8-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): November 10, 2021

SYNLOGIC, INC.

(Exact name of registrant as specified in its charter)

Delaware	001-37566	26-1824804
(State or other jurisdiction of incorporation)	(Commission File Number)	(IRS Employer Identification No.)

301 Binney St., Suite 402 Cambridge, MA	02142
(Address of principal executive offices)	(Zip Code)

Registrant’s telephone number, including area code: (617) 401-9975

Not applicable

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Common Stock	SYBX	The Nasdaq Capital Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (17 CFR §230.405) or Rule 12b-2 of the Securities Exchange Act of 1934 (17 CFR §240.12b-2).

Emerging Growth Company  ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☐

Item 2.02 Results of Operations and Financial Condition

On November 10, 2021, Synlogic, Inc. (the “Company”) announced its financial results for the quarter ended September 30, 2021. The full text of the press release and the subsequent presentation issued in connection with the announcement is furnished as Exhibit 99.1 and 99.2, respectively, to this Current Report on Form 8-K.

The information in this Current Report on Form 8-K (including Exhibit 99.1 and 99.2) shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”) or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such filing.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

Exhibit No.	Description
99.1	Press Release dated November 10, 2021.
99.2	Presentation dated November 10, 2021.
104	Cover Page Interactive Data File (embedded within the Inline XBRL document)

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Date: November 10, 2021	Synlogic, Inc.
	By:	/s/ Gregg Beloff
	Name:	Gregg Beloff
	Title:	Interim Chief Financial Officer

EX-99.1

Exhibit 99.1

Synlogic Reports Third Quarter Financial Results and Provides Business Update

- Interim analysis of Phase 2 SynPheny-1 study demonstrated proof of concept in phenylketonuria. Program to advance to Phase 3 development -

- Research milestone in inflammatory bowel disease collaboration with Roche achieved -

- $150.1 million in cash, cash equivalents and short-term investments supports projected runway into 2024 -

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

Cambridge, Mass. (PR Newswire) November 10, 2021 – Synlogic, Inc. (Nasdaq: SYBX), a clinical-stage company bringing the transformative potential of synthetic biology to medicine, today reported financial results for the third quarter ended September 30, 2021 and provided an update on clinical programs.

“We are very pleased to be moving our Phenylketonuria (PKU) program into late-phase clinical development with the goal of bringing forward a clinically meaningful and differentiated medicine to the PKU community. The positive interim analysis from the Phase 2 SynPheny-1 study gives us confidence as we prepare to launch a Phase 3 program in PKU in 2022,” said Aoife Brennan, M.B. Ch.B., Synlogic President and Chief Executive Officer. “We continue to advance oral metabolic programs in other areas of high unmet need as well as drive our research engine forward, including achieving an important early milestone in our IBD collaboration with Roche. The Synthetic Biotic^TM platform is proving to be a potent and rapid source of novel therapeutic candidates.”

Recent Portfolio Highlights

Metabolic Portfolio

Phenylketonuria (PKU): Proof of concept of SYNB1618 achieved in an interim analysis. Full study results of both SYNB1618 and SYNB1934, and advancement of Phase 3 program, expected in 2022.

• In September, the Company reported SYNB1618 demonstrated proof of concept in PKU patients, with a clinically meaningful and statistically significant reduction of plasma phenylalanine (Phe) levels in an interim analysis of the Phase 2 SynPheny-1 study.

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• SYNB1934, an optimized strain of SYNB1618, further demonstrated a two-fold increase in biomarkers of Phe metabolism compared to SYNB1618 in a head-to-head healthy volunteer study.

• The Phase 2 SynPheny-1 study has been amended to incorporate SYNB1934, with results expected in the first half of 2022.

• Synlogic is preparing to start a Phase 3 program with the preferred strain based on the SynPheny-1 study data in phenylketonuria (PKU) in 2022.

• Further data on the Synlogic PKU program will be presented at the 14th International Congress of Inborn Errors of Metabolism (ICIEM) meeting to be held in Sydney, Australia and virtually on November 21 – 24, 2021.

