Human Gene Therapy Clinical Development最新文献

The advancement of gene therapy-based approaches to treat heart disease represents a need for clinically relevant animal models with characteristics equivalent to human pathologies. Rodent models of cardiac disease do not precisely reproduce heart failure phenotype and molecular defects. This has motivated researchers to use large animals whose heart size and physiological processes more similar and comparable to those of humans. Today, adeno-associated viruses (AAV)-based vectors are undoubtedly among the most promising DNA delivery vehicles. Here, AAV biology and technology are reviewed and discussed in the context of their use and efficacy for cardiac gene delivery in large-animal models of heart failure, using different surgical approaches. The remaining challenges and opportunities for the use of AAV-based vector delivery for gene therapy applications in the clinic are also highlighted.

Steady state bone marrow (BM) is the preferred hematopoietic stem cell (HSC) source for gene therapy in sickle cell disease (SCD) due to the recognized risk of vaso-occlusive crisis during granulocyte colony-stimulating factor mobilization. We previously established clinically relevant HSC gene transfer in the rhesus model following transplantation of mobilized peripheral blood (PB) CD34⁺ cells transduced with lentiviral vectors. In this study, we examined steady state bone marrow (BM) in the rhesus competitive repopulation model and demonstrate similar gene marking in vitro and in vivo, as compared with mobilized PB CD34⁺ cells. We then evaluated PB and steady state BM in subjects with SCD and observed a higher frequency of CD34⁺ cells when compared with controls, likely due to enhanced hematopoiesis. However, CD34⁺ cell counts were reduced in both the PB and BM in patients treated with hydroxyurea, and hydroxyurea treatment strongly inhibited iPS cell generation from SCD subjects. Our data support that steady state BM is a useful HSC source for SCD gene therapy with similar transduction. The lower CD34⁺ percentages observed with hydroxyurea treatment warrants withholding hydroxyurea temporarily prior to harvesting HSCs. Our results are important for the design of gene targeting strategies for SCD.

Cystic fibrosis (CF) is an autosomal recessive disease that is potentially treatable by gene therapy. Since the identification of the gene encoding CF transmembrane conductance regulator, a number of preclinical and clinical trials have been conducted using the first generation of adeno-associated virus, AAV2. All these studies showed that AAV gene therapy for CF is safe, but clinical benefit was not clearly demonstrated. Thus, a new generation of AAV vectors based on other serotypes is needed to move the field forward. This study tested two AAV serotypes (AAV1 and AAV5) using a dual-luciferase reporter system with firefly and Renilla luciferase genes packaged into AAV1 or AAV5, respectively. Two male and two female Rhesus macaques were each instilled in their lungs with both serotypes using a Penn-Century microsprayer. Both AAV1 and AAV5 vector genomes were detected in all the lung samples when measured at the time of necropsy, 45 days after instillation. However, the vector genome number for AAV1 was at least 10-fold higher than for AAV5. Likewise, luciferase activity was also detected in the same samples at 45 days. AAV1-derived activity was not statistically greater than that derived from AAV5. These data suggest that gene transfer is greater for AAV1 than for AAV5 in macaque lungs. Serum neutralizing antibodies were increased dramatically against both serotypes but were less abundant with AAV1 than with AAV5. No adverse events were noted, again indicating that AAV gene therapy is safe. These results suggest that with more lung-tropic serotypes such as AAV1, new clinical studies of gene therapy using AAV are warranted.

Vesicular stomatitis virus (VSV) is a negative-stranded RNA virus that naturally causes disease in livestock including horses, cattle and pigs. The two main identified VSV serotypes are New Jersey (VSNJV) and Indiana (VSIV). VSV is a rapidly replicating, potently immunogenic virus that has been engineered to develop novel oncolytic therapies for cancer treatment. Swine are a natural host for VSV and provide a relevant and well-established model, amenable to biological sampling to monitor virus shedding and neutralizing antibodies. Previous reports have documented the pathogenicity and transmissibility of wild-type isolates and recombinant strains of VSIV and VSNJV using the swine model. Oncolytic VSV engineered to express interferon-beta (IFNβ) and the sodium iodide symporter (NIS), VSV-IFNβ-NIS, has been shown to be a potent new therapeutic agent inducing rapid and durable tumor remission following systemic therapy in preclinical mouse models. VSV-IFNβ-NIS is currently undergoing clinical evaluation for the treatment of advanced cancer in human and canine patients. To support clinical studies and comprehensively assess the risk of transmission to susceptible species, we tested the pathogenicity and transmissibility of oncolytic VSV-IFNβ-NIS using the swine model. Following previously established protocols to evaluate VSV pathogenicity, intradermal inoculation with 10⁷ TCID₅₀ VSV-IFNβ-NIS caused no observable symptoms in pigs. There was no detectable shedding of infectious virus in VSV-IFNβ-NIS in biological excreta of inoculated pigs or exposed naive pigs kept in direct contact throughout the experiment. VSV-IFNβ-NIS inoculated pigs became seropositive for VSV antibodies, while contact pigs displayed no symptoms of VSV infection, and importantly did not seroconvert. These data indicate that oncolytic VSV is both nonpathogenic and not transmissible in pigs, a natural host. These findings support further clinical development of oncolytic VSV-IFNβ-NIS as a safe therapeutic for human and canine cancer.