Chimeric Antigen Receptor-Modified T Cells Redirected to EphA2 for the Immunotherapy of Non-Small Cell Lung Cancer

Abstract

Erythropoietin-producing hepatocellular carcinoma A2 (EphA2) is overexpressed in more than 90% of non-small cell lung cancer (NSCLC) but not significantly in normal lung tissue. It is therefore an important tumor antigen target for chimeric antigen receptors (CAR)-T-based therapy in NSCLC. Here, we developed a specific CAR targeted to EphA2, and the anti-tumor effects of this CAR were investigated. A second generation CAR with co-stimulatory receptor 4-1BB targeted to EphA2 was developed. The functionality of EphA2-specific T cells in vitro was tested with flow cytometry and real-time cell electronic sensing system assays. The effect in vivo was evaluated in xenograft SCID Beige mouse model of EphA2 positive NSCLC. These EphA2-specifc T cells can cause tumor cell lysis by producing the cytokines IFN-γ when cocultured with EphA2-positive targets, and the cytotoxicity effects was specific in vitro. In vivo, the tumor signals of mice treated with EphA2-specifc T cells presented the tendency of decrease, and was much lower than the mice treated with non-transduced T cells. The anti-tumor effects of this CAR-T technology in vivo and vitro had been confirmed. Thus, EphA2-specific T-cell immunotherapy may be a promising approach for the treatment of EphA2-positive NSCLC.

Figure 1

Erythropoietin-producing hepatocellular carcinoma A2 (EphA2) is expressed in lung cancer cell lines and malignant pleural effusions. (A) FCM showed that EphA2 was expressed in the lung cancer cell lines but not in the leukemia cell line K562. (B) EphA2 were found in cancerous pleural effusion of lung adenocarcinoma patients.

Figure 2

Generation of erythropoietin-producing hepatocellular carcinoma A2 (EphA2)-specific T cells. (A) The EphA2-specific chimeric antigen receptors (CAR) was generated by cloning a single chain variable fragment derived from the EphA2 monoclonal antibody 4H5 upstream of an IgG1-CH2CH3 domain, a CD8α TM domain, and costimulatory domains derived from 4-1BB and CD3-ζ into an SFG retroviral vector. (B) EphA2-CAR expression was detected by staining T cells with a corresponding antibody. Fluorescence activated cell sorting analysis revealed expression of EphA2-specific CARs on the cell surface of transduced T cells as compared with controls. The percentage of CAR-expressing T cells were 40.5% and 45.5% in two normal healthy donors LTR, long terminal repeats; TM, transmembrane.

Figure 3

Erythropoietin-producing hepatocellular carcinoma A2 (EphA2)-specific T cells recognize and kill EphA2-positive lung cancer cells. (A) Non-transduced (NT) or EphA2-specific T cells were cocultured with target cells at 5:1, 1:1 and 1:5 ratio, and after 24 hours, percentage of IFN-γ-expressing T cells was determined by FCM. A higher percentage of IFN-γ-expressing T cells was occurred in comparison to the EphA2-negative T cells and K562. (B) EphA2-specific T cells showed a significant lower CI against A549 whereas non-transduced T cells, and a rapid and precipitous increase in CI occurred in the control group (only A549). And the stronger cytotoxic activity against A549 was observed at the higher effector to target (E: T) ratio of 20:1.

Figure 4

Erythropoietin-producing hepatocellular carcinoma A2 (EphA2)-specific cells induce regression of established lung cancer in vivo. (A)2.5 × 10⁶ A549.GFP. Luc cells were injected into the caudal vein of SCID Beige mice on day 0 and treated with 1 × 10⁷ EphA2-specific T cells into the previous stereotactic tumor coordinates on day 7. Mice treated with non-transduced (NT) T cells served as controls. Bioluminescence imaging was used to follow tumor progression. All mice had detectable tumors just prior to treatment (day 7). (B) The bioluminescence signal from the tumors over time. Dotted lines represent each individual mouse while the solid black line represents the mean radiance for the group at the given time.