1493 The armoured T-cell antigen coupler receptor (TAC) T cells with the integrated CD28 signaling, TAC28-T

<h3>Background</h3> T cell Antigen Coupler receptor (TAC) T cells harness all signaling subunits of endogenous T cell receptor (TCR) to activate T cells and lyse target cells with minimal release of cytokines.^1–4 To enhance the cytotoxicity of TAC-T cells to solid tumors, we have constructed armoured TAC-T cell integrated with the co-stimulatory cytoplasmic domain such as CD28 and secreting IL-15 super-agonist, CCL21 and other Immunomodulators, i.e., combining the first, the second and the third signals. Nectin4 are found to be over-expressed on the tumor cell surface in more than 10 common solid tumors.⁵ NKG2DL is not expressed in normal cells or in very small amount, but when the cells are infected or cancerous or stressed or senescent, the ligands will be up-regulated significantly, making them ideal targets for anti-tumor, anti-infection and anti-aging immunotherapy.^{6 7} FAP is selectively and highly expressed on the surface of cancer-associated fibroblasts (CAFs). CAFs play an important role in promoting the growth, invasion, metastasis and immunosuppression of tumor cells.^8–10 IL7, IL-15 super-agonist, CCL21, anti-PD-1 scFv and anti-TGFβ1 scFv can synergistically improve the tumor microenvironment, thereby enhancing the anti-tumor effect and activating the body to produce an intrinsic active anti-tumor immune effect.^11–19 <h3>Methods</h3> The integrated co-stimulatory CD28 better than 4-1BB cytoplasmic domain promoted the activation and proliferation of Nectin4 TAC28-T cells. Moreover, Nectin4 TAC28-T cells elicited superior antitumor potency in vitro and in vivo, as compared with Nectin4 TAC-T cells. Furthermore, we have conducted clinical trials of BCMA/NKG2DL/FAP-targeted TAC28-T cells secreting IL7 and CCL21 for the treatment of relapsed/refractory (R/R) multiple myeloma (NCT03778346, ChiCTR2300073645). Similarly, the Nectin-4/NKG2DL/FAP-targeted TAC28-T cells secreting IL7, CCL21, anti-PD-1 scFv, anti-TGFβ1 scFv have being used to treat 10 more common types of relapsed/refractory advanced solid tumors such as non-small cell lung cancer, liver cancer and glioblastoma (NCT03932565, ChiCTR2200062548, ChiCTR2200056085). <h3>Results</h3> 10 cases of R/R multiple myeloma have achieved 100% complete remission (CR) and no recurrence after follow-up of 32–66 months with only 1–2 day‘s fever after i.v. infusion of the TAC28-T cells. 10 patients were treated with the follow-up of 8–32 months, including 1 case of CR for 24 months (non-small lung cancer, 8 cases of very good partial response (VGPR) and 1 case of stable disease (SD). <h3>Conclusions</h3> To put together, our data highlighted that TAC28-T cells may represent a safe and highly effective cell therapy for hematological and solid tumors. <h3>Acknowledgements</h3> The study has been partially supported by the ‘Pioneer’ and ‘Leading Goose’ R&amp;D Program of Zhejiang (2024C03163), Shandong Provincial Key R &amp; D programs (2021CXGC011102) and Construction Fund of Key Medical Disciplines of Hangzhou (OO20200055). <h3>Trial Registration</h3> NCT03778346 and ChiCTR2300073645 for relapsed/refractory multiple myeloma; NCT03932565, ChiCTR2200062548 and ChiCTR2200056085 for relapsed/refractory advanced solid tumors such as non-small cell lung cancer, liver cancer, cholangiocarcinoma,head and neck cancer, thymic cancer and glioblastoma. <h3>References</h3> Duan D, Wang K, Wei C, <i>et al.</i> The BCMA-targeted fourth-generation CAR-T cells secreting IL7 and CCL19 for therapy for therapy of refractory/recurrent multiple myeloma. <i>Front Immunol</i> 2021;<b>12</b>:609421. Li F, Zhao S, Wei C, <i>et al</i>. Development of Nectin4/FAP-targeted CAR-T cells secreting IL7, CCL19, and IL12 for malignant solid tumors. <i>Front Immunol</i>. 