Combination of T cell-redirecting strategies with a bispecific antibody blocking TGF-β and PD-L1 enhances antitumor responses

ABSTRACT

T cell-based immunotherapies for solid tumors have not achieved the clinical success observed in hematological malignancies, partially due to the immunosuppressive effect promoted by the tumor microenvironment, where PD-L1 and TGF-β play a pivotal role. However, durable responses to immune checkpoint inhibitors remain limited to a minority of patients, while TGF-β inhibitors have not reached the market yet. Here, we describe a bispecific antibody for dual blockade of PD-L1 and TFG-β, termed AxF (scFv)₂, under the premise that combination with T cell redirecting strategies would improve clinical benefit. The AxF (scFv)₂ antibody was well expressed in mammalian and yeast cells, bound both targets and inhibited dose-dependently the corresponding signaling pathways in luminescence-based cellular reporter systems. Moreover, combined treatment with trispecific T-cell engagers (TriTE) or CAR-T cells significantly boosted T cell activation status and cytotoxic response in breast, lung and colorectal (CRC) cancer models. Importantly, the combination of an EpCAMxCD3×EGFR TriTE with the AxF (scFv)₂ delayed CRC tumor growth in vivo and significantly enhanced survival compared to monotherapy with the trispecific antibody. In summary, we demonstrated the feasibility of concomitant blockade of PD-L1 and TGF-β by a single molecule, as well as its therapeutic potential in combination with different T cell redirecting agents to overcome tumor microenvironment-mediated immunosuppression.

KEYWORDS:

• Bispecific antibody
• trispecific antibody
• T-cell engager
• CAR-T cell
• cancer immunotherapy
• combination therapy
• colorectal cancer

Abbreviations

bsAb, bispecific antibody; CAR, chimeric antigen receptor; EMT, epithelial mesenchymal transition; ICI, immune checkpoint inhibitor; EGFR, epidermal growth factor receptor; EpCAM, epithelial cell adhesion molecule; HER2, Human epidermal growth factor receptor-2; scFv, single-chain variable fragment; PBMCs, peripheral blood mononuclear cells; PD-L1, Programmed Death-ligand 1; TAA, tumor-associated antigens; TCE, T-cell engager; TGF-β, transforming growth factor beta; TME, tumor microenvironment; TriTE, trispecific T-cell engager.

Acknowledgments

The authors wish to thank donors and Biobank of HUPH/IDIPHISA for the human specimens used in this study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/2162402X.2024.2338558

Contributions

Conception and design: LS, ATG. Development of methodology: ATG, ISR, JN, PIH, SAG, AJR, SK, TT. Acquisition, analysis and interpretation of data: ATG, ISR, JN, PIH, LS. Writing, and/or review of the manuscript: ATG, ISR, JN, PIH, SAG, AJR, MC, SK, TT, PC, JL, LAV and LS.

Data availability statement

The data that support the findings of this study are available from the corresponding author, [LS], upon reasonable request.

Ethics approval

All procedures involving animals were in accordance with the ethical standards of the corresponding institutional and regional/national committees.

Additional information

Funding

This study was funded by grants from Carlos III Health Institute [PI19/00132 and PI22/00085], partially supported by the European Regional Development Fund [ERDF] to LS, by grants from the Spanish Ministry of Science and Innovation [PID2020-117323RB-100 and PDC2021-121711-100], the Carlos III Health Institute [DTS20/00089], the CRIS Cancer Foundation [FCRIS-2021-0090], the Spanish Association Against Cancer [PROYE19084ALVA and PRYGN234844ALVA], the Fundación ‘‘La Caixa’’ [HR21-00761 project IL7R_LungCan], and Comunidad de Madrid [P2022/BMD-7225 NEXT_GEN_CART_MAD-CM] to LAV, and Comunidad de Madrid [ANTICIPA-REACT-EU] to JL. ATG was supported by a predoctoral fellowship from Comunidad Autónoma de Madrid [PEJD-2018-PRE/BMD-8314].