Table of Contents As filed with the Securities and Exchange Commission on September 28, 2023. Registration Statement No. 333-274421 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Amendment No. 2 FORM S-1 REGISTRATION STATEMENT Under THE SECURITIES ACT OF 1933 SYNLOGIC, INC. (Exact name of registrant as specified in its charter) Copies to: Lewis J. Geffen, Esq. Daniel A. Bagliebter, Esq. Nishant M. Dharia, Esq. Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C. One Financial Center ...

Table of Contents (State or other jurisdiction of incorporation or organization) (Primary Standard Industrial Classification Code Number) As filed with the Securities and Exchange Commission on September 26, 2023. Registration Statement No. 333-274421 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Amendment No. 1 FORM S-1 REGISTRATION STATEMENT Under THE SECURITIES ACT OF 1933 SYNLOGIC, INC. (Exact name of registrant as specified in its charter) Delaware 2834 26-1824804 (I.R.S. Empl ...

Table of Contents As filed with the Securities and Exchange Commission on September 8, 2023. Registration Statement No. 333- UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-1 REGISTRATION STATEMENT Under THE SECURITIES ACT OF 1933 SYNLOGIC, INC. (Exact name of registrant as specified in its charter) (State or other jurisdiction of incorporation or organization) Delaware 2834 26-1824804 (Primary Standard Industrial Classification Code Number) (I.R.S. Employer Identification Num ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2023 ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM TO Commission File Number 001-37566 SYNLOGIC, INC. (Exact name of Registrant as specified in its Charter) Delaware (State or other jurisdiction of incorporation o ...

© 2023 SYNLOGIC. CORPORATE PRESENTATION. ALL RIGHTS RESERVED. | 36 LS mean change over Placebo, +/- 90% CI, all days baseline and treated. 1. Proof-of-Concept Study of Oxalate-Consuming Synthetic Biotic Medicine SYNB8802 in Enteric Hyperoxaluria after Roux-en-Y Surgery, American Society of Nephrology Kidney Week, November 5, 2021 | --- | --- | --- | --- | --- | --- | --- | |-------|------------------------------|-------|-------|-----------|---------------------|-----------------------| | | | | | | | | | | U ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2023 ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM TO Commission File Number 001-37566 SYNLOGIC, INC. (Exact name of Registrant as specified in its Charter) Delaware (State or other jurisdiction of incorporation ...

