Multiple Tumor Cell Lines Research Articles

Abstract CT098: Phase I study of GQ1005, a new generation HER2-ADC, in patients with HER2-expressing and HER2 mutated advanced solid tumors

Abstract Background: GQ1005 is a new generation antibody-drug conjugate, targeting HER2-expressing tumor cells with Topoisomerase I inhibitors (DXd) as its payload via a stable and cleavable linker. In preclinical studies, GQ1005 demonstrated comparable antitumor activity compared to Enhertu in multiple tumor cell line xenograft models with no noticeable toxicity, indicating higher therapeutic index. GLP toxicity studies demonstrated that GQ1005 was well tolerated, with the highest non-severe toxic dose determined to be 60mg/kg. This report presents the preliminary findings of an ongoing phase I study, which aims to evaluate the safety, tolerability, pharmacokinetics, and antitumor activity of GQ1005 in patients with advanced solid tumors expressing HER2 or harboring HER2 mutations. Methods: GQ1005 was administrated intravenously every 3 weeks. An accelerated titration design was employed for the initial 2mg/kg dose, followed by Bayesian Optimal Interval Design for subsequent dose levels of 4, 6, 7.2, and 8.4 mg/kg. The primary objective of this study was to evaluate the safety, tolerability, and to determine the MTD or RP2D. Results: As of Oct. 13th, 2023, 46 (30 in dose-escalation and 16 in dose-expansion phase) subjects with HER2-expressing/mutated advanced solid tumors, predominantly in breast cancer (18), and lung cancer (18) , were enrolled into the study. Patients received a median of 3 (range, 1-11) prior lines of treatment, and 86.4% of pts previously received anti-HER2 therapies before. During dose escalation, No DLT was observed in all doses, MTD was not reached up to 8.4 mg/kg. Treatment-related adverse events (TRAEs) occurred in 44 (95.7%) subjects. The most common TRAEs were grade 1 or 2, including nausea (52.2%), vomiting (39.2%), aspartate aminotransferase (AST) increased (39.1%), alanine aminotransferase (ALT) increased (23.9%), anemia (23.9%), anorexia (21.7%), fatigue (19.6%), leukopenia (15.2%), infusion-related reactions (15.2%) , decreased lymphocyte count (15.2%) and dizziness (15.2%). Grade ≥3 TRAEs only occurred in 4 subjects (8.7%), including anemia, decreased lymphocyte count and γ-glutamyltransferase (GGT) increased. Interstitial lung disease was observed in 6 pts received highest dose level and most of them have recovered. No drug-related deaths. The pharmacokinetics analysis showed the concentration of GQ1005 and TAb generally peaked rapidly and declined in a roughly biphasic manner. Among 38 evaluable subjects, 1 pt achieved complete response, 18 cases achieved confirmed partial response, and 11 had stable disease, the objective response rate was 50% (19/38), the disease control rate was 78.9% (30/38) , and the 6-month PFS rate was 43.0% in all patients. Conclusions: GQ1005 demonstrated a promising antitumor activity in HER2-expressing/mutated advanced solid tumors patients previously heavily treated, and showed a good tolerance and manageable safety profile. The dose expansion study is on-going at 7.2 mg/kg to establish the RP2D in four cohorts. (NCT06154343; sponsored by GeneQuantum Healthcare (Suzhou) Co., Ltd.) Citation Format: Caicun Zhou, Bo Yang, Ting Deng, Biyun Wang, Jian Zhang, Yuping Sun, Linlin Wang, Hongwei Yang, Jingfen Wang, Wei Li, Qi Song, Yuchong Yang. Phase I study of GQ1005, a new generation HER2-ADC, in patients with HER2-expressing and HER2 mutated advanced 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 CT098.

Overcoming Solubility Challenges: Liposomal isoCoQ-Carbazole as a Promising Anti-Tumor Agent for Inoperable and Radiation-Insensitive cancers.

This study evaluated the potential of isoCoQ-Carbazole, a diheterocyclic analog of isoCA-4, as an anti-tumor agent. To overcome its low aqueous solubility, liposomes were developed as a delivery system for the compound. In vitro experiments showed that loaded liposomes exhibited similar activity to the free form on multiple human tumor cell lines. In vivo experiments using a palliative intratumoral injection chemotherapy approach further demonstrated that isoCoQ-Carbazole loaded liposomes significantly reduced tumor growth in a CA-4-resistant HT29 cell model, without inducing any observable toxicity or weight loss in the treated mice. These findings suggest that liposomal isoCoQ-Carbazole may hold promise as a potential therapeutic agent for the treatment of inoperable, radiation-insensitive cancers.

Abstract 1871: Discovery and characterization of NXV01c, an EGFR × cMET bispecific nanobody drug conjugate with potent anti-tumor activity