Enteric Hyperoxaluria: Proof of concept data of SYNB8802 anticipated in 2022.

• In April, the Company reported that SYNB8802 demonstrated proof of mechanism in Part A of an ongoing Phase 1 study, with robust and dose-dependent evidence of urinary oxalate lowering in healthy volunteers given a high oxalate diet.

• Part B of the study is continuing to evaluate of SYNB8802 in patients with enteric hyperoxaluria secondary to Roux-en-Y gastric bypass surgery, with data expected next year.

• Further data on SYNB8802 and enteric hyperoxaluria were presented at the American Urological Association 2021 Annual Meeting and the American Society of Nephrology Kidney Week 2021, including real-world evidence demonstrating a relationship between higher urinary oxalate levels and increased incidence of chronic kidney disease.

Homocystinuria (HCU): Synlogic and Ginkgo announced that SYNB1353 for the treatment of homocystinuria has been advanced into IND-enabling studies, with entry into the clinic expected in 2022.

• SYNB1353 was developed using Synlogic’s Synthetic Biotic platform incorporating components of Ginkgo Bioworks’ codebase. Synlogic holds worldwide development and commercialization rights.

• Further data on this program will be presented at the 14th International Congress of Inborn Errors of Metabolism (ICIEM) meeting to be held in Sydney, Australia and virtually on November 21 – 24, 2021.

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• Synlogic and Ginkgo continue to advance their long-term strategic platform collaboration with multiple undisclosed metabolic and immunology programs now in preclinical development.

Immunomodulation Portfolio

Achievement of preclinical milestone in research collaboration with Roche

• In June 2021, Synlogic and Roche entered into a research collaboration agreement for the discovery of a novel Synthetic Biotic medicine for the treatment of inflammatory bowel disease (IBD), addressing an undisclosed novel target in IBD.

• During the third quarter, Synlogic achieved a prespecified research milestone and earned the first milestone payment due under the terms of the collaboration.

Phase 1 study of SYNB1891 in combination with PD-L1 checkpoint inhibitor patients with advanced solid tumors or lymphoma has completed enrollment.

• Results will be presented at the Society for Immunotherapy of Cancer 2021 annual meeting to be held in Washington, D.C. and virtually on November 10 – 14, 2021.

• No further studies are planned for SYNB1891 at this time.

Corporate Updates

Synlogic strengthens balance sheet and builds leadership team

• In September, Synlogic completed an underwritten public offering of 17.3 million shares, resulting in net proceeds to Synlogic of approximately $48.4 million.

• Synlogic appointed Molly Harper to the newly created position of Chief Business Officer. Ms. Harper will provide strategic leadership to the commercial, corporate development and business development functions, and lead the planning and commercialization of Synlogic’s growing pipeline.

Third Quarter 2021 Financial Results

As of September 30, 2021, Synlogic had cash, cash equivalents, and short-term investments of $150.1 million.

For the three months ended September 30, 2021, Synlogic reported a consolidated net loss of $16.0 million, or $0.29 per share, compared to a consolidated net loss of $13.2 million, or $0.36 per share, for the corresponding period in 2020.

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Research and development expenses were $13.4 million for the three months ended September 30, 2021 compared to $10.5 million for the corresponding period in 2020.

General and administrative expenses for the three months ended September 30, 2021 were $3.6 million compared to $3.0 million for the corresponding period in 2020.

Revenue was $0.9 million for the three months ended September 30, 2021. There was no revenue for the three months ended September 30, 2020. Revenue in 2021 was associated with the ongoing research collaboration with Roche for the discovery of a novel Synthetic Biotic medicine for the treatment of IBD.

Financial Outlook

Based upon its current operating plan and balance sheet as of September 30, 2021 Synlogic expects to have sufficient cash to be able to fund operations into 2024.

