(SGMO) Presents Data At 11th Annual WorldSymposium On In Vivo Protein Replacement Platform

Novel ZFN Genome Editing Approach Results in Sustained Levels of Enzymes Associated with Hunter, Hurler and Gaucher Syndromes

RICHMOND, Calif., Feb. 12, 2015  — Sangamo BioSciences, Inc. (NASDAQ: SGMO) announced the presentation of preclinical data from its In Vivo Protein Replacement Platform (IVPRP) program for the development of proprietary ZFP Therapeutics^® for the potential cure of lysosomal storage disorders (LSDs). The study was presented at the WORLDSymposium^™ 2015 Meeting, a multidisciplinary forum presenting the latest information from basic science, translational research, and clinical trials for lysosomal diseases, which is being held in Orlando, Florida, from February 9-13, 2015. The data were generated by Sangamo scientists and their collaborators at the University of Minnesota and University of Massachusetts Medical School.

Data presented at WORLDSymposium^™ 2015 demonstrate that Sangamo’s zinc finger nuclease (ZFN) genome editing technology can specifically integrate into the albumin locus of normal mice, human genes encoding functional enzymes that are defective in the LSDs Hunter, Hurler and Gaucher syndromes. Following ZFN-mediated genome editing, robust levels of protein expression were observed in the liver, blood plasma and spleen, leading to increases in enzymatic activity of up to 100-fold. Furthermore, elevated enzyme activity in the blood plasma was sustained over the course of the two month study.

“For lysosomal storage diseases, the population in greatest need is small children. To intervene in the very young and achieve a long-lasting therapeutic effect from a single administration demands stability of enzyme expression over the lifetime of the patient. It is precisely this ability to drive a permanent change at the DNA level that is enabled by our ZFN-driven in vivo protein replacement strategy,” stated Philip Gregory, D. Phil., Sangamo’s senior vice president of research and chief scientific officer. “These data show substantial increases in the activity of the target enzymes in the liver, blood plasma, and spleen, consistent with the effective production, secretion, and importantly, uptake, of the functional therapeutic proteins by other cells and tissues of the body. Thus, by harnessing a tiny fraction of the liver’s powerful albumin promoter and synthesis pathway, we are able to produce sustainable levels of LSD enzymes for the potentially long-term treatment of various lysosomal storage disorders.”

“These data highlight that our proprietary ZFN-enabled genome editing technology can generate broadly applicable and disruptive approaches for the potential cure of numerous monogenic diseases including LSDs,” stated Edward Lanphier, Sangamo’s president and CEO. “Our goal is to move our Hunter and Hurler ZFN Therapeutic programs through IND-enabling studies in 2015.”

About Lysosomal Storage Disorders
Lysosomal storage disorders are a heterogeneous group of inherited genetic disorders, including Hunter, Hurler, and Gaucher syndromes, that are caused by defects in genes that encode enzymes that break down and eliminate unwanted substances in the cells of the body. These enzymes are found in structures called lysosomes which act as recycling sites in cells, breaking down unwanted material into simple products for the cell to reuse. A defect in a lysosomal enzyme leads to the accumulation of toxic levels of the substance that the enzyme would normally break-down and results in cell damage which can lead to serious health consequences.

There are nearly 50 LSDs altogether and they may affect different parts of the body, including the skeleton, brain, skin, heart and CNS. Currently, there are no cures for LSDs, and treatments have not yet been developed for many of these diseases. For certain disorders, including Hunter and Hurler syndromes, costly enzyme replacement therapies (ERTs) are available, but require frequent administration in order to be effective. Over time, patients may also develop an immunogenic response to the administered protein, rendering the ERT less efficacious.

Background on Sangamo’s IVPRP Approach
The IVPRP approach makes use of the albumin gene locus, a highly expressing and liver-specific genomic “safe-harbor site”, that can be edited with zinc finger nucleases (ZFNs) to accept and express any therapeutic gene. The platform enables the patient’s liver to permanently produce therapeutic levels of a corrective protein product such as factor VIII or IX to treat hemophilia, or replacement enzymes to treat lysosomal storage disorders. With such a large capacity for protein production (approximately 15g/day of albumin), which is in excess of the body’s requirements, targeting and co-opting only a very small percentage of the albumin gene’s capacity is sufficient to produce the needed replacement protein at therapeutically relevant levels with no significant effect on albumin production.

About Sangamo
Sangamo BioSciences, Inc. is focused on Engineering Genetic Cures^TM for monogenic and infectious diseases by deploying its novel DNA-binding protein technology platform in therapeutic gene regulation and genome editing. The Company has clinical stage programs to evaluate the safety and efficacy of novel ZFP Therapeutics^® for the treatment of HIV/AIDS (SB-728-T), beta-thalassemia (SB-BCLmR-HSPC), and NGF-AAV for Alzheimer’s disease (CERE-110). Sangamo’s other therapeutic programs are focused on monogenic and rare diseases. The Company has formed a strategic collaboration with Shire International GmbH to develop therapeutics for hemophilia, Huntington’s disease and other monogenic diseases, and with Biogen Idec for hemoglobinopathies, such as sickle cell disease and beta-thalassemia. It has also established strategic partnerships with companies in non-therapeutic applications of its technology, including Dow AgroSciences and Sigma-Aldrich Corporation. For more information about Sangamo, visit the Company’s website at www.sangamo.com.

ZFP Therapeutic^® is a registered trademark of Sangamo BioSciences, Inc.

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; the potential of Sangamo’s ZFP technology to treat LSDs, Hunter, Hurler and Gaucher syndromes and the safety of the approach of using ZFP-mediated genome editing in vivo; the expected IND studies for Hunter and Hurler programs; and the applicability of Sangamo’s ZFP technology in monogenic diseases. 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 safety, tolerability and efficacy of ZFNs and ZFP TFs, 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 public filings with the Securities and Exchange Commission, including the risk factors described in its Annual Report on Form 10-K and its most recent Quarterly Report on Form 10-Q. Sangamo assumes no obligation to update the forward-looking information contained in this press release.