Cellular Cytotoxicity Research Articles

Induction of NK cell reactivity against acute myeloid leukemia by Fc-optimized CD276 (B7-H3) antibody.

Acute myeloid leukemia (AML) remains a therapeutic challenge despite recent therapeutic advances. Although monoclonal antibodies (mAbs) engaging natural killer (NK) cells via antibody-dependent cellular cytotoxicity (ADCC) hold promise in cancer therapy, almost none have received clinical approval for AML, so far. Recently, CD276 (B7-H3) has emerged as a promising target for AML immunotherapy, due to its high expression on leukemic blasts of AML patients. Here, we present the preclinical development of the Fc-optimized CD276 mAb 8H8_SDIE with enhanced CD16 affinity. We demonstrate that 8H8_SDIE specifically binds to CD276 on AML cell lines and primary AML cells and induces pronounced NK cell activation and degranulation as measured by CD69, CD25, and CD107a. Secretion of IFNγ, TNF, granzyme B, granulysin, and perforin, which mediate NK cell effector functions, was induced by 8H8_SDIE. A pronounced target cell-restricted lysis of AML cell lines and primary AML cells was observed in cytotoxicity assays using 8H8_SDIE. Finally, xenograft models with 8H8_SDIE did not cause off-target immune activation and effectively inhibited leukemia growth in vivo. We here present a novel attractive immunotherapeutic compound that potently induces anti-leukemic NK cell reactivity in vitro and in vivo as treatment option for AML.

Effect of anti-claudin 18.2 monoclonal antibody zolbetuximab alone or combined with chemotherapy or programmed cell death-1 blockade in syngeneic and xenograft gastric cancer models

The development of targeted cancer therapies based on monoclonal antibodies against tumor-associated antigens has progressed markedly over recent decades. This approach is dependent on the identification of tumor-specific, normal tissue-sparing antigenic targets. The transmembrane protein claudin-18 splice variant 2 (CLDN18.2) is frequently and preferentially displayed on the surface of primary gastric adenocarcinomas, making it a promising monoclonal antibody target. Phase 3 studies of zolbetuximab, a chimeric immunoglobulin G1 monoclonal antibody targeting CLDN18.2, combined with 5-fluorouracil/leucovorin plus oxaliplatin (modified FOLFOX6) or capecitabine plus oxaliplatin (CAPOX) in advanced or metastatic first-line gastric or gastroesophageal junction (G/GEJ) adenocarcinoma have demonstrated favorable clinical results with zolbetuximab. In studies using xenograft or syngeneic models with gastric cancer cell lines, zolbetuximab mediated death of CLDN18.2-positive human cancer cell lines via antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity in vitro and demonstrated anti-tumor efficacy as monotherapy and combined with chemotherapy in vivo. Mice treated with zolbetuximab plus chemotherapy displayed a significantly higher frequency of tumor-infiltrating CD8+ T cells versus vehicle/isotype control-treated mice. Furthermore, zolbetuximab combined with an anti-mouse programmed cell death-1 antibody more potently inhibited tumor growth compared with either agent alone. These results support the potential of zolbetuximab as a novel treatment option for G/GEJ adenocarcinoma.

Concordance between In Vitro and In Vivo Relative Toxic Potencies of Diesel Exhaust Particles from Different Biodiesel Blends.

Diesel exhaust particles (DEPs) contribute to air pollution exposure-related adverse health impacts. Here, we examined in vitro, and in vivo toxicities of DEPs from a Caterpillar C11 heavy-duty diesel engine emissions using ultra-low-sulfur diesel (ULSD) and biodiesel blends (20% v/v) of canola (B20C), soy (B20S), or tallow-waste fry oil (B20T) in ULSD. The in vitro effects of DEPs (DEPULSD, DEPB20C, DEPB20S, and DEPB20T) in exposed mouse monocyte/macrophage cells (J774A.1) were examined by analyzing the cellular cytotoxicity endpoints (CTB, LDH, and ATP) and secreted proteins. The in vivo effects were assessed in BALB/c mice (n = 6/group) exposed to DEPs (250 µg), carbon black (CB), or saline via intratracheal instillation 24 h post-exposure. Bronchoalveolar lavage fluid (BALF) cell counts, cytokines, lung/heart mRNA, and plasma markers were examined. In vitro cytotoxic potencies (e.g., ATP) and secreted TNF-α were positively correlated (p < 0.05) with in vivo inflammatory potency (BALF cytokines, lung/heart mRNA, and plasma markers). Overall, DEPULSD and DEPB20C appeared to be more potent compared to DEPB20S and DEPB20T. These findings suggested that biodiesel blend-derived DEP potencies can be influenced by biodiesel sources, and inflammatory process- was one of the potential underlying toxicity mechanisms. These observations were consistent across in vitro and in vivo exposures, and this work adds value to the health risk analysis of cleaner fuel alternatives.

Maitake Beta-Glucan Enhances the Therapeutic Effect of Trastuzumab via Antibody-Dependent Cellular Cytotoxicity and Complement-Dependent Cytotoxicity.

