UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ý QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2022 OR ☐ 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: 001-37798 Selecta Biosciences, Inc. (Exact name of registrant as specified in its charter) Delaware 26-1622110 (I.R.S. Employe ...

Company Overview - Selecta Biosciences' ImmTOR platform has broad applicability in biologics and gene therapy, with a diversified pipeline expanding to autoimmune diseases and targeted partnerships to maximize platform potential[6] - The company's precision immune tolerance platform aims to restore self-tolerance in autoimmune disease and overcome immunogenicity of gene therapies and biologics[6] - Selecta Biosciences has funding into mid-2024 to support development across pipeline programs[6, 144] ImmTOR Platform & Technology - ImmTOR combines nanoparticle technology with an FDA-approved anti-inflammatory and immunomodulatory drug to generate antigen-specific immune tolerance[9] - Preclinical data indicates a potentially profound synergy of ImmTOR and engineered Treg-selective IL-2 (ImmTOR-IL) to expand antigen-specific Tregs and improve durability of immune tolerance[6] - ImmTOR, by inhibiting the formation of neutralizing antibodies, could make redosing of gene therapies possible[58] Clinical Programs & Pipeline - SEL-212 in chronic refractory gout has dosed over 400 patients, with Phase 3 DISSOLVE I expected readout in Q4 2022[6] - SEL-302: IND for gene therapy program in methylmalonic acidemia (MMA) was submitted in Q3 2021, with Phase 1 start expected in 2H 2022[6, 88] - In a Phase 2 trial, 66% of patients treated with SEL-212 (pegadricase + ImmTOR) maintained control of serum uric acid (SUA), compared to only 15% treated with pegadricase alone[112, 115] - In a study with healthy volunteers, 100% of subjects dosed with 0.3 mg/kg ImmTOR had NAb titers ≤1:25 at Day 30[77]

Financial Data and Key Metrics Changes - As of December 31, 2021, the company had $129.4 million in liquidity, down from $140.1 million a year earlier [29] - Net cash used for the fiscal year 2021 was $60.4 million, compared to a net cash provided by operating activities of $34.9 million in 2020 [30] - Collaboration and license revenue for Q4 2021 was $29.9 million, and for the full year, it was $85.1 million, significantly up from $12 million and $16.6 million in 2020 [31] - The company reported a net income of $12.2 million for Q4 2021, compared to a net loss of $15.4 million in Q4 2020, while the full-year net loss was $25.7 million, down from $68.9 million in 2020 [37][38] Business Line Data and Key Metrics Changes - Research and development expenses for Q4 2021 were $20.3 million, up from $15.1 million in Q4 2020, and for the full year, they were $68.7 million compared to $54.5 million in 2020 [32] - General and administrative expenses for Q4 2021 were $5.5 million, compared to $4.8 million in Q4 2020, with full-year expenses at $20.9 million versus $18.9 million in 2020 [33] Market Data and Key Metrics Changes - The company is focusing on the gene therapy market, particularly with the upcoming Phase 1 trial of SEL-302 for Methylmalonic acidemia (MMA), expected to start in the second half of 2022 [7][22] - The collaboration with Takeda aims to combine ImmTOR with targeted gene therapies for lysosomal storage disorders, indicating a strategic move into rare disease markets [16] Company Strategy and Development Direction - The company aims to advance its precision immune tolerance platform, particularly through the development of ImmTOR-IL, which combines ImmTOR with a Treg-selective IL-2 molecule [9][41] - The focus for 2022 includes accelerating the development of ImmTOR-IL and continuing IND enabling studies for the primary biliary cholangitis program [14] - The company is also exploring partnerships to enhance its gene therapy capabilities, particularly in addressing immunogenicity issues [18] Management's Comments on Operating Environment and Future Outlook - Management expressed confidence in the broad applicability of the ImmTOR platform to restore self-tolerance in autoimmune diseases and mitigate immunogenicity in gene therapies and biologics [40] - The company anticipates multiple catalysts in 2022, including updates on gene therapy opportunities and the completion of the DISSOLVE Phase 3 trial for SEL-212 [42] Other Important Information - The company has taken proactive measures to address the impact of the geopolitical situation in Ukraine and Russia on its clinical trials, including temporarily closing sites in those regions [26][75] - The company is working closely with regulatory authorities to ensure the safety of patients and investigators amid the ongoing conflict [26] Q&A Session Summary Question: Can you discuss the CMC-related items for the hold and future studies? - Management indicated that the FDA had questions regarding the AAV capsid and additional analytics, which were addressed before starting the trial, providing a clearer regulatory path [47][48] Question: How will the FDA's draft guidance on immunogenicity impact physician behavior? - Management noted that their platform specifically addresses anti-drug antibodies (ADAs), which could foster more interest in their technology as it helps overcome challenges faced by many biologics [50] Question: What are the details of the SEL-302 study design for MMA? - The trial will involve administering MMA-101 with three doses of ImmTOR, with provisions for dose escalation based on antibody production [60][63] Question: How will the DISSOLVE II trial be affected by the conflict in Ukraine? - Management confirmed that DISSOLVE I has completed enrollment and is unaffected, while DISSOLVE II has faced disruptions, leading to the addition of U.S. sites to offset enrollment challenges [75] Question: Is there a plan for re-dosing in the SEL-302 trial? - The protocol does not currently include provisions for re-dosing within the first three months, but the FDA is open to discussions based on trial results [100]

