Combined delivery of a TGF-ß inhibitor and an adenoviral vector expressing interleukin-12 potentiates cancer immunotherapy.

Cancer immunotherapy appears to have a promising future, but it can be thwarted by secretion of immunosuppressive factors, such as transforming growth factor-ß (TGF-ß), which inhibits local immune responses to tumors. To weaken immune resistance of tumors and simultaneously strengthen immune responses, we developed a multifunctional polymer that could co-deliver hydrophobic TGF-ß inhibitor and an adenovirus gene vector to tumor sites. This co-delivery system sustainably released TGF-ß inhibitor SB-505124 and effectively transferred the adenovirus vector carrying the interleukin-12 gene. In addition, it significantly delayed growth of B16 melanoma xenografts in mice and increased animal survival. Mechanistic studies showed that this combination therapy enhanced anti-tumor immune response by activating CD4+ and CD8+ T cells, natural killer cells and interferon-γ secretion in the tumor microenvironment. STATEMENT OF SIGNIFICANCE: To weaken immune resistance of tumors and simultaneously strengthen tumors' immune responses, we synthesized a structurally simple, low-toxic but functional polymer ß-cyclodextrin-PEI to encapsulate a hydrophobic TGF-ß inhibitor SB-505124 and to complex adenovirus vectors expressing IL-12. This is the first report demonstrating that combining TGF-ß inhibitor with IL-12 could provide effective immunotherapy against melanoma by the sustainable release of SB-505124 and the effectible transduction of IL-12 gene in tumor cells. The rational delivery system presented a comprehensive and valued platform to be a candidate vector for co-delivering hydrophobic small-molecule drugs and therapeutic genes for treating cancer, providing a new approach for cancer immunotherapy.

Bio-inspired polymer envelopes around adenoviral vectors to reduce immunogenicity and improve in vivo kinetics.

Adenoviral vectors have attracted substantial interest for systemic tumor gene therapy, but further work is needed to reduce their immunogenicity and alter their biodistribution before they can be used in the clinic. Here we describe a bio-inspired, cleavable PEGylated ß-cyclodextrin-polyethyleneimine conjugate (CDPCP) that spontaneously coats adenovirus in solution. This cleavable PEG coating reduces the innate and adaptive immunogenicity of adenovirus particles, as well as improves their biodistribution away from the liver and into the tumor. Insertion of a matrix metalloproteinase substrate sequence into the conjugate allows PEG cleavage at the tumor site, simultaneously reducing liver biodistribution and increasing transgene expression in tumors, thereby avoiding the "PEG dilemma". Cationic ß-cyclodextrin-PEI not only provides electrostatic attraction to promote envelope attachment to the viral capsid, but it also improves vector internalization and transduction after PEG cleavage. These results suggest that CDPCP may help expand the use of adenoviral vectors in cancer gene therapy. STATEMENT OF SIGNIFICANCE: The synthesized ß-cyclodextrin-PEI-MMP-cleavable-PEG polymer (CDPCP), held great potential for gene therapy when applied for adenovirus coating. The ß-cyclodextrin-PEI provided a powerful electrostatic attraction to attach the whole polymer onto the viral capsid, while the MMPs-cleavable PEG reduced innate and adaptive immunogenicity and improved the biodistribution of adenovirus vectors due to the tumor-specific enzyme triggered PEG cleavage. More importantly, an ingenious cooperation between the two components could solve the PEG dilemma. The CDPCP/Ad complexes exhibited a comprehensive and valued profile to be a candidate vector for future tumor gene therapy, we believe the current investigation on this kind of biomaterial may be of particular interest to the readership of Acta biomaterialia.

Enzyme-responsive liposomes modified adenoviral vectors for enhanced tumor cell transduction and reduced immunogenicity.

Limitations of adenoviral (Ad) vectors for cancer gene therapy could be overcome by their combination with pharmaceutical technologies. Here we show that an enzyme-responsive liposomal formulation could significantly enhance the tumor cell transduction abilities and reduce the immunogenicity of Ad vectors. In the current research, the enzymatically cleavable PEG-lipids composed of a PEG/matrix metalloproteinase (MMP)-substrate peptide/cholesterol (PPC) were synthesized and characterized by (1)H NMR and TOF MS ES(+). The obtained MMP-cleavable lipids were inserted into the anionic liposomal Ad vectors (AL-Ad) by the post-insertion method. The results of in vitro infection assays indicated that the enzymatically cleavable formulation (PPC-AL-Ad) displayed a much higher gene expression than naked Ad5 and the non-cleavable PEG-lipid modified Ad vectors in tumor cells. More importantly, PPC-AL-Ad induces a lower production of neutralizing antibody and lower innate immune response, as well as significantly reduced liver toxicity in vivo. These findings suggest that PPC-AL-Ad is a promising system for gene delivery in tumor therapy.