Background:
Chimeric antigen receptor T cell (CAR-T) therapy faces multiple challenges in solid tumors, especially the heterogeneity of tumor antigens. Glypican-3 (GPC3) and trophoblast cell-surface antigen 2 (TROP2) are highly expressed antigens in lung squamous cell carcinoma (LUSC) for development of dual-targeted therapy. The absence of GPC3 in any normal tissues of adults makes it an ideal target for CAR-T therapy. However, TROP2 is expressed in the epithelial cells of various normal tissues and thus is not acceptable for direct design of CAR-T therapy due to the high risk of “on-target off-tumor” effects. Here we developed a dual-targeted LUSC therapy featuring a GPC3-targeted CAR-T cell secreting TROP2-directed bispecific T cell engagers (GPC3 CAR-T. TROP2 BiTE), and verified the antitumor activity
in vitro
and
in vivo
, respectively.
Methods:
Immunohistochemistry (IHC) was used to confirm the expression of GPC3 and TROP2 in LUSC and normal tissues. CAR-T cells were produced through lentiviral transduction of CAR genes. Real-time cytotoxicity assay (RTCA) was used to assess the cytotoxic effect of CAR-T cells on LUSC cells. Flow cytometry was utilized to examine the CAR-T cell phenotype, exhaustion and activation. Enzyme-linked immunosorbent assay (ELISA) was performed to detect the release of cytokines. To evaluate the activity of CAR-T cells
in vivo
, tumor-bearing immunodeficient mice were given a single intravenous injection of CAR-T cells, and the tumor burden and CAR-T cell expansion were regularly monitored.
Results:
GPC3 was overexpressed in 70% of LUSC tissues, while negatively expressed in all normal tissues. Positive expression of TROP2 was observed in all LUSC tissues and also in many normal tissues. Compared with GPC3 CAR-T and TROP2 CAR-T, GPC3 CAR-T. TROP2 BiTE exhibited cytotoxicity to both GPC3
+
and TROP2
+
LUSC cells, and thereby showed faster killing and durable antitumor effect against LUSC cells with heterogenous expression of GPC3 and TROP2. In tumor-bearing mice, GPC3 CAR-T. TROP2 BiTE showed strong ability to eliminate tumors.
Conclusions:This study demonstrated that GPC3 CAR-T. TROP2 BiTE was a potent therapy for LUSC and provided a strategy for overcoming the antigen heterogeneity in solid tumors.
