Overview of gene therapy clinical progress including cancer treatment with gene-modified T cells

STAT3 Decoy Oligodeoxynucleotides-Loaded Solid Lipid Nanoparticles Induce Cell Death and Inhibit Invasion in Ovarian Cancer Cells

Recent advances in the synthesis of multi-functional nanoparticles have opened up tremendous opportunities for the targeted delivery of genes of interest. Cationic solid lipid nanoparticles (SLN) can efficiently bind nucleic acid molecules and transfect genes in vitro. Few reports have combined SLN with therapy using decoy oligodeoxynucleotides (ODN). In the present study, we prepared SLN to encapsulate STAT3 decoy ODN; then, the properties and in vitro behavior of SLN-STAT3 decoy ODN complexes were investigated. SLN-STAT3 decoy ODN complexes were efficiently taken up by human ovarian cancer cells and significantly suppressed cell growth. Blockage of the STAT3 pathway by SLN-STAT3 decoy ODN complexes resulted in an evident induction of cell death, including apoptotic and autophagic death. The mechanism involved the increased expression of cleaved caspase 3, Bax, Beclin-1 and LC3-II and reduced expression of Bcl-2, pro-caspase 3, Survivin, p-Akt and p-mTOR. In addition, SLN-STAT3 decoy ODN complexes inhibited cell invasion by up-regulating E-cadherin expression and down-regulating Snail and MMP-9 expression. These findings confirmed that SLN as STAT3 decoy ODN carriers can induce cell death and inhibit invasion of ovarian cancer cells. We propose that SLN represent a potential approach for targeted gene delivery in cancer therapy.

Therapeutic properties of a vector carrying the HSV thymidine kinase and GM-CSF genes and delivered as a complex with a cationic copolymer

BACKGROUND

Gene-directed enzyme prodrug therapy (GDEPT) represents a technology to improve drug selectivity for cancer cells. It consists of delivery into tumor cells of a suicide gene responsible for in situ conversion of a prodrug into cytotoxic metabolites. Major limitations of GDEPT that hinder its clinical application include inefficient delivery into cancer cells and poor prodrug activation by suicide enzymes. We tried to overcome these constraints through a combination of suicide gene therapy with immunomodulating therapy. Viral vectors dominate in present-day GDEPT clinical trials due to efficient transfection and production of therapeutic genes. However, safety concerns associated with severe immune and inflammatory responses as well as high cost of the production of therapeutic viruses can limit therapeutic use of virus-based therapeutics. We tried to overcome this problem by using a simple nonviral delivery system.

METHODS

We studied the antitumor efficacy of a PEI (polyethylenimine)-PEG (polyethylene glycol) copolymer carrying the HSVtk gene combined in one vector with granulocyte-macrophage colony-stimulating factor (GM-CSF) cDNA. The system HSVtk-GM-CSF/PEI-PEG was tested in vitro in various mouse and human cell lines, ex vivo and in vivo using mouse models.

RESULTS

We showed that the HSVtk-GM-CSF/PEI-PEG system effectively inhibited the growth of transplanted human and mouse tumors, suppressed metastasis and increased animal lifespan.

CONCLUSIONS

We demonstrated that appreciable tumor shrinkage and metastasis inhibition could be achieved with a simple and low toxic chemical carrier - a PEI-PEG copolymer. Our data indicate that combined suicide and cytokine gene therapy may provide a powerful approach for the treatment of solid tumors and their metastases.

Cationic lipid nanosystems as carriers for nucleic acids

Solid lipid nanoparticles (SLNs) consisting of tristearin or tribehenin, and monoolein aqueous dispersions (MADs) consisting of glyceryl-monoolein have been studied as potential nanocarriers for nucleic acids. The cationic character of nanocarriers was obtained by adding cationic surfactants, such as diisobutylphenoxyethyl-dimethylbenzyl ammonium chloride (DEBDA) or PEG-15 Cocopolyamine (PCPA), to the lipid composition. The products were characterised in terms of size and morphology by Cryo-TEM and PCS. The charge properties were determined by measuring the zeta potential. Our experimental protocol enabled us to obtain homogeneous and stable cationic nanosystems within 3-6 months of production. Assessment of cytotoxicity on HepG2 cells by MTT assays indicated that MAD preparations were less toxic than SLN, and in general PCPA-containing formulations are less cytotoxic than DEBDA-containing ones. The formation of electrostatic complexes with salmon sperm or plasmid DNA, used as model nucleic acids, was evaluated by electrophoresis on agarose gel. The results confirmed that all the formulations studied are able to form the complex. Finally, we investigated the ability of SLN and MAD to deliver DNA into HepG2 cells, and to this purpose we exploited expression plasmids for green fluorescent protein or firefly luciferase. Although with reduced efficiency, the results showed that the produced nanocarriers are able to convey plasmids into cells. The data obtained encourage further study aimed at improving these new formulations and proposing them as novel in vitro transfection reagents with potential application to in vivo delivery of nucleic acids.

