Ladies and gentlemen, thank you for standing by, and welcome to the Fourth Quarter 2021 Seres Therapeutics, Inc. Earnings Conference Call. At this time, all participants are in a listen-only mode. After the speaker presentation, there will be a question-and-answer session. [Operator Instructions] It’s now my pleasure to introduce, Dr. Carlo Tanzi, of Investor Relations.

Thank you and good morning. Our press release with the company’s fourth quarter 2021 financial results and a business update became available at 7:00 AM Eastern Time this morning; it can be found on the new Investors and News sections of the company’s website. I would like to remind you that we will be making forward-looking statements related to the timing, enrollment, and results of our clinical studies. The anticipated safety profile of our products, the timing of potential regulatory approval for SER-109, the success of our agreement with Nestlé Health Science, the anticipated market for SER-109, and the promise and potential impact of any of our microbiome therapeutics. Actual results may differ materially. Additionally, these statements are subject to certain risks and uncertainties which are discussed under the Risk Factor section of our recent SEC filings. Any forward-looking statements made on today’s call represent our views as of today only. We may update these statements in the future but we disclaim any obligation to do so. On today’s call with prepared remarks, I am joined by Eric Shaff, President and Chief Executive Officer; Dr. Lisa von Moltke, Chief Medical Officer; Dr. Matthew Henn, Chief Scientific Officer; and David Arkowitz, Chief Financial Officer. During the Q&A portion of the call, we will also be joined by Dr. Terri Young, Chief Commercial and Strategy Officer; and Dr. David Ege, Chief Technology Officer. With that, I’ll pass the call to Eric.

Thank you, Carlo, and good morning, everyone. 2021 was a very productive year for Seres, where we have made meaningful advancements in our microbiome therapeutics pipeline. At the center of this progress was our lead SER-109 program and our momentum towards an expected BLA filing in the middle of this year. The significance of SER-109 and our successful pivotal clinical data in recurrent C. difficile infection was recently highlighted by the publication of the Phase 3 study in the New England Journal of Medicine. We believe that SER-109 has the potential to become the first ever FDA approved microbiome therapeutic, a landmark for this emerging class of medicines. Pending SER-109 FDA approval, we believe we have the opportunity to transform the treatments of recurrent C. diff infection. To remind you of our SER-109 efficacy results, our Phase 3 data demonstrated a significant reduction in the proportion of recurrent C. diff patients experiencing further recurrence demonstrating superiority versus antibiotics alone. Furthermore, the Phase 3 data surpassed statistical thresholds communicated to us by the FDA that could allow the single clinical study to fulfill efficacy requirements for BLA. The FDA had also communicated that our BLA filing should include a safety database of at least 300 subjects receiving the Phase 3 dose, and with a 24-week follow-up. Our SER-109 open-label study is fully enrolled, and we continue to gather the required safety data. Notably, the SER-109 open-label study also includes individuals with a first recurrence of C. diff infection, an expansion compared to the Phase 3 study population, which included only those with multiple recurrent CDI. The combination of first recurrent and multiply recurrent patients across our studies represents a broad segment of patients living with recurrent CDI. As we prepare for a SER-109 BLA filing, we are also conducting a SER-109 expanded access program. This program is designed to enable adults with recurrent C. diff infection, including those with the first recurrence to obtain access to SER-109 ahead of potential FDA product approval. We’ve continued to make excellent progress towards our planned rolling submission of the BLA, and we continue to plan to complete the full BLA submission, including the required 24 weeks of safety datasets in mid-2022. Given that SER-109 has obtained Breakthrough Therapy designation with the FDA, we anticipate receiving priority review. This results in an expedited timeline, including a 2-month BLA acceptance period, followed by a 6-month review period. The approval and launch of SER-109 would represent a landmark event for patients living with recurrent CDI and for Seres. In collaboration with our partners at Nestlé Health Science, we continue to prepare for a successful commercial launch. There are approximately 170,000 cases of recurrent CDI in the U.S. per year, and CDI results in over 20,000 deaths per year. Recurrent CDI patients do not have attractive treatment choices today. Some of these patients are currently being provided regimens and procedures that are not FDA approved, including stool microbiota transplantation and extended courses of antibiotics. The pending product approval, we believe that SER-109 could address this entire patient group suffering from recurrent CDI. Furthermore, we believe that SER-109 represents a substantial economic opportunity for Seres. The cost of a patient with recurrent CDI has been estimated to result in approximately $34,000 in annual direct healthcare expenses, and this does not include the substantial indirect costs associated with this disease. We believe that with a highly attractive SER-109 profile and the tremendous level of unmet need, this could translate into significant value for patients, payers, and for the company. Based on our discussions with healthcare practitioners, there was an eagerness for new, safe, effective, and FDA approved treatment options. We believe SER-109 could provide a transformational new therapeutic option for recurrent CDI and we are working with urgency to bring our therapeutic forward to the market as quickly as possible. During the fourth quarter, we announced the collaboration with Bacthera, a global leader in biopharmaceutical product manufacturing that increases our longer-term SER-109 product supply. This collaboration adds to our existing manufacturing capabilities. Bacthera is building a dedicated facility for commercial manufacturing in its new microbiome center of excellence, a manufacturing site dedicated to the production of live biotherapeutic products. We look forward to working with Bacthera to expand our current production capacity, which we expect to fully support the initial launch period. With this agreement, we anticipate meeting demand growth beyond the initial phase of launch, and under all anticipated commercial uptake scenarios. Beyond the direct benefit that SER-109 demonstrated in recurrent CDI in our Phase 3 study, we also believe that our data provides important proof-of-concept for the potential for microbiome therapeutics in infection protection more broadly. In January, we held an investor event that detailed the supporting data and our strategy to address this important opportunity. We believe that infection protection represents a tremendous strategic opportunity for Seres and we intend to advance additional therapeutic programs in 2022 and beyond. I’d like to now pass the call over to Lisa to discuss our clinical initiatives in more detail.