Conference Call & Webcast Information

Synlogic will host a conference call and live webcast at 8:30 a.m. ET today, Wednesday, November 10, 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 5450919. A replay will be available for 30 days on the Investors and Media section of the Synlogic website.

About Synlogic

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

About SYNB1618 and SYNB1934

SYNB1618 and SYNB1934 are orally administered Synthetic Biotic medicines being developed as potential treatments for phenylketonuria (PKU). They are intended to address the needs of patients of all age groups through the consumption of Phe in the gastrointestinal tract, which has the potential to lower blood Phe levels and enable the consumption of more natural protein in the diet.

Page 4 of 7

About SYNB8802

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.

About SYNB1353

SYNB1353 is a novel medicine in development for the treatment of diseases of methionine metabolism including homocystinuria (HCU). SYNB1353 was developed using Synlogic’s Synthetic Biotic platform incorporating components of Ginkgo Bioworks’ codebase. Synlogic holds worldwide development and commercialization rights to SYNB1353.

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 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 date hereof.

-more-

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MEDIA CONTACT:	INVESTOR CONTACT:
Bill Berry Berry & Company Public Relations Phone: 212-253-8881 Email: bberry@berrypr.com	Daniel Rosan Synlogic, Inc. Phone: 617-401-9152 Email: dan.rosan@synlogictx.com

###

Synlogic, Inc.

Condensed Consolidated Statements of Operations

(unaudited)

(in thousands,except share and per share data)	For the three months ended						For the nine months ended
	September 30, 2021			September 30, 2020			September 30, 2021			September 30, 2020
Revenue	$	916		$	—		$	1,162		$	545
Operating expenses
Research and development		13,355			10,481			35,254			36,067
General and administrative		3,616			2,956			11,528			10,250
Total operating expenses		16,971			13,437			46,782			46,317
Loss from operations		(16,055	)		(13,437	)		(45,620	)		(45,772	)
Other income, net		39			215			148			1,187
Net loss	$	(16,016	)	$	(13,222	)	$	(45,472	)	$	(44,585	)
Net loss per share—basic and diluted	$	(0.29	)	$	(0.36	)	$	(0.91	)	$	(1.27	)
Weighted-average common shares used in computing net loss per share—basic and diluted		55,336,936			36,297,780			49,730,231			35,174,203

Page 6 of 7

Synlogic, Inc.

Condensed Consolidated Balance Sheets

(unaudited)

( in thousands, except share data)	September 30, 2021		December 31, 2020
Assets
Cash, cash equivalents, and short-term investments	$	150,054	$	100,444
Fixed assets	$	9,625		10,776
Other assets	$	30,857		32,620
Total assets	$	190,536	$	143,840
Liabilities and stockholders’ equity
Current liabilities	$	10,591	$	8,301
Long-term liabilities	$	18,363		20,404
Total liabilities		28,954		28,705
Total stockholders’ equity	$	161,582		115,135
Total liabilities and stockholders’ equity
		$190,536		$143,840
Common stock and common stock equivalents
Common stock		69,707,541		38,183,273
Common stock warrants (pre-funded)		2,548,117		2,548,117
Total common stock		72,255,658		40,731,390

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EX-99.2

Bringing the Transformative Power of Synthetic Biology to Medicine Q3 Financial Results & Business Update 10 November 2021 Exhibit 99.2