Abstract EGFR and cMET are proven cancer targets co-expressed in diverse tumor types. EGFR × cMET bispecific antibody has been approved for the treatment of NSCLC, supporting a simultaneous targeting strategy. In addition to this dual targeting benefit, bispecific antibody drug conjugates (ADCs) targeting EGFR and cMET have also been developed to further improve anti-tumor activity and tissue selectivity. Sufficient target affinity, good cellular internalization and high tumor infiltration are critical for an ADC to mediate therapeutic activity. To this end, we developed the first EGFR × cMET bispecific nanobody conjugated with monomethyl auristatin E (MMAE) as payload (NXV01c). Lead nanobodies against EGFR and cMET were respectively selected from immune libraries by phage display, followed by highly efficient humanization and optimization by neoX’s computation platform. The bispecific nanobody with Fc (NXV01) was constructed by “knobs-into-holes” heterodimerization and then homogeneously conjugated with MMAE via a lysosomal cleavable valine-citrulline dipeptide linker. The resulting bispecific nanobody drug conjugate (NDC), NXV01c, was evaluated in multiple tumor cell lines and tumor xenograft models. NXV01, the pre-conjugate bispecific nanobody, bound EGFR and cMET with nanomolar potency (BLI) and inhibited the phosphorylation of cellular EGFR and cMET with nanomolar IC50 (ELISA). Moreover, it did not activate cellular cMET. Importantly, the NDC NXV01c is highly homogeneous: it has an average DAR of 3.87 and >95% of NXV01c has a DAR of 4. To examine stability of conjugation, NXV01C was incubated in human plasma (37°C) for 14 days, the maximum free drug release rate (by LC/MS/MS) is 0.68%, which is much lower than that of DS8201. In vitro, NXV01c was rapidly internalized into H1975 cells which co-expressed EGFR and cMET. It inhibited the growth of H1975 (lung) and SNU5 (gastric) cancer cells with picomolar activity but spared normal keratinocytes. NXV01c also inhibited the proliferation of additional cell lines derived from lung, gastric, esophageal, and liver cancer, and the level of inhibition positively associated with the expression density of both targets. In an H1975 cell line-derived xenograft model, NXV01C exhibited potent and dose-dependent anti-tumor activity. Treatments at 3 and 10 mg/kg once per week for 2 weeks led to shrinkage and complete regression of tumor, respectively. In patient-derived xenograft models of NSCLC and esophageal cancer, NXV01C led to tumor regression and elimination without noticeable toxic effects. EGFR × cMET bispecific nanobody drug conjugate NXV01c has favorable drug-like properties and demonstrated superior anti-tumor effect in vitro and in vivo. The results suggest NXV01C can be an effective solution for EGFR/cMET bearing tumors commonly found in diverse malignancies. Citation Format: Ran Wu, Puwei Yuan, Yang Xie, Jianxiu Guo, Fei Zhang, Fan Liu, Taylor B. Guo. Discovery and characterization of NXV01c, an EGFR × cMET bispecific nanobody drug conjugate with potent anti-tumor activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1871.

Abstract 598: HSK42360: A potent, brain permeable, BRAF paradox breaker for the treatment of BRAF-driven cancers

Abstract Mutations in the BRAF gene are among the most common identified in human cancers approximately 7% of all cancers evaluated, including 70% of melanomas, 50% of thyroid-like cancers, 10% to 20% of colorectal cancers, 13% of serous ovarian cancers, 3-7% of non-small-cell lung cancers, and most recently, hairy cell leukemia. Approved BRAF inhibitors (or +MEKi) against BRAFV600E/K improved initial clinical efficacy. However intrinsic and acquired resistance often arise through BRAF paradoxical activation, limiting durable responses to current BRAF inhibitors. In addition, Approved BRAFi responds poorly to patients with BRAF mutant gliomas or brain metastases, mainly due to limited brain permeability. More effective therapeutic options are therefore needed. To address this clinical challenge, we developed a potent, brain-penetrating paradox breaker HSK42360, as a promising therapy for patients with BRAFV600E mutation, progression or brain metastases following treatment with approved BRAFi or BRAFi/MEKi therapies. HSK42360 is a potent BRAFV600E inhibitor with IC50 value of 5 nM at enzymatic level. Further characterization showed that HSK42360 did not induce homodimer or heterodimer of CRAF with CRAF or BRAF and thereby blocked reactivation of the MAPK pathway in HCT116 cells, whereas Dabrafenib significantly induced RAF dimerization and MAPK reactivation. HSK42360 exhibited significant anti-proliferation activity against multiple tumor cell lines with BRAFV600E, including A375 (melanoma), DU4475 (breast cancer), and COLO205 (colon cancer), but was highly selective for BRAF wild-type cells. HSK42360 was administered orally once daily and showed broad-spectrum antitumor activity in the COLO205 and A375 CDX models. Immunohistochemistry showed a close correlation between the inhibition of tumor growth and ERK1/2 phosphorylation in A375 CDX tumor tissues. To explored the impact of HSK42360 in a brain micro-metastasis model aimed at mimicking early CNS metastatic spread, tumor progression was monitored through BLI (full name) imaging, which revealed that HSK42360 was highly brain penetrant with Kp,uu greater than 1 and triggered potent antitumor activity and prolonged survival in brain metastatic models of melanoma. We next tested the hypothesis that HSK42360 could retain activity in models presenting RAF dimer-driven resistance. Surprisingly, HSK42360 demonstrated promising antitumor effects in the first gen-resistant NRASmA375(NRASQ61K, BRAFV600E) CDX model, supporting its use as a follow-on therapy for current BRAFi resistance. Collectively, these preclinical studies validated that HSK42360 is a novel brain-permeable BRAF paradox breaker that exhibits outstanding antitumor activity in brain metastasis and RAF dimer-driven resistance. Citation Format: Shidong Gao, Yangguang Li, Ju Wang, Pingming Tang, Zongjun Shi, Yao Li, Pangke Yan. HSK42360: A potent, brain permeable, BRAF paradox breaker for the treatment of BRAF-driven cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 598.