2022;<b>13</b>:958082. Wu W, Zhou Q, Masubuchi T, <i>et al.</i> Multiple Signaling Roles of CD3ε and Its Application in CAR-T Cell Therapy. <i>Cell</i>. 2020;<b>182</b>(4):855–871.e23. Helsen CW, Hammill JA, Lau VWC, <i>et al.</i> The chimeric TAC receptor co-opts the T cell receptor yielding robust anti-tumor activity without toxicity. <i>Nat Commun</i>. 2018;<b>9</b>(1):3049. Bouleftour W, Guillot A, Magné N. The Anti-Nectin 4: a promising tumor cells target. a systematic review. <i>Mol Cancer Ther</i>. 2022;<b>21</b>(4):493–501. Wei C, Xia K, Xie Y, <i>et al</i>. Combination of 4-1BB and DAP10 promotes proliferation and persistence of NKG2D(bbz) CAR-T cells. <i>Front Oncol</i>. 2022;<b>12</b>:893124. Teng X, Rong Z, Li S, Yang W, Lu Z. T cells engineered with full-length NKG2D linked to signaling domains of 4-1BB and CD3ζ show enhanced antitumor activity. <i>Immunol Cell Biol</i>. 2023;<b>101</b>(5):458–464. Peltier A, Seban RD, Buvat I et al. Fibroblast heterogeneity in solid tumors: from single cell analysis to whole-body imaging. <i>Semin Cancer Biol</i>. 2022;<b>86</b>(Pt3):262–272. Zhao L, Chen J, Pang Y, <i>et al.</i> Fibroblast activation protein-based theranostics in cancer research: a state-of-the-art review. <i>Theranostics</i>. 2022;<b>12</b>(4):1557–1569. Sakemura R, Hefazi M, Siegler EL, <i>et al</i>. Targeting Cancer-Associated Fibroblasts in the Bone Marrow Prevents Resistance to CAR-T-Cell Therapy in Multiple Myeloma. <i>Blood</i>. 2022;<b>139</b>(26):3708–3721. Propper DJ, Balkwill FR. Harnessing cytokines and chemokines for cancer therapy. <i>Nat Rev Clin Oncol</i>. 2022;<b>19</b>(4):237–253. Hauser MA, Legler DF. Common and biased signaling pathways of the chemokine receptor CCR7 elicited by its ligands CCL19 and CCL21 in leukocytes. <i>J Leukoc Biol</i>. 2016;<b>99</b>(6):869–82. Knudson KM, Hodge JW, Schlom J, <i>et al.</i> Rationale for IL-15 Superagonists in Cancer Immunotherapy. <i>Expert Opin Biol Ther</i> 2020:1–5. Castiglioni A, Yang Y, Williams K, <i>et al.</i> Combined PD-L1/TGFβ blockade allows expansion and differentiation of stem cell-like CD8 T cells in immune excluded tumors. <i>Nat Commun</i>. 2023;<b>14</b>(1):4703. Martin CJ, Datta A, Littlefield C, <i>et al.</i> Selective inhibition of TGFβ1 activation overcomes primary resistance to checkpoint blockade therapy by altering tumor immune landscape. <i>Sci Transl Med</i>. 2020;<b>12</b>(536):eaay8456. Rafiq S, Yeku O, Jackson HJ, <i>et al.</i> Targeted delivery of a PD-1-blocking scFv by CAR-T cells enhances anti-tumor efficacy in vivo. <i>Nat Biotechnol</i>. 2018;<b>36</b>(9):847–856. Goebeler ME, Bargou RC. T cell-engaging therapies - BiTEs and beyond. <i>Nat Rev Clin Oncol</i>. 2020;<b>17</b>(7):418–434. Lei W, Zhao A, Liu H, <i>et al.</i> Safety and feasibility of anti-CD19 CAR T cells expressing inducible IL-7 and CCL19 in patients with relapsed or refractory large B-cell lymphoma. <i>Cell Discov</i>. 2024;<b>10</b>(1):5. Mojsilovic S, Mojsilovic SS, Bjelica S, Santibanez JF. Transforming growth factor-beta1 and myeloid-derived suppressor cells: a cancerous partnership. <i>Dev Dyn</i>. 2022;<b>251</b>(1):105–124. <h3>Ethics Approval</h3> The study obtained ethics approvals as follow, and the participants gave informed consent before taking part. 1.The ethics committees of Lishui People’s Hospital (LWW-FO-401) and the First Foshan People’s Hospital (2022-100) for relapsed/refractory multiple myeloma (NCT03778346, ChiCTR2300073645). 2.The ethics committees of Lishui People’s Hospital (2019-01-001), the Seventh Affiliated Hospital of Sun Yat-Sen University and Peking University Shenzhen Hospital for relapsed/refractory advanced solid tumors (NCT03932565, ChiCTR2200062548, ChiCTR2200056085).