Changing viral tropism using immunoliposomes alters the stability of gene expression: implications for viral vector design

Designer nanocarriers for navigating the systemic delivery of oncolytic viruses

Nanotechnology is paving the way for new carrier systems designed to overcome the greatest challenges of oncolytic virotherapy; systemic administration and subsequent implications of immune responses and specific cell binding and entry. Systemic administration of oncolytic agents is vital for disseminated neoplasms, however transition of nanoparticles (NP) to virotherapy has yielded modest results. Their success relies on how they navigate the merry-go-round of often-contradictory phases of NP delivery: circulatory longevity, tissue permeation and cellular interaction, with many studies postulating design features optimal for each phase. This review discusses the optimal design of NPs for the transport of oncolytic viruses within these phases, to determine whether improved virotherapeutic efficacy lies in the pharmacokinetic/pharmacodynamics characteristics of the NP-oncolytic viruses complexes rather than manipulation of the virus and targeting ligands.

Improving antitumor efficacy via combinatorial regimens of oncolytic virotherapy

As a promising therapeutic strategy, oncolytic virotherapy has shown potent anticancer efficacy in numerous pre-clinical and clinical trials. Oncolytic viruses have the capacity for conditional-replication within carcinoma cells leading to cell death via multiple mechanisms, including direct lysis of neoplasms, induction of immunogenic cell death, and elicitation of innate and adaptive immunity. In addition, these viruses can be engineered to express cytokines or chemokines to alter tumor microenvironments. Combination of oncolytic virotherapy with other antitumor therapeutic modalities, such as chemotherapy and radiation therapy as well as cancer immunotherapy can be used to target a wider range of tumors and promote therapeutic efficacy. In this review, we outline the basic biological characteristics of oncolytic viruses and the underlying mechanisms that support their use as promising antitumor drugs. We also describe the enhanced efficacy attributed to virotherapy combined with other drugs for the treatment of cancer.

Virus-like particles-universal molecular toolboxes

Virus-like particles (VLPs) are highly organised spheres that self-assemble from virus-derived structural antigens. These stable and versatile subviral particles possess excellent adjuvant properties capable of inducing innate and cognate immune responses. Commercialised VLP-based vaccines have been successful in protecting humans from hepatitis B virus (HBV) and human papillomavirus (HPV) infection and are currently explored for their potential to combat other infectious diseases and cancer. Much insight into VLP-mediated immune stimulation and optimised VLP design has been gained from human immunodeficiency virus (HIV)-derived VLPs presenting promising components of current AIDS vaccine approaches. Owing to their unique features, VLPs and virosomes, the in vitro-reconstituted VLP counterparts, have recently gained ground in the field of nanobiotechnology as organic templates for the development of new biomaterials.

More trouble ahead; is gene therapy coming of age?

BACKGROUND

A recent incident, the halting of a Phase I/II trial utilising an adeno-associated vector, highlights the fact that there are more hurdles to overcome prior to a full realisation of gene therapy in the clinical arena.

METHODS

The sources of information used to prepare the paper were obtained through published work on Pubmed/Medline and materials published on the US/UK governmental agency websites.

RESULTS/CONCLUSION

Over the years, two fatal incidents associated with viral vector usage have been reported. Viral vectors used as carriers for gene therapy have failed in safety trials on two occasions. Also, the human immune response and the oncogenic property of the vectors have restricted the advancement of gene therapy as a therapeutic tool. Nonetheless, gene therapy has now progressed from its infancy 'proof of concept' stage, to the next stage in which we try to overcome the problems associated with therapeutic application. However, this progression has been slow as more and more setbacks have occurred. This calls for a new perspective and radical thinking about future vector development.