Synlogic Reports First Quarter 2022 Financial Results and Provides Business Update - Clinical readouts anticipated for phenylketonuria (PKU), homocystinuria (HCU) and enteric hyperoxaluria programs in H2 2022 - PKU progr

Synlogic Reports First Quarter 2022 Financial Results and Provides Business Update

- Clinical readouts anticipated for phenylketonuria (PKU), homocystinuria (HCU) and enteric hyperoxaluria programs in H2 2022

- PKU program progressing with Phase 3 readiness activities underway

- $120.5 million in cash, cash equivalents and short-term investments support projected runway into 2024

- Conference call and webcast at 8:30 a.m. ET today

Cambridge, Mass. May 12, 2022 Synlogic, Inc. (Nasdaq: SYBX), a clinical-stage biotechnology company developing medicines for

metabolic and immunological diseases through its proprietary approach to synthetic biology, today reported financial results for the first quarter ended March 31, 2022 and provided an update on pipeline programs.

We are pleased to share this progress as we seek to advance our novel phenylketonuria (PKU) program towards Phase 3 initiation, said Synlogic

President and Chief Executive Officer Aoife Brennan, M.B. Ch.B. We believe that we have a unique opportunity to advance a potential treatment for the 55,000 people around the globe with PKU, of whom more than 75% remain in need of additional

treatment options either monotherapy or adjunctive. We are pleased with the progress across our additional programs with expected milestones in 2022, including our homocystinuria (HCU) and enteric hyperoxaluria programs, as well as research

progress including our ongoing collaborations with Ginkgo Bioworks and Roche.

Anticipated Upcoming Milestones

Recent Business Highlights

First Quarter 2022 Financial Results

March 31, 2022, Synlogic had cash, cash equivalents and short-term investments of $120.5 million.

Revenue was $0.2 million for the three

months ended March 31, 2022. Revenue in 2022 was associated with the ongoing research collaboration with Roche for the discovery of a novel Synthetic Biotic for the treatment of IBD. There was no revenue for the three months ended

For the three months ended March 31, 2022, Synlogic reported a consolidated net loss of $15.7 million, or $0.22 per share,

compared to a consolidated net loss of $15.0 million, or $0.36 per share, for the corresponding period in 2021.

Research and development expenses

were $11.7 million for the three months ended March 31, 2022 compared to $11.2 million for the corresponding period in 2021.

administrative expenses were $4.3 million for the three months ended March 31, 2022 compared to $3.9 million for the corresponding period in 2021.

Based upon its current operating plan and balance sheet as of March 31, 2022, Synlogic expects to have sufficient cash to be able to fund operations into

Investor & Industry Conference Participation

Synlogic will participate in the following upcoming investor and industry conferences:

Live webcasts of the presentations, if available, will be accessible under the Event Calendar in the Investors & Media section of

the Synlogic website. Archived versions will be available afterwards at the same location.

Conference Call & Webcast Information

Synlogic will host a conference call and live webcast at 8:30 a.m. ET today, May 12, 2022. To access the live webcast, please visit the Event

Calendar page within the Investors and Media section of the Synlogic website. Investors may listen to the call by dialing +1 (844) 815-2882 from locations in the United States or (213) 660-0926 from outside the United States. The conference ID number is 5149412. A replay will be available for 30 days on the Investors and Media section of the Synlogic website.

Synlogic is a clinical-stage biotechnology company developing medicines through its proprietary approach to synthetic biology. Synlogic s pipeline

includes its lead program in phenylketonuria (PKU), which has demonstrated proof of concept, and additional novel drug candidates designed to treat homocystinuria (HCU) and enteric hyperoxaluria. The rapid advancement of these potential

biotherapeutics, called Synthetic Biotics, has been enabled by Synlogic s proprietary, reproducible, target-specific drug design. Synlogic uses programmable, precision genetic engineering of well-characterized probiotics to exert localized

activity for therapeutic benefit, with a focus on metabolic and immunologic diseases. Synlogic is also working with Roche in a research collaboration focused on the discovery of a novel Synthetic Biotic for the treatment of inflammatory bowel

disease and with Ginkgo Bioworks to include additional undisclosed preclinical assets, combining Synlogic s approach to Synthetic Biotics with Ginkgo s Codebase and Foundry services. For additional information visit

Forward-Looking Statements

This press release contains forward-looking statements that involve substantial risks and uncertainties for purposes of the safe harbor provided by

the Private Securities Litigation Reform Act of 1995. All statements, other than statements of historical facts, included in this press release regarding strategy, future operations, clinical development plans, future financial position, future

revenue, projected expenses, prospects, plans and objectives of management are forward-looking statements. In addition, when or if used in this press release, the words may, could, should, anticipate,

believe, estimate, expect, on track, intend, plan, predict and similar expressions and their variants, as they relate to Synlogic may identify forward-looking

statements. Examples of forward-looking statements, include, but are not limited to, statements regarding the potential of Synlogic s approach to Synthetic Biotics to develop therapeutics to address a wide range of diseases including inborn

errors of metabolism, metabolic diseases, and inflammatory and immune disorders; our expectations about sufficiency of our existing cash balance; the future clinical development of Synthetic Biotics; the approach Synlogic is taking to discover and

develop novel therapeutics using synthetic biology; our research and other collaborations; and the expected timing of Synlogic s clinical trials of SYNB1618, SYNB1934, SYNB1353 and SYNB8802 and availability of clinical trial data. Actual

results could differ materially from those contained in any forward-looking statement as a result of various factors, including: the uncertainties inherent in the clinical and preclinical development process; the ability of Synlogic to protect its

intellectual property rights; and legislative, regulatory, political and economic developments, as well as those risks identified under the heading Risk Factors in Synlogic s filings with the Securities and Exchange Commission. The

forward-looking statements contained in this press release reflect Synlogic s current views with respect to future events. Synlogic anticipates that subsequent events and developments will cause its views to change. However, while Synlogic may

elect to update these forward-looking statements in the future, Synlogic specifically disclaims any obligation to do so. These forward-looking statements should not be relied upon as representing Synlogic s view as of any date subsequent to the

Condensed Consolidated Statements of Operations

Condensed Consolidated Balance Sheets