Trastuzumab, an anti-HER2 monoclonal antibody, is the mainstay treatment for of HER2-positive breast cancer. However, trastuzumab resistance is often observed during treatment. Therefore, new therapeutic strategies are needed to enhance the clinical benefits of trastuzumab. Maitake β-glucan MD-Fraction, isolated from Grifola frondosa, inhibits tumor growth by enhancing immune responses. In this study, we examined the effect of MD-Fraction on trastuzumab treatment of HER2-positive breast cancer. MD-Fraction did not directly inhibit the survival of HER2-positive breast cancer cells, alone or in the presence of trastuzumab in vitro. In HER2-positive xenograft models, the combination of MD-Fraction and trastuzumab was more effective than trastuzumab alone. Peripheral blood lymphocytes and splenic natural killer cells isolated from BALB/c nu/nu mice treated with MD-Fraction showed enhanced trastuzumab-induced antibody-dependent cellular cytotoxicity (ADCC) ex vivo. MD-Fraction-treated macrophages and neutrophils did not show enhanced trastuzumab cytotoxicity in the presence of heat-inactivated serum, but they showed enhanced cytotoxicity in the presence of native serum. These results suggest that MD-Fraction-treated macrophages and neutrophils enhance trastuzumab-induced complement-dependent cellular cytotoxicity (CDCC). Treatment of HER2-positive breast cancer cells with MD-Fraction in the presence of trastuzumab and native serum increased C3a release and tumor cell lysis in a dose-dependent manner, indicating that MD-Fraction enhanced trastuzumab-induced complement-dependent cytotoxicity (CDC) by activating the complement system. This study demonstrates that the combination of trastuzumab and MD-Fraction exerts a greater antitumor effect than trastuzumab alone by enhancing ADCC, CDCC, and CDC in HER2-positive breast cancer.

Cholestane-3β,5α,6β-triol Induces Multiple Cell Death in A549 Cells via ER Stress and Autophagy Activation.

Cholestane-3β,5α,6β-triol (CT) and its analogues are abundant in natural sources and are reported to demonstrate cytotoxicity toward different kinds of tumor cells without a deep probe into their mechanism of action. CT is also one of the major metabolic oxysterols of cholesterol in mammals and is found to accumulate in various diseases. An extensive exploration of the biological roles of CT over the past few decades has established its identity as an apoptosis inducer. In this study, the effects of CT on A549 cell death were investigated through cell viability assays. RNA-sequencing analysis and western blot of CT-treated A549 cells revealed the role of CT in inducing endoplasmic reticulum (ER) stress response and enhancing autophagy flux, suggesting a putative mechanism of CT-induced cell-death activation involving reactive oxygen species (ROS)-mediated ER stress and autophagy. It is reported for the first time that the upregulation of autophagy induced by CT can serve as a cellular cytotoxicity response in accelerating CT-induced cell death in A549 cells. This research provides evidence for the effect of CT as an oxysterol in cell response to oxidative damage and allows for a deep understanding of cholesterol in its response in an oxidative stress environment that commonly occurs in the progression of various diseases.

Targeting sinonasal undifferentiated carcinoma with a combinatory immunotherapy approach

PurposeSinonasal undifferentiated carcinoma (SNUC) is a rare, aggressive malignancy of the sinonasal cavity with poor prognosis and limited treatment options. To investigate the potential for SNUC sensitivity to combinatory immunotherapy, we performed in vitro studies with SNUC cell lines and used multi-spectral immunofluorescence to characterize the in vivo patient SNUC tumor immune microenvironment (TIME). Experimental designHuman-derived SNUC cell lines were used for in vitro studies of tumor cell susceptibility to natural killer (NK) cell-based immunotherapeutic strategies. Tumor samples from 14 treatment naïve SNUC patients were examined via multi-spectral immunofluorescence and clinical correlations assessed. ResultsAnti-PD-L1 blockade enhanced NK cell lysis of SNUC cell lines ∼5.4 fold (P ≤ 0.0001). This effect was blocked by a CD16 neutralizing antibody demonstrating activity through an antibody-dependent cellular cytotoxicity (ADCC) mediated pathway. ADCC-dependent lysis of SNUC cells was further enhanced by upregulation of PD-L1 on tumor cells by exogenous interferon-gamma (IFN-γ) administration or interleukin-15 (IL-15) stimulated IFN-γ release from NK cells. Combination treatment with anti-PD-L1 blockade and IL-15 superagonism enhanced NK-cell killing of SNUC cells 9.6-fold (P ≤ 0.0001). Untreated SNUC patient tumor samples were found to have an NK cell infiltrate and PD-L1+ tumor cells at a median of 5.4 cells per mm2. A striking 55.7-fold increase in CKlow tumor cell/NK cell interactions was observed in patients without disease recurrence after treatment (P = 0.022). Patients with higher CD3+CD8+ in the stroma had a significantly improved 5-year overall survival (P = 0.0029) and a significant increase in CKlow tumor cell/CD8+ cytotoxic T cell interactions was noted in long-term survivors (P = 0.0225). ConclusionThese data provide the pre-clinical rationale for ongoing investigation into combinatory immunotherapy approaches for SNUC.

