ShRNA-mediated silencing of PD-1 augments the efficacy of chimeric antigen receptor T cells on subcutaneous prostate and leukemia xenograft

• Published in: Biomedicine & pharmacotherapy Vol. 137; p. 111339
• Main Authors: Zhou, Jing-e, Yu, Jing, Wang, Yeying, Wang, Hao, Wang, Jing, Wang, Yiting, Yu, Lei, Yan, Zhiqiang
• Format: Journal Article
• Language: English
• Published: France Elsevier Masson SAS 01.05.2021
• Subjects: Animals; Antigens, CD19 - metabolism; Cell Line, Tumor; Gene Silencing - immunology; Heterografts - drug effects; Humans; Immunotherapy; Immunotherapy, Adoptive - methods; Leukemia - drug therapy; Leukemia - immunology; Male; Mice; Mice, Inbred NOD; Mice, SCID; PD-1 silenced CAR-T cells; PD-1/PD-L1; Programmed Cell Death 1 Receptor - antagonists & inhibitors; Programmed Cell Death 1 Receptor - genetics; Prostatic Neoplasms - drug therapy; Prostatic Neoplasms - immunology; Receptors, Chimeric Antigen - immunology; RNA, Small Interfering - pharmacology; ShRNA; Subcutaneous xenograft; T-Lymphocytes - immunology; Xenograft Model Antitumor Assays; ShRNA; PD-1 silenced CAR-T cells; Immunotherapy; PD-1/PD-L1; Subcutaneous xenograft
• ISSN: 0753-3322; 1950-6007; 1950-6007
• DOI: 10.1016/j.biopha.2021.111339

Chimeric antigen receptor T cells (CAR-T) immunotherapy has shown promising clinical results in the treatment of leukemia and lymphoma, but the effectiveness is limited for solid tumors. The PD-1/PD-L1 pathway is a key immunosuppressive mechanism for cancer cells to avoid eradication by CAR-T cells. In this study, the shRNA (short hair RNA) gene-silencing technique was used to construct the third-generation of CAR-T cells with PD-1 silencing which targeted CD19 antigen (CD19/△PD-1 CAR-T) and prostate stem cell antigen (PSCA/△PD-1 CAR-T), thereby blocking the PD-1/PD-L1 pathway in treatment of lymphoma and prostate subcutaneous xenograft and enhancing the anti-tumor effect of CAR-T cells. The cell experiments showed that PD-1 silencing in CAR-T cells effectively blocked the PD-1 / PD-L1 pathway. When the ratio of effector to target cell is 8:1, △PD-1 CAR-T cells exhibited higher killing ability and cytokine releasing ability than normal CAR-T cells did. The subcutaneous tumor models were constructed using human chronic myelogenous leukemia cells expressing CD19 (K562-CD19) and human prostate cancer cells expressing PSCA (PC3-PSCA), and treated with CD19/△PD-1 CAR-T and PSCA/△PD-1 CAR-T cells, respectively. The tumor volumes significantly reduced within one week, indicating the good tumor growth inhibitory effect of △PD-1 CAR-T cells. Mice injected with △PD-1 CAR-T cells showed a significantly prolonged survival time compared to those with normal CAR-T cells. This study proved that shRNA-mediated PD-1 silencing technology is an effective strategy for blocking the PD-1/PD-L1 immunosuppression pathway and enhancing the therapeutic effect of CAR-T cells on subcutaneous xenograft. The effect of CAR-T in treating solid tumors has not been as successful as that in hematological malignancies. The key immunosuppressive mechanism is the expression of PD-1/PD-L1. We used gene silencing technique mediated by shRNA (short hair RNA) to block the PD-1/PD-L1 pathway in lymphoma and prostate tumors, thus enhancing the anti-tumor effect of CAR-T cells on subcutaneous xenograft. [Display omitted] •The expression of PD-1/PD-L1 is a key immunosuppressive mechanism.•ShRNA-mediated PD-1 silencing technology is an effective strategy in CAR-T therapy.•Using PD-1 knockdown CAR-T cells could enhance the therapeutic effect.