Abstract 13: Discovery and development of T cell receptors targeting MAGE family antigens for adoptive T cell therapy against solid tumors

Abstract Background: T cell receptors (TCRs) recognize epitopes from intracellular and cell surface antigens, enabling targeting of diverse tumor antigen classes including overexpressed, differentiation, cancer-testis antigens, as well as those from driver mutations, frameshift mutations, splice variants, and human endogenous retroviral elements (HERV). Melanoma-associated antigens (MAGE) are highly expressed in various solid tumor types, including melanoma, non-small cell lung cancers (NSCLC), bladder, and head and neck cancers, representing promising targets for TCR-T therapy. However, discovering robust and specific MAGE-reactive TCRs remains challenging due to limited throughput of TCR screening methodologies, and the inherently low frequency of tumor-reactive T cells in tumor samples and peripheral blood. Methods: We employ a proprietary mass-cytometry-based multiplexed tetramer staining approach, TargetScape®, to screen and characterize CD8+ T cells in healthy donors and patients’ samples. Our screening panels contain multiple peptides for MAGE family antigens including A1, C2, and A10. Subsequent single cell sequencing or single cell PCR (scPCR) of identified tumor antigen-specific T cells with high sensitivity enables comprehensive analysis of T cell phenotype, transcriptome, TCR specificity, and paired TCR sequence. TCRs identified through this method are transduced for expression in Jurkat reporter cell lines and their reactivity to corresponding peptides is assessed. Selected TCR candidates are then transduced into primary T cells and evaluated for activation and effector function using a variety of cancer cell lines expressing the corresponding endogenous antigens. Specificity assessment is performed through alanine scans and identification of potential off-target peptides and screening for reactivity. Results: We utilized this approach to discover natural TCRs that target several MAGE family antigens. Through Jurkat reporter screening, we observed specific activation of multiple TCRs in the presence of antigen presenting cells and the peptide initially employed to identify the TCRs. Primary T-cells expressing promising TCR candidates exhibited killing activities and cytokine release when confronted with multiple solid tumor cell lines expressing endogenous levels of the MAGE antigen. Specificity assessment is currently in progress, with preliminary data indicating overall favorable specificity profiles for selected TCRs. Conclusions: Our Deep Immunomics platform enables us to detect, characterize, and validate TCR candidates against highly clinically relevant shared cancer antigens. Leveraging this platform, we identified various natural tumor specific TCRs exhibiting activities against a range of solid tumor cell lines expressing MAGE antigens. Promising candidates are currently undergoing in vivo efficacy studies. Citation Format: Juliana Velez Lujan, Hannah Fields, Kan Xing Wu, Yovita Purwanti, Emily Xin Zi Tang, Michael Cordeau, Kathleen Mendez, Melissa Wirawan, Michael Fehlings, Katja Fink, Zilei Liu, Daniel MacLeod. Discovery and development of T cell receptors targeting MAGE family antigens for adoptive T cell therapy against solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 13.

Abstract 2620: BCG016, a first-in-class bispecific antibody-drug conjugate targeting 5T4 and MUC1, demonstrates potent preclinical anti-tumor activity

Abstract 5T4 is a highly expressed tumor-associated antigen associated with adverse clinical outcomes in solid tumors, and is an attractive therapeutic target due to low expression on normal adult tissues. While several therapeutic agents targeting 5T4 antigen are currently being evaluated in human clinical trials, none have yet entered the market. Another target, MUC1, is currently under clinical investigation, with most drugs in clinical trials showing limited efficacy due to shedding of the target antigen MUC1-N. 5T4 and MUC1 are commonly co-expressed in various solid tumors, including lung, breast, colorectal and pancreatic cancers, suggesting that targeting both antigens with a single drug could be a promising therapeutic strategy. We previously identified and evaluated antibodies targeting human 5T4 and MUC1-C (cleaved MUC1) using RenLite® fully human common light chain mice. Here, selected antibodies were constructed into 5T4 × MUC1 bispecific antibodies (bsAb). The 5T4-MUC1 bsAb demonstrated high avidity in multiple human tumor cell lines by flow cytometry. Notably, the parental 5T4 antibody also binds strongly to many tumor cell lines. Internalization assays demonstrate that the internalization of 5T4-MUC1 bsAb in breast cancer cells was enhanced compared to the parental anti-5T4 and anti-MUC1 monoclonal antibodies, as measured by Incucyte® live cell imaging. Subsequently, the 5T4-MUC1 bsAb was then conjugated with monomethyl auristatin E (MMAE) to generate 5T4 x MUC1 bsADC (BCG016). Cytotoxicity assays indicate that BCG016 improved tumor cell killing in vitro compared to benchmark ADCs, and in vivo efficacy studies showed superior anti-tumor efficacy of BCG016 in patient-derived NSCLC xenografts compared to benchmark ADCs and parental ADC combination therapy. In summary, we have generated a novel bispecific ADC targeting 5T4 and the cleaved MUC1-C protein, which remains membrane-bound on tumor cells. The 5T4-MUC1 bsADC showed superior anti-tumor efficacy in PDX models and has the potential to be a novel therapeutic for 5T4 and MUC1 co-expressing tumors. Citation Format: Zhenyan Han, Chengzhang Shang, Yifu Zhang, Gao An, Chaoshe Guo, W. Frank An, Yi Yang. BCG016, a first-in-class bispecific antibody-drug conjugate targeting 5T4 and MUC1, demonstrates potent preclinical anti-tumor activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2620.