Biophysical insight into the binding mechanism of epigallocatechin-3-gallate and cholecalciferol to albumin and its preventive effect against AGEs formation: An in vitro and in silico approach

Advanced glycation end products (AGEs) are produced non-enzymatically through the process of glycation. Increased AGEs production has been linked to several diseases including polycystic ovary syndrome (PCOS). PCOS contributes to the development of secondary comorbidities, such as diabetes, cardiovascular complications, infertility, etc. Consequently, research is going on AGEs-inhibiting phytochemicals for their potential to remediate and impede the progression of hyperglycaemia associated disorders. In this study human serum albumin is used as a model protein, as albumin is predominantly present in follicular fluid. This article focusses on the interaction and antiglycating potential of (−)-Epigallocatechin-3-gallate (EGCG) and vitamin D in combination using various techniques. The formation of the HSA-EGCG and HSA-vitamin D complex was confirmed by UV and fluorescence spectroscopy. Thermodynamic analysis verified the spontaneity of reaction, and presence of hydrogen bonds and van der Waals interactions. FRET confirms high possibility of energy transfer. Cumulative antiglycation resulted in almost 60 % prevention in AGEs formation, decreased alterations at lysine and arginine, and reduced protein carbonylation. Secondary and tertiary structural changes were analysed by circular dichroism, Raman spectroscopy and ANS binding assay. Type and size of aggregates were confirmed by Rayleigh and dynamic light scattering, ThT fluorescence, SEM and SDS-PAGE. Effect on cellular redox status, DNA integrity and cytotoxicity was analysed in lymphocytes using dichlorofluorescein (DCFH-DA), DAPI and MTT assay which depicted an enhancement in antioxidant level by cumulative treatment. These findings indicate that EGCG and vitamin D binds strongly to HSA and have antiglycation ability which enhances upon synergism.

Polymorphism Dependent Cytotoxicity, Cellular Uptake, and Live Cell Imaging Studies on Napthalimide-Vinyl-Phenothiazine Conjugate.

Polymorphism-dependent cytotoxicity and cellular uptake of drug molecules have been studied for the past two decades. However, the visualization of polymorph-dependent cellular uptake and cytotoxicity using microscopy imaging techniques has not yet been reported. The luminescent polymorph is an ideal candidate to validate the above hypothesis. Herein, we report the polymorph-dependent cellular uptake, cytotoxicity, and bio-imaging functions of polymorphs 1Y and 1R of a naphthalimide-phenothiazine dyad. These polymorphs show different luminescence colors in the solid state and exhibit aggregation-induced enhanced emission (AIEE) in the DMSO-Water mixture. Bioimaging, cytotoxicity assay, and fluorescence-activated cell sorting (FACS) studies revealed that these polymorphs show different levels of cytotoxicity, cellular uptake, localization, and imaging potential. Detailed photophysical, morphological, and biological studies revealed that the difference in molecular conformation in these polymorphs enables them to form aggregates of different sizes and morphology, which leads to the differential uptake of these into the cells and consequently shows different cytotoxicity and imaging potentials.

Abstract CT132: A Phase I/IIa clinical trial (TranStar101) to evaluate the safety, tolerability and pharmacokinetics of OSEMITAMAB administered as monotherapy or in combination with nivolumab or standard of care in patients with locally advanced or metastatic solid tumors

Abstract Introduction: TST001/osemitamab is a novel, recombinant humanized IgG1 mAb with improved CLDN18.2 binding affinity and enhanced antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) and can result in more efficient cytotoxicity of tumors expressing human CLDN18.2 across a broad range of levels including low to medium expression. Methods: This is an open-label, multi-center phase I/IIa first in human (FIH) study of osemitamab administered as monotherapy or in combination with nivolumab or standard of care for patients with locally advanced or metastatic solid tumors. The study includes two parts: Part A (completed), a dose escalation of osemitamab as a monotherapy in solid tumors, osemitamab intravenous infusion at dose from 1mg/kg to 10mg/kg and once every two weeks (Q2W) or once every three weeks (Q3W) were evaluated; Part B (ongoing) includes expansion cohorts of osemitamab in combination with other therapies (cohort A and B). Cohort A includes combination of osemitamab, nivolumab, and mFOLFOX6 as the 1st line treatment for G/GEJ cancer. Cohort B includes osemitamab in combination with nivolumab in advanced pre-treated G/GEJ cancer. Results: As of Nov. 30, 2023, 68 patients have been treated: 38 patients were enrolled in the Part A dose escalation,13 in Part B Cohort A, and 17 in Part B Cohort B. The population (N=68) consisted of 59% males, median age 62 years and 50% with G/GEJ cancer. Doses evaluated are 3 to 10mg/kg Q3W and 1 to 6 mg/kg Q2W in part A. One dose limiting toxicity of Grade 3 infusion related reaction was reported at the 1mg/kg dose Q2W. The MTD was not reached. The recommended phase 2 dose was determined as 6mg/kg Q3W or 4mg/kg Q2W based on the totality of available safety, efficacy, PK/PD data including information from another phase I/II study (TranStar102). The most common TRAEs (occurred in ≥ 20% subjects) were nausea (73.5%), vomiting (48.5%), fatigue (30.9%). TRAE of Grade ≥ 3 across all tested doses (3-10 mg/kg) that occurred in ≥3% of patients included nausea, vomiting, hypoalbuminemia, hypertension, infusion related reaction, and lymphocyte count increased. Within the dose ranges studied, PK exposures increased as dose increased. The mean CLss value of osemitamab ranged from 9.4 to 13.7 mL/day/kg across different dose levels, without a clear dose relationship. Mild accumulation was observed following Q2W and Q3W dosing. Conclusion: Osemitamab as monotherapy or in combination with nivolumab or mFOLFOX plus nivolumab is well tolerated and safe with a PK profile consistent with other studies (TranStar 102 study -NCT04495296). TranStar 101 is currently ongoing. More information will be shared. Clinical trial information: NCT04396821. Study Sponsor: Suzhou Transcenta Therapeutics Co., Ltd. Citation Format: Yelena Janjigian, Anthony Tolcher, Rutika Mehta, Michael Cecchini, Brian Van Tine, Madappa Kundranda, Alese Olatunji, Manish R. Patel, Jordan Berlin, Caio Max Sao Pedro Rocha-Lima, Dulabh Monga, Ben George, Aaron Scott, Zhenzhong Xia, Mohamed Elsafy, Erikca Jones, Zhenling Yao, Chuan Qi, Caroline Germa, Nash Gabrail. A Phase I/IIa clinical trial (TranStar101) to evaluate the safety, tolerability and pharmacokinetics of OSEMITAMAB administered as monotherapy or in combination with nivolumab or standard of care in patients with locally advanced or 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 CT132.