Financial Performance - Synlogic reported net losses of approximately $66.1 million and $60.6 million for the years ended December 31, 2022 and 2021, respectively, with an accumulated deficit of approximately $357.0 million as of December 31, 2022[466]. - Revenue for the year ended December 31, 2022, was $1.2 million, a decrease of 33% from $1.8 million in 2021[496]. - Other income increased significantly to $1.3 million in 2022, up 524% from $0.2 million in 2021, primarily due to higher interest income from cash and investments[500]. - The company incurred a net cash outflow of $56.9 million from operating activities in 2022, primarily due to the net loss[505]. - The company anticipates continued substantial net losses as it develops product candidates and invests in technology[511]. - The existing cash and marketable securities are expected to provide a cash runway extending into the second half of fiscal 2024[513]. Research and Development - Total research and development expenses for the year ended December 31, 2022, amounted to $52.044 million, an increase from $47.127 million in 2021[475]. - Research and development expenses for specific product candidates included $4.380 million for SYNB1934 and $3.436 million for SYNB1618 in 2022[475]. - The company anticipates substantial research and development costs for the foreseeable future as programs progress through clinical trials[474]. - The company plans to expand its infrastructure and hire additional staff to support growth in research and development efforts[468]. - The company expects significant clinical trial expenditures with CROs and CMOs, which are generally cancellable without penalties[523]. Product Development and Pipeline - The lead drug candidate, SYNB1934, is anticipated to enter the pivotal Phase 3 study, Synpheny-3, in the first half of 2023[448][456]. - SYNB1934 demonstrated approximately two-fold higher activity in metabolizing phenylalanine compared to its predecessor SYNB1618, based on clinical study results[453][454]. - SYNB8802 achieved a dose-dependent reduction in urinary oxalate levels, with a -28% reduction at the 1x10^11 TID dose and a -38% reduction at the 3x10^11 TID dose compared to placebo[459]. - SYNB1353 received Fast Track, Orphan Drug, and Rare Pediatric Disease designations from the FDA for the treatment of homocystinuria, following positive Phase 1 study results[458]. - Synlogic's pipeline includes drug candidates targeting metabolic diseases such as phenylketonuria (PKU), homocystinuria (HCU), enteric hyperoxaluria, and gout[448][460]. Collaborations and Partnerships - The company is collaborating with Roche to discover a novel Synthetic Biotic for the treatment of inflammatory bowel disease (IBD)[462]. - Revenue for the year ended December 31, 2022, was generated from the Roche Collaboration and Option Agreement[471]. Operational and Administrative Expenses - General and administrative expenses are expected to increase as the company prepares for potential commercialization of its product candidates[477]. - General and administrative expenses rose to $16.6 million in 2022, an increase of 8% from $15.4 million in 2021, mainly driven by higher employee-related costs[499]. Risks and Uncertainties - The successful development of product candidates is highly uncertain and subject to various risks[473]. - The ongoing effects of the COVID-19 pandemic continue to pose uncertainties for the company's operating results and financial condition[469]. - The Company faces risks common to early-stage life science companies, including the ability to raise additional capital and regulatory approval processes[524]. Lease and Facility Costs - The total estimated project cost for access to the Azzur Suite during the Initial Term was $4.8 million[518]. - The Company agreed to pay Azzur $0.7 million for renovations and upgrades to the cleanroom space under the Third SOW[520]. - The total remaining liability associated with the Azzur lease was approximately $2.9 million as of December 31, 2022[521]. - The Fourth SOW extended the lease term through March 2023, resulting in an adjustment of $1.8 million to the operating lease right-of-use asset and liabilities[520]. - The Fifth SOW extended the lease term through December 2023 and included options to extend through June 2024 and December 2024[521]. - The Company is reasonably certain not to exercise the termination option through June 2024[522]. Inflation and Economic Impact - The impact of inflation on labor costs and operational expenses is being monitored, although it has not materially affected the business to date[470]. - The Company does not have off-balance sheet arrangements that expose it to financing, liquidity, market, or credit risk[525]. - The Company is classified as a smaller reporting company and is not required to provide certain market risk disclosures[527].

Exploratory Preclinical Phenylketonuria (PKU) RPDD FT ODD SYNB8802 SYNB2081 Inflammatory Bowel Disease (IBD) © 2023 SYNLOGIC. CORPORATE PRESENTATION. ALL RIGHTS RESERVED. | 7 Advanced Clinical Programs with Strong Commercial Potential 1. Assumes indicated for pediatric through adult 2. Assumes indicated for pediatric through adult 3. Assumes market of adults with highly recurrent stones due to enteric hyperoxaluria SYNB1934 for Phenylketonuria (PKU) PKU: Unique Opportunity for Value Creation * First generat ...

SYNB8802 Differentiation: Site of Action, Flexibility, Reversibility | --- | --- | |------------------|---------| | | | | Reversible | Current | | (non-colonizing) | Status | Pending POC data © 2023 SYNLOGIC. CORPORATE PRESENTATION. ALL RIGHTS RESERVED. | 43 LS mean change over Placebo, +/- 90% CI, all days baseline and treated. 1. Proof-of-Concept Study of Oxalate-Consuming Synthetic Biotic Medicine SYNB8802 in Enteric Hyperoxaluria after Roux-en-Y Surgery, American Society of Nephrology Kidney Week, Novem ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2022 ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM TO Commission File Number 001-37566 SYNLOGIC, INC. (Exact name of Registrant as specified in its Charter) Delaware (State or other jurisdiction of incorporat ...