Abstract 4535: JAB-26766: A small-molecule, orally bioavailable PARP7 inhibitor with high potency and selectivity

Abstract Background: PARP7 (also referred to as TIPARP or ARTD14) is a mono-ADP-ribosyl transferase that inhibits type I interferon (IFN) signaling. Targeting PARP7 to restore antitumor immunity represents a promising treatment strategy. We have developed JAB-26766, an orally bioavailable, highly potent, and selective PARP7 inhibitor. Methods: A time-resolved fluorescence energy transfer (TR-FRET) assay was applied to determine the binding and inhibition of PARP7 by JAB-26766. IFN-β secretion assay, STAT1 phosphorylation assay, and ISG (interferon stimulated gene) mRNA assay were performed to evaluate the inhibitory activities of JAB-26766 on the downstream signaling of PARP7. CellTiter-Glo assay was performed to evaluate cell viability upon treatment of JAB-26766. In vivo PK-PD study was conducted to evaluate the relationship between JAB-26766 concentration and the level of tumor STAT1 phosphorylation. The antitumor activity of JAB-26766 either as a single agent or in different drug combinations was evaluated in multiple mouse models. Results: High potency of JAB-26766 on PARP7 inhibition as well as >1800-fold selectivity over PARP2 was observed through biochemical assays. At the cellular level, JAB-26766 induced IFN-β secretion, up-regulated ISG mRNA levels, increased phosphorylation of STAT1, and inhibited cell viability of multiple tumor cell lines (with most IC50 values below 50 nM). JAB-26766 combined with a STING agonist resulted in synergistic activation of STING pathway, as evidenced by increased CXCL10 secretion, and inhibited tumor cell proliferation. In vivo PK-PD study showed that JAB-26766 exposure in plasma and tumor has good correlation with induction of tumor STAT1 phosphorylation. Furthermore, JAB-26766 showed potent antitumor activity and good tolerability either as monotherapy or combined with STING agonist or anti-PD-1 antibody in mouse models of non-small cell lung cancer, breast cancer and colorectal cancer. Conclusions: JAB-26766 is an orally bioavailable, highly potent, and selective PARP7 inhibitor that shows early promising anti-tumor activities. Citation Format: Di Kang, Yanping Wang, Xin Sun, Man Yan, Haijun Li, Mingming Chen, Yiwei Lin, Wei Long. JAB-26766: A small-molecule, orally bioavailable PARP7 inhibitor with high potency and selectivity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4535.

Abstract 1332: Allogeneic CD19-directed CAR-iNKT cells and their phenotypic subsets for the treatment of CD19+ hematological malignancies

Abstract Invariant Natural Killer T (iNKT) cells are a unique subset of innate lymphocytes, constituting <1% of human T cells. iNKT cells express a semi-invariant TCR (iTCR) recognizing glycolipids presented by the monomorphic, MHC-like molecule CD1d. Previous studies indicate that due to distinctive TCR constitution and antigen recognition properties, iNKT cells do not induce acute graft-versus-host disease. Based on the CD4 and CD8 expression, mature human iNKT cells can be classified into CD4+CD8-, CD4-CD8- & CD4-CD8+ subsets with overlapping and distinct functions. The functional profiling of CAR19-iNKT cell subsets serves the dual purpose of ensuring their safety and efficacy as a therapeutic intervention. Here we characterized the phenotypic and functional profile of CD4+ and CD4- CAR19-iNKT cells. iNKT cells were isolated with >99% purity from healthy donors' peripheral blood and were transduced with a CD19 CAR-encoding 3rd generation lentivirus. After expansion, the CAR19-iNKT cells were cryopreserved and later analyzed post-thawing. Differential expression of CD27 and PD1 was noted in CAR+CD4+ and CAR+CD4- iNKT cells compared to other markers. For functional profiling, CAR+CD4+ iNKT cells were positively selected, and 24h cytotoxicity assays were performed using several tumor cell lines including SEM, Ramos and C1R-CD1d (+/- α-GalCer). The CAR+CD4- iNKT cells exhibited superior cytotoxicity to multiple tumor cell lines compared to that of CAR+CD4+ iNKT cells from two donors. However, both subsets lysed α-GalCer pulsed C1R-CD1d cells in a comparable manner indicating the potential of these subsets to recognize antigen through the iTCR. Subsequently, we assessed the proliferation ability of the CAR+CD4+ and CAR+CD4- subsets by exposing the cells to three rounds of stimulation, 24h apart, using SEM (CD19+CD1d-) or K562 (CD19-CD1d-) tumor cells with or without IL-15. Proliferation was assessed seven days following the first stimulation. The CAR+CD4+ subset of CAR19-iNKT cells demonstrated faster proliferation than CAR+CD4- cells in the presence of IL-15 after repeated exposure to tumor cells. Ongoing RNA seq analysis of CAR+CD4+/CAR+CD4- cells will further elucidate differences between these subsets. The outcomes of these studies have shown encouraging results, indicating the potential benefit of having diverse subsets among CAR19-iNKT cells for treating CD19+ cancers. The therapeutic potential of CAR+CD4+ iNKT cell subset could be enhanced to match that of CAR+CD4- subset with the use of α-GalCer. In summary, inclusion of both CD4+ and CD4- iNKT cells is critical for the functionality of allogeneic CAR-iNKT cell therapy. Extensive characterization is crucial for clinical translation, but additional research, including preclinical and clinical trials, is essential to determine the safety and effectiveness of CAR19-iNKT cell therapy in real-world applications. Citation Format: Kanagaraju Ponnusamy, Simon Poon, Nicole van der Weerden, Robson Dossa, Michael J. Baker, Mini Bharathan, Anastasios Karadimitris. Allogeneic CD19-directed CAR-iNKT cells and their phenotypic subsets for the treatment of CD19+ hematological malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1332.

