Epidermal growth factor receptor (ErbB1, EGFR) is overexpressed in a variety of human cancer cells. It has been considered as a rational target for drug delivery. To identify novel ligands with specific binding capabilities to EGFR, we screened a phage display peptide library and found an enriched phage clone encoding the amino acid sequence YHWYGYTPQNVI (designated as GE11). Competitive binding assay and Scatchard analysis revealed that GE11 peptide bound specifically and efficiently to EGFR with a dissociation constant of approximately 22 nM, but with much lower mitogenic activity than with EGF. We showed that the peptides were internalized preferentially into EGFR highly expressing cells, and they accumulated in EGFR overexpressing tumor xenografts after i.v. delivery in vivo. In gene delivery studies, GE11-conjugated polyethylenimine (PEI) vectors were less mitogenic, but still quite efficient at transfecting genes into EGFR highly expressing cells and tumor xenografts. Taken together, GE11 is a potentially safe and efficient targeting moiety for selective drug delivery systems mediated through EGFR.

Purpose: The aim of our study is to elucidate whether T cells expressing GPC3-targeted chimeric antigen receptor (CAR) can efficiently eliminate GPC3-positive HCC cells and their potential in the treatment of HCC. Experimental Design: T cells expressing a first-generation and third-generation GPC3-targeted CAR were prepared using lentiviral vector transduction. The in vitro and in vivo cytotoxic activities of the genetically engineered CAR T cells were evaluated against various HCC cell lines. Results: GPC3-targeted CAR T cells could efficiently kill GPC3-positive HCC cells but not GPC3-negative cells in vitro. These cytotoxic activities seemed to be positively correlated with GPC3 expression levels in the target cells. In addition, T cells expressing the third-generation GPC3-targeted CAR could eradicate HCC xenografts with high level of GPC3 expression and efficiently suppress the growth of HCC xenografts with low GPC3 expression level in vivo. The survival of the mice bearing established orthotopic Huh-7 xenografts was significantly prolonged by the treatment with the third-generation GPC3-targeted CAR T cells. Conclusions: GPC3-targeted CAR T cells could potently eliminate GPC3-positive HCC cells, thereby providing a promising therapeutic intervention for GPC3-positive HCC. Clin Cancer Res; 20(24); 6418–28. ©2014 AACR.

Purpose: Our preclinical studies demonstrated the potential of chimeric antigen receptor (CAR)-glypican-3 (GPC3) T-cell therapy for hepatocellular carcinoma (HCC). We report herein the first published results of CAR-GPC3 T-cell therapy for HCC. Patients and Methods: In two prospective phase I studies, adult patients with advanced GPC3 þ HCC (Child-Pugh A) received autologous CAR-GPC3 T-cell therapy following cyclophosphamide-and fludarabine-induced lymphodepletion. The primary objective was to assess the treatment's safety. Adverse events were graded using the Common Terminology Criteria for Adverse Events (version 4.03). Tumor responses were evaluated using the RECIST (version 1.1). Results: A total of 13 patients received a median of 19.9 Â 10 8 CAR-GPC3 T cells by a data cutoff date of July 24, 2019. We observed pyrexia, decreased lymphocyte count, and cytokine release syndrome (CRS) in 13, 12, and nine patients, respectively. CRS (grade 1/2) was reversible in eight patients. One patient experienced grade 5 CRS. No patients had grade 3/4 neurotoxicity. The overall survival rates at 3 years, 1 year, and 6 months were 10.5%, 42.0%, and 50.3%, respectively, according to the Kaplan-Meier method. We confirmed two partial responses. One patient with sustained stable disease was alive after 44.2 months. CAR T-cell expansion tended to be positively associated with tumor response. Conclusions: This report demonstrated the initial safety profile of CAR-GPC3 T-cell therapy. We observed early signs of antitumor activity of CAR-GPC3 T cells in patients with advanced HCC.

Caspase-3 (CASP3) is a major mediator of apoptosis activated during cellular exposure to cytotoxic drugs, radiotherapy or immunotherapy. It is often used as a marker for efficacy of cancer therapy. However, recent reports indicate that caspase-3 has also non-apoptotic roles such as promotion of tumor relapse and tumor angiogenesis. Therefore, the roles of caspase-3 in tumor progression remain to be defined clearly. In our study, we established caspase-3 knockout (KO) colon cancer cell lines by use of the CRISPR technology. In vitro, caspase-3 knockout HCT116 cells were significantly less clonogenic in soft agar assays. They were also significantly less invasive and more sensitive to radiation and mitomycin C than control cells. In vivo, CASP3KO cells formed tumors at rates similar to control cells but were significantly more sensitive to radiotherapy. They were also less prone to pulmonary metastasis when inoculated either subcutaneously or intravenously. At the mechanistic level, caspase-3 gene knockout appeared to cause reduced EMT phenotypes when compared to parental HCT116 cells. Indeed, they showed significantly increased E-cadherin expression, reduced N-cadherin, Snail, Slug and ZEB1 expression than control cells. Therefore, therapeutic targeting of caspase-3 may not only increase the sensitivity of cancer cell to chemotherapy and radiotherapy, but also inhibit cancer cell invasion and metastasis.

