A conditionally-active, dual-targeting TCE with superior tumor selectivity for the treatment of solid tumors
Presenter: Steffen Dickopf, PhD Session: T Cell Engagers 1 Time: 4/20/2026 9:00:00 AM → 4/20/2026 12:00:00 PM
Authors
Steffen Dickopf , Jorge A. Lerma Romero , Jessica Seib , Laura Perucho-Aznar , Steffen Runz , Abdul-Habib Maag , Anna Pryszlak , Anja Schreiber , Martha Gschwandtner , Christoph Erkel , Richard J. Austin VERAXA Biotech GmbH, Heidelberg, Germany
Abstract
Background T cell engagers (TCEs) represent a rapidly advancing class of immunotherapies that have demonstrated remarkable clinical efficacy in hematologic malignancies. However, their application in solid tumors remains limited by on-target, off-tumor toxicities resulting from antigen expression in healthy tissues. Moreover, off-target, off-tumor effects can arise from systemic T cell engagement and nonspecific activation, leading to cytokine release syndrome (CRS). To overcome these challenges, we have developed an innovative TCE platform incorporating an AND-gated safety mechanism that enables selective killing of tumor cells while sparing healthy cells. Method The Bi-targeted Tumor-Associated Cytotoxicity (BiTAC) T cell engager builds up on the previously described hemibody concept 1 and employs an on-cell assembly mechanism of two complementary compounds to achieve conditional activation. Each compound comprises a tumor-binding domain recognizing a distinct tumor-associated antigen (TAA) and a split T cell-binding moiety. Individually, the compounds do not engage T cells. Productive T cell activation occurs only when both compounds co-bind and accumulate on tumor cells co-expressing the respective antigens, leading to reconstitution of an active CD3 binder. The BiTAC-TCE was optimized for developability, stability, and potent functional activity in both in vitro and in vivo settings. Results Our bioinformatics pipeline identified a TAA pair highly co-expressed in colorectal and lung cancers. Constitutively active drugs targeting each TAA individually have been tested in humans and revealed target-associated toxicities. An antibody format with favorable manufacturability and developability was subsequently selected. Using in vitro T cell-dependent cellular cytotoxicity (TDCC) assays across multiple cell lines in 2D and 3D cultures, we demonstrate that the combinatorial design of BiTAC-TCE enables T cells to selectively eliminate dual-target-positive tumor cells while sparing single-positive healthy cells. Individual compounds/BiTAC precursors don’t bind T cells and don’t induce TDCC in vitro and in vivo. Furthermore, BiTAC-TCE exhibits strong antitumor efficacy in PBMC-engrafted mice bearing colorectal tumors and displays a favorable pharmacokinetic (PK) profile in preclinical mouse studies. Conclusion Our BiTAC-TCE platform enables precise targeting of solid tumors through TAAs not druggable by current immunotherapies. Both TAAs addressed are broadly expressed but not co-expressed on healthy cells of different tissues, leading to failure of monotargeting T cell engagers in clinical settings. Our lead BiTAC-TCE for the treatment of colorectal and lung cancers has recently entered formal preclinical development and IND-enabling studies. 1 Banaszek, A. et al. Nat Commun 10, 5387 (2019)
Disclosure
S. Dickopf, None.. J. A. Lerma Romero, None.. J. Seib, None.. L. Perucho-Aznar, None.. S. Runz, None.. A. Maag, None.. A. Pryszlak, None.. A. Schreiber, None.. M. Gschwandtner, None.. C. Erkel, None.. R. J. Austin, None.
Cited in
Control: 3744 · Presentation Id: 5103 · Meeting 21436