Abstract 5229: Enhancing solid tumor treatment with engineered blood-derived Vδ1 platform: Safe and effective targeting of mesothelin-expressing tumors with Vδ1 γδT cells

Abstract Mesothelin (MSLN) is a solid tumor-associated antigen that has been thoroughly studied and is expressed in several tumor indications that have significant unmet therapeutic needs. Vδ1-enriched γδT cells differentiate themselves from other MSLN-targeted modalities by mitigating the challenges of targeting tumors with heterogeneous MSLN expression through their inherent capability to detect malignant cells while sparing normal cells. The ability to effectively combat cancer cells that express mesothelin is significantly increased by the expression of a chimeric antigen receptor (CAR). Novel armoring is being evaluated to improve engineered Vδ1 persistence in the solid tumor microenvironment. Cytokine armoring, through novel engineering, enhances sensitivity to cytokines and recovers cell fitness that is impaired by 'traditional' cytokine armoring options. Extensive in vitro and in vivo safety and efficacy studies were carried out to validate the product's potency. These studies aimed to determine cytotoxicity, expansion, and persistence. MSLN CAR cytokine-armored Vδ1 cells exhibited high post-thaw viability and survival. Furthermore, cytokine-armored Vδ1 cells displayed elevated innate receptor expression and gene-engineered cells maintained their baseline innate phenotype, indicating that they can maintain their ‘innate’ effectiveness over time. In vitro studies demonstrated broad anti-tumor activity against multiple tumor cell lines expressing various levels of mesothelin. Additionally, in long-term cytotoxicity assays, cytokine-armored cells demonstrated improved tumor-clearance capabilities. The effector cells also exhibited an enhanced innate cytotoxic phenotype that equips the cells with the capability to persist and proliferate in response to soluble cytokines and upon cytokine trans-presentation by adjacent cells. In vitro studies further revealed that there is a distinction in the killing activity between tumor and normal cells, which is important for ensuring that the product is safe for use in patients. An orthotopic lung tumor-bearing mouse model was developed to confirm their anti-tumor effectiveness in vivo. The model's outcomes demonstrated that MSLN CAR cytokine-armored Vδ1 cells exhibit higher in vivo efficacy in comparison to their unarmored counterparts at low effector-to-target ratios. With no significant healthy tissue damage found, the histopathology report confirmed an excellent safety profile. Terminal biodistribution studies demonstrated that armored drug candidates preferentially home to and persist in tumor-bearing tissues. Overall, these findings imply that the product might be highly effective in treating tumors that express mesothelin. This strategy could greatly advance our knowledge of how Vδ1-enriched γδT cells function as a platform against solid tumors. Citation Format: Nandhu Mohan Sobhana, Andre Simoes, Sarah Edwards, Sweta Mishra, Gary Gu, George Papadopoulos, Stefan Kiesgen, Rebecca Alade, njing Li, Andrea Venuso, Jyothi Kumaran, Kristy Waddington, Tabassum Huseni, Rajeev Karattil, Lilly Reynolds, Maria Sharif, David Wotherspoon, Corina Tudor, Istvan Kovacs, Mei Rosa Ng, Yana Wang, Lan Cao. Enhancing solid tumor treatment with engineered blood-derived Vδ1 platform: Safe and effective targeting of mesothelin-expressing tumors with Vδ1 γδT cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5229.

Abstract 1866: Discovery of mutation-independent EGFR degrading bispecific antibodies that suppress tumor growth in preclinical tumor models

Abstract Extracellular targeted protein degradation (eTPD) has emerged as a promising new drug modality focused on targeted elimination of extracellular and transmembrane proteins. In contrast to intracellular protein degraders, such as proteolysis targeting chimeras (PROTACs) and molecular glues which require ubiquitin-proteosome cellular degradation pathways, extracellular protein degraders can additionally harness endosomal-lysosomal protein degradation. Two recently published examples of extracellular protein degraders include AbTACs (antibody-based PROTAC) which co-engage a protein of interest (POI) and transmembrane E3 ligases, and KineTACs (cytokine receptor-targeting chimeras) which utilize endogenous cytokine receptors to degrade extracellular POIs. These bispecific antibody degrader platforms not only have advantageous pharmacological and drug-like manufacturing properties, but can also be engineered for tissue-specificity and to address multiple complementary targets, with the goal of increased efficacy and decreased toxicity. To that end, we have greatly expanded the extracellular degrader repertoire beyond AbTACs and KineTACs, with a novel bispecific antibody degrader platform called TrainTACs (tissue receptor antigen internalization targeting chimeras). To demonstrate the potential of this novel extracellular degrading platform, we developed degraders for the canonical receptor tyrosine kinase epidermal growth factor receptor (EGFR). EGFR is an oncogenic driver, that has been clinically validated in lung, colorectal and head and neck cancers, but patient benefit has been limited by treatment-related acquired resistance mutations and on-target/off-tumor dose-limiting toxicities. The potential of our TrainTACs, AbTACs and KineTACs to overcome the limitations of current therapeutic modalities was assessed. Gene expression profiles from tumor and normal tissues were evaluated to identify potential degraders co-expressed with EGFR in tumors. More than 70 unique bispecific antibody constructs spanning 20 receptors were generated and screened in tumor cell-based assays to evaluate EGFR antagonism, internalization, and degradation. TrainTACs, AbTACs and KineTACs degraded EGFR in multiple tumor cell lines covering a range of EGFR mutations. Degradation of EGFR led to deep inhibition of EGFR signaling, robust inhibitory effects on tumor spheroids, and in xenograft mouse tumor models. In conclusion, eTPD represents a promising new drug modality, and TrainTACs, AbTACs and KineTACs have expanded the toolbox of extracellular targeted protein degraders that can be utilized in a target-, tissue- and disease-specific manner. Citation Format: Jonathan Sitrin, Lisa Marshall, Hai Tran, Kenneth Ng, Kimberly Hoi, Josef Gramespacher, Zhong Huang, Andy Goodrich, Filomena Housley, May Dayao, Man-Tzu Wang, Katarina Pance, Aleysha Chen, Kevin Carlin, Lichao Zhang, James Lee, Rami Hannoush, Ken Flanagan, Maia Vinogradova, Isaac Rondon, Shyra Gardai. Discovery of mutation-independent EGFR degrading bispecific antibodies that suppress tumor growth in preclinical tumor models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1866.

