Zinc fingers

Zinc-finger nucleases make the cut in HIV

Sangamo’s lead zinc-finger therapeutic supports the potential of gene-editing technology, but CRISPR-based gene-editing therapeutics are close behind.

On 6 March, Sangamo BioSciences released the latest encouraging results for its potential anti-HIV therapy SB-728-T, a zinc-finger nuclease (ZFN) gene-editing drug. Phase I and II trials showed continued signs of safety and efficacy, it reported in the New England Journal of Medicine (N. Engl. J. Med. 370, 901–910; 2014) and in several abstracts presented at the Conference on Retroviruses and Opportunistic Infections (CROI) in Boston, Massachusetts, USA.

SB-728-T works by targeting the CC-chemokine receptor 5 (CCR5) gene, which encodes a cell-surface receptor that HIV uses to gain entry into CD4 T cells. CCR5 is well validated as a drug target: GlaxoSmithKline’s small-molecule CCR5 inhibitor maraviroc was approved as an anti-HIV drug in 2007, people with loss-of-function CCR5 mutations are immune to many common strains of HIV, and one person, Timothy Brown — known as the ‘Berlin patient’ — has been cured of HIV since receiving a bone marrow transplant from a CCR5-mutant donor. Sangamo’s treatment breaks new ground by taking CD4 cells from a patient, disabling CCR5 by editing the gene-coding sequence and then reintroducing the modified cells back into the patient to proliferate and replace vulnerable and infected cells. Read more in NRDD.