Tetraphase Pharmaceuticals to Present Eravacycline

– Four Abstracts Selected for Poster Presentations –

– Presentations Include New Eravacycline Pooled Analysis of IGNITE 1 and IGNITE4 and Data Highlighting the Pre-Clinical Activity of TP-6076 –

WATERTOWN, Mass., May 21, 2018 (GLOBE NEWSWIRE) -- Tetraphase Pharmaceuticals, Inc. (NASDAQ: TTPH ), a biopharmaceutical company focused on developing and commercializing novel antibiotics to treat life-threatening multidrug-resistant (MDR) infections, today announced four poster presentations at the American Society for Microbiology (ASM) Microbe 2018 Annual Meeting, taking place June 7-11 in Atlanta, GA. Presentations will include information about the Company’s lead drug candidate, eravacycline, which is currently under review by the United States Food and Drug Administration (FDA) for the treatment of complicated intra-abdominal infections (cIAI), as well as data for TP-6076, its second-generation candidate to target MDR Gram-negative bacteria, which is currently in Phase 1 clinical testing.

The details for the data presentations at ASM are as follows:

Eravacycline poster presentations

Poster title:  Microbiological Efficacy of Eravacycline Against Enterobacteriaceae and Acinetobacter , Including MDR Isolates: A Pooled Analysis from IGNITE1 and IGNITE4, Two Phase 3 Trials of Complicated Intra-Abdominal Infection Date and time: Saturday, June 9 from 11:00 a.m. – 1:00 p.m. ET Location: Exhibit and Poster Hall, Building B, Halls B2-B5 Poster number:   629 Session information: 236 - AAR09 - Pharmacological Studies of Antimicrobial Agents Pre-NDA (Phase 2/3): New Agents Between Phase 2 and FDA Approval

Poster Title:   In Vitro Activity of Eravacycline and Comparators Against Enterobacteriaceae , Acinetobacter baumannii , Stenotrophomonas maltophilia , Including Multidrug-Resistant Isolates, Collected Globally in 2016 Date and time: Saturday, June 9 from 11:00 a.m. – 1:00 p.m. ET Location: Exhibit and Poster Hall, Building B, Halls B2-B5 Poster number: 630 Session information: 236 - AAR09 - Pharmacological Studies of Antimicrobial Agents Pre-NDA (Phase 2/3): New Agents Between Phase 2 and FDA Approval

Poster title:   Eravacycline In Vitro Activity Against Clinical Isolates Obtained in the U.S. in 2016 from Urinary and Gastrointestinal Sources, Including Drug-resistant Pathogens Date and time: Saturday, June 9 from 11:00 a.m. – 1:00 p.m. ET Location: Exhibit and Poster Hall, Building B, Halls B2-B5 Poster number: 631 Session information: 236 - AAR09 - Pharmacological Studies of Antimicrobial Agents Pre-NDA (Phase 2/3): New Agents Between Phase 2 and FDA Approval

TP-6076 poster presentation

Poster title:  TP-6076 is Active Against Bacterial Isolates Carrying Emergent Resistance Types Date and time: Saturday, June 9 from 11:00 a.m. – 1:00 p.m. ET Location: Exhibit and Poster Hall, Building B, Halls B2-B5 Poster number: 655 Session information: 236 - AAR09 - Pharmacological Studies of Antimicrobial Agents Pre-NDA (Phase 2/3): New Agents Between Phase 2 and FDA Approval

Additional activity:

Tetraphase will have a medical information booth set up throughout the ASM Microbe Conference. Booth number: 3221 Booth hours: Friday, June 8 from 10:30 a.m. – 5.00 p.m.; Saturday, June 9 from 10:30 a.m. – 5:00 p.m.; and Sunday, June 10 from 10:00 a.m. – 4:00 p.m.

Additional mentions:

Poster title:  A Multi-Site Study Comparing A Commercially Prepared Dried MIC Susceptibility System to the CLSI Broth Microdilution Method for Eravacycline Using Fastidious Organisms Date and time: Saturday, June 9 from 11:00 a.m. – 1:00 p.m. ET Location: Exhibit and Poster Hall, Building B, Halls B2-B5 Poster number:   209 Session information: 219 - CPHM02 - Antimicrobial Susceptibility Testing: Gram-Positive and Fastidious Bacteria

Poster title:  A Multi-Site Study Comparing A Commercially Prepared Dried MIC Susceptibility System to the CLSI/ISO Broth Microdilution Method for Eravacycline Using Gram-Positive and Gram-Negative Non-Fastidious Organisms Date and time: Friday, June 8 from 11:00 a.m. – 1:00 p.m. ET Location: Exhibit and Poster Hall, Building B, Halls B2-B5 Poster number:   242 Session information: 042 - CPHM02 - Antimicrobial Susceptibility Testing: Gram-Negative Bacteria

Poster title:  Development of Eravacycline MIC Assay for Gram-Negative Bacteria on Microscan Dried Gram-Negative MIC Panels Date and time: Friday, June 8 from 11:00 a.m. – 1:00 p.m. ET Location: Exhibit and Poster Hall, Building B, Halls B2-B5 Poster number:   235 Session information: 042 - CPHM02 - Antimicrobial Susceptibility Testing: Gram-Negative Bacteria

Full abstracts can be found on the ASM website at www.asm.org .

About Tetraphase Pharmaceuticals, Inc. Tetraphase is a biopharmaceutical company using its proprietary chemistry technology to create novel antibiotics for serious and life-threatening bacterial infections, including those caused by many of the multidrug-resistant bacteria highlighted as urgent public health threats by the Centers for Disease Control and Prevention. The Company has created more than 3,000 novel tetracycline compounds using its proprietary technology platform. Tetraphase's pipeline includes three antibiotic clinical candidates: eravacycline, which has completed phase 3 clinical trials and is under review for potential approval in complicated intra-abdominal infections by the FDA and the European Medicines Agency, and TP-271 and TP-6076, which are in phase 1 clinical trials. Eravacycline is an investigational product only and has not been approved for commercial use. Please visit www.tphase.com for more Company information.

Forward-Looking Statements Any statements in this press release about our future expectations, plans and prospects, including statements regarding our strategy, future operations, prospects, plans and objectives, and other statements containing the words "anticipates," "believes," "expects," "plans," "will" and similar expressions, constitute forward-looking statements within the meaning of The Private Securities Litigation Reform Act of 1995. Actual results may differ materially from those indicated by such forward-looking statements as a result of various important factors, including: whether the Company's regulatory submission will receive approval from the United States Food and Drug Administration or equivalent foreign regulatory agencies; whether, if any clinical candidate, including eravacycline obtains approval, it will be successfully distributed and marketed; and other factors discussed in the "Risk Factors" section of our quarterly report on Form 10-Q for the period  ended March 31, 2018, filed with the Securities and Exchange Commission on May 3, 2018. In addition, the forward-looking statements included in this press release represent our views as of May 21, 2018. We anticipate that subsequent events and developments will cause our views to change. However, while we may elect to update these forward-looking statements at some point in the future, we specifically disclaim any obligation to do so.

Media and Investor Contact: Jennifer Viera jviera@tphase.com   617-600-7040