Synlogic Reports Second 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 Second 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

- Immunomodulation portfolio expanded via strategic research collaboration in IBD -

- Synlogic ends 2Q 2021 with $115.5 million in cash, cash equivalents and investments

supporting projected runway into 2H 2023 -

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

Cambridge, Mass. (PR Newswire) August 12, 2021 Synlogic, Inc. (Nasdaq: SYBX), a clinical stage company bringing the

transformative potential of synthetic biology to medicine, today reported financial results for the second quarter ended June 30, 2021, and provided an update on its clinical and preclinical programs.

We are executing across our co-lead metabolic programs and advancing towards proof of concept readouts of our

Synthetic Biotic medicines for the treatment of Phenylketonuria and Enteric Hyperoxaluria, said Aoife Brennan, M.B. Ch.B., Synlogic s President and Chief Executive Officer.

With a next-generation strain in a Phase 1 study for the treatment of Phenylketonuria, a strategic collaboration in place to expand our IBD pipeline and an advancing pre-clinical pipeline of metabolic

disease programs, we have a robust set of potential therapies that could provide meaningful benefit to patients. We look forward to communicating results and next steps over the coming months.

Proof of concept data of SYNB1618 for the treatment of Phenylketonuria (PKU) anticipated in second half of 2021, Phase 1 study of

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.

Proof of concept data of SYNB8802 for the treatment of Enteric Hyperoxaluria anticipated in second half of 2021.

SYNB8802 is an orally administered Synthetic Biotic medicine being

developed as a potential treatment for Enteric Hyperoxaluria. SYNB8802 is designed to consume oxalate in the GI tract to prevent the increased absorption of oxalate in Enteric Hyperoxaluria patients.

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. Approximately 100,000 patients in the US suffer from chronic and recurrent kidney stones as a result of severe Enteric Hyperoxaluria.

The Immunomodulation Portfolio:

SYNB1891 in combination arm dosing with PD-L1 checkpoint inhibitor in Phase 1 study in patients with advanced solid tumors or lymphoma.

SYNB1891 is an investigational drug for the intra-tumoral treatment of solid tumors and lymphoma, composed of an engineered Synthetic

Biotic strain of E. coli Nissle that produces cyclic di-AMP (CDA), a stimulator of the STING (STimulator of INterferon Genes) pathway.

Advancement of preclinical programs in Inflammatory Bowel Disease.

Synlogic strengthens Balance Sheet and advances synthetic biology capabilities.

Second Quarter 2021 Financial Results

As of June 30, 2021, Synlogic had cash, cash equivalents, and short-term investments of $115.5 million.

For the three months ended June 30, 2021, Synlogic reported a consolidated net loss of $14.5 million, or $0.28 per share, compared to a consolidated

net loss of $15.5 million, or $0.44 per share, for the corresponding period in 2020.

Research and development expenses were $10.7 million for

the three months ended June 30, 2021 compared to $12.9 million for the corresponding period in 2020.

General and administrative expenses for

the three months ended June 30, 2021 were $4.1 million compared to $3.5 million for the corresponding period in 2020.

$0.2 million for the three months ended June 30, 2021, compared to $0.4 million for the corresponding period in 2020. Revenue for the three months ended June 30, 2021 was due to the collaboration with Roche, for the discovery of

a novel Synthetic Biotic medicine for treatment of inflammatory bowel disease (IBD). Under the terms of the agreement, Synlogic and Roche will collaborate to develop a Synthetic Biotic medicine addressing an undisclosed novel target in IBD. Revenue

for the three months ended June 30, 2020 was due to the prior 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

and balance sheet as of June 30, 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, August 12, 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 7586239. 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. More

information about Synlogic s programs and pipeline can be found at https://www.synlogictx.com.

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

Condensed Consolidated Statements of Operations

Condensed Consolidated Balance Sheets