ImmTOR Platform and Applications - The ImmTOR platform encapsulates rapamycin in biodegradable nanoparticles, designed to induce antigen-specific immune tolerance[18]. - ImmTOR has demonstrated the ability to inhibit the formation of neutralizing antibodies to adeno-associated virus (AAV) capsids, potentially enabling re-dosing of gene therapies[21]. - ImmTOR is manufactured under current good manufacturing practice (cGMP) requirements, enhancing the scalability of tolerance programs[26]. - ImmTOR has shown potential hepatoprotective effects in preclinical studies, which may allow for multiple lower doses of AAV vectors to mitigate toxicity risks[41]. - The ImmTOR platform is focused on genetic metabolic diseases, with potential applications in lysosomal storage diseases and genetic muscular diseases, and has been licensed to AskBio, Sarepta, and Takeda for specific targets[47]. - ImmTOR-IL has the potential to improve the efficacy and safety profile of biologic therapies beyond ImmTOR alone[21]. - Preclinical studies indicate that ImmTOR can induce antigen-specific T regulatory cells, potentially offering a novel approach to autoimmune disease treatment[91]. - The lead autoimmune disease indication is Primary Biliary Cholangitis (PBC), which has a significant unmet medical need and is targeted by the ImmTOR immune tolerance platform[94]. Clinical Trials and Results - The combination of ImmTOR and pegadricase is currently being evaluated in a Phase 3 clinical trial for chronic refractory gout[21]. - SEL-212, which combines ImmTOR with pegadricase, is in two pivotal Phase 3 studies (DISSOLVE I and DISSOLVE II), with top-line data expected in Q4 2022[58]. - In Phase 1b trials, increasing doses of ImmTOR showed a dose-related reduction in uricase ADAs and an increase in pegadricase half-life, leading to substantial reductions in serum uric acid levels[66]. - In the Phase 2 trial of SEL-212, 66% of patients (21 out of 32) achieved a reduction of SUA to less than 6.0 mg/dL after five monthly doses[67]. - The DISSOLVE clinical program consists of two trials, each expected to enroll up to 120 patients, with a primary endpoint of maintaining SUA levels below 6 mg/dL at six months[75]. - The SEL-399 clinical trial demonstrated that AAV8 empty capsids elicited peak median anti-AAV8 neutralizing antibody titers of 1:6875, with significant reductions to 1:25 and 1:5 in the 0.15 mg/kg and 0.3 mg/kg ImmTOR cohorts, respectively, representing a 50-fold and 250-fold difference compared to control subjects[43]. - At Day 30, 100% of subjects receiving 0.3 mg/kg ImmTOR exhibited NAb titers of 1:25 or less, while 67% of these subjects had titers of 1:5 or less[43]. - In the Phase 2 COMPARE trial, SEL-212 showed a 58% responder rate in patients with tophi at baseline compared to 39% for pegloticase[73]. Strategic Collaborations and Licensing - The company plans to pursue strategic collaborations and licensing transactions to develop proprietary compounds and expand its portfolio[22]. - The company is partnering with Ginkgo Bioworks to design novel enzymes and proteins that can be paired with ImmTOR for treating rare diseases[38]. - The collaboration with IGAN Biosciences includes an exclusive license to develop IgA proteases for IgA-mediated diseases[80]. - The company has entered into multiple strategic licensing agreements, including potential milestone payments of up to $1.124 billion with Takeda Pharmaceuticals for the ImmTOR technology[102]. - The collaboration with Ginkgo Bioworks includes milestone payments of up to $1.1 billion for the development of novel AAV capsids[97]. - The AskBio License Agreement includes upfront fees of $7 million and potential milestone payments of up to $237 million for products targeting Pompe Disease[108]. - The strategic licensing agreement with Genovis includes milestone payments and royalties based on worldwide sales in the low double digits[98]. Financial Overview and Funding - The company incurred net losses of $25.7 million for the year ended December 31, 2021, and $68.9 million and $55.4 million for the years ended December 31, 2020 and 2019, respectively, with an accumulated deficit of $430.3 million as of December 31, 2021[193]. - The company has no source of product revenue and does not expect to generate product revenue for the foreseeable future[193]. - The company expects to incur significant expenses and operating losses for the foreseeable future as it continues to develop its ImmTOR platform and product candidates[194]. - The company anticipates needing substantial additional funding to complete the development of its product candidates and commercialize its products if approved[193]. - The company expects to fund its current planned operations into Q3 2023 with existing cash and cash equivalents, but may need additional funding to continue operations and product development[198]. - Future capital requirements will depend on various factors, including the success of clinical trials and the ability to raise additional funds on favorable terms[199]. - The company has a term loan of up to $35 million, with $25 million funded as Term A Loan and $10 million as Term B Loan, which may restrict operational flexibility[201]. Regulatory Environment and Challenges - The company is subject to significant regulatory scrutiny, particularly regarding the approval of gene therapy products in the U.S. and EU[193]. - Regulatory approval processes for gene therapy candidates are expected to be lengthy and rigorous, potentially delaying commercialization[213]. - The company is facing challenges in the regulatory approval process for its product candidates, which may lead to delays or increased costs[215]. - Regulatory authorities have substantial discretion in the approval process, which may result in the rejection of marketing applications or requests for additional studies[216]. - Changes in regulatory guidelines could significantly impact the timeline and feasibility of bringing products to market[215]. - The FDA aims to review 90% of standard BLAs within 10 months and 90% of priority BLAs within 6 months from the filing date, although it does not always meet these goals[149]. - The FDA requires rigorous post-approval compliance with cGMP regulations, including quality control and reporting of adverse effects[157]. - The ongoing COVID-19 pandemic has impacted business operations and may continue to disrupt clinical trials and preclinical studies[210]. Employee and Operational Insights - The company has a voluntary turnover rate of 12.87% as of 2021, with 66% of its employees holding advanced degrees[185]. - The company pays 100% of an employee's deductible and co-insurance payments to assist with healthcare costs[187]. - The company has invested in employee well-being through competitive compensation and benefits, including equity compensation programs[187]. - The company relies on third parties for the manufacture of its product candidates and for conducting clinical trials, which may not perform satisfactorily[193]. - The company maintains close coordination with regulatory authorities, but this does not guarantee success in the approval process[216]. Market Competition and Risks - The company faces competition from larger pharmaceutical firms and smaller biopharmaceutical companies, which may have greater resources and market presence[129]. - SEL-212 may compete with existing therapies for gout, including pegloticase, which could impact its market potential[132]. - The company is at risk of incurring additional costs or experiencing delays due to potential adverse side effects or immune responses to its product candidates[217]. - Adverse developments in clinical trials of gene therapy products by other companies may influence regulatory bodies to revise approval requirements, negatively affecting the company's prospects[216].

