FINAL PROGRAM - American Society of Gene & Cell Therapy

13 th AnnUAL MEETing | Washington, DC USA May 19-22, 2010 59Program ScheduleScientific Symposium 31510:30 am - 12:30 pmRoom: Marriott Ballroom Salons 2 & 3Genetic Modification of Stem Cells for Therapeutic ApplicationsChairFrederic D. Bushman, PhDSpeakersChristof von Kalle, MD PhDThe Clonal Distribution of Insertion Site RepertoiresRetroviral vectors have been successfully used for the correction of inherited immune diseases in clinical trials. However, qualitative and quantitative in vivo monitoring ofgene modified hematopoiesis in several clinical gene therapy trials revealed that vector induced side effects, ranging from subtle and not clinically obvious effects to clonaldominance and, rarely, leukemogenesis, have to be considered.Clonality data on oncoretroviral and lentiviral clinical gene therapy trials (i.e. CGD, SCID, WAS, ALD) show that integration site distribution is non-random and mayinfluence cellular gene expression, thus inducing changes in the clonality of the hematopoietic repopulation. Incorporation of next generation sequencing technologiessubstantially improve in depth analyses and monitoring of individual and global clonal contribution in a hitherto unexpected resolution. Prospective monitoring of vectorintegration sites in clinical gene therapy studies is feasible, can detect side effects of gene therapy at the clonal level, and may help to gain new insights into the basicmechanisms leading to specific clonal behaviour in vivo. Genome wide insertion studies will allow to improve the safety and performance of viral and non-viral integratingvector systems.Matthew H. Porteus, MD, PhDGene Targeting with Zinc Finger Nucleases in Primary CellsGene targeting by homologous recombination has the potential to be both a safer and more efficacious approach to gene therapy. Therapeutically relevant rates of genetargeting have been achieved by using zinc finger nucleases in a variety of tissue culture cell lines and some primary human cells. We now demonstrate that therapeuticallyrelevant frequencies of gene targeting by homologous recombination can be achieved in primary cells and that these modified cells can be successfully transplantedback into a recipient. The demonstration that primary cells can be isolated, precisely modified ex vivo and then transplanted back into a recipient mimics the strategy weare working towards in humans as a cure for patients with monogenic diseases.Frederic D. Bushman, PhDHIV DNA Integration: Mechanism and ConsequencesThe lecture will cover integration by HIV and HIV-based vectors. Recent results from gene therapy trials will be presented. The lecture will also cover development ofimproved new methods for integration site isolation and analysis.Ko Mitani, PhDChromosomal Manipulation of Human Pluripotent Stem Cells using Adenoviral VectorsIn order to fully utilize human induced pluripotent stem (iPS) cells and embryonic stem (ES) cells for basic research and clinical applications, it is essential to developefficient methods for homologous recombination (HR) in these cells. We have shown that, by delivering gene-targeting cassettes using helper-dependent adenoviralvectors (HDAdVs) into human ES/iPS cells, gene knock-in/-out has been efficiently achieved at both transcriptionally active and inactive loci. On average, one out of2 - 20 x 105 infected cells was homologous recombinant. The efficiencies of HR per chromosomal integration were 10 - 50% (30 - 90% with negative selection), whichwere ~100-fold higher than those obtained by other DNA delivery methods. These findings suggest that HDAdV-mediated HR is not only a highly efficient strategy forchromosomal manipulation of pluripotent stem cells but also a viable option for ex vivo gene repair therapy using iPS cells derived from patients of inherited diseases,which would overcome the risk of insertional mutagenesis.Friday, May 21 stLunch Break12:30 pm – 2:00 pm