Super-Enhancer Dysregulation in Rhabdoid Tumor Cells Is Regulated by the SWI/SNF ATPase BRG1.

Mutations in the SWI/SNF chromatin remodeling complex occur in ~20% of cancers. In rhabdoid tumors defined by loss of the SWI/SNF subunit SMARCB1, dysregulation of enhancer-mediated gene expression is pivotal in driving oncogenesis. Enhancer dysregulation in this setting is tied to retention of the SWI/SNF ATPase BRG1-which becomes essential in the absence of SMARCB1-but precisely how BRG1 contributes to this process remains unknown. To characterize how BRG1 participates in chromatin remodeling and gene expression in SMARCB1-deficient cells, we performed a genome-wide characterization of the impact of BRG1 depletion in multiple rhabdoid tumor cell lines. We find that although BRG1-regulated open chromatin sites are distinct at the locus level, the biological characteristics of the loci are very similar, converging on a set of thematically related genes and pointing to the involvement of the AP-1 transcription factor. The open chromatin sites regulated by BRG1 colocalize with histone-marked enhancers and intriguingly include almost all super-enhancers, revealing that BRG1 plays a critical role in maintaining super-enhancer function in this setting. These studies can explain the essentiality of BRG1 to rhabdoid tumor cell identity and survival and implicate the involvement of AP-1 as a critical downstream effector of rhabdoid tumor cell transcriptional programs.

Isolation and expansion of pure and functional γδ T cells.

γδ T cells are important components of the immune system due to their ability to elicit a fast and strong response against infected and transformed cells. Because they can specifically and effectively kill target cells in an MHC independent fashion, there is great interest to utilize these cells in anti-tumor therapies where antigen presentation may be hampered. Since only a small fraction of T cells in the blood or tumor tissue are γδ T cells, they require extensive expansion to allow for fundamental, preclinical and ex vivo research. Although expansion protocols can be successful, most are based on depletion of other cell types rather than γδ T cell specific isolation, resulting in unpredictable purity of the isolated fraction. Moreover, the primary focus only lies with expansion of Vδ2+ T cells, while Vδ1+ T cells likewise have anti-tumor potential. Here, we investigated whether γδ T cells directly isolated from blood could be efficiently expanded while maintaining function. γδ T cell subsets were isolated using MACS separation, followed by FACS sorting, yielding >99% pure γδ T cells. Isolated Vδ1+ and Vδ2+ T cells could effectively expand immediately after isolation or upon freeze/thawing and reached expansion ratios between 200 to 2000-fold starting from varying numbers using cytokine supported feeder stimulations. MACS/FACS isolated and PHA stimulated γδ T cells expanded as good as immobilized antibody mediated stimulated cells in PBMCs, but delivered purer cells. After expansion, potential effector functions of γδ T cells were demonstrated by IFN-γ, TNF-α and granzyme B production upon PMA/ionomycin stimulation and effective killing capacity of multiple tumor cell lines was confirmed in killing assays. In conclusion, pure γδ T cells can productively be expanded while maintaining their anti-tumor effector functions against tumor cells. Moreover, γδ T cells could be expanded from low starting numbers suggesting that this protocol may even allow for expansion of cells extracted from tumor biopsies.

Anticancer Potential of a Synthetic Quinoline, 9IV-c, by Inducing Apoptosis in A549 Cell and In vivo BALB/c Mice Models

Background: In a previous work from the author of this study, the compound of 9IV-c, ((E)-2-(3,4- dimethoxystyryl)-6,7,8-trimethoxy-N-(3,4,5-trimethoxyphenyl)quinoline-4-amine) was synthesized, and the effects of potent activity on the multiple human tumor cell lines were evaluated considering the spindle formation together with the microtubule network. Methods: Accordingly, cytotoxic activity, apoptotic effects, and the therapeutic efficiency of compound 9IV-c on A549 and C26 cell lines were investigated in this study. Results: The compound 9IV-c demonstrated high cytotoxicity against A549 and C26 cell lines with IC50 = 1.66 and 1.21 μM, respectively. The flow cytometric analysis of the A549 cancer cell line treated with compounds 9IV-c showed that these compounds induced cell cycle arrest at the G2/M phase and apoptosis. Western blotting analysis displayed that compound 9IV-c also elevated the Bax/Bcl-2 ratio and increased the activation of caspase- 9 and -3 but not caspase -8. Conclusion: These data presented that the intrinsic pathway was responsible for 9IV-c -induced cell apoptosis. In vivo studies demonstrated that treatment with the compound of 9IV-c at 10 mg/kg dose led to a decrease in tumor growth compared to the control group. It was found that there was not any apparent body weight loss in the period of treatment. Also, in the vital organs of the BALB/c mice, observable pathologic changes were not detected.

Inducing mitochondriopathy-like damages by transformable nucleopeptide nanoparticles for targeted therapy of bladder cancer.