Abstract LB129: Preclinical development of a bispecific antibody-trap selectively targeting CD38 and CD47 for treating hematologic malignancies

Abstract CD38 and CD47 are co-expressed in various hematologic malignancies including multiple myeloma (MM), B-cell non-Hodgkin lymphoma (NHL), B-cell acute lymphoblastic leukemia (ALL), T-cell ALL and B-cell chronic lymphocytic leukemia (CLL). We present, herein, several CD38 antibody - CD47 ligand trap bispecific antibodies (BsAbs) in an ADCC-enhanced IgG1 form that harbor high CD38 binding affinity, low CD47 binding affinity, along with negligible affinity to red blood cells (RBCs) and no induction of RBCs agglutination. Using flow cytometry and Biolayer interferometry (BLI), we confirmed that our BsAbs can simultaneously bind to both CD38 and CD47, and that binding to either antigen first does not prevent binding to the other antigen subsequently. On CD47+/CD38low Jurkat (T leukemic) cells, our BsAbs reveal less blocking effect on the CD47/SIRPα interaction than a monospecific CD47 ligand trap molecule based on which our BsAbs were designed; conversely, on CD38/CD47 double-positive Reh (pro-B ALL) cells, our BsAbs reveal 200-500-fold greater blocking effect on the CD47/SIRPα interaction than the same monospecific CD47 ligand trap molecule, indicating that the inhibition of CD47/SIRPα by our BsAbs is depended on the engagement of CD38 on tumor cells. On CD47+/CD38+ Daudi (B NHL) lymphoma cells and L-1236 (B Hodgkin) lymphoma cells, four of our BsAbs inhibited CD38 enzymatic activity, which is responsible for immune-suppressive adenosine production in tumor microenvironment. Our BsAbs presented potent dose-dependent antibody-dependent cellular cytotoxicity (ADCC) against CD47+/CD38+ Raji (B NHL) and NCI-H929 (B plasmacytoma myeloma) cells, while revealing negligible ADCC activity against CD47+/CD38− cells, indicating low off-tumor toxicity. Likewise, our BsAbs also harbor potent antibody-dependent cellular phagocytosis (ADCP) activity against Raji NHL cells, varied degree of complement-dependent cytotoxicity (CDC) activity and direct apoptosis induction against Daudi NHL cells. In a mouse xenograft model harboring NCI-H929 multiple myeloma, our BsAbs produced more potent tumor growth inhibition, than monospecific anti-CD47 ligand trap, anti-CD38 (isatuximab) or combination of isatuximab and anti-CD47 ligand trap, at the same molecular dose per body weight. Notably, clone IMM5605-12C10 eradicated all tumors and achieved 100% complete response rate in a group of six mice. In summary, simultaneous targeting CD38 and CD47 using our CD38 antibody - CD47 ligand trap bispecific design in an ADCC-enhanced IgG1 form presents a novel multimodal approach for treating hematologic malignancies that are resistant to anti-CD38 antibodies. Citation Format: Wenzhi Tian, Song Li, Dianze Chen, Yanan Yang, Huiqin Guo, Dandan Liu, Ruliang Zhang, Fan Zhang. Preclinical development of a bispecific antibody-trap selectively targeting CD38 and CD47 for treating hematologic malignancies [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 LB129.

