T cells expressing CD5/CD7 bispecific chimeric antigen receptors with fully human heavy-chain-only domains mitigate tumor antigen escape

Abstract

Bispecific chimeric antigen receptor T-cell (CAR-T) therapies have shown promising results in clinical trials for advanced B-cell malignancies. However, it is challenging to broaden the success of bispecific CAR-T therapies to treat refractory/relapse (r/r) T-cell leukemia/lymphoma because targeting multiple T-cell-expressing antigens leads to exacerbated CAR-T cell fratricide and potential safety concerns. Fully human heavy chain variable (FHVH) antibodies that specifically target CD5 or CD7 were screened and constructed to CD5/CD7 bispecific CARs. A truncated Epidermal growth factor receptor were integrated into CAR constructs to address safety concerns. To tackle the fratricidal issue of CAR-T cells targeting T-cell-pan marker(s), CRISPR/Cas9-based CD5 and CD7 genes knockout were performed before lentiviral transduction of bispecific CARs. Functional comparison between different bispecific CAR structures: tandem CARs and dual CAR were performed in vitro and in vivo to determine the optimal construct suitable for addressing T-cell malignancy antigen escape in clinical setting. Knockout of CD5 and CD7 prevents fratricide of CD5/CD7 bispecific CAR-T cells, and FHVH-derived CD5/CD7 bispecific CAR-T cells demonstrate potent antitumor activity in vitro and in vivo. The fratricide-resistant FHVH-derived CD5/CD7 bispecific CAR-T cells have potent antitumor activity against T-cell malignancies, and tandem CARs are more effective than dual CAR in preventing tumor escape in heterogeneous leukemic cells. The meaningful clinical efficacy and safety of tandem CD5/CD7 CAR-T cells deserve to be explored urgently.

Current Status and Perspectives of Dual-Targeting Chimeric Antigen Receptor T-Cell Therapy for the Treatment of Hematological Malignancies

“…By comparison, the bivalent vector is smaller than the bicistronic vector because only one co-stimulatory domain needs to be generated by the vector. Therefore, lower transduction efficiencies in bicistronic Bi-CAR T cells targeting BCMA/CS1 and CD5/CD7 were observed, compared to bivalent Bi-CAR T cells [41,42]. Similarly, the transduction efficiency in the CD19/CD22 Loop Bi-CAR T cells expressing LoopCAR6 with a longer linker was lower than the Loop Bi-CAR T cells expressing LoopCAR3 with a shorter linker [33].…”

Tumor buster - where will the CAR-T cell therapy ‘missile’ go?

“…Bispecific CAR-T cells are currently being explored for use in T-NHL. Researchers made CD5/CD7 CAR-T cells that showed anti-tumor substantial effects in malignant T cell lines such as Jurkat, CCRF-CEM, MOLT, and in xenogeneic mouse models established using CCRF-CEM-ffLuc cell injections [ 66 ]. The following clinical trials are urgently needed to validate their clinical efficacy and safety.…”

“…3–4(0%), Neurotoxicity gr.3–4 (7%) [ 424 ] Phase 1 (ChiCTR-ONC-17013648) CD19/CD22 Child, Adult 21 4-Dec-17 Beijing Boren Hospital, Beijing, China 4-1BB-CD3ζ 14CR 0.486–5.0× 10 5 (CD19), 0.32–5.0× 10 5 (CD22) CRS gr. 3–4 (0%), Neurotoxicity gr.3–4 (0%) [ 86 ] CD20/CD22,CD19/CD123,CD19/BAFF-R [ 82 , 425 , 426 ] T-ALL CD5/CD7 [ 66 ] AML CD123/CD19,FLT3/NKG2DL,CD123/CLL1,CD13/TIM3,CD123/FRβ [ 427 – 431 ] CLL Phase 1 (NCT03019055) CD19/CD20 Adult, Older Adult 3 16-Oct-17 Froedtert Hospital & Medical College of Wisconsin, Milwaukee, Wisconsin, United States 4-1BB-CD3ζ 2CR 2.5 × 10 5 –2.5× 10 6 unknown [ 51 ] MM Phase 1 (ChiCTR1800018143) BCMA/CD38 Adult, Older Adult 23 1-Sep-18 Institute of Hematology, Union Hospital Affiliated to Tongji Medical College, Huazhong University of science and technology 4-1BB-CD3ζ 12CR 0.5,1.0,2.0,3.0 and 4.0× 10 6 CRS gr. 3–4 (22%), Neurotoxicity gr.3–4 (0%) [ 169 ] Phase 2 (ChiCTR1800017051) BCMA/CD38 Adult, Older Adult 22 1-Jun-18 The first central hospital of Tianjin, Tianjin, China …”

Allogenic and Autologous anti-CD7 CAR-T cell Therapies in Relapsed or Refractory T-Cell Malignancies

“…CAR-T cell therapies have been explored in T-cell ALL and lymphoma and their targets include CD7, CD5, CD99 and CD38 (11)(12)(13). CD7 is a transmembrane glycoprotein highly expressed in T-cell lymphoblastic leukemias and lymphomas (> 95%), and is also present on the majority of T cells, NK cells, and their precursors (14)(15)(16)).…”