Antengene to Present Results From Four Cutting Edge Preclinical Studies at AACR 2025 with Focuses Including AnTenGagerTM TCEs and Synthetic Lethality

SHANGHAI and HONG KONG, March 26, 2025 /PRNewswire/ -- Antengene Corporation Limited ("Antengene", SEHK: 6996.HK), a leading innovative, commercial-stage global biopharmaceutical company dedicated to discovering, developing and commercializing first-in-class and/or best-in-class medicines for hematologic malignancies and solid tumors, today announced that it will release results from four preclinical studies in poster presentations at the 2025 American Association for Cancer Research Annual Meeting (AACR 2025), taking place from April 25^th to 30^th at the McCormick Place Convention Center, Chicago, the United States. These four posters will feature Antengene's four highly differentiated and high-potential programs, including ATG-201 (CD19 x CD3 TCE) and ATG-042 (MTAP^null-selective PRMT5 Inhibitor), which are poised to enter clinical development in the second half of 2025; ATG-110 (LY6G6D x CD3 TCE), which was developed on the AnTenGager^TM TCE 2.0 platform for the treatment of microsatellite stable colorectal cancer; and a companion diagnostic antibody developed to assess CD24 expression and guide clinical studies of CD24-targeted therapies.

Details of the Poster Presentation:
ATG-201 (CD19 x CD3 T cell engager)
Title: ATG-201, a novel T-cell engager (TCE) effectively depletes B cells with reduced risk of CRS for the treatment of B cell malignancies and B cell related autoimmune diseases
Abstract Number: 7326
Session Category: Immunology
Session Title: T Cell Engagers and Novel Antibody-Based Therapies
Date: April 30, 2025
Time: 9:00 AM - 12:00 PM (Central Time)
10:00 PM, April 30, 2025 - 1:00 AM, May 1, 2025 (Beijing Time)
Location: Poster Section 40

• Introduction: By depleting autoreactive B cells, CD19-targeted CAR-T have shown early yet promising efficacy in treating patients with B cell-driven autoimmune diseases. However, the clinical application of TCE continues to be greatly hindered by the unfavorable pharmacokinetics and toxicity associated with cytokine release syndrome. To overcome these limitations, Antengene developed ATG-201, a "2+1" CD19 x CD3 TCE, which was evaluated in a series of in vitro studies for binding affinity, T cell dependent cytotoxicity (TDCC) cytokine release, and drug developability. The in vivo anti-lymphoma efficacy and pharmacodynamic effect were evaluated in Raji xenograft model. The tissue resident B cell depletion was assessed in CD34+ hematopoietic stem cells humanized mice. Pharmacokinetic parameters of ATG-201 were evaluated in normal Balb/c mice.
• Results: Compared to benchmark TCEs, ATG-201 demonstrated stronger naïve B cell depletion activity with much lower cytokine release in vitro. ATG-201 showed potent anti-lymphoma activity in PBMC-humanized subcutaneous Raji xenograft model with significant augment of infiltrated CD8+ T cells in tumor microenvironment and limited proinflammatory cytokines detected in plasma. Single dose ATG-201 completely and deeply depleted B cells in blood, bone marrow and spleen of CD34+ cells humanized mice. ATG-201 demonstrated potent efficacy in mouse systemic lupus erythematosus model, inhibiting the lymph node swelling and auto-antibody producing.
• Conclusions: ATG-201 demonstrated CD19-dependent CD3 binding and activation, inducing effective B cell depletion in vitro and in vivo with low cytokine release, which provides potential for the treatment of B cell malignancies and B cell related autoimmune diseases. ATG-201 is poised to enter clinical development in the second half of 2025.