Abstract LB130: Identification of fully human CCR8 antibodies that demonstrate excellent ADCC function, potent blocking activity, and robust anti-tumor immune responses

Abstract Immune checkpoint inhibitors have demonstrated significant benefits in treating various types of tumors. However, a considerable number of patients do not respond to this therapy. One proposed mechanism for resistance to immune checkpoint inhibitors is the infiltration of large numbers of regulatory T cells (Tregs) into tumors, which hinders the development of effective antitumor immunity and is often linked to poor prognosis. CCR8 is a G-protein-coupled receptor (GPCR) which is predominantly expressed on Tregs infiltrating tumors. The development of CCR8-specific human antibodies to deplete CCR8+ Tregs is a promising therapeutic strategy for cancer treatment. Here, we report the development and characterization of fully human monoclonal antibodies targeting CCR8 that exhibit potent antibody-dependent cellular cytotoxicity (ADCC) activity. These antibodies were generated in CCR8 knock-out RenMab® mice, which were immunized with native CCR8 antigen prepared via a proprietary cell-free membrane protein synthesis technology. Epitope mapping of the antibodies revealed recognition of a unique epitope on the N-terminus extracellular domain of CCR8. Binding assays indicated cross-reactivity of the antibodies across multiple species; importantly, however, these antibodies did not recognize related chemokine receptors, such as CCR2, CCR4, CCR5, or CX3CR1. In vitro, CCR8 antibodies effectively inhibited calcium flux induced by CCL1 binding to the CCR8 receptor. Furthermore, introduction of DE (S239D, I332E) mutations in the Fc region enhanced ADCC activity of these antibodies. To compare the efficacy of these antibodies with anti-CCR8 benchmarks in vivo, we generated benchmark analogs in-house with the same DE mutations and established syngeneic MC38 tumor models in humanized B-hCCR8 mice. In this assay, our CCR8 antibodies demonstrated potent anti-tumor activity. Notably, one mutant clone with optimized developability demonstrated robust inhibition of tumor growth when compared to both benchmark analogs and its original clone. Taken together, our fully human CCR8 antibodies demonstrate enhanced ADCC function, strong blocking activity, and superior in vivo anti-tumor activity, which may support further development into a novel cancer immunotherapy targeting Tregs. Citation Format: Huichao Liang, Yanan Guo, Meimei Yin, Aki Kawagishi, Takaho Terada, Yoshihiko Kihara, Toru Kanke, Chaoshe Guo, W. Frank An, Yi Yang. Identification of fully human CCR8 antibodies that demonstrate excellent ADCC function, potent blocking activity, and robust anti-tumor immune responses [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 LB130.

Abstract CT162: Trial in progress: A phase I, open-label, multicenter study of ZL-1218, an anti-CCR8 IgG1, as a single agent and as combination therapy with anti-PD-1 antibody to evaluate the safety, tolerability, and pharmacokinetics in subjects with advanced solid tumor

Abstract Background ZL-1218 is an anti-chemokine receptor 8 (CCR8) humanized IgG1 antibody with enhanced antibody-dependent cellular cytotoxicity (ADCC) activity. CCR8 demonstrates a preferential expression in tumor-associated Tregs over peripheral Tregs. Thus, targeting CCR8 may allow for specific depletion of intratumoral Tregs without impacting peripheral Tregs/other immune cells. ZL-1218 is intended to decrease the intratumoral Tregs by binding to both high- and low-expressing CCR8+ cells and eliciting potent ADCC activity. ZL-1218 blocked CCR8 ligand CCL1 from binding to CCR8, and reduced Treg recruitment by blocking chemotaxis of CCR8+ cells (unpublished data). Additionally, ZL-1218 demonstrated enhanced antitumor activity in preclinical models in combination with anti-PD-1. Methods This is a Phase I study of ZL-1218 as a single agent and in combination with pembrolizumab (P) to evaluate the safety, tolerability, pharmacokinetics/pharmacodynamics, and preliminary antitumor activity in subjects with advanced solid tumor malignancies. The study consists of Part 1 Dose Escalation and Part 2 Cohort Expansion. In Part 1, subjects will be treated with escalating doses of ZL-1218 alone and in combination with a fixed dose of P to identify the maximum tolerated dose (MTD) and/or the recommended expansion dose (RD). The Bayesian optimal interval (BOIN) design is used and adopted with overdose control. Upon progression in the single agent group, a subject may enroll into combination therapy of ZL-1218 with P. Subjects will start at their respective single agent dose or the cleared combination dose level, whichever is lower. Part 2 will explore the combination with pembrolizumab in subjects with selected tumor types, with or without prior CPI therapy. Major inclusion criteria include: (1) Subjects must have histologically confirmed and documented diagnosis of locally advanced unresectable/metastatic advanced solid tumor that is refractory/intolerant to standard treatment, or for which no standard treatment exists, and no greater than 3 prior lines of therapy in the relapse/refractory setting (2). Subjects must have at least one target lesion as defined by RECIST v1.1 on CT, PET/CT, or MRI scan. (3) Subjects must have a site of disease which is not previously irradiated and is safe and amenable to biopsy. Major exclusion criteria include: (1) Prior exposure to CCR8 inhibitor, or severe hypersensitivity (≥ Grade 3) to P and/or any of its excipients. (2) Subjects with symptomatic or uncontrolled brain metastasis requiring concurrent treatment, impaired major organ functions, active autoimmune disease, or active infections. Part 1 Dose Escalation is ongoing in the US and EU. Citation Format: Elena Garralda, Valentina Boni, David Vincente Baz, Arvind Chaudhry, Ignacio Gil Bazo, Martin Gutierrez, Jyoti Malhotra, Casal Guzman Alonso, Valentina Gambardella, Michael Chisamore, Renke Zhou, Maria Tea, Deborah Doroshow. Trial in progress: A phase I, open-label, multicenter study of ZL-1218, an anti-CCR8 IgG1, as a single agent and as combination therapy with anti-PD-1 antibody to evaluate the safety, tolerability, and pharmacokinetics in subjects with advanced solid tumor [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 CT162.