Cancer immunotherapy has made unprecedented breakthrough in the fields of chimeric antigen receptor-redirected T (CAR T) cell therapy and immune modulation. Combination of CAR modification and the disruption of endogenous inhibitory immune checkpoints on T cells represent a promising immunotherapeutic modality for cancer treatment. However, the potential for the treatment of hepatocellular carcinoma (HCC) has not been explored. In this study, the gene expressing the programmed death 1 receptor (PD-1) on the Glypican-3 (GPC3)-targeted second-generation CAR T cells employing CD28 as the co-stimulatory domain was disrupted using the CRISPR/Cas9 gene-editing system. It was found that, in vitro, the CAR T cells with the deficient PD-1 showed the stronger CAR-dependent anti-tumor activity against native programmed death 1 ligand 1-expressing HCC cell PLC/PRF/5 compared with the wild-type CAR T cells, and meanwhile, the CD4 and CD8 subsets, and activation status of CAR T cells were stable with the disruption of endogenous PD-1. Additionally, the disruption of PD-1 could protect the GPC3-CAR T cells from exhaustion when combating with native PD-L1-expressing HCC, as the levels of Akt phosphorylation and anti-apoptotic protein Bcl-xL expression in PD-1 deficient GPC3-CAR T cells were significantly higher than those in wild-type GPC3-CAR T cells after coculturing with PLC/PRF/5. Furthermore, the in vivo anti-tumor activity of the CAR T cells with the deficient PD-1 was investigated using the subcutaneous xenograft tumor model established by the injection of PLC/PRF/5 into NOD-scid-IL-2Rγ-/- (NSG) mice. The results indicated that the disruption of PD-1 enhanced the in vivo anti-tumor activity of CAR T cells against HCC, improved the persistence and infiltration of CAR T cells in the NSG mice bearing the tumor, and strengthened the inhibition of tumor-related genes expression in the xenograft tumors caused by the GPC3-CAR T cells. This study indicates the enhanced anti-tumor efficacy of PD-1-deficient CAR T cells against HCC and suggests the potential of precision gene editing on the immune checkpoints to enhance the CAR T cell therapies against HCC.

SUMMARY The fate of disseminated tumor cells is largely determined by microenvironment (ME) niche. The osteogenic niche promotes cancer cell proliferation and bone metastasis progression. We investigated the underlying mechanisms using pre-clinical models and analyses of clinical data. We discovered that the osteogenic niche serves as a calcium (Ca) reservoir for cancer cells through gap junction (GJs). Cancer cells cannot efficiently absorb Ca from ME, but depend on osteogenic cells to increase intracellular Ca concentration. The Ca signaling, together with previously identified mTOR signaling, promotes bone metastasis progression. Interestingly, effective inhibition of these pathways can be achieved by danusertib, or combination of everolimus and arsenic trioxide, which provide possibilities of eliminating bone micrometastases (BMM) using clinically established drugs.

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Chimeric antigen receptor (CAR)-modified natural killer (NK) cells represent a promising immunotherapeutic modality for cancer treatment. However, their potential utilities have not been explored in hepatocellular carcinoma (HCC). Glypian-3 (GPC3) is a rational immunotherapeutic target for HCC. In this study, we developed GPC3-specific NK cells and explored their potential in the treatment of HCC. The NK-92/9.28.z cell line was established by engineering NK-92, a highly cytotoxic NK cell line with second-generation GPC3-specific CAR. Exposure of GPC3 HCC cells to this engineered cell line resulted in significant in vitro cytotoxicity and cytokine production. In addition, soluble GPC3 and TGF-β did not significantly inhibit the cytotoxicity of NK-92/9.28.z cells in vitro, and no significant difference in anti-tumor activities was observed in hypoxic (1%) conditions. Potent anti-tumor activities of NK-92/9.28.z cells were observed in multiple HCC xenografts with both high and low GPC3 expression, but not in those without GPC3 expression. Obvious infiltration of NK-92/9.28.z cells, decreased tumor proliferation, and increased tumor apoptosis were observed in the GPC3 HCC xenografts. Similarly, efficient retargeting on primary NK cells was achieved. These results justified clinical translation of this GPC3-specific, NK cell-based therapeutic as a novel treatment option for patients with GPC3 HCC.