Forward Looking Statements This presentation 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 presentation regarding strategy, future operations, 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 presentation, the words “may,” “could,” “should,” “anticipate,” “believe,” “estimate,” “expect,” “intend,” “plan,” “predict” and similar expressions and their variants may identify forward-looking statements. Examples of forward-looking statements include, but are not limited to, the approach we are taking to discover and develop novel therapeutics using synthetic biology; statements regarding the potential of our platform to develop therapeutics to address a wide range of diseases, including: metabolic diseases, inflammatory and immune disorders, and cancer; the future clinical development of Synthetic Biotic medicines; the potential of our technology to treat phenylketonuria and cancer; the expected timing of our anticipated clinical trial initiations and availability of clinical data; the benefit of orphan drug and fast track status; the adequacy of our capital to support our future operations and our ability to successfully initiate and complete clinical trials; the results of our collaborations; and the difficulty in predicting the time and cost of development of our product candidates. Actual results could differ materially from those contained in any forward-looking statement as a result of various factors, including, without limitation: the uncertainties inherent in the preclinical development process; our ability to protect our intellectual property rights; and legislative, regulatory, political and economic developments, as well as those risks identified under the heading “Risk Factors” in our filings with the SEC. The foregoing review of important factors that could cause actual events to differ from expectations should not be construed as exhaustive and should be read in conjunction with statements that are included herein and elsewhere, including the risk factors included in our quarterly report on Form 10-Q filed with the SEC on November 10, 2021, and in any subsequent filings we make with the SEC. The forward-looking statements contained in this presentation reflect our current views with respect to future events. We anticipate that subsequent events and developments will cause our views to change. However, while we may elect to update these forward-looking statements in the future, we specifically disclaim any obligation to do so. These forward-looking statements should not be relied upon as representing our view as of any date subsequent to the date hereof.

© 2020 SYNLOGIC. QU©AR2T0E1R9LYSYRNELSOUGLTICS.. AALLLL RRIIGGHHTTSS RREESSEERRVVEEDD.. || 33 Opening Remarks Dr. Aoife Brennan MB CHB President & CEO

Solid Tumors SYNB1891 combination study with PD-1 has completed enrollment. No further studies planned at this time Inflammatory Bowel Disease Advancing research collaboration with Roche on novel IBD target; achieved first milestone Metabolic programs Immunology Multiple high value indications accessible with Synthetic Biotic Medicines Phenylketonuria (PKU) SYNB1618 strain achieved prespecified 20% Phe lowering target in PKU patients in interim analysis SYNB1934 strain demonstrated two-fold greater activity than SYNB1618 in healthy volunteers Other Inborn Errors of Metabolism SYNB1353 progressing to IND-enabling studies for treatment of homocystinuria Enteric Hyperoxaluria SYNB8802 achieved proof of mechanism in Phase 1A in dietary hyperoxaluria induced in healthy volunteers Dose dependent consumption of oxalate in the GI tract shown Phase 1B patient data expected 2022 in patients with enteric hyperoxaluria Clinical benefit of the Synthetic Biotic platform demonstrated

Phenylketonuria (PKU) SYNB1618 Inflammatory Bowel Disease Enteric Hyperoxaluria SYNB8802 SYNB1618 Homocystinuria Undisclosed Metabolic Program PoC 2022 Combo study late ‘21 Robust pipeline moving forward Metabolic Metabolite consumption in the GI tract Immunology SYNB1934 Undisclosed IBD Program Exploratory Preclinical IND-Enabling Studies Phase 1 Phase 2 FIH 2022 FIH: First in Human. PoC: Proof of Concept. SYNB1353

Progress against our strategy PKU Demonstrated plasma Phe lowering in patients with classical PKU PKU Demonstrated higher potency of next generation strain in humans HOX Progressed Phase 1B study IBD Achieved first Roche research collaboration milestone Other Metabolic Advanced third oral metabolic program, SYNB1353 for the treatment of HCU, into IND-enabling studies

Synthetic Biotic Medicines: Differentiated Potential in PKU Molly Harper Chief Business Officer

PKU: Significant Disease Burden, Need for New Treatment Options Inherited defects in PAH enzyme impairs ability to metabolize Phe Neurocognitive risk remains: 8X risk for intellectual disabilities1 70% had significant neuropsych comorbidity (50% had multiple)2 1 Bilder et al. 2017; 2 Levy et al. 2020 3 Berry et al. 2013 Phe build-up can cause irreversible neurological damage and neurocognitive defects >70% of adults with PKU are not actively treated by metabolic clinics3

