
We believe our ZFP technology has potential application in the treatment
of human diseases in the following ways:
- Through the development of ZFP Therapeutics™, ZFP TF™ for therapeutic gene regulation and ZFN™-based therapeutics for therapeutic gene correction and gene disruption.
- Through the use of our technology in enabling technology
applications to enhance the production yield of protein pharmaceuticals
We are developing engineered Zinc finger DNA-binding protein Transcription Factors (ZFP TFs) for Therapeutic Gene Regulation. We couple the ZFP DNA binding domain to a functional
domain, creating a ZFP TF™ capable of controlling or regulating a target gene. For instance, an activation domain causes a target gene to be “turned on.” Alternatively, a repression domain causes the gene to be “turned off.”
We are currently
developing ZFP TFs for the treatment of the following human diseases:
Diabetic Neuropathy
Diabetic peripheral sensory and motor neuropathy is one of the most frequent complications of diabetes. Apart from rigorous control of blood glucose, the only therapies approved by the FDA for the treatment of diabetic neuropathy are analgesics and antidepressants that address only the symptoms and do not retard or reverse the progression of the disease. Sangamo's drug, SB-509, is designed to up-regulate the endogenous VEGF-A gene. VEGF-A has been demonstrated to have direct neuroproliferative, neuroregenerative and neuroprotective properties.
We have completed a placebo-controlled Phase 1 clinical trial (SB-509-401) in subjects with mild to moderate DN. The data from this trial were very encouraging demonstrating that the drug was well-tolerated and that there were clinically relevant improvements in a number of measures of nerve health in SB-509 treated subjects compared to placebo-treated subjects.
We have three ongoing Phase 2 clinical trials with this drug in this indication.
Phase 2 Clinical Trials of SB-509 in DN
SB-509-601: A repeat-dosing, placebo-controlled, double-blind multicenter trial in subjects with mild to moderate diabetic neuropathy to evaluate the safety of SB-509 administration in this population. Interim data at 180 days post treatment demonstrated that the drug was safe but that no difference was observed in a number of measures of nerve health between placebo and SB-509-treated subjects. The trial and analysis of these data are ongoing.
SB-509-701: Single-blind, repeat-dosing trials of SB-509 in subjects that have a so-called “blocked nerve” or no measurable nerve conduction velocity (NCV) in their lower limb to evaluate safety of SB-509, dosing frequency and effect of the drug on NCV.
SB-509-703: Single-blind, placebo-controlled study in subjects with mild to moderate DN designed to evaluate the pharmacokinetics of stem cell mobilization into the bloodstream after treatment with varying doses of SB-509 as well as the clinical safety and clinical effects of SB-509 administration.
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Amyotrophic Lateral Sclerosis (ALS).
We are also evaluating SB-509 in amyotrophic lateral sclerosis (ALS). ALS, commonly referred to as “Lou Gehrig’s disease,” is a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord and is generally fatal. The progressive degeneration of the motor neurons in ALS is the primary reason that the disease is fatal. When the motor neurons die, the ability of the brain to initiate and control muscle movement is lost. Muscle weakness is a hallmark initial sign in ALS, occurring in approximately 60% of patients. The hands and feet may be affected first, causing difficulty in lifting, walking or using the hands. As the weakening and paralysis continue to spread to the muscles of the trunk, the disease eventually affects speech, swallowing, chewing and breathing. When the breathing muscles become affected, ultimately, patients need permanent ventilatory support in order to survive. More than 5,600 Americans are diagnosed with ALS each year. Approximately 35,000 people at any given time are living with ALS in the United States.
There are no drugs available to cure ALS. The FDA has approved a single medication, Rilutek© (Riluzole) which modestly increases lifespan in ALS patients.
There are both animal and clinical data that suggest that a defect or deficiency in VEGF expression plays a role in ALS.
We are evaluating in a Phase 2 trial whether a regional muscle or systemic effect of SB-509 delivery will result in a therapeutic effect in ALS.
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We are engineering ZFNs for Therapeutic Gene Modification:
Gene Correction and Gene Disruption.
The ZFP DNA binding domain may also be coupled to the cleavage domain of a restriction endonuclease—an enzyme that cuts DNA—creating a zinc finger nuclease or ZFN™.