ATG-042 (MTAP^null-selective PRMT5 Inhibitor)
Title: Preclinical characterization of ATG-042, a novel MTAP^null-selective PRMT5 inhibitor
Abstract Number: 4230
Session Category: Experimental and Molecular Therapeutics
Session Title: HDAC and Methyltransferase Inhibitors
Date: April 29, 2025
Time: 9:00 AM - 12:00 PM (Central Time)
10:00 PM, April 29, 2025 - 1:00 AM, April 30, 2025 (Beijing Time)
Location: Poster Section 16

• Introduction: Targeting the PRMT5-MTA complex has become a promising strategy for treating MTAP^null cancer in a synthetically lethal manner, avoiding on-target off-tumor hematological toxicity when using first-generation, non-selective PRMT5 inhibitors. Herein, Antengene developed ATG-042, a novel MTAP^null-selective PRMT5 small molecule inhibitor with good brain penetration. In this study, the in vitro activity and MTAP selectivity of ATG-042 were profiled using HCT116 MTAP wild type (wt) cells, HCT116 MTAP knock out (ko) cells and multiple endogenous MTAP^null cell lines. The in vivo efficacy was tested in cell derived xenograft (CDX) mouse models with HCT116 MTAP wt cells, HCT116 MTAP ko cells, LU99 cells (MTAP^null) and U87MG-luc (MTAP^null). The pharmacokinetic and toxicological properties were assessed with corresponding assay methods.
• Results: ATG-042 showed excellent anti-proliferative activities on multiple endogenous MTAP^null cell lines with IC₅₀ values between 10nM and 100nM. ATG-042 demonstrated high permeability, good metabolic stability, and low risk of drug-drug interaction. In vivo PK study shows that ATG-042 is well absorbed, with a dose-dependent increase in plasma distribution and high oral bioavailability in mice, SD rats and beagle dogs. Furthermore, ATG-042 is brain-penetrable (B/P ratio=51% in mice; KPuu_brain=0.73 in rats). ATG-042 showed robust in vivo efficacy in both subcutaneous CDX models (HCT116 -MTAP ko, LU99) and orthotopic CDX model (U87MG-luc) as a single agent. In addition, ATG-042 also exhibited potential synergy in combination with other drugs for antitumor therapy.
• Conclusions: ATG-042 is an oral MTAP^null-selective PRMT5 inhibitor with potent efficacy against MTAP^null tumor. It also demonstrated good tolerability and brain penetrability. ATG-042 is poised to enter clinical development in the second half of 2025.

ATG-110 (LY6G6D x CD3 T cell engager)
Title: ATG-110, a novel "2+1" LY6G6D-targeted T-cell engager (TCE) for the treatment of MSS colorectal cancer
Abstract Number: 3509
Session Category: Immunology
Session Title: T Cell Engagers
Date: April 28, 2025
Time: 2:00 PM - 5:00 PM (Central Time)
3:00 AM - 6:00 AM, April 29, 2025 (Beijing Time)
Location: Poster Section 38

• Introduction: Colorectal cancer (CRC) is one of the most common cancers worldwide and requires more effective and safer therapies to improve the poor survival outcome, particularly in patients with microsatellite stable (MSS) colorectal cancer, who exhibit primary resistance to immune checkpoint inhibitors and lack effective treatment options. T cell engagers have shown encouraging efficacy in treating hematological malignancies, while exhibiting suboptimal clinical efficacies in solid tumors. The risk of cytokine release syndrome (CRS) remains as a significant challenge clinically. ATG-110 is a novel "2+1" LY6G6D x CD3 TCE developed by Antengene. In this study, ATG-110 was evaluated in a series of preclinical in vitro studies for binding affinity, T cell activation and cytokine release, T cell dependent cytotoxicity (TDCC), and drug developability. The in vivo anti-tumor efficacy was evaluated in PBMC-humanized immunodeficient NDG mice engrafted with LY6G6D^medium-expression HT55 or LY6G6D^{very low}-expression SW480 MSS CRC cells.
• Results: ATG-110 binds to LY6G6D-positive cell lines, including LY6G6D-overexpression 293T, HT55, LS1034, with the nanomolar grade EC₅₀. The CD3 binding site of ATG-110 is concealed by the LY6G6D Fab arm before binding to LY6G6D, due to the steric hindrance. Therefore, ATG-110 demonstrated limited binding capability to CD3+ cells before LY6G6D crosslinking. It activates T cells and induces cytokine release only in the presence of LY6G6D+ cells. In vitro, ATG-110 resulted in potent T cell dependent cytotoxicity with single-digit pM IC₅₀ values on HT55 and SW480 cells. ATG-110 also showed potent anti-tumor activity in PBMC-humanized SW480 xenograft model and exhibited complete response (CR) in PBMC-humanized HT55 xenograft model. Furthermore, ATG-110 also demonstrated good drug developability.
• Conclusions: ATG-110 demonstrated LY6G6D-dependent CD3 binding and activation with low risk of CRS. It showed powerful in vitro and in vivo anti-tumor efficacy against colorectal cancer, which warrants further clinical evaluation.