Current options leave behind the majority that live with PKU Self-injection, daily 6-12 month titration Boxed warning: anaphylaxis “at any time during treatment” Restricted REMS Only approved for adults4 30% response rate1 10% mean fasting Phe reduction for all-comers2 Adult daily pill burden can exceed 10 tablets3 sapropterin pegvaliase-pqpz 1 Burton et al. 2007; 2 FDA Statistical Review & Evaluation of sapropterin dihydrochloride 2007 3 U.S. Prescribing Information for Kuvan 4 U.S. Prescribing Information for Palynziq 5 NORD 6 Puurunen et al, Global PKU Patient Meeting, September 2021 90% of patients and caregivers express need for greater natural protein intake (6) US PKU Population: ~17,000 5 Uncontrolled (~60%) Controlled (~40%)

Synthetic Biotic™ Medicines are designed for PKU Taken orally, 3 x day with meals Monotherapy or adjunctive Local delivery, without systemic AEs Dietary Phe Reduce plasma Phe Converted by Synthetic Biotic to harmless metabolites (TCA)

Interim Analysis of SYNB1618 SynPheny-1 Phase 2 Study in PKU

Synthetic Biotic Medicines: a novel approach in Phenylketonuria (PKU) Potential to treat all PKU patients with a safe oral approach Synthetic Biotic Medicines Meaningful data: two trials with interim results Current and emerging treatment options leave many patients behind PKU SYNB1618 strain achieved prespecified 20% plasma Phe lowering target in PKU patients SYNB1934 strain demonstrated two-fold greater activity than SYNB1618 in healthy volunteers Ph. 1 HV

6-day diet run in Individualized diet plan to match baseline Phe intake Stable study diet: diet run-in through 2 weeks post treatment Diet Control Endpoints Fasting Plasma Phe levels (day -1, 7, 14, 29) Labelled D5-Phe 24hr AUC, change from baseline after meal challenge (day -1, 15) Day 29 Fasting Phe 3 days Dose 1 1e11 Dose 3 1e12 Dose 4 2e12 7 days Diet run-in 6 days 2 days D5-Phe AUC Baseline Fasting Phe Dose 2 3e11 3 days D5-Phe AUC Day 14 Fasting Phe Day 7 Fasting Phe Population IA of 8 subjects receiving SYNB1618 Adult PKU patients, plasma Phe levels ≥ 600 µmol/L  Stable diet No use of Kuvan or Palynziq in SYNB1618 arm SYNB1618 Phase 2 SynPheny-1 study in PKU: Design Safety Follow Up

SYNB1618 metabolized Phe into TCA and prevented Phe absorption after meal challenge Percent change from baseline +/- 95% confidence interval. TCA = trans-cinnamic acid. AUC = Area under curve. 4 of 8 patients experienced >40% D5-Phe lowering after meal challenge TCA Production Phe absorption into plasma D5 Phe Meal Challenge (2e12 dose, N=8, Days -1 and 15)

SYNB1618 reduced fasting plasma Phe levels Fasting Plasma Phe Levels (N=8) Percent change from baseline +/- 95% confidence interval. * = Statistically significant Cessation of treatment 4 of 8 patients experienced >30% reduction in fasting Plasma Phe at Day 7 or Day 14

Mean +/- 90% confidence interval. TCA = trans-cinnamic acid HA = hippuric acid SYNB1934 demonstrated two-fold improvement over SYNB1618 in biomarkers of Phe metabolism SYNB1934 and SYNB1618 D5-TCA and D5-HA N = 12 SYNB1934 Developed from SYNB1618 using directed evolution Potential for increased Phe lowering and flexibility to optimize clinical profile Evaluated in a head-to-head study in healthy volunteers Moving into a new arm of the Phase 2 SynPheny study

Healthy volunteers PKU Patients SYNB1618 1e12 dose SYNB1934 1e12 dose 7% D5-Phe reduction post-meal 27% D5-Phe reduction post-meal 20% Fasting plasma Phe Expectation of improved clinical profile SYNB1934 to be evaluated in new arm of SynPheny-1 study