Mitochondriopathy inspired adenosine triphosphate (ATP) depletions have been recognized as a powerful way for controlling tumor growth. Nevertheless, selective sequestration or exhaustion of ATP under complex biological environments remains a prodigious challenge. Harnessing the advantages of in vivo self-assembled nanomaterials, we designed an Intracellular ATP Sequestration (IAS) system to specifically construct nanofibrous nanostructures on the surface of tumor nuclei with exposed ATP binding sites, leading to highly efficient suppression of bladder cancer by induction of mitochondriopathy-like damages. Briefly, the reported transformable nucleopeptide (NLS-FF-T) self-assembled into nuclear-targeted nanoparticles with ATP binding sites encapsulated inside under aqueous conditions. By interaction with KPNA2, the NLS-FF-T transformed into a nanofibrous-based ATP trapper on the surface of tumor nuclei, which prevented the production of intracellular energy. As a result, multiple bladder tumor cell lines (T24, EJ and RT-112) revealed that the half-maximal inhibitory concentration (IC50) of NLS-FF-T was reduced by approximately 4-fold when compared to NLS-T. Following intravenous administration, NLS-FF-T was found to be dose-dependently accumulated at the tumor site of T24 xenograft mice. More significantly, this IAS system exhibited an extremely antitumor efficacy according to the deterioration of T24 tumors and simultaneously prolonged the overall survival of T24 orthotopic xenograft mice. Together, our findings clearly demonstrated the therapeutic advantages of intracellular ATP sequestration-induced mitochondriopathy-like damages, which provides a potential treatment strategy for malignancies.

Porphyrin Derivative with Binary Properties of Photodynamic Therapy and Water-Dependent Reversible Photoacidity Therapy for Treating Hypoxic Tumor.

Porphyrin photosensitizers are the classic drugs in clinical photodynamic therapy (PDT), but the hypoxia of tumor environment and the rapid oxygen consumption of PDT severely weaken their therapeutic effect. A recently reported water-dependent reversible photoacidity therapy (W-RPAT) is O2 -independence, providing a solution for the treatment of hypoxic tumors. In this work, TPP-O-PEG5, a porphyrin derivative with binary properties of PDT and W-RPAT, is designed and synthesized for the first time. The nanoparticles (NPs) of TPP-O-PEG5 encapsulated with DSPE-mPEG2000, an amphiphilic polymer approved by Food and Drug Administration, can simultaneously produce reactive oxygen species and H+ under irradiation of a 660nm laser, and revert the H+ back under darkness, presenting strong phototoxicity to multiple tumor cell lines with no obvious difference between the IC50 values tested under normoxic (≈20% O2 ) and hypoxic (<0.5% O2 ) conditions. Excitingly, in vivo experiments show that the therapeutic effect of TPP-O-PEG5 NPs on large hypoxic tumors is better than that of NPe6, a clinical porphin PDT drug. This work provides a novel strategy for porphyrin photosensitizers to break through the limitation of hypoxic environment, and significantly improve the phototherapeutic effect on hypoxic tumors.

Adoptive immunotherapy with cells from tumor-draining lymph nodes activated and expanded in vitro.

Tumor-draining lymph nodes (tumor-DLNs) provide a rich source of tumor-reactive lymphocytes which can be used in adoptive immunotherapy (AIT) and that circumvent the need to resect autologous tumor, without the challenges and shortcomings associated with using autologous tumor or anti-CD3 monoclonal antibody. Bryostatin/Ionomycin (Bryo/Io) provide a useful method of activating tumor-DLNs such that they can readily be expanded to sufficient numbers to be used in AIT, and growing the tumor-DLN lymphocytes in the gamma chain cytokines IL-7 plus IL-15 is superior to IL-2 in terms of T cell numbers and phenotype. AIT with these cells induces tumor regression and provides protection against metastases and future tumor challenge. Here, we provide a stepwise protocol to sensitize tumor-DLN cells in donor mice, activate tumor-DLN T cells ex vivo using Bryo/Io, expansion of these cells in gamma chain cytokines and adoptive transfer of the expanded cells back into tumor-bearing hosts. Methods relevant to these experiments, such as injecting tumor cells intravenously and monitoring for pulmonary metastases, tumor volume measurement and resection, and use of luciferase-expressing tumor cells to monitor for metastases following resection, are described in detail. The methods outlined herein can be easily adapted to suit similar experiments across multiple tumor cell lines and syngeneic mouse models.

CCRG-06. PP2A DEFICIENCY INDUCES CELLULAR SENESCENCE AND SENSITIZES P53 MUTANT TUMORS TO SENOLYTIC THERAPY

Abstract Loss of p53 can promote tumor progression by preventing induction of senescence, a critical tumor-suppressive mechanism that limits tumor proliferation. Promotion of senescence in a p53-independent manner can be a novel strategy to overcome treatment resistance in p53-mutant brain tumors. Protein-Phosphatase-2A (PP2A), a ubiquitous serine/threonine phosphatase, regulates various cellular processes including cell-cycle progression. We hypothesize that PP2A-deficiency can induce tumor senescence independent of p53-mutational-status and sensitize tumors to senolytic therapy. CRISPR-KO of PP2A was generated in multiple p53-mutant tumor cell lines: D425 (human medulloblastoma), SB28 and GL261 (murine glioma). Hallmarks of senescence such as b-galactosidase, p21, and p16 were assessed via flow cytometry, RT-PCR and Western-Blot. Secretion of senescence-associated secretory phenotype (SASP), such as IL8, was assessed through ELISA. b-galactosidase, p21, p16 and IL8 were dramatically increased in PP2A-KO compared to WT at baseline. The effect was further enhanced when combined with radiation therapy (RT), a known inducer of senescence, demonstrating PP2A-deficiency synergizes with RT and significantly increases cellular senescence. Expression of CD1d, a MHC1-like molecule associated with senescence and required for invariant NKT cell-activation (iNKT), was dramatically increased in PP2A-KO in comparison to WT via flow-cytometry. In-vitro, sensitivity to WT and PP2A-KO cells to senolytic treatments, such as ABT-737 and iNKT-cell therapy, was tested using an XCelligence-assay system and flow-cytometry-based cytotoxicity assay. PP2A-deficient cells were sensitized to ABT-737, a BCL-xL inhibitor that preferentially targets and kills senescent cells. Co-culture revealed increased cytotoxicity of iNKT-cells against PP2A-deficient tumors compared to WT. In vivo, D425 WT or PP2A-KO cells were injected intracranially into nude NU/J mice, radiated 2 days post-injection, and monitored till endpoint. At baseline, PP2A-KO mice survived longer than WT, and those with PP2A-KO and RT survived the longest. In conclusion, we report that PP2A-deficiency in tumor cells can induce p53-independent senescence and sensitize brain tumors to senolytic therapy.

