Development of a TGFβ—IL-2/15 Switch Receptor for Use in Adoptive Cell Therapy

Abstract

Therapy employing T cells modified with chimeric antigen receptors (CARs) is effective in hematological malignancies but not yet in solid cancers. CAR T cell activity in solid tumors is limited by immunosuppressive factors, including transforming growth factor β (TGFβ). Here, we describe the development of a switch receptor (SwR), in which the extracellular domains of the TGFβ receptor are fused to the intracellular domains from the IL-2/15 receptor. We evaluated the SwR in tandem with two variants of a CAR that we have developed against STEAP1, a protein highly expressed in prostate cancer. The SwR-CAR T cell activity was assessed against a panel of STEAP1+/− prostate cancer cell lines with or without over-expression of TGFβ, or with added TGFβ, by use of flow cytometry cytokine and killing assays, Luminex cytokine profiling, cell counts, and flow cytometry phenotyping. The results showed that the SwR-CAR constructs improved the functionality of CAR T cells in TGFβ-rich environments, as measured by T cell proliferation and survival, cytokine response, and cytotoxicity. In assays with four repeated target-cell stimulations, the SwR-CAR T cells developed an activated effector memory phenotype with retained STEAP1-specific activity. In conclusion, the SwR confers CAR T cells with potent and durable in vitro functionality in TGFβ-rich environments. The SwR may be used as an add-on construct for CAR T cells or other forms of adoptive cell therapy.

Comparative Evaluation of STEAP1 Targeting Chimeric Antigen Receptors with Different Costimulatory Domains and Spacers

“…The CD19 CAR is identical to JK11, except for the scFv, and resembles the construct used in tisagenlecleucel (fmc63scFv_CD8aTM/spacer_41BB-z), which is approved for use against leukemia [ 1 ]. The T cells were co-cultured overnight with tumor target cells using a panel of STEAP1-positive (22Rv1, C2-4B, LNCap) and STEAP1-negative (22Rv1 STEAP1 knockout) prostate cancer cells that we have previously described [ 13 , 36 ]. The production of IFNγ and TNFα was measured by flow cytometry.…”

Shifting the paradigm: engaging multicellular networks for cancer therapy

“…CAR T cells armored with factors that can reduce chemo-repulsion may be able to overcome the functional or dynamic barriers that exclude them from tumor nests [ 20 ]. Examples include dominant negative [ 58 ] or switch TGF-β receptors that make CAR T cells resistant to the immune repulsive and suppressive effects of TGF-β [ 47 , 59 , 60 ]. Moreover, epigenetic knockdown of PD1 expression in response to Ag encounter can overcome dynamic barriers dependent upon PD1/programmed death ligand 1 at the periphery of tumor nests [ 20 , 61 ].…”

Armored Bicistronic CAR T Cells with Dominant-negative TGF-β Receptor II to Overcome Resistance in Glioblastoma

“…21 Given its dual role in both promoting tumor growth and suppressing immune cells, multiple strategies are currently being explored to mitigate the effects of TGF-β. These include targeting the latency-associated peptide, 22 leveraging the αv integrin/TGF-β axis, 23 inhibiting the TGF-β 24 or kinase receptor type I using small molecule inhibitors, 25 employing TGF-β switch receptor, [26][27][28] and TGF-β CAR T cells. 29 However, these methodologies also raise considerable safety issues, as it has been confirmed that first-generation TGF-βRI inhibitors can result in cardiac toxicity.…”