Journal: Molecular Cancer Therapeutics

Article Title: TPP-45142—an Anti-HER2 T-cell Engager—Designed for Selective HER2-Low Cancer Immunotherapy

doi: 10.1158/1535-7163.MCT-25-0654

Figure Lengend Snippet: TPP-45142 is a bispecific molecule that binds with a novel epitope of HER2. A, Schematic representation of TPP-45142. Green, two HER2-binding NANOBODY domains; orange, anti-TCRαβ NANOBODY domain; and gray, Fc domain with effectorless function. B, Cryo-EM structure of the complex HER2–29E09–Fab was obtained at 2.78 Å resolution. Left, colored electron density map. Right, full model. C, Cryo-EM structure of the 27A05–HER2–47D05–Fab complex was obtained at 2.66 Å resolution. Left, colored electron density map. Center, full model. Right, 27A05–HER2 interface. D, Structural superposition showing the relative location of pertuzumab and trastuzumab (based on PDB 6OGE) versus 27A05 and 29E09 as observed using cryo-EM. E, Structural superposition of 29E09 and 27A05. [ A, Created in BioRender. Vintem, A.P. (2026) https://BioRender.com/lk4spzo .]

Article Snippet: Human, cyno, and mouse HER2 Fc proteins were immobilized on a ProteOn GLC sensor chip (BioRad Laboratories, Inc. cat. #176-5011; 20 μg/mL, 10 mmol/L acetate pH 4.0, 120 seconds, 30 μL/minute).

Techniques: Binding Assay, Cryo-EM Sample Prep

Journal: Molecular Cancer Therapeutics

Article Title: TPP-45142—an Anti-HER2 T-cell Engager—Designed for Selective HER2-Low Cancer Immunotherapy

doi: 10.1158/1535-7163.MCT-25-0654

Figure Lengend Snippet: Cytotoxicity of TPP-45142 and its mechanism of action toward HER2-low breast cancer cell lines. A–D, TDCC of TPP-45142 for three T-cell donors compared with that of non-HER2 negative control (TPP-45161); co-cultures of human T cells with HCC1954, ZR-75-1, BT-20, or BT-549 cells were used at an E:T ratio of 5:1. E, TDCC of TPP-45142 for three T-cell donors compared with that of TPP-45161 in a co-culture of human T cells with BT20 3D spheroids at an E:T ratio of 1:5. F, T-cell activation induced by TPP-45142 as measured by expression of CD25 and CD69 expression on both CD4 + and CD8 + T cells as per FC analysis of ZR-75-1 and BT20 cells. G, Production of IFN-γ, IL2, IL6, IL8, IL10, and TNF-α cytokines in the culture supernatants obtained in the T-cell activation assay was measured using electrochemiluminescence assays.

Article Snippet: Human, cyno, and mouse HER2 Fc proteins were immobilized on a ProteOn GLC sensor chip (BioRad Laboratories, Inc. cat. #176-5011; 20 μg/mL, 10 mmol/L acetate pH 4.0, 120 seconds, 30 μL/minute).

Techniques: Negative Control, Co-Culture Assay, Activation Assay, Expressing, Electrochemiluminescence

Journal: Molecular Cancer Therapeutics

Article Title: TPP-45142—an Anti-HER2 T-cell Engager—Designed for Selective HER2-Low Cancer Immunotherapy

doi: 10.1158/1535-7163.MCT-25-0654

Figure Lengend Snippet: PK profiles and antitumor efficacy of TPP-45142 in the ZR-75-1 HER2-low breast cancer mouse model. A, TPP-45142 PK behavior in the ZR-75-1 xenograft model. Human T cells were administered to female NGS mice bearing intramammary ZR-75-1 tumors, and they were treated once with 89 Zr-TPP-45142 or the non-HER2 negative control 89 Zr-TPP-45161 ( n = 3). Microsamples (5 µL/time point) of blood were collected, and radioactivity was measured extemporaneously using a gamma counter (time: after radiolabeled-compound injection). B, Tumor accumulation of 89 Zr-TPP-45142 or non-HER2 negative control 89 Zr-TPP-45161 as measured by PET/CT imaging ( n = 3; time: after radiolabeled-compound injection). C, Antitumor activity of TPP-45142 in the ZR-75-1 xenograft model. Human T cells (10 × 10 6 ) were administered to female NSG mice bearing ZR-75-1 tumors, and they were treated on days 22 and 29 with TPP-45142 (500, 100, 50, and 10 μg/kg) and non-HER2 negative control TPP-45161 (500 μg/kg; n = 10 per group). ID, injected dose; MAD, median absolute deviation.

Article Snippet: Human, cyno, and mouse HER2 Fc proteins were immobilized on a ProteOn GLC sensor chip (BioRad Laboratories, Inc. cat. #176-5011; 20 μg/mL, 10 mmol/L acetate pH 4.0, 120 seconds, 30 μL/minute).

Techniques: Negative Control, Radioactivity, Injection, Positron Emission Tomography-Computed Tomography, Imaging, Activity Assay

Journal: Molecular Cancer Therapeutics

Article Title: TPP-45142—an Anti-HER2 T-cell Engager—Designed for Selective HER2-Low Cancer Immunotherapy

doi: 10.1158/1535-7163.MCT-25-0654

Figure Lengend Snippet: Safety profile of TPP-45142. A, T cell–mediated lysis of human cardiomyocytes was measured by impedance using xCELLigence. For donor 3, nine doses were tested in the range of 3 × 10 −11 to 5 × 10 −7 mol/L, whereas for donors 1 and 2, only the highest three doses were tested. B and C, HER2 distribution on the cell surface of BT-549 and HCM, respectively, via immunofluorescence. Arrowheads point to large HER2-enriched areas. D, Comparison of HER2 distribution between BT-549 ( B ) and HCM ( C ) cells via frequency distribution analysis of objects sorted by area. E, Heatmap of cytokine concentration as measured using the Luminex multiplex array after MIMIC CRA.

Article Snippet: Human, cyno, and mouse HER2 Fc proteins were immobilized on a ProteOn GLC sensor chip (BioRad Laboratories, Inc. cat. #176-5011; 20 μg/mL, 10 mmol/L acetate pH 4.0, 120 seconds, 30 μL/minute).

Techniques: Lysis, Immunofluorescence, Comparison, Concentration Assay, Luminex, Multiplex Assay