Generation of rejuvenated antigen-specific T cells by reprogramming to pluripotency and redifferentiation

Adoptive immunotherapy with functional T cells is potentially an effective therapeutic strategy for combating many types of cancer and viral infection. However, exhaustion of antigen-specific T cells represents a major challenge to this type of approach. In an effort to overcome this problem, we reprogrammed clonally expanded antigen-specific CD8(+) T cells from an HIV-1-infected patient to pluripotency. The T cell-derived induced pluripotent stem cells were then redifferentiated into CD8(+) T cells that had a high proliferative capacity and elongated telomeres. These "rejuvenated" cells possessed antigen-specific killing activity and exhibited T cell receptor gene-rearrangement patterns identical to those of the original T cell clone from the patient. We also found that this method can be effective for generating specific T cells for other pathology-associated antigens. Thus, this type of approach may have broad applications in the field of adoptive immunotherapy.

A novel transfection method for eukaryotic cells using polyethylenimine coated albumin microbubbles

Albumin microbubbles have been intensively studied for their application in gene delivery. However, with negative surface potential, albumin microbubbles hardly bind plasmid DNA, which might contribute to their low transgene efficiency. In this study, we developed polyethylenimine (PEI) coated albumin microbubbles (PAMB) which were prepared by sonicating the mixture of human albumin, PEI, polyethylene glycol and glucose. CHO cells, COS cells and 293T cells were transfected with PEI, PEI+albumin, PAMB and Lipofectamine 2000, respectively. Our results showed that the surface potential was elevated and PAMB could bind plasmid DNA. The transgene efficiency of PAMB was higher than PEI and PEI+albumin (P<0.05), and PAMB performed the same transgene effect as Lipofectamine 2000 did but with lower cytotoxicity than Lipofectamine 2000. Albumin microbubbles modified by PEI has high transgene efficiency and low cytotoxicity even without ultrasound medication, making it a useful non-virus gene delivery method in vitro.

Gene-modified T lymphocytes in the setting of hematopoietic cell transplantation: potential benefits and possible risks

INTRODUCTION

Allogeneic hematopoietic cell transplantation (HCT) is a consolidated treatment for several hematologic malignancies. Donor T lymphocytes can mediate a graft versus tumor (GVT) effect and control opportunistic infections but can also cause severe graft versus host disease (GVHD). Gene-transfer strategies are appealing tools to modulate T cell functions when infused after HCT.

AREAS COVERED

The current and potential future applications of T cell gene-transfer approaches to HCT. This review is not limited to GVHD control but covers the issues of GVT and immune reconstitution. Clinical data are used to discuss more general issues, perspectives and concerns common to gene-modification of T cells. An overview of the results and limitations emerging from clinical trials with herpes simplex virus-thymidine kinase (HSV-TK) engineered lymphocytes is provided. The review provides perspectives on additional gene-transfer strategies, currently at preclinical level or that have just entered clinical trials, to increase the efficacy and safety of HCT.

EXPERT OPINION

Gene-transfer can positively interfere with T cell functions after HCT. TK-lymphocytes have proven effective in controlling GVHD while retaining an acceptable GVT effect. Strategies exploiting new suicide molecules or engineered T cell receptors (TCRs) should be further explored to address current limitations with TK-lymphocytes and augment the efficacy and specificity of GVT and antiviral activity.

