Gene Editing ofCCR5in Autologous CD4 T Cells of Persons Infected with HIV

Abstract

BACKGROUND CCR5 is the major coreceptor for human immunodeficiency virus (HIV). We investigated whether site-specific modification of the gene (“gene editing”) — in this case, the infusion of autologous CD4 T cells in which the CCR5 gene was rendered permanently dysfunctional by a zinc-finger nuclease (ZFN) — is safe. METHODS We enrolled 12 patients in an open-label, nonrandomized, uncontrolled study of a single dose of ZFN-modified autologous CD4 T cells. The patients had chronic aviremic HIV infection while they were receiving highly active antiretroviral therapy. Six of them underwent an interruption in antiretroviral treatment 4 weeks after the infusion of 10 billion autologous CD4 T cells, 11 to 28% of which were genetically modified with the ZFN. The primary outcome was safety as assessed by treatment-related adverse events. Secondary outcomes included measures of immune reconstitution and HIV resistance. RESULTS One serious adverse event was associated with infusion of the ZFN-modified autologous CD4 T cells and was attributed to a transfusion reaction. The median CD4 T-cell count was 1517 per cubic millimeter at week 1, a significant increase from the preinfusion count of 448 per cubic millimeter (P<0.001). The median concentration of CCR5-modified CD4 T cells at 1 week was 250 cells per cubic millimeter. This constituted 8.8% of circulating peripheral-blood mononuclear cells and 13.9% of circulating CD4 T cells. Modified cells had an estimated mean half-life of 48 weeks. During treatment interruption and the resultant viremia, the decline in circulating CCR5-modified cells (−1.81 cells per day) was significantly less than the decline in unmodified cells (−7.25 cells per day) (P = 0.02). HIV RNA became undetectable in one of four patients who could be evaluated. The blood level of HIV DNA decreased in most patients. CONCLUSIONS CCR5-modified autologous CD4 T-cell infusions are safe within the limits of this study. (Funded by the National Institute of Allergy and Infectious Diseases and others; ClinicalTrials.gov number, NCT00842634.)

Engineering HIV-Resistant, Anti-HIV Chimeric Antigen Receptor T Cells

“…Either gene-editing method could be used to generate further preclinical data. Ex vivo gene editing of CCR5 by NHEJ has been shown to be safe and effective in a phase I clinical trial, 44 whereas HDR is a newer technology that has not yet been tested clinically. However, HDR has a potential advantage in that it limits the number of possible integration events and may reduce the risk of insertional mutagenesis.…”

“…36,37 Individuals with an allelic variant that is not functional (CCR5D32) are protected from CCR5-tropic HIV infection. 38 Hematopoietic stem cell transplant using a CCR5D32 donor led to the only known cure of HIV-1 infection, 39,40 and T cells treated with engineered nucleases that introduce mutations at the CCR5 locus are resistant to HIV, [41][42][43][44][45] accelerating ongoing efforts to develop gene editing-and cell-based therapeutic agents for HIV. 11,46 Using new gene-editing techniques, it has recently become possible to achieve high rates of homology-directed recombination (HDR) of therapeutic cassettes into targeted loci, including CCR5 in primary T cells.…”

Use of the CRISPR/Cas9 system as an intracellular defense against HIV-1 infection in human cells

“…In addition, inserting the stably expressed CRISPR/Cas9 system into a T-cell line conferred long-term protection against HIV-1 infection. With recent successful developments, gene-editing technologies have shown great promise in anti-HIV therapy for both preclinical studies and ongoing clinical trials [38][39][40] . As our data show, the system could work on physiologically relevant HIV-1 reservoir cell types and we expect that this system can be further exploited to develop alternative antiviral therapies in the future.…”

Don’t edit the human germ line

“…This consensus is most visible in western Europe, where 15 of 22 nations prohibit the modification of the germ line 4 . Although the United States has not officially prohibited germline modification, the US National Institutes of Health's Recombinant DNA Advisory Committee explicitly states that it "will not at present entertain proposals for germ line alterations" (see go.nature.com/mgscb2).…”