Enteric Hyperoxaluria (HOX) Enteric Hyperoxaluria results in significant, irreversible, and progressive kidney damage SYNB8802 proof of mechanism established: potential for best-in-class urinary oxalate lowering Proof of concept data expected 2022

Oral therapy An innovative approach in an area of high unmet medical need Our approach Consume Oxalate in the GI Tract Reduce Oxalate in the urine Differentiation from other approaches Ph 1B Proof of Concept in Enteric Hyperoxaluria patients (Roux-en-Y population) initiated Consumes oxalate in each GI compartment, throughout GI tract

SYNB8802 Demonstrates Dose-related Oxalate consumption * LS mean change over Placebo, +/- 90% CI, all days baseline and treated % Change Urinary Ox over Placebo % Change in Fecal Oxalate Consistent evidence of oxalate consumption across endpoints in dietary hyperoxaluria in healthy volunteers ASN Kidney Week 2021

SYNB8802 3e11 live cells dose advancing to Ph1B in patients LS mean change over Placebo, +/- 90% std error of mean, all days; and 24hr UOx after 5 days of dosing, +/- 90% std error of mean. 600mg daily oxalate. Change in UOx UOx Levels Clinically meaningful lowering of urinary oxalate demonstrated at a well tolerated dose Upper limit of normal

Balance Sheet (unaudited) 30 September 2021 31 December 2020 Cash, Cash Equivalents, and Marketable Securities $150.1 M $100.4 M Statement of Operations (unaudited) 30 September 2021 30 September 2020 R&D Expenses $13.4 M $10.5 M G&A Expenses $3.6 M $3.0 M Net Loss $16.0 M $13.2 M Net loss per share – basic and diluted* $0.29 $0.36 Weighted Average Shares Outstanding* 55.3 M 36.3 M Three Months Ended * weighted average shares used in computing net loss per shares - basic and diluted Third Quarter, 2021 Summary Results

© 2020 SYNLOGIC. QU©AR2TE1R9LYSYRNELSOUGLTICS.. AALLLL RRIIGGHHTTSS RREESSEERRVVEEDD.. || 1414 Concluding Remarks Dr. Aoife Brennan MD CHB President & CEO

Synlogic continues to deliver meaningful data Robust portfolio with significant milestones over the next 18 months PKU Enteric Hyperoxaluria SYNB8802 Ph1B proof of concept read-out H1 2022 2021 SYNB1934 Ph2 SynPheny proof of concept read-out SYNB1618 Delivered SYNB1934 Head to Head data in HV SYNB1934 Delivered Ph1A study in HV read-out SYNB8802 Delivered H2 2022 Start of pivotal program SYNB1618 or SYNB1934 Homocystinuria Ph1 initiation SYNB1353

Available For Questions Dave Hava, PhD Chief Scientific Officer Caroline Kurtz, PhD Chief Development Officer Daniel Rosan Head of Finance & Investor Relations Aoife Brennan, MB ChB President & CEO Antoine Awad Chief Operating Officer Gregg Beloff, JD MBA Interim CFO Molly Harper Chief Business Officer

XML

Document and Entity Information	Nov. 10, 2021
Cover [Abstract]
Security Exchange Name	NASDAQ
Amendment Flag	false
Entity Central Index Key	0001527599
Document Type	8-K
Document Period End Date	Nov. 10, 2021
Entity Registrant Name	SYNLOGIC, INC.
Entity Incorporation State Country Code	DE
Entity File Number	001-37566
Entity Tax Identification Number	26-1824804
Entity Address, Address Line One	301 Binney St.
Entity Address, Address Line Two	Suite 402
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02142
City Area Code	(617)
Local Phone Number	401-9975
Written Communications	false
Soliciting Material	false
Pre Commencement Tender Offer	false
Pre Commencement Issuer Tender Offer	false
Security 12b Title	Common Stock
Trading Symbol	SYBX
Entity Emerging Growth Company	false