Exploiting T cells specific for human minor histocompatibility antigens for therapy of leukemia

Minor histocompatibility (H) antigens are major targets of a graft-versus-leukemia (GVL) effect mediated by donor CD8(+) and CD4(+) T cells following allogeneic hematopoietic cell transplantation (HCT) between human leukocyte antigen identical individuals. In the 15 years since the first molecular characterization of human minor H antigens, significant strides in minor H antigen discovery have been made as a consequence of advances in cellular, genetic and molecular techniques. Much has been learned about the mechanisms of minor H antigen immunogenicity, their expression on normal and malignant cells, and their role in GVL responses. T cells specific for minor H antigens expressed on leukemic cells, including leukemic stem cells, can be isolated and expanded in vitro and infused into allogeneic HCT recipients to augment the GVL effect to prevent and treat relapse. The first report of the adoptive transfer of minor H antigen-specific T-cell clones to patients with leukemic relapse in 2010 illustrates the potential for the manipulation of alloreactivity for therapeutic benefit. This review describes the recent developments in T-cell recognition of human minor H antigens, and efforts to translate these discoveries to reduce leukemia relapse after allogeneic HCT.

Exploiting T cells specific for human minor histocompatibility antigens for therapy of leukemia

Minor histocompatibility (H) antigens are major targets of a graft-versus-leukemia (GVL) effect mediated by donor CD8(+) and CD4(+) T cells following allogeneic hematopoietic cell transplantation (HCT) between human leukocyte antigen identical individuals. In the 15 years since the first molecular characterization of human minor H antigens, significant strides in minor H antigen discovery have been made as a consequence of advances in cellular, genetic and molecular techniques. Much has been learned about the mechanisms of minor H antigen immunogenicity, their expression on normal and malignant cells, and their role in GVL responses. T cells specific for minor H antigens expressed on leukemic cells, including leukemic stem cells, can be isolated and expanded in vitro and infused into allogeneic HCT recipients to augment the GVL effect to prevent and treat relapse. The first report of the adoptive transfer of minor H antigen-specific T-cell clones to patients with leukemic relapse in 2010 illustrates the potential for the manipulation of alloreactivity for therapeutic benefit. This review describes the recent developments in T-cell recognition of human minor H antigens, and efforts to translate these discoveries to reduce leukemia relapse after allogeneic HCT.

Cytokine-induced killer cells for cell therapy of acute myeloid leukemia: improvement of their immune activity by expression of CD33-specific chimeric receptors

BACKGROUND

Cytokine-induced killer cells are ex vivo-expanded cells with potent antitumor activity. The infusion of cytokine-induced killer cells in patients with acute myeloid leukemia relapsing after allogeneic hematopoietic stem cell transplant is well tolerated, but limited clinical responses have been observed. To improve their effector functions against acute myeloid leukemia, we genetically modified cytokine-induced killer cells with chimeric receptors specific for the CD33 myeloid antigen.

DESIGN AND METHODS

SFG-retroviral vectors coding for anti-CD33-ζ and anti-CD33-CD28-OX40-ζ chimeric receptors were used to transduce cytokine-induced killer cells. Transduced cells were characterized in vitro for their ability to lyse leukemic targets (4-hour (51)chromium-release and 6-day co-cultures assays on human stromal mesenchymal cells), to proliferate ((3)H-thymidine-incorporation assay) and to secrete cytokines (flow cytomix assay) after contact with acute myeloid leukemia cells. Their activity against normal CD34(+) hematopoietic progenitor cells was evaluated by analyzing the colony-forming unit capacity after co-incubation.

RESULTS

Cytokine-induced killer cells were efficiently transduced with the anti-CD33 chimeric receptors, maintaining their native phenotype and functions and acquiring potent cytotoxicity (up to 80% lysis after 4-hour incubation) against different acute myeloid leukemia targets, as also confirmed in long-term killing experiments. Moreover, introduction of the anti-CD33 chimeric receptors was accompanied by prominent CD33-specific proliferative activity, with the release of high levels of immunostimulatory cytokines. The presence of CD28-OX40 in chimeric receptor endodomain was associated with a significant amelioration of the anti-leukemic activity of cytokine-induced killer cells. Importantly, even though the cytokine-induced killer cells transduced with anti-CD33 chimeric receptors showed toxicity against normal hematopoietic CD34(+) progenitor cells, residual clonogenic activity was preserved.

CONCLUSIONS

Our results indicate that anti-CD33 chimeric receptors strongly enhance anti-leukemic cytokine-induced killer cell functions, suggesting that cytokine-induced killer cells transduced with these molecules might represent a promising optimized tool for acute myeloid leukemia immunotherapy.