were prepared and characterised in terms of physicochemical properties, drug release, and peptide-polymer compatibility. Antibacterial and antibiofilm activity, bacterial toxin elimination, cell migration, and cell cytotoxicity activities were investigated. LL37-AC-CS hydrogel was effective against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. LL37-AC-CS hydrogel bound more endotoxin than AC with CS hydrogel alone. The hydrogel also induced cell migration after 72h and showed no cytotoxicity towards NHDF after 72h of treatment. In conclusion, the LL37-AC-CS hydrogel was shown to be a stable, non-toxic advanced wound dressing method with enhanced antimicrobial and antitoxin activity, and it can potentially be applied to chronic wound infections to accelerate wound healing.

Emetine induces oxidative stress, cell differentiation and NF-κB inhibition, suppressing AML stem/progenitor cells

Acute myeloid leukemia (AML) is a fatal malignancy of the blood and bone marrow. Leukemic stem cells (LSCs) are a rare subset of leukemic cells that promote the development and progression of AML, and eradication of LSCs is critical for effective control of this disease. Emetine is an FDA-approved antiparasitic drug with antitumor properties; however, little is known about its potential against LSCs. Herein, we explored the antileukemic potential of emetine, focusing on its effects on AML stem/progenitor cells. Emetine exhibited potent cytotoxic activity both in hematologic and solid cancer cells and induced AML cell differentiation. Emetine also inhibited AML stem/progenitor cells, as evidenced by decreased expression of CD34, CD97, CD99, and CD123 in KG-1a cells, indicating anti-AML stem/progenitor cell activities. The administration of emetine at a dosage of 10 mg/kg for two weeks showed no significant toxicity and significantly reduced xenograft leukemic growth in vivo. NF-κB activation was reduced in emetine-treated KG-1a cells, as shown by reduced phospho-NF-κB p65 (S529) and nuclear NF-κB p65. DNA fragmentation, YO-PRO-1 staining, mitochondrial depolarization and increased levels of active caspase-3 and cleaved PARP (Asp214) were detected in emetine-treated KG-1a cells. Moreover, treatment with the pancaspase inhibitor Z-VAD(OMe)-FMK partially prevented the apoptotic cell death induced by emetine. Emetine treatment also increased cellular and mitochondrial reactive oxygen species, and emetine-induced apoptosis in KG-1a cells was partially prevented by the antioxidant N-acetylcysteine, indicating that emetine induces apoptosis, at least in part, by inducing oxidative stress. Overall, these studies indicate that emetine is a novel potential anti-AML agent with promising activity against stem/progenitor cells, encouraging the development of further studies aimed at its clinical application.

Abstract CT076: AFNT-211: A phase1 study of autologous CD4+ and CD8+ T cells engineered to express a high avidity HLA-A*11:01-restricted, KRAS G12V-specific, transgenic TCR; CD8α/β coreceptor; and a FAS41BB switch receptor in patients with advanced/metastatic solid tumors

