Sangamo BioSciences Presents Study At Society For Neuroscience Meeting Demonstrating In Vivo Reversal Of Huntington's Disease Signs And Symptoms

RICHMOND, Calif., Nov. 19, 2014 /PRNewswire/ -- Sangamo BioSciences, Inc. SGMO announced that positive preclinical data from its joint program with Shire plc, to develop a novel ZFP Therapeutic^® approach to Huntington's disease (HD), will be presented at the 2014 Annual Meeting of the Society for Neuroscience.  The data were generated by Sangamo scientists and the CHDI Foundation. Neuroscience 2014, which is the world's largest forum for neuroscientists to present their research, is being held in Washington D.C. from November 15-19, 2014. 

"These data are very exciting and represent a significant step forward in the quest for a therapeutic for Huntington's disease," said Nancy Wexler, Ph.D., Higgins Professor of Neuropsychology in the Departments of Neurology and Psychiatry of the College of Physicians and Surgeons at Columbia University, and the President of the Hereditary Disease Foundation. "They provide the first demonstration of a therapeutic approach that can not only prevent, but reverse the accumulation of mutant Huntingtin protein aggregates in the brains of animal models of the disease. Furthermore, the treatment does not affect the expression of the normal form of the protein, which is believed to be essential."

The mutant form of the Huntingtin protein (Htt) accumulates in cells and forms protein aggregates which are associated with disease symptoms. Pioneering basic research in transgenic animal models has shown that the levels of the defective Htt protein correlate with disease progression, stimulating the search for strategies to reduce mutant Htt levels as a therapeutic intervention.  However, most "Htt-lowering" methods decrease the levels of both disease-causing and normal forms of Htt. Decreasing the levels of normal Htt raises concerns as the protein appears to be essential and mice lacking Htt die before birth.

"We have demonstrated that by intervening directly at the level of the mutated DNA we can achieve a selective and potent effect on the expression of the mutant gene. This translates to molecular and symptomatic improvements in several animal models and patient-derived cells that span the full range of mutations relevant to human disease," stated Philip Gregory, D. Phil., Sangamo's senior vice president of research and chief scientific officer.  "Huntington's disease is a monogenic disease with a distinct DNA signature and we believe the application of our ZFP technology, which functions at the DNA level, provides the best therapeutic approach to address this intractable disease."

Data presented at Neuroscience 2014 demonstrate that Sangamo's zinc finger DNA-binding protein (ZFP) gene regulation technology can selectively repress expression of the mutant form of the huntingtin gene (HTT) which causes the disease, while leaving the normal gene largely unchanged in both patient-derived cells and in several mouse models.  Importantly, the data also demonstrate the selective effects over the full range of HTT mutations relevant to human disease.

When delivered to the brain in an animal model of the disease, the ZFP Therapeutic not only prevented formation of aggregates if administered at early time points in disease progression, but reversed aggregate formation when administered at later time points. The effects observed in both cases were statistically significant (p<0.001).  ZFP treatment of the animals also maintains expression of markers of medium spiny neurons, a particular class of nerve cell in the striatum of the brain primarily lost in patients with HD. In addition, ZFP treatment reverses physical indications of disease as manifest in a statistically significant reduction in "clasping behavior" compared to controls (p=0.015). "Clasping" is an HD-associated symptom exhibited by a mouse model of HD (R6/2) that mimics the motor symptoms of the human disease.

ZFP-mediated selective repression of mutant HTT had statistically significant positive effects on the health of HD-patient-derived nerve cells as measured by several molecular markers.  These effects included an increase in indicators of cellular metabolism and protection of the cells from programmed cell death when growth factors were withdrawn from the culture medium (p<0.01). Strong support for the prospective safety of this approach was provided by a genome-wide expression analysis that confirmed that the exquisite specificity of the mutant HTT-targeted ZFP TF. 

"These data highlight the exquisite specificity that can be achieved with Sangamo's zinc finger technology platform," stated Edward Lanphier, Sangamo's president and CEO. "We are very pleased with the progress of this program and to be working with Shire to develop this ZFP Therapeutic for patients with HD."

Scientific Presentation at Neuroscience 2014
Wednesday, November 19, 2014, 3:45 – 4:00PM; WCC, Room 147B
769.12: Engineering zinc finger transcriptional repressors selectively inhibit mutant huntingtin expression and reverse disease phenotypes in Huntington's disease patient-derived neurons and in rodent models.  H. S. Zhang, B. Zeitler, S. Froelich, Q. Yu, J. Pearl, D. E. Paschon, J. C. Miller, A. E. Kudwa, Y. Sedaghat, D. Li, K. Marlen, D. Guschin, L. Zhang, M. Mendel, E. J. Rebar, F. D. Urnov, S. Kwak, V. Mack, I. Munoz-Sanjuan, P. D. Gregory

Sangamo's ZFP Therapeutic^® for Huntington's disease
HD is caused by a mutation in a single gene, the huntingtin (HTT) gene, which encodes a protein of the same name.  Most patients inherit one normal and one defective or mutant copy of the HTT gene, which is enough to cause HD. The mutation is characterized by expansion of a repeated stretch of DNA sequence within the gene called a "CAG repeat."  A normal copy of the HTT gene usually has 10 to 29 of these CAG repeats but a defective copy has many more – generally greater than 39 repeats.   While the protein produced by the normal copy of the gene appears to be essential for development (mice lacking the gene do not survive to birth), the product of the mutated gene is damaging to nerve cells.   It is well-documented that the greater the number of CAG repeats, the earlier the onset of HD symptoms.

Sangamo scientists designed and engineered zinc finger transcription factors (ZFP TFs) targeting the expanded CAG repeat, the genetic signature of HD. In multiple independent cell lines derived from HD patients carrying different, disease-causing CAG repeat lengths, they demonstrated that these ZFP TFs decreased production of the mutant HTT messenger RNA (mRNA) by >90% while leaving the levels of the normal HTT mRNA largely unchanged; in turn, this achieved similar selective reduction in levels of mutant protein compared to normal HTT protein.

About Huntington's Disease
Huntington's disease is an inherited, progressive neurologic disease for which there is no treatment or cure. Symptoms, which include deterioration of muscle control, cognition and memory, develop between 35 and 44 years of age, but can start earlier.  HD is usually fatal within 10 to 20 years after the onset of symptoms. The disease has a high prevalence for an inherited disorder, affecting approximately 30,000 people (one in 10,000) in the US. An additional 150,000 people in the U.S. carry a 50% risk of developing the disease. 

About Sangamo
Sangamo BioSciences, Inc. is focused on Engineering Genetic Cures™ for monogenic and infectious diseases by deploying its novel DNA-binding protein technology platform in therapeutic gene regulation and genome editing. The Company has ongoing Phase 2 clinical trials to evaluate the safety and efficacy of a novel ZFP Therapeutic® for the treatment of HIV/AIDS (SB-728-T) 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 Huntington's disease, the safety of the approach of using ZFP-mediated repression of mutant HTT, and Sangamo's collaboration with Shire for the treatment of Huntington's disease and other inherited genetic 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.

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