Abstract ND08: M3554, a novel anti-GD2 antibody drug conjugate

Abstract The glycosphingolipid GD2 is a cell membrane component of a limited number of normal tissues including nerve cells, melanocytes or lymphocytes. However, in some tumor types as neuroblastoma, osteosarcoma, glioma, or soft tissue sarcoma, GD2 is found on cell membranes with high levels. This tumor associated expression pattern makes GD2 an attractive target for therapeutic antibodies like dinutuximab (ch14.18) and naxitamab, which have been approved for neuroblastoma. M3554 is designed a be novel anti-GD2 ADC based on the humanized ch14.18 anti-GD2 antibody. The payload linker consists of the Topoisomerase I inhibitor (TOP1i) payload exatecan and a cleavable beta-glucuronide linker structure, which demonstrated higher potency, better bystander effects and improved activity in multidrug resistant cancer cells compared to other TOP1i payloads. While the antitumor effect of approved anti-GD2 antibodies is presumably related to Antibody-Dependent Cellular Cytotoxicity (ADCC) and Complement- Dependent Cytotoxicity (CDC), M3554 will exploit the high antigen density for direct tumor cytotoxicity by the payload. As the ADCC and CDC effector functions are believed to cause side effects for the approved GD2 antibodies, we have modified the M3554 antibody moiety with mutations in the Fc-region to reduce or eliminate these Fcγ receptor mediated functions. The cytotoxicity of M3554 was in the subnanomolar IC50 range for the GD2-positive neuroblastoma cell line CHP134. M3554 showed strong in vivo antitumor activity with tumor regressions in the CHP134 xenograft model and in patient-derived xenografts from neuroblastoma, osteosarcoma or glioma at doses ranging from 3 to 10 mg/kg. In addition, M3554 showed favorable pharmacokinetics in rats and monkeys, indicating a very stable linker-payload, and a favorable safety profile. In conclusion, M3554 represents a novel therapeutic approach for oncology indications with a high unmet medical need and high GD2 prevalence. Disclosures: Christiane Amendt, Christine Knuehl, Willem Sloot, Stanley Sweeney-Lasch, Joao NS Pereira, Julia Dotterweich, Hans-Henning Boehm and Jan Anderl are employees of the healthcare business of Merck KGaA, Darmstadt, Germany. Timothy Crandall is an employee of EMD Serono. Mira Toister-Achituv is an employee of Inter-Lab Ltd., Yavne, Israel, an affiliate of Merck KGaA, Darmstadt, Germany.Sponsor: This study was sponsored by the healthcare business of Merck KGaA, Darmstadt, Germany (CrossRef Funder ID: 10.13039/100009945). Citation Format: Christiane Amendt, Christine Knuehl, Timothy Crandall, Willem Sloot, Mira Toister-Achituv, Stanley Sweeney-Lasch, Joao NS Pereira, Julia Dotterweich, Hans_Henning Boehm, Jianguo Ma, Jan Anderl. M3554, a novel anti-GD2 antibody drug conjugate [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 ND08.

Abstract LB364: Generation and Application of a Robust Humanized Mouse Tumor Model System for Evaluation of NK-Targeting Therapeutics

Abstract With the new waves of anti-tumor immunotherapy development, novel immunotherapies based on NK cells have emerged and advanced rapidly. Considering the inherent mechanisms of NK cells, various strategies are employed in tumor immunotherapy to maximize the efficacy of NK cells, including the following: 1) immune checkpoint inhibitors to relieve NK cell inhibition signals; 2) activation of NK cell activity; 3) targeted antibody therapy for tumor cell killing via antibody-dependent cellular cytotoxicity (ADCC), and 4) cell therapy, such as CAR-NK. Although numerous NK-targeting immune therapeutics or various NK-modulating modalities have been developed or advanced toward clinical trials, there is a lack of clinically relevant preclinical animal models that can be widely accepted for the evaluation of NK-modulating agents, particularly for models that involve functional human NK cells in the test system. This study generated a humanized mouse tumor model system which involves specific reconstitution of functional and durable human NK cells in a murine system, providing a clinically relevant tumor microenvironment. We first engineered a stable monoclonal feeder cell line in vitro to expand NK cells isolated from human peripheral blood mononuclear cells (hPBMCs) using magnetic bead separation. Using this approach, the human primary NK cells were robustly and consistently amplified (up to hundreds of fold) while maintaining their purity and functionality. When compared with primary NK cells using in vitro immune assays including ADCC and FACs, the expanded NK cells showed comparable results as the parental cells. In vivo experimental results indicated that a durable and functional NK reconstitution can be established in tumor-bearing severely immune deficient mice expressing hIL-15. Furthermore, this NK-humanized tumor model system was proven to respond to standard of care (SOC) NK-targeting drugs. In summary, this novel NK humanized in vivo model may represent an effective preclinical tool for assessing NK-modulating drugs, with the hope of facilitating the development process of novel immune therapeutics employing both adaptive and innate immunity. Citation Format: Feng Lu, Weiqun Ding, Guangliang Yang, Yaoqing Jia, Zhaoxiang Wang, Xusheng Yuan, Ming Yin, Zhijian Yang, WenQing Yang. Generation and Application of a Robust Humanized Mouse Tumor Model System for Evaluation of NK-Targeting Therapeutics [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 LB364.

