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BACKGROUNDIn previous clinical trials involving children with X-linked severe combined immunodeficiency (SCID-X1), a Moloney murine leukemia virus–based γ-retrovirus vector expressing interleukin-2 receptor γ-chain (γc) complementary DNA successfully restored immunity in most patients but resulted in vector-induced leukemia through enhancer-mediated mutagenesis in 25% of patients. We assessed the efficacy and safety of a self-inactivating retrovirus for the treatment of SCID-X1.METHODSWe enrolled nine boys with SCID-X1 in parallel trials in Europe and the United States to evaluate treatment with a self-inactivating (SIN) γ-retrovirus vector containing deletions in viral enhancer sequences expressing γc (SIN-γc).RESULTSAll patients received bone marrow–derived CD34+ cells transduced with the SIN-γc vector, without preparative conditioning. After 12.1 to 38.7 months of follow-up, eight of the nine children were still alive. One patient died from an overwhelming adenoviral infection before reconstitution with genetically modified T cells. Of the remaining eight patients, seven had recovery of peripheral-blood T cells that were functional and led to resolution of infections. The patients remained healthy thereafter. The kinetics of CD3+ T-cell recovery was not significantly different from that observed in previous trials. Assessment of insertion sites in peripheral blood from patients in the current trial as compared with those in previous trials revealed significantly less clustering of insertion sites within LMO2 , MECOM, and other lymphoid proto-oncogenes in our patients.CONCLUSIONSThis modified γ-retrovirus vector was found to retain efficacy in the treatment of SCID-X1. The long-term effect of this therapy on leukemogenesis remains unknown. (Funded by the National Institutes of Health and others; ClinicalTrials.gov numbers, NCT01410019, NCT01175239, and NCT01129544.)

Severe combined immunodeficiencies have long been targeted as a group of disorders amenable to gene therapy because of their defined molecular biology and pathophysiology, and the prediction that corrected cells would have profound growth and survival advantage. Recently, several clinical studies have shown that conventional gene transfer technology can produce major beneficial therapeutic effects in these patients, but, as for all cellular and pharmacological treatment approaches, with a finite potential for toxicity.Gene Therapy (2003) 10, 1999-2004. doi:10.1038/sj.gt.3302150 [ABSTRACT FROM AUTHOR]

Retroviral transfer of Herpes simplex virus thymidine kinase to T cells has been used to confer sensitivity to the antiviral agent ganciclovir. This has allowed therapeutic approaches to be developed in which T cells mediating graft-versus-host disease after bone marrow transplantation can be selectively eliminated by the administration of ganciclovir. Although the strategy has been shown to be generally successful in early clinical trials, there are concerns about possible resistance to ganciclovir and the risk of myelosuppressive side-effects at the doses required to induce T cell suicide. We have incorporated the enhanced mutant HSV-TKSR39 into retroviral vectors tailored to exhibit high levels of expression in T cells and have used protocols optimized for the transduction and selection of primary lymphocytes. We demonstrate that leukemic and primary T cells can be efficiently transduced and highly enriched under conditions that should be readily adaptable for clinical use. T cells carrying HSV-TKSR39 were inhibited by exposure to ganciclovir at concentrations an order of magnitude below those required for wild-type HSV-TK. The less toxic agent aciclovir also eliminated T cells transduced with HSV-TKSR39 (but not HSV-TK), underlining the increased therapeutic potential of the mutant suicide gene system in the bone marrow transplantation setting. [ABSTRACT FROM AUTHOR]

Focuses on the inhibition of retinal neovascularization by gene transfer of soluble vascular endothelial growth factor sFlt-1. Treatment of retinal angiogenesis, one of the leading causes of blindness; Induction of proliferative retinopathy in mice; Adenovirus-mediated growth factor protein expression.

Describes the generation of immunostimulatory dendritic cells from the malignant clone in patients with juvenile myelomonocytic leukemia. Induction of anti-leukemia T cell responses; Measurement of the dendritic cell production of interleukin-2; Reflection of the heterogeneity of myeloid lineage leukemia; Characteristics of immature dendritic cell morphology.

Inherited retinal degenerations are a major cause of blindness for which there are currently no effective therapies. Significant progress concerning in vivo gene transfer has allowed retardation of degeneration or retinal functional improvement in different animal models. To date, there has been no evaluation of the impact of these treatments on higher visual function, a critical step for validating gene therapy treatment strategies.Here, we have used adeno-associated (AAV2)-mediated gene transfer of Prph2 in the Prph2Rd2/Rd2 mouse model. We then assessed higher visual function by recording from central visually responsive neurons in the superior colliculus and improvements were correlated in individual animals with retinal function (ERG) and histological and biochemical changes. Although gene replacement therapy only partially restores photoreceptor morphology, it results in a 300% increase of the visual cycle protein rhodopsin, leading to retinal function improvement (250% increase of b-wave amplitude) and significantly higher central visual responses (166% increase at 24 cd/m2). These findings suggest that gene replacement therapy leading to even relatively modest structural improvement may result in improved central visual function. [Copyright &y& Elsevier]