Forward Looking Statements This communication contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. All statements contained in this communication that do not relate to matters of historical fact should be considered forward-looking statements, including statements about: the timing and results of our clinical studies and data readouts; current or future products or product candidates and their potential benefits; our clinical development plans; comm ...

Seres Therapeutics Investor Presentation May 2025 Disclaimers 2 Seres Therapeutics, Inc. © 2025 2 Transforming patient outcomes using proprietary consortia of live biotherapeutics Strong Foundation Forward Looking Statements This communication contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. All statements contained in this communication that do not relate to matters of historical fact should be considered forward-looking statements, including s ...

Financial Data and Key Metrics Changes - Seres reported a net loss from continuing operations of $15.7 million for Q4 2024, compared to a net loss of $34.7 million for the same period in 2023, indicating a significant improvement [49] - For the full year 2024, the net loss from continuing operations was $125.8 million, down from $190.1 million in 2023, primarily due to lower operating expenses of approximately $74 million [49] - Research and development (R&D) expenses for Q4 2024 were $12.8 million, down from $23 million in Q4 2023, reflecting a focus on the lead program SER-155 [51] - General and administrative (G&A) expenses for Q4 2024 were $12.5 million, compared to $14 million in Q4 2023, also showing cost management efforts [52] Business Line Data and Key Metrics Changes - The company has made substantial progress with SER-155, a biotherapeutic aimed at preventing bloodstream infections in allo-HSCT patients, showing a 77% relative risk reduction in bloodstream infection rates in a Phase 1b study [10][23] - Manufacturing services expenses were introduced as a new category in 2024, amounting to $3.5 million for Q4 2024, related to services under the transition agreement with Nestle [53] Market Data and Key Metrics Changes - The commercial opportunity in allo-HSCT alone is considered sizable, with approximately 9,300 procedures conducted annually in the US and around 20,000 in Europe [43] - Market research indicates a high unmet need for preventing bacterial bloodstream infections, with healthcare professionals and payers expressing a desire for better prophylactic options [40][41] Company Strategy and Development Direction - The company is focused on advancing SER-155 and exploring partnerships to maximize its potential, with plans to submit a draft study protocol to the FDA in Q2 2025 [21][56] - SER-155 is positioned to address not only allo-HSCT but also other medically vulnerable patient populations, including those with inflammatory bowel disease [35][61] Management's Comments on Operating Environment and Future Outlook - Management expressed optimism about the progress made with SER-155, highlighting the breakthrough therapy designation received from the FDA and the constructive feedback from the agency [58] - The company aims to operationally prepare for the next study of SER-155 while seeking additional guidance from the FDA [15][19] Other Important Information - The VOWST sale transaction closed in September 2024, providing Seres with $155 million, which has allowed the company to retire its debt and simplify operations [46][48] - The company expects to fund operations into Q1 2026 based on its current cash position and anticipated payments from the VOWST transaction [55] Q&A Session Summary Question: Feedback from the FDA regarding manufacturing and patient enrollment - Management indicated that the FDA's feedback was comprehensive and that they are confident in their manufacturing plans moving forward [67][75] Question: Recent FDA feedback relative to expectations and Phase 2/3 study differences - Management found the FDA's feedback constructive and noted that a Phase 2/3 study would require more pre-specification and discussions with the agency [80][83] Question: Safety database considerations based on VOWST experience - Management acknowledged the importance of the safety database and indicated that discussions with the FDA would evolve as more data is generated [88][92] Question: Potential size of the next study and additional efficacy endpoints - Management suggested that a standalone Phase 2 study could provide meaningful data quickly, with additional endpoints including febrile neutropenia and antibiotic use being considered [100][102]