Abstract Background: Activating mutations in KRAS (including KRAS G12V) are well-described oncogenic drivers in solid tumors. Patients with KRAS driver mutations have a poor prognosis, and most KRAS-mutated cancers lack effective therapies. T cell receptor (TCR)-T cell therapies targeting mutant KRAS have demonstrated proof of concept in the clinic, but duration of response remains a challenge. AFNT-211 represents a novel strategy to address the immunosuppressive tumor microenvironment and improve response rate and duration in solid tumors. Rationale: AFNT-211 autologous CD4+ and CD8+ T cells are engineered to express a high avidity HLA-A*11:01restricted, KRAS G12V-specific, transgenic TCR; the wildtype CD8α/β coreceptor; and a FAS-41BB switch receptor. The intended mechanism of action is recognition and elimination of KRAS G12V-mutated tumor cells by AFNT-211. AFNT-211 is designed to enhance anti-tumor activity via the following mechanisms of action as shown in preclinical models: (1) the CD8α/β coreceptor enables MHC-I-‍restricted TCR recognition of the KRAS G12V target by CD4+ T cells; (2) engaging CD4+ helper T cell responses drives enhanced CD8+ T cell cytotoxic activity and prevents T cell exhaustion; (3) the FAS-41BB chimeric switch receptor drives increased T cell activity, circumventing native FAS apoptotic signaling. Methods: This ongoing Phase 1, first-in-human, multicenter, open-label study of AFNT-211 (1) evaluates safety/tolerability, (2) determines the optimal biological dose (OBD) and recommended Phase 2 dose (RP2D), and (3) assesses preliminary antitumor activity. The study consists of 2 parts: dose escalation and dose expansion. Dose escalation is guided by the Bayesian optimal interval Phase 1/2 (BOIN12) design to determine the OBD. The BOIN12 design quantifies the desirability of a dose in terms of toxicity-efficacy tradeoff and adaptively allocates patients to the dose with the highest estimated desirability. The RP2D will be selected based on the BOIN12 design and the totality of benefit/risk assessment. Patients enrolling in dose expansion will be treated at the OBD/RP2D in indication-specific cohorts. This study is conducted in patients aged ≥ 18 years who are HLA-A*11:01-positive with advanced/metastatic solid tumors harboring a KRAS G12V mutation, and intolerance of/progression on at least 1 prior systemic therapy. Patients undergo leukapheresis to collect T cells for the manufacturing of AFNT-211 and receive lymphodepleting chemotherapy prior to AFNT-211 infusion. This is followed by a 28-day dose-limiting toxicity observation period (dose escalation only) and a post-treatment follow-up period for 24 months/until disease progression. The study is open for recruitment in the United States (NCT06105021). Citation Format: Shaunica Mitchell, Binaish Khan, Francis Payumo, E. Gabriela Chiorean, Zhubin Gahvari, J. Randolph Hecht, Michael Hurwitz, Rom Leidner, Heinz-Josef Lenz, Meredith Pelster, Salman Punekar, Adam Schoenfeld, Dan Zhao, Markus Vallaster, Dirk Nagorsen. AFNT-211: A phase1 study of autologous CD4+ and CD8+ T cells engineered to express a high avidity HLA-A*11:01-restricted, KRAS G12V-specific, transgenic TCR; CD8α/β coreceptor; and a FAS41BB switch receptor in patients with advanced/metastatic solid 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 CT076.

Abstract LB363: A novel humanized NKP46 mouse model to support xenograft studies evaluating NK cell-based cancer immunotherapies

Abstract The NKP46 receptor is expressed by all NK cells, and plays a key role in the recognition and activation of NK cells against tumor cells. Cross-linking of NKp46 by monoclonal antibodies triggers both NK cell cytotoxic activity and cytokine release. As the only NCR present in mice, NKP46 is well conserved, but differences between the murine and human NKP46 protein necessitate use of humanized mice for evaluating preclinical efficacy of novel NKP46-targeting antibodies. Previously, we established humanized NKP46 mice on immunocompetent backgrounds for evaluating antibody efficacy in preventing growth of syngeneic tumor models. However, xenograft models in immunodeficient mice have also been widely employed as important in vivo models. Here, we describe a novel humanized NKP46 mouse on the CB-17-SCID background in order to inoculate human tumor cells for therapeutic efficacy testing. In this model, using gene editing technology, the portion of the mouse NKp46 gene encoding the extracellular domain was replaced by the corresponding human NKP46 coding sequences. Human NKP46 protein expression was confirmed on NK cells derived from splenocytes and bone marrow of B-hNKP46 mice(CB17-SCID) by flow cytometry. Subsequently, assessment of leukocyte populations in the humanized model indicated no significant alterations in the percentages of NK cells, dendritic cells, granulocytes, monocytes and macrophages in the spleen, bone marrow or blood of the humanized mice compared with wild-type CB17-SCID mice. Finally, tumor efficacy studies demonstrate that treatment with an anti-human NKP46 antibody significantly reduced BxPC-3 tumor growth at a range of doses in homozygous hNKP46 mice compared to PBS-injected controls. In summary, humanized B-hBKP46 mice(CB17-SCID) provide a suitable model for evaluating the efficacy of anti-human NKP46 antibody candidates. Citation Format: Zhenlan Niu, Yongshun Li, Xiaofei Zhou, Jiawei Yao, Qingcong Lin, Meiqi Zhang, Qingqing Xu. A novel humanized NKP46 mouse model to support xenograft studies evaluating NK cell-based cancer immunotherapies [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 LB363.