ATG1144 (CD24 CDx Antibody)
Title: Development of a diagnostic antibody for CD24 targeted therapy
Abstract Number: 671
Session Category: Clinical Research
Session Title: Diagnostic Biomarkers 2
Date: April 27, 2025
Time: 2:00 PM - 5:00 PM (Central Time)
3:00 AM - 6:00 AM, April 28, 2025 (Beijing Time)
Location: Poster Section 29

• Introduction: CD24 has emerged as a promising therapeutic target for anti-cancer treatment. Several clinical trials are being conducted to evaluate the safety and efficacy of CD24-targeted therapies. Here, Antengene developed and characterized an anti-CD24 diagnostic antibody to enhance the screening and selection of patients based on CD24 expression. In this study, the authors described the discovery of the diagnostic antibody, and the evaluation of accuracy, sensitivity (selectivity), specificity, and assay precision of the antibody.
• Results: Monoclonal antibody clone ATG1144 binds to the hCD24 core peptide in ELISA with an EC₅₀ of 0.06 nM. Distinct membrane staining on human normal esophageal tissue FFPE specimens can also be observed with IHC staining using ATG1144. For accuracy assessment, six CDX and twenty human specimens, comprising both positive and negative specimens (including solid tumors and B-cell non-Hodgkin lymphomas), were validated. Samples exhibiting high, medium, and low CD24 expression levels were evaluated for sensitivity and specificity, and the interpreted results aligned with the reference outcomes. FFPE tissues from three distinct patients were evaluated for assay precision assessment. The TMA IHC staining result revealed that 50-80% of patients with lung, breast, bladder, ovarian, or liver cancer have CD24 expression on tumor cell surface with low expression in the para-cancerous normal tissue.
• Conclusions: ATG1144 specifically binds to human CD24 with high sensitivity as demonstrated by IHC staining. The development and validation of the method have been finalized using Leica Bond III platforms. These data suggest a potential diagnostic use of ATG1144 for identifying CD24+ patients.

About Antengene

Antengene Corporation Limited ("Antengene", SEHK: 6996.HK) is a leading commercial-stage R&D-driven global biopharmaceutical company focused on the discovery, development, manufacturing and commercialization of innovative first-in-class/best-in-class therapeutics for the treatment of hematologic malignancies and solid tumors, in realizing its vision of "Treating Patients Beyond Borders".

Antengene has built a pipeline of 9 oncology assets at various stages going from clinical to commercial, including 6 with global rights, and 3 with rights for the APAC region. To date, Antengene has obtained 31 investigational new drug (IND) approvals in the U.S. and Asia, and submitted new drug applications (NDAs) in 11 Asia Pacific markets, with the NDA for XPOVIO® (selinexor) already approved in Mainland of China, Taiwan China, Hong Kong China, Macau China, South Korea, Singapore, Malaysia, Thailand, Indonesia and Australia.

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SOURCE Antengene Corporation Limited