Abstract LB062: ADT3_A potential first-in-class Vδ1-engager for in situ activation of Vδ1 γδ T cells and enhanced cytotoxicity towards solid tumors

Abstract Gamma delta (γδ) T cells are crucial in stress surveillance for infections and cancer. Studies have shown that tumour-infiltrating γδ T cells are a positive prognostic factor in cancer therapy. While γδ T cells share many characteristics with their αβ T cell counterpart, such as cytotoxic effector functions, they express a distinct TCR that is composed of a γ and a δ chain, belong to the HLA-class-I unrestricted immune cell subset with the ability to discriminate and specifically kill tumor cells via recognition of tumor stress ligands. Clinical trials using Vδ1 γδ T cell therapies have demonstrated promising results in Ph 1 trials, with early signs of favorable efficacy and safety profile.ADT3, is a novel bispecific engager that activates tissue-resident Vδ1+ T cells via (Epidermal Growth Factor Receptor) EGFR crosslinking on tumor cells. VD1 T cells isolated from skin biopsies, when activated, enhance the selective killing of EGFR positive tumor cells through innate mechanisms that recognize stress ligands that are otherwise absent on healthy cells. As a bispecific engager, ADT3 preserves high affinity binding to VD1 TCR through the Fab end of the molecule, and binding to two EGFR binding sites via the modified Fc domain. Crosslinking of VD1 and EGFR+ tumor cells with ADT3, mediates a series of events leading to proliferation of VD1 cells, upregulation of activation markers, CD107a degranulation and secretion of chemokines and cytokines (such as TNFa and IFNg) and tumor kill as determined by its potent cytotoxic activity in a T-cell dependent cellular cytotoxicity assay (TDCC). Apart from direct tumor kill, the secretion of such cytokines and chemokines via ADT3 activation are required for induction of immune orchestration of non-Vδ1 immune cells to enhance tumor kill. Preclinical data supports future clinical entry of ADT3, and IND enabling studies are in progress Citation Format: Joshua Freedman, Georgia Stevens, Julie Julie Hoong, Mihirban Tuna, Yaoyao Shi, Kathy J. Seidl, Katherine Galvin, Andrew Hutton, Antara Banerjee. ADT3_A potential first-in-class Vδ1-engager for in situ activation of Vδ1 γδ T cells and enhanced cytotoxicity towards 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 LB062.

Immunoglobulins and serum proteins impair anti-tumor NK cell effector functions in malignant ascites.

Malignant ascites indicates ovarian cancer progression and predicts poor clinical outcome. Various ascites components induce an immunosuppressive crosstalk between tumor and immune cells, which is poorly understood. In our previous study, imbalanced electrolytes, particularly high sodium content in malignant ascites, have been identified as a main immunosuppressive mechanism that impaired NK and T-cell activity. In the present study, we explored the role of high concentrations of ascites proteins and immunoglobulins on antitumoral NK effector functions. To this end, a coculture system consisting of healthy donor NK cells and ovarian cancer cells was used. The anti-EGFR antibody Cetuximab was added to induce antibody-dependent cellular cytotoxicity (ADCC). NK activity was assessed in the presence of different patient ascites samples and immunoglobulins that were isolated from ascites. Overall high protein concentration in ascites impaired NK cell degranulation, conjugation to tumor cells, and intracellular calcium signaling. Immunoglobulins isolated from ascites samples competitively interfered with NK ADCC and inhibited the conjugation to target cells. Furthermore, downregulation of regulatory surface markers CD16 and DNAM-1 on NK cells was prevented by ascites-derived immunoglobulins during NK cell activation. Our data show that high protein concentrations in biological fluids are able to suppress antitumoral activity of NK cells independent from the mechanism mediated by imbalanced electrolytes. The competitive interference between immunoglobulins of ascites and specific therapeutic antibodies could diminish the efficacy of antibody-based therapies and should be considered in antibody-based immunotherapies.

Immunoglobulin-like transcript 2 as an impaired anti-tumor cytotoxicity marker of natural killer cells in patients with hepatocellular carcinoma.

