The first presentation described data from the SB-728-T Phase 1 study (SB-728-902, Cohorts 1-3) demonstrating that SB-728-T treatment of HIV-infected subjects leads to durable reconstitution of the immune system driven by increases in total CD4+ central memory T-cells (TCM) and CCR5-protected TCM. TCM are long-lived, self-renewing cells that have the ability to remember and react against foreign antigens including HIV. The data also showed that certain cell surface marker and gene expression profiles may predict which patients will likely respond best to SB-728-T treatment.
"These important data extend our understanding of why SB-728-T treatment improves the immune system as well as the conditions required for optimal engraftment of ZFN-modified T-cells," said
"The ability of SB-728-T to durably reconstitute the immune system in HIV-infected subjects after a single treatment has never been observed before with any other therapeutic approach," commented
HIV destroys the immune system by killing CD4+ T cells. The current standard of care for HIV/AIDS is daily treatment with antiretroviral therapy (ART), which suppresses viral load in the blood of most subjects but does not eliminate the reservoir of HIV-infected cells. In addition, a significant proportion of treated HIV-infected individuals do not experience a restoration of CD4+ T-cell counts to normal levels. SB-728-T treatment, by eliminating the co-receptor, CCR5, which is necessary for HIV entry to CD4+ cells, is designed to provide a CCR5-negative population of CD4+ T-cells that cannot be infected by HIV but are able to fight opportunistic infections and enable the immune system to control and eliminate the virus. Sangamo's clinical studies have demonstrated successful ZFN-dependent CCR5 gene modification of T-cell populations, including critical cell types such as the T CM. Studies to date have demonstrated that engraftment of SB-728-T is safe, the modified cells are durable and demonstrate prolonged trafficking and dynamic immunological responsiveness in the gut mucosa, an important HIV reservoir. The data presented today demonstrate that SB-728-T treatment leads to unprecedented durable increases in total CD4+ T cells that are correlated with increases in TCM and ZFN-mediated CCR5-modified TCM.
"These exciting data support our development program for SB-728-T as a potential functional cure for HIV/AIDS," stated
The first of these ongoing trials (SB-728-902 Cohort 5) evaluates the approximate doubling of bi-allelic engraftment that can be achieved in individuals that have a natural mutation of one of their CCR5 gene copies, CCR5 delta-32 heterozygotes, and seeks to confirm an observation of the occurrence of aviremia during ART treatment interruption (TI). The second trial (SB-728-1101) examines the ability of a lymphopenic preconditioning regimen to enhance bi-allelic engraftment and reduce viral load during a TI in subjects in which CCR5 is not mutated.
Sangamo expects to present preliminary data in the first half of 2013 and the full data set from both trials by the end of 2013.
Abstract #126 "The Central Memory T-cell is the Critical Component for Sustained CD4+ Reconstitution in HIV Subjects Receiving ZFN CCR5 Modified CD4+ T-cells (SB-728-T)"
HIV-infected subjects were enrolled in a Phase 1 clinical trial (SB-728-902, Cohorts 1-3) and received a single dose of SB-728-T (5 to 30 billion cells). All subjects were on ART and had stably controlled undetectable levels of HIV in their blood.
The study evaluated safety and tolerability, changes in CD4+ T-cell counts and the ratio of CD4+ to CD8+ T-cells, as well as persistence of SB-728-T in the blood and trafficking of these ZFN-modified cells into gut-associated lymph tissue.
Analysis of data from subjects in the study presented today demonstrated:
In the same oral session, data were also presented from a research stage study conducted in collaboration with scientists in the laboratory of Dr.
Abstract #129 "T-Cells Edited to Express CCR5 or CXCR4 Fused to the C34 Peptide from gp41 Heptad Repeat-2 Exhibit Robust Protection from Diverse HIV-1 Isolates"
The data demonstrate potent inhibition of HIV infection in cells expressing a chimeric protein comprising a portion of the HIV envelope fused to either the CXCR4 or CCR5 HIV co-receptors. Scientists fused the C34 peptide from the gp41 portion of the HIV envelope to the amino terminus of either the CXCR4 (C34-X4) or CCR5 (C34-R5) proteins. Importantly, both C34-X4 and C34-R5 demonstrated potent inhibition of infection by either an X4-tropic or R5-tropic HIV-1 isolate in primary CD4+ T cells, the natural target of HIV.
Webcasts of all the presentations at CROI 2013 can be accessed via the following link: http://webcasts.retroconference.org/m/2013
SB-728-T is an autologous CD4+ T-cell product in which the gene for CCR5, a co-receptor for HIV entry, is modified via ZFN-mediated genome editing to disrupt the CCR5 protein. T-cells with a disrupted CCR5 protein are resistant to infection by the most common strain of HIV.
ZFP Therapeutic® is a registered trademark of
This press release may contain forward-looking statements based on Sangamo's current expectations. These forward-looking statements include, without limitation, references relating to research and development of novel ZFP TFs and ZFNs and therapeutic applications of Sangamo's ZFP technology platform for the treatment of HIV/AIDS, including a potential functional cure of HIV/AIDS, the expansion of clinical studies of SB-728-T in HIV-infected individuals, expected timing for the presentation of clinical trial data and the initiation of additional preclinical and clinical studies of ZFN-gene modification. Actual results may differ materially from these forward-looking statements due to a number of factors, including uncertainties relating to the initiation and completion of stages of our clinical trials, whether the clinical trials will validate and support the tolerability and
efficacy of ZFNs, technological challenges, Sangamo's ability to develop commercially viable products and technological developments by our competitors. For a more detailed discussion of these and other risks, please see Sangamo's
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