EXTH-15. A NOVEL IMMUNE-BASED TREATMENT STRATEGY FOR COMBATTING PROTEIN TUMOR HETEROGENEITY

Abstract Cell-based immunotherapy has revolutionized the treatment of many hematological malignancies but has mostly fail against solid tumors, including glioblastoma (GBM). The reason for this failure is multi-fold, but one of the most significant barriers is the extensive intratumoral heterogeneity that characterizes these tumors. Unfortunately, this problem has not been eliminated by personalized medicine strategies aimed at sequencing individual tumors and targeting the uncovered neoantigens. Thinking “outside the box” led us to examine other types of tumor-specific alterations that might more ubiquitously characterize tumor cells, while still being targetable by an immune-based platform. Our investigations led us to the phospholipid phosphatidylserine (PS). PS is typically present on the cytoplasm-facing side of the plasma membrane, where it remains out of view to the immune system. Cellular stresses can lead to dysregulation of processes that keep PS facing internally and instead promote PS exposure on the cell surface. We show here that tumor cells frequently lose the capacity to regulate their plasma membrane and exhibit detectable levels of PS on their surface. Moreover, inducing cell stress through radiation and chemotherapy of tumor cells further enhanced PS exposure. In this study, we aimed to target PS with an immune-based therapy. To this end, we engineered a bi-specific T cell engager (BiTE) consisting of the natural high-affinity PS receptor TIM4 linked to an anti-CD3scFv. This TIM4 BiTE is hypothesized to redirect all T cells to PS, resulting in T cell-mediated killing of tumor cells with exposed PS. Indeed, TIM4 BiTE facilitated potent killing of multiple human tumor cell lines in vitro, including in models of protein heterogeneous tumors. When TIM4 BiTE was delivered intratumorally to a heterogeneous glioma-bearing mouse, survival was significantly extended. These data provide evidence that targeting PS with an immune-based platform represents a potential novel treatment strategy for combatting tumor heterogeneity.

EXTH-38. VELCRIN MOLECULAR GLUES INDUCE CELL DEATH IN GLIOBLASTOMAS WITH HIGH PDE3A AND SLFN12 EXPRESSION

Abstract Velcrins are molecular glues that kill cells by inducing the formation of a protein complex between the RNase, SLFN12, and the phosphodiesterase, PDE3A. Formation of the complex activates SLFN12, which cleaves tRNALeu(TAA) and induces apoptosis. Velcrins such as the clinical investigational compound, BAY 2666605, were found to have activity across multiple solid tumor cell lines from the Cancer Cell Line Encyclopedia (CCLE), including glioblastoma cell lines. We therefore aimed to characterize velcrins as novel therapeutic agents in glioblastoma. We measured PDE3A and SLFN12 expression levels in commercially available glioblastoma cells as well as glioblastoma neurospheres from the Center for Patient Derived Models at Dana Farber Cancer Institute. We identified velcrin-sensitive glioblastoma cell lines and neurospheres, and determined that velcrin response is highly correlated with PDE3A expression. We also determined that sensitive cells exhibit a reduction in nascent polypeptide formation upon velcrin treatment, which is rescued by CRISPR-induced knockout of PDE3A. To assess velcrin efficacy in vivo, we measured central nervous system and plasma levels of the velcrin, BAY 2666605, and determined that it freely crosses the blood brain barrier. We also determined that twice daily dosing of BAY 2666605 elicits full tumor regression in an orthotopic glioblastoma xenograft model, with sustained complete responses after treatment withdrawal. Lastly, we demonstrated that the velcrins BAY 2666605 and BAY 2501293 induce tumor regression in biomarker-positive subcutaneous glioblastoma patient-derived xenograft models. In summary, our data demonstrates that velcrins have anti-tumor activity in preclinical models of glioblastoma, warranting further investigation as potential therapeutic agents.

Safety and Toxicology Study of Hu7691, a Novel AKT Inhibitor, following Oral Administration in Rats.

Hu7691 represents a novel Pan-Akt kinase inhibitor, demonstrating excellent selectivity towards non-AGC kinase families and pronounced inhibitory effects on the proliferation of multiple tumor cell lines. However, there is currently a notable absence of in vivo toxicological research evidence concerning Hu7691. This study represents the first investigation into the 14-day repeated-dose toxicity of Hu7691 in male and female Sprague Dawley (SD) rats. Male rats were administered daily doses of 12.5, 50, 100, and 150 mg/kg/day, while female rats received doses of 12.5, 25, 50, and 75 mg/kg/day for 14 consecutive days. Hematological assessments, organ weights, and histopathological examinations revealed corresponding alterations, suggesting potential target organs for toxicity including the spleen, thymus, and gastrointestinal tract. It is worth noting that the test substance may also impact the liver, kidneys, heart, and ovaries. The No Observed Effect Level (NOAEL) was determined to be no greater than 12.5 mg/kg/day. Based on the observed gender-related toxicity differences in preliminary trials, it is recommended that the high dose reference dose for male animals in formal experiments should not be less than 100 mg/kg/day, while for female animals, it should be less than 50 mg/kg/day.