Natural killer (NK) cells play a pivotal role in immune surveillance in the liver. We aimed to identify potential targets for NK cell-mediated immune intervention by revealing the functional molecules on NK cells in HCC patients. To evaluate the impact of aging on NK cell phenotypes, we examined NK cells from healthy volunteers (HVs) of various ages. Because ILT2 expression on CD56dim NK cells increased with increasing age, we enrolled age-matched HCC patients and HVs. We determined the NK cell phenotypes in blood mononuclear cells (PBMCs) and intrahepatic lymphocytes (IHLs) from cancerous and non-cancerous tissues. We evaluated cytotoxicity and antibody-dependent cellular cytotoxicity (ADCC) of NK cells in vitro. ILT2-positive CD56dim NK cells in PBMCs were increased in HCC patients compared with HVs. In HCC patients, ILT2-positive CD56dim NK cells were increased in cancerous IHLs compared with non-cancerous IHLs and PBMCs. We examined the impact of macrophage migration inhibitory factor (MIF) on ILT2 expression in co-cultures of HCC cells and NK cells. The enhanced expression of ILT2 on CD56dim NK cells from HCC patients was inhibited by masking antibodies against MIF and CXCR4. ILT2-positive CD56dim NK cells exhibited lower capacities for cytotoxicity and ADCC than ILT2-negative cells, which were partially restored by ILT2 blockade. In HCC patients, ILT2 is a signature molecule for cancerous CD56dim NK cells with impaired cytolytic capacity. The MIF-CXCR4 interaction is associated with ILT2 induction on CD56dim NK cells and ILT2 serves as a target for functional NK cell restoration.

Al/ZnO nanoparticle as an effective nanocarrier in delivery of lenalidomide anti-multiple myeloma cancer drug

ABSTRACT Lenalidomide is a key drug in multiple myeloma. Moreover, Al-ZnO has garnered significant attention due to its distinct physicochemical characteristics. This investigation introduces an economic approach for fabrication and characterization of Al-ZnO nanoparticles by SEM, TEM, FT-IR, XPS, UV-VIS, EDS, and XRD techniques. Subsequently, the research explored capacity of the created nanostructure to serve as a nanocarrier for Lenalidomide. Findings indicated an approximate 71% drug loading capacity that is dependent on pH and duration time. The release profile depicted a gradual release under physiological conditions (pH 7.4, 28%), contrasting with a notably accelerated release rate at pH 6.2 (78%) in 48 h. Furthermore, an in vitro assessment of cellular cytotoxicity performed on U266 multiple myeloma cancer cell line to evaluate safety and effectiveness of Al-ZnO nanoparticles. Results from MTT assay affirmed the potential of this nanoparticle as a promising vehicle for Lenalidomide delivery.

Advancing apoptosis induction in triple negative breast cancer: Empowering treatment with tyrosine-stapled mixed micelles of lapatinib

The available treatment modalities for triple-negative breast cancer (TNBC) face several challenges, including discouraging overall survival outcomes, unavoidable toxicities, and the emergence of drug resistance. Further, there is an amplified requirement for various amino acids to support the uncontrolled proliferation of TNBC. Hence, targeted therapy for enhancing the treatment of TNBC was explored which encompassed hydrophobized (using α-linolenic acid) Pluronic-based mixed micelles having inherent L-type/Large neutral amino acid transporter 1 targeting (tyrosine-stapled) ability (LPT T-MM). LPT T-MM had optimal size (142.34 ± 30.23 nm), polydispersity index (0.224 ± 0.01), and enhanced drug loading capacity (∼10 %). Transmission electron microscopy confirmed their spherical shape. In vitro release studies showed sustained drug release without hemolysis risk. LPT T-MM had higher cellular uptake and cytotoxicity than free LPT. IC50 values for LPT T-MM were significantly reduced in MDA-MB-231 (∼1.64-fold) and 4 T1 (∼1.88-fold) cell lines; apoptosis index was superior in MDA-MB-231 (∼2.04-fold) and 4 T1 cell line (∼2.09-fold) compared to free LPT. LPT T-MM generated more reactive oxygen species and caused mitochondrial membrane depolarization, indicating increased cell death by apoptosis. Thus, LPT T-MM had the ability to promote apoptosis, showed promise in enhancing the payload capabilities and targeting in TNBC.

Immunotherapy for gastrointestinal cancer

Cancers of gastrointestinal tract make up the largest group of solid tumour diseases in Germany. The prognosis at diagnosis is often critical. Drug therapies reduce the risk of relapse after resection and can halt the progression of metastatic disease. Immunotherapies contribute increasingly to the treatment of gastrointestinal tumours. Monoclonal antibodies (mAB) against surface receptors from the epidermal growth factor receptor family (EGFR, Her2) are well established. The effect is partly based on the interruption of the oncogenic downstream signalling cascades and partly on immune effector mechanisms such as antibody-dependent cellular cytotoxicity. In clinical practice mAB directed against programmed cell death protein 1 (PD-1), its ligand (PD-L1) and cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) - so-called immune checkpoint inhibitors - play an increasing role and change the natural history of some subgroups of gastrointestinal cancers, especially those with deficient DNA mismatch repair which leads to genomic microsatellite instability.