Natural killer cell subsets and their functional molecules in peripheral blood of the patients with breast cancer.

Natural killer (NK) cells, CD3- lymphocytes, are critical players in cancer immune surveillance. This study aimed to assess two types of CD3- NK cell classifications (subsets), that is, convectional subsets (based on CD56 and CD16 expression) and new subsets (based on CD56, CD27, and CD11b expression), and their functional molecules in the peripheral blood of patients with breast cancer (BC) in comparison with healthy donors (HDs). Thirty untreated females with BC and 20 age-matched healthy women were enrolled. Peripheral blood samples were collected and directly incubated with fluorochrome-conjugated antibodies against CD3, CD56, CD16, CD27, CD11b, CD96, NKG2C, NKG2D, NKp44, CXCR3, perforin, and granzyme B. Red blood cells were then lysed using lysing solution, and the stained cells were acquired on four-color flow cytometer. Our results indicated 15% of lymphocytes in peripheral blood of patients with BC and HDs had NK cells phenotype. However, the frequency of total NK cells (CD3-CD56+), and NK subsets (based on conventional and new classifications) was not significantly different between patients and HDs. We observed mean fluorescent intensity (MFI) of CXCR3 in total NK cells (p = .02) and the conventional cytotoxic (CD3-CD56dim CD16+) NK cells (p = .03) were significantly elevated in the patients with BC compared to HDs. Despite this, the MFI of granzyme B expression in conventional regulatory (CD3-CD56brightCD16- /+) NK cells and CD3-CD56-CD16+ NK cells (p = .03 and p = .004, respectively) in the patients was lower than healthy subjects. The higher expression of chemokine receptor CXCR3 on total NK cells in patients with BC may be associated with increased chemotaxis-related NK cell infiltration. However, lower expression of granzyme B in conventional regulatory NK cells and CD3-CD56-CD16+ NK cells in the patients compared to HDs suggests reduced cytotoxic activity of the NK cells in BC. These results might demonstrate accumulating NK subsets with a dysfunctional phenotype in the peripheral blood of patients with BC.

GD2-Targeting CAR T-cell Therapy for Patients with GD2+ Medulloblastoma.

Medulloblastoma (MB), the most common childhood malignant brain tumor, has a poor prognosis in about 30% of patients. The current standard of care, which includes surgery, radiation, and chemotherapy, is often responsible for cognitive, neurologic, and endocrine side effects. We investigated whether chimeric antigen receptor (CAR) T cells directed toward the disialoganglioside GD2 can represent a potentially more effective treatment with reduced long-term side effects. GD2 expression was evaluated on primary tumor biopsies of MB children by flow cytometry. GD2 expression in MB cells was also evaluated in response to an EZH2 inhibitor (tazemetostat). In in vitro and in vivo models, GD2+ MB cells were targeted by a CAR-GD2.CD28.4-1BBζ (CAR.GD2)-T construct, including the suicide gene inducible caspase-9. GD2 was expressed in 82.68% of MB tumors. The SHH and G3-G4 subtypes expressed the highest levels of GD2, whereas the WNT subtype expressed the lowest. In in vitro coculture assays, CAR.GD2 T cells were able to kill GD2+ MB cells. Pretreatment with tazemetostat upregulated GD2 expression, sensitizing GD2dimMB cells to CAR.GD2 T cells cytotoxic activity. In orthotopic mouse models of MB, intravenously injected CAR.GD2 T cells significantly controlled tumor growth, prolonging the overall survival of treated mice. Moreover, the dimerizing drug AP1903 was able to cross the murine blood-brain barrier and to eliminate both blood-circulating and tumor-infiltrating CAR.GD2 T cells. Our experimental data indicate the potential efficacy of CAR.GD2 T-cell therapy. A phase I/II clinical trial is ongoing in our center (NCT05298995) to evaluate the safety and therapeutic efficacy of CAR.GD2 therapy in high-risk MB patients.