We can design a ZFN to facilitate either :
- ZFN-mediated gene correction: the replacement of a disease-causing mutation with a "normal" or "corrected" DNA sequence, (e.g. for mongenic diseases such as X-linked SCID, sickle cell anemia, beta-thalassemia) or
- ZFN-mediated gene-disruption: disruption of a disease-related gene resulting in the expression of a truncated or non-functional protein (e.g. for HIV/AIDS treatment)
Our ZFN technology allows us to facilitate modification of a DNA sequence at a very specific point in the genome without the need for integration of foreign DNA sequences into the genome of cells. ZFN-mediated gene correction will allow the corrected gene to be expressed in its natural chromosomal context
and may provide a safe and effective approach to the precise repair of DNA sequence mutations. In April 2005, in Nature, Sangamo scientists published data demonstrating highly efficient permanent ZFN-mediated gene correction in primary human cells (Urnov, F.D. et al., April 4, 2005, Nature Advance Online Publication
doi: 10.1038/nature 03556).
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We are developing ZFNs for therapeutic gene disruption as a potential therapy for:
Human Immunodeficiency Virus (HIV) and Acquired Immunodeficiency Syndrome (AIDS)
HIV infection results in the death of immune
system cells and thus leads to AIDS, a condition in which the body’s
immune system is depleted to such a degree that the patient is unable to
fight off common infections and ultimately succumbs to opportunistic
infections or cancers. CCR5 is the co-receptor for HIV entry into
T-cells and without CCR5 expressed on their surface, HIV cannot infect these
cells. A population of individuals has been identified that is immune
to HIV infection, despite multiple exposures to the virus. They have a natural
mutation, CCRΔ532, that results in the expression of a shortened,
non-functional CCR5 protein. This mutation appears to have no observable
deleterious effect on the growth or survival or these individuals. We are
using our ZFN-mediated gene disruption technology to disrupt the CCR5 gene
in cells of a patient’s immune system to make these cells permanently
resistant to HIV infection. The aim is to provide a population of
HIV-resistant cells that can fight opportunistic infections. In collaboration
with scientists at the University of Pennsylvania and the University of
Los Angeles California, UCLA, we are pursuing both ex- and in vivo approaches
in T-cells and hematopoietic. Sangamo anticipates filing an IND for this
therapeutic in 2008.
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Cancer (Glioblastoma)
Gliomas are the most common type of primary brain tumors; 20,000 cases
are diagnosed and 14,000 glioma-related deaths occur annually in the United
States. Glioblastoma multiforme, a type of glioma, is rapidly progressive
and nearly uniformly lethal. In collaboration with researchers
at City of Hope who have developed a "zetakine" engineered T-cell
therapy for this cancer, Sangamo is developing a ZFP Therapeutic that
uses our ZFN technology to disrupt the expression of the gene encoding
the glucocorticoid receptor in these T-cells. Sangamo anticipates filing
an IND for this therapeutic in 2009.
We are developing ZFNs for therapeutic gene correction of the following monogenic diseases:
Sickle Cell Anemia (SCA).
SCA is caused by a mutation in the human β-globin gene. According to the National Heart, Lung and Blood Institute of the NIH, approximately 72,000 people in the U.S. have sickle cell disease. Moreover, approximately 2.5 million Americans carry the sickle cell trait. Sangamo scientists
and collaborators are developing methods for ZFN-mediated correction of the β-globin gene mutation that causes sickle cell anemia. We are collaborating on this program with the Children’s Hospital of Oakland Research Institute.
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Beta-Thalassemia.
Beta-Thalassemia is an inherited blood disorder that causes mild or
severe anemia due to reduced hemoglobin and fewer red blood cells than normal. Sangamo scientists and
collaborators are developing methods for ZFN-mediated correction of the β-globin gene mutation that
causes β-Thalassemia.
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X-linked Severe Combined Immunodeficiency (X-linked SCID)
Mutations in the gene encoding the IL2Rγ protein invariably cause X-linked SCID (X-linked Severe Combined Immunodeficiency Disease) or so-called Bubble–boy disease. Patients with such mutations do not produce a functional IL2Rγ protein; never develop a functional immune system and die of severe infections
within 12-18 months of birth. Sangamo scientists have used ZFN-mediated gene correction in model cells and primary cells to correct this genetic lesion. This work was published in Nature magazine in April, 2005. We are developing these ZFNs for use in hematopoietic stem cells as a potential therapeutic.
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Commercialization of ZFP Therapeutics.
We plan to develop and commercialize ZFP-Therapeutics
in partnership with pharmaceutical and biotechnology companies. For certain
ZFP-Therapeutics we intend to negotiate partnerships with terms that will
provide partners with exclusive rights to the regulation of specific genes
for certain clinical indications and geographic areas covered under the
agreement. For other ZFP-Therapeutics, we intend to retain certain commercial
product rights or negotiate partnerships for such products after substantial
internal development.
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