Synthetic Biologics on Track to Initiate Clinical Program for SYN-004 to Protect Against C. difficile

— Executed Agreement with Evonik for Formulation Development, Analytical Services andClinical Drug Manufacturing —

— Toxicology Study Nearing Completion; Phase I Clinical Trials Expected to Begin in Q4 —

ROCKVILLE, Md., Aug. 5, 2014 /PRNewswire/ — Synthetic Biologics, Inc. (NYSE MKT: SYN), a developer of novel anti-infective biologic and drug candidates targeting specific pathogens that cause serious infections and diseases, today announced that, with a new multi-service agreement in place, the Company is on track to initiate Phase Ia and Ib clinical trials of SYN-004 for the prevention of Clostridium difficile (C. difficile) during the fourth quarter of 2014. The Company has entered into an agreement with Evonik for oral formulation development, analytical services, and clinical drug manufacturing in accordance to GMP guidelines, of the Company’s proprietary oral beta-lactamase enzyme, SYN-004, for use in the planned clinical trials. Evonik plans to formulate and encapsulate enterically coated SYN-004 for oral delivery using material generated by Synthetic Biologics’ API manufacturer FUJIFILM Diosynth Biotechnologies UK Limited.

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SYN-004 is designed as the first and only prophylactic treatment intended to prevent the development of C. difficile infections, by binding with and neutralizing certain intravenous (IV) beta-lactam antibiotics in the gut. SYN-004 is intended to block the effects of antibiotics within the gastrointestinal tract, maintaining the natural balance of bacterial flora (the gut microbiome), potentially preventing the 1.1 million C. difficile infections in the U.S. each year1.

“SYN-004 has the potential to have a significant impact on mitigating the effects of C. difficile, a major public health issue, and we are thrilled to be advancing rapidly toward the clinic with our novel and differentiated approach,” stated Jeffrey Riley, Chief Executive Officer of Synthetic Biologics. “While we await the topline results of the ongoing toxicology study, we are pleased to have begun working with our strategic partner Evonik, to optimize formulation variables and manufacture GMP clinical trial drug supply to support our planned human studies, once our IND is in place.”

The U.S. Centers for Disease Control and Prevention (CDC) has classified harmful and potentially deadly C. difficile as an “urgent public health threat,” surpassing Methicillin-resistant Staphylococcus aureus (MRSA) as the number one hospital-acquired infection in the United States.

Prior to initiating cGMP manufacturing of SYN-004 capsules, Evonik successfully formulated and manufactured nonclinical trial material for the ongoing canine toxicology study, from which Synthetic Biologics expects to report topline results next month. With these critical milestones underway, the Company remains on schedule to file an Investigational New Drug (IND) application for SYN-004, and intends to initiate Phase Ia and Ib clinical studies in the fourth quarter of 2014. Preliminary Phase I topline data is expected by year-end 2014, and a Phase II efficacy study of SYN-004 is planned to begin in the first half of 2015.

About Evonik

Evonik, the creative industrial group from Germany, is one of the world leaders in specialty chemicals. Profitable growth and a sustained increase in the value of the company form the heart of Evonik’s corporate strategy. Its activities focus on the key megatrends health, nutrition, resource efficiency and globalization. Evonik benefits specifically from its innovative prowess and integrated technology platforms. Evonik is active in over 100 countries around the world. In fiscal 2013, more than 33,500 employees generated sales of around €12.7 billion and an operating profit (adjusted EBITDA) of about €2.0 billion. For more information, please visit Evonik’s website at www.evonik.com.

About Synthetic Biologics, Inc.

Synthetic Biologics, Inc. (NYSE MKT: SYN) is a biotechnology company focused on the development of novel anti-infective biologic and drug candidates targeting specific pathogens that cause serious infections and diseases. The Company is developing an oral biologic to protect the gastrointestinal microflora from the effects of IV antibiotics for the prevention of Clostridium difficile (C. difficile) infection, an oral treatment to reduce the impact of methane producing organisms on constipation-predominant irritable bowel syndrome (C-IBS), a series of monoclonal antibodies for the treatment of Pertussis and Acinetobacter infections, and a biologic targeted at the prevention and treatment of a root cause of a subset of IBS. In addition, the Company is developing an oral estriol drug for the treatment of relapsing-remitting multiple sclerosis (MS) and cognitive dysfunction in MS. For more information, please visit Synthetic Biologics’ website at www.therivabio.com.

This release includes forward-looking statements on Synthetic Biologics’ current expectations and projections about future events. In some cases forward-looking statements can be identified by terminology such as “may,” “should,” “potential,” “continue,” “expects,” “anticipates,” “intends,” “plans,” “believes,” “estimates,” and similar expressions. These statements are based upon current beliefs, expectations and assumptions and are subject to a number of risks and uncertainties, many of which are difficult to predict and include statements regarding the intended effects and potential impact of SYN-004, the timing of initiation of the Phase Ia and Ib clinical studies, the preliminary Phase I topline data and initiation of Phase II efficacy study and the expected size of the market for C. diff therapeutics. The forward-looking statements are subject to risks and uncertainties that could cause actual results to differ materially from those set forth or implied by any forward-looking statements. Important factors that could cause actual results to differ materially from those reflected in Synthetic Biologics’ forward-looking statements include, among others, our inability to timely commence or complete the clinical trials consistent with our current expectations and otherwise demonstrate the ability of SYN-004 to have a significant impact on mitigating the effects of C. difficile, our ability to successfully manufacture cGMP product, receive regulatory approvals for or to commercialize a new product candidate to prevent C. diff infection and other factors described in Synthetic Biologics’ report on Form 10-K for the year ended December 31, 2013 and any other filings with the SEC. The information in this release is provided only as of the date of this release, and Synthetic Biologics undertakes no obligation to update any forward-looking statements contained in this release on account of new information, future events, or otherwise, except as required by law.

1This information is an estimate derived from the use of information under license from the following IMS Health Incorporated information service: CDM Hospital database for full year 2012. IMS expressly reserves all rights, including rights of copying, distribution and republication.

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SOURCE Synthetic Biologics, Inc.