Precision-activated T-cell engagers targeting HER2 or EGFR and CD3 mitigate on-target, off-tumor toxicity for immunotherapy in solid tumors

Abstract

To enhance the therapeutic index of T-cell engagers (TCEs), we engineered masked, precision-activated TCEs (XPAT proteins), targeting a tumor antigen (human epidermal growth factor receptor 2 (HER2) or epidermal growth factor receptor (EGFR)) and CD3. Unstructured XTEN polypeptide masks flank the N and C termini of the TCE and are designed to be released by proteases in the tumor microenvironment. In vitro, unmasked HER2-XPAT (uTCE) demonstrates potent cytotoxicity, with XTEN polypeptide masking providing up to 4-log-fold protection. In vivo, HER2-XPAT protein induces protease-dependent antitumor activity and is proteolytically stable in healthy tissues. In non-human primates, HER2-XPAT protein demonstrates a strong safety margin (>400-fold increase in tolerated maximum concentration versus uTCE). HER2-XPAT protein cleavage is low and similar in plasma samples from healthy and diseased humans and non-human primates, supporting translatability of stability to patients. EGFR-XPAT protein confirmed the utility of XPAT technology for tumor targets more widely expressed in healthy tissues.

Targeted pH-Activated Peptide-Based Nanomaterials for Combined Photodynamic Therapy with Immunotherapy

“…Ensuring the production of an ample number of functional T cells, specifically CD3 + cells, is paramount in the context of tumor immunotherapy. − Among these T cells, the CD3 + CD8 + subpopulation, known as cytotoxic T lymphocytes (CTL), possesses the capability to effectively recognize and eliminate tumor cells, whereas the CD3 + CD4 + subpopulation, termed helper T lymphocytes (Th), plays a vital role in orchestrating the antitumor immune response. − The immune responses associated with PRGD/NLG919 nanosheets were scrutinized through FACS. In this experiment, the proliferation of both CD3 + CD8 + T cells and CD3 + CD4 + T cells in peripheral blood mononuclear cells (PBMCs) was assessed under various conditions: PBMC monoculture, PBMCs cocultured with PBS-treated HeLa cells, PBMCs cocultured with PRGD/NLG919 nanosheets-treated HeLa cells without or with 660 nm laser irradiation at 0.12 W cm –2 for 5 min ( n = 3).…”

“…Ensuring the production of an ample number of functional T cells, specifically CD3 + cells, is paramount in the context of tumor immunotherapy. 48 − 50 Among these T cells, the CD3 + CD8 + subpopulation, known as cytotoxic T lymphocytes (CTL), possesses the capability to effectively recognize and eliminate tumor cells, whereas the CD3 + CD4 + subpopulation, termed helper T lymphocytes (Th), plays a vital role in orchestrating the antitumor immune response. 51 − 54 The immune responses associated with PRGD/NLG919 nanosheets were scrutinized through FACS.…”

Bispecific T-Cell Engagers and Chimeric Antigen Receptor T-Cell Therapies in Glioblastoma: An Update

“…Building on the concept of spatial control, conditional BsAbs are engineered to only become active once conditions associated with the tumor are met, for example, by including a peptide mask that is cleaved by tumor proteases or by requiring the presence of two antigens for unmasking and dimerization of the CD3 binding domain [ 141 , 142 , 143 , 144 , 145 , 146 , 147 ]. These platforms are yet to be tested in GBM but would likely be applicable, especially if designed for activation in a hypoxic TME, for example.…”

Conditional activation of an anti-IgM antibody-drug conjugate for precise B cell lymphoma targeting

“…cathepsin S) frequently overexpressed in tumor tissues ( 17 – 19 ). Previous masking attempts put forth antibody therapeutics with improved safety profiles, while retaining anti-disease activity ( 20 – 24 ). The versatile probody therapeutic technology platform developed by CytomX Therapeutics has been applied to target a variety of receptors including CTLA-4, EGFR, as well as molecules considered undruggable because of their broad tissue expression, such as CD71 and EpCAM ( 25 – 27 ).…”