September 3, 2008

Sangamo BioSciences Initiates Phase 2 Clinical Trial of Treatment for Amyotrophic Lateral Sclerosis (ALS)

RICHMOND, Calif., Sept. 3 /PRNewswire-FirstCall/ -- Sangamo BioSciences, Inc. announced today that it has opened a Phase 2 clinical trial (SB-509-801) to evaluate its drug, SB-509, in subjects with ALS, a progressive, degenerative motor-neuron disease for which there are limited treatment options and no cure.

Sangamo's drug, SB-509, is an injectable formulation of a plasmid encoding a zinc finger DNA-binding protein transcription factor (ZFP TF(TM)) designed to upregulate the expression of the gene encoding vascular endothelial growth factor (VEGF-A). SB-509 is also in three additional Phase 2 clinical trials for diabetic neuropathy and stem cell mobilization. VEGF-A has been shown to have nerve protection properties as well as promoting nerve, blood vessel and muscle growth.

In ALS, the motor nerves comprised of nerve cells in the brain and spinal cord that control the body's voluntary muscles, gradually degenerate. As the nerve cells begin to die, the muscles weaken and shrink. As the disease progresses, patients gradually lose the use of their limb and neck muscles, ultimately becoming paralyzed and unable to breathe without assistance. Fifty percent of patients with ALS die within three to five years of diagnosis. Currently, there is only one approved drug for ALS; Riluzole has been demonstrated to slow the progression of this debilitating disease with only modest clinical benefit, extending the survival of ALS patients by approximately three months.

"Initiation of a Phase 2 clinical study of SB-509 in subjects with a motor neuron and muscle disease such as ALS is an obvious next step in the evaluation of this novel therapeutic," stated Dale Ando, M.D., Sangamo's vice president of therapeutic development and chief medical officer. "The drug is designed to activate the expression of the subject's own VEGF-A gene. There is mounting pre-clinical and clinical evidence to support a correlation between reduced VEGF-A levels and progression of this life-threatening disease. Our Phase 1 clinical studies of SB-509 in diabetic neuropathy have shown that the drug is well tolerated. Data from this clinical study and pre-clinical studies in animal models of nerve damage reveal positive effects of SB-509 on motor nerve function and muscle composition. Similar effects on motor nerves and muscles in these patients may slow the progression of ALS by preserving nerve function and improving muscle fiber composition and strength."

The Phase 2 trial (SB-509-801) is a randomized repeat-dosing, open-label, multi-center study designed to evaluate the effect of intramuscular administration of SB-509 on the progression of the disease in subjects with ALS, as measured by the ALS Functional Rating Scale-Revised (ALSFRS-R) a validated rating instrument for monitoring the progression of disability in patients with ALS. Efficacy of SB-509 will be evaluated by comparing the rate of ALS disease progression in subjects treated with SB-509 in this study to historical placebo controls. In addition to gathering data on safety and tolerability of SB-509 in subjects with ALS, data will be collected to evaluate the effect of SB-509 on additional clinical measures. These measures include Forced Vital Capacity (FVC), a test of lung function; Neurophysiologic Index (NI), a measure of neurologic impairment; Manual Muscle Test (MMT), a test of muscle strength; and survival. Finally, the study will also evaluate stem cell mobilization in subjects with ALS receiving SB-509.

"We are pleased to meet our goal of beginning a Phase 2 clinical trial in ALS this year and are very excited to begin these proof of principle studies," said Edward Lanphier, Sangamo's president and CEO. "VEGF has been demonstrated to have a fundamental role in the growth and health of blood vessels, nerves and muscle and we believe that our approach of using a ZFP TF to stimulate the expression of all of the natural forms of a subject's own VEGF-A gene may have potential therapeutic benefit for a variety of neurodegenerative conditions including ALS."

About the Study, SB-509-801

A total of 40 subjects with ALS will be enrolled in this trial and randomized into one of two treatment cohorts. The first cohort of 35 subjects will receive 60 mg of SB-509 in a divided dose into muscles in the arm, leg, and along the spine on both sides of the body. A second cohort of 5 subjects will receive 60 mg of SB-509 in a divided dose into the muscles in the lower limb in both legs. Each subject will receive a total of two treatments of 60 mg of SB-509 intramuscularly three months apart on Day 0 and Day 90. The study will be carried out over 11 months, including 2 months for screening, 3 months for two study treatments, and 6 months of follow-up after administration of the final dose. Individuals interested in participating in this trial should visit or

About Amyotrophic Lateral Sclerosis (ALS)

More than 30,000 Americans have ALS, according to the ALS Association, a nonprofit organization that supports ALS research and public and patient education about the disease. 3,000 to 5,000 new cases of the disease are diagnosed every year. Men and women of all ethnic and racial groups are equally affected, usually between the ages of 40 and 70. The disease attacks the motor nerves, nerve cells in the brain and spinal cord that control the body's voluntary muscles. As the motor nerves begin to die, the muscles weaken and shrink. Early symptoms of ALS may include unusual tiredness and clumsiness, muscle weakness, slurred speech, and difficulty swallowing. As the disease progresses, patients gradually lose the use of their hands, arms, legs, and neck muscles, ultimately becoming paralyzed. They can speak and swallow only with great difficulty. About half of people with ALS die within three to five years of diagnosis.

About Sangamo

Sangamo BioSciences, Inc. is focused on the research and development of novel DNA-binding proteins for therapeutic gene regulation and modification. The most advanced ZFP Therapeutic(TM) development program is currently in Phase 2 clinical trials for evaluation of safety and clinical effect in patients with diabetic neuropathy and ALS. Other therapeutic development programs are focused on cancer, HIV/AIDS, neuropathic pain, nerve regeneration, Parkinson's disease and monogenic diseases. Sangamo's core competencies enable the engineering of a class of DNA-binding proteins known as zinc finger DNA-binding proteins (ZFPs). By engineering ZFPs that recognize a specific DNA sequence Sangamo has created ZFP transcription factors (ZFP TF(TM)) that can control gene expression and, consequently, cell function. Sangamo is also developing sequence-specific ZFP Nucleases (ZFN(TM)) for gene modification. Sangamo has established strategic partnerships with companies outside of the human therapeutic space including Dow AgroSciences, Sigma-Aldrich Corporation and several companies applying its ZFP Technology to enhance the production of protein pharmaceuticals. For more information about Sangamo, visit the company's web site at

This press release may contain forward-looking statements based on Sangamo's current expectations. These forward-looking statements include, without limitation, references to clinical trials of SB-509 and the potential for further study and development of SB-509, research and development of novel ZFP TFs and ZFNs and therapeutic applications of Sangamo's ZFP technology platform. 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 the SB-509 clinical trials, whether the SB-509 clinical trials will validate and support safety, tolerability and efficacy of SB-509, technological challenges, Sangamo's ability to develop commercially viable products and technological developments by our competitors. See Sangamo's SEC filings, and in particular, the risk factors described in its Annual Report on Form 10-K and its most recent Quarterly Report on Form 10-Q. Sangamo BioSciences, Inc. assumes no obligation to update the forward-looking information contained in this press release.

Sangamo BioSciences, Inc.

CONTACT: Elizabeth Wolffe, Ph.D. of Sangamo BioSciences, Inc. ,+1-510-970-6000, ext. 271, [email protected]

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