Synlogic Reports First Quarter Financial Results and Provides Business Update - Proof of concept studies for co-lead metabolic programs SYNB1618 in PKU and SYNB8802 in Enteric Hyperoxaluria on track for 2H 2021 readouts

Synlogic Reports First Quarter Financial Results and Provides Business Update

- Proof of concept studies for co-lead metabolic programs SYNB1618 in PKU and SYNB8802 in Enteric

Hyperoxaluria on track for 2H 2021 readouts -

- $94.4 million in cash, cash equivalents, and short-term investments as of

March 31 plus April financing of $32.6 million (net) enables runway extension to 2H 2023 -

- Management to host

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

Cambridge, Mass. (PR Newswire) May 13, 2021 Synlogic, Inc.

(Nasdaq: SYBX), a clinical stage company bringing the transformative potential of synthetic biology to medicine, today reported financial results for the first quarter ended March 31, 2021, and provided an update on its clinical and

preclinical programs.

We are building momentum and executing on our plans to demonstrate the clinical potential of our Synthetic Biotic platform in

2021, said Aoife Brennan, M.B. Ch.B., Synlogic s President and Chief Executive Officer. With proof of mechanism established in our two lead metabolic programs and a strengthened balance sheet, we are well positioned to deliver proof

of concept readouts for both SYNB1618 in Phenylketonuria (PKU) and SYNB8802 in Enteric Hyperoxaluria later this year.

The Metabolic Portfolio:

Continued development of Synthetic Biotic medicines for the treatment of PKU.

SYNB1618 and SYNB1934 are orally administered Synthetic Biotic medicines being developed as potential

treatments for PKU. They are intended to address the needs of patients of all age groups through the consumption of Phe in the gastrointestinal (GI) tract, which has the potential to lower blood Phe levels and enable the consumption of more natural

protein in the diet.

Demonstration of proof of mechanism of SYNB8802, a Synthetic Biotic medicine being developed for the treatment of Enteric

SYNB8802 is an orally administered Synthetic Biotic medicine being developed as a potential treatment for Enteric Hyperoxaluria. Enteric Hyperoxaluria results

in dangerously high urinary oxalate levels causing progressive kidney damage, kidney stone formation, and nephrocalcinosis. Enteric Hyperoxaluria has no approved treatment options. SYNB8802 is designed to consume oxalate in the GI tract to prevent

the increased absorption of oxalate in patients with Enteric Hyperoxaluria.

The Immunomodulation Portfolio:

Progression of SYNB1891 in combination arm dosing with PDL1 checkpoint inhibitor in an ongoing Phase 1 clinical study in patients with advanced solid tumors

SYNB1891 is an intratumorally administered Synthetic Biotic medicine engineered to act as a dual innate and adaptive immune

activator. Data from both arms of the Phase 1 study will continue to be reported over the course of 2021, with mature combination therapy data expected by the end of the year.

Synlogic strengthens Balance

Synlogic advances strategic partnerships and expands manufacturing capabilities.

First Quarter 2021 Financial Results

March 31, 2021, Synlogic had cash, cash equivalents and short-term investments of $94.4 million.

For the three months ended March 31,

2021, Synlogic reported a consolidated net loss of $15.0 million, or $0.36 per share, compared to a consolidated net loss of $15.8 million, or $0.46 per share, for the corresponding period in 2020.

Research and development expenses were $11.2 million for the three months ended March 31, 2021 compared to

$12.7 million for the corresponding period in 2020.

General and administrative expenses for the three months ended March 31, 2021 were

$3.9 million compared to $3.8 million for the corresponding period in 2020.

There was no revenue for the three months ended March 31, 2021

compared to $0.1 million for the corresponding period in 2020. Revenue for the prior period was associated with Synlogic s collaboration with AbbVie to develop Synthetic Biotic medicines for the treatment of Inflammatory Bowel Disease

which was terminated in May 2020.

Based upon its current operating plan, balance sheet as of March 31st, 2021 and proceeds from the recent

public offering in April 2021, Synlogic expects to have sufficient cash to be able to fund the base operating plan into the second half of 2023.

Conference Call & Webcast Information

will host a conference call and live webcast at 8:30 a.m. ET today, Thursday, May 13, 2021. 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 +1 (213) 660-0926 from outside the United States. The

conference ID number is 2526209. A replay will be available for 30 days on the Investors and Media section of the Synlogic website.

Synlogic is bringing the transformative potential of synthetic biology to medicine. With a

premiere synthetic biology platform that leverages a reproducible, modular approach to microbial engineering, Synlogic designs Synthetic Biotic medicines that target validated underlying biology to treat disease in new ways. Synlogic s

proprietary pipeline includes Synthetic Biotics for the treatment of metabolic disorders including Phenylketonuria (PKU) and Enteric Hyperoxaluria. The company is also building a portfolio of partner-able assets in immunology and oncology.

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, 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 platform to develop therapeutics to address a wide range of diseases including: cancer, 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 Biotic medicines; the approach Synlogic is taking to discover and develop novel therapeutics using synthetic biology; and the

expected timing of Synlogic s clinical trials 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 SEC. 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 date hereof.

Condensed Consolidated Statements Of Operations

Condensed consolidated Balance Sheets