Selecta Biosciences Corporate Presentation SELB January 2022 Safe harbor / disclaimer Any statements in this presentation about the future expectations, plans and prospects of Selecta Biosciences, Inc. ("the company"), including without limitation, statements regarding the progress of the clinical development of SEL-212, the anticipated timing of the head-to-head trial comparing SEL-212 and pegloticase and related data readouts, the potential of ImmTOR™ to reduce AAV vector immunogenicity and enable redosin ...

Selecta Biosciences, Inc. (SELB) Q3 2021 Earnings Conference Call November 9, 2021 8:30 AM ET Company Participants Kevin Tan - Chief Financial Officer Carsten Brunn - President and CEO Peter Traber - Chief Medical Officer Kei Kishimoto - Chief Scientific Officer Conference Call Participants Kristen Kluska - Cantor Fitzgerald Raju Prasad - William Blair Gil Blum - Needham & Company Shu Zhiqiang - BTIG Operator Good morning. And welcome to the Selecta Biosciences Third Quarter 2021 Financial Results and Corpo ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ý QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2021 OR ☐ 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: 001-37798 Selecta Biosciences, Inc. (Exact name of registrant as specified in its charter) Delaware 26-1622110 (I.R.S. Emp ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ý QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2021 OR ☐ 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: 001-37798 (Address of principal executive offices) (Zip Code) (617) 923-1400 (Registrant's telephone number, including area cod ...

Selecta Biosciences, Inc. (SELB) Q2 2021 Earnings Conference Call August 12, 2021 8:30 AM ET Company Participants Kristen Baldwin - Chief People Officer Carsten Brunn - President and CEO Takashi Kishimoto - Chief Scientific Officer Peter Traber - Chief Medical Officer Conference Call Participants Kristen Kluska - Cantor Fitzgerald Raju Prasad - William Blair John Newman - Canaccord Dan Clark - Mizuho Securities Yun Zhong - BTIG Gil Blum - Needham & Company Boobalan Pachaiyappan - H.C. Wainwright Operator Go ...

O ရှဲ Selecta… Biosciences Corporate Presentation May 2021 SELB Nasdaq Safe harbor / disclaimer Any statements in this presentation about the future expectations, plans and prospects of Selecta Biosciences, Inc. ("the company"), including without limitation, statements regarding the progress of the clinical development of SEL-212, the anticipated timing of the head-to-head trial comparing SEL-212 and pegloticase and related data readouts, the potential of ImmTOR™ to reduce AAV vector immunogenicity and enab ...