Thanks, Eric. Since obtaining the initial SER-109 top-line results in July of 2020, we have presented various datasets at a number of prominent conferences attended by infectious disease physicians and gastroenterologists. Well, we certainly in January, we were very pleased to have published the complete Phase 3 study results in the New England Journal of Medicine. The publication highlights study results that demonstrated SER-109 to be superior to placebo in reducing CDI recurrence, with 88% of SER-109 patients achieving a sustained clinical response compared to 60% on placebo. This was a highly statistically significant difference. In this study, SER-109 was also observed to be well tolerated, with a side effect profile comparable to placebo, and no serious drug-related adverse events observed. The New England Journal publication has had the benefit of increasing physician awareness and interest in SER-109. As a result of the publication, we have seen a marked increase in the number of inbound inquiries we’ve received about the program, and we believe that there is a high level of physician interest in incorporating SER-109, pending FDA approval, into their clinical practice. In addition to demonstrating the opportunity for microbiome therapeutics to impact recurrent CDI, we believe that our SER-109 data have also provided clear clinical and mechanistic evidence supporting microbiome therapeutics' potential impact on infection protection more broadly. The gastrointestinal tract is known to have an important role in preventing pathogen infection, including from life-threatening pathogens that can harbor antibiotic resistance. The increasing emergence of antibiotic-resistant bacteria has become a significant public health threat, and new non-antibiotic treatment approaches are desperately needed. Our SER-109 data demonstrates that microbiome therapeutics can result in significant restructuring of the gut microbiome and that these changes can lead to significant reductions in pathogenic bacteria, including those associated with antibiotic-resistant infection. We believe that there are numerous opportunities in addition to C. diff infection, where we can apply our microbiome therapeutic approach in infection protection. More specifically, we plan to apply our technology toward multiple medically compromised patient groups who are known to be at high risk of life-threatening bacterial infections. Beyond SER-109, our next most advanced program in infection protection is SER-155, which we are developing for individuals receiving allogeneic stem cell transplants. These patients are at very high risk for serious infections, as well as graft versus host disease. And we believe that SER-155 has the potential to address both issues. We have an ongoing Phase 1b trial to assess the safety, microbiome engraftment, and efficacy of SER-155, working with our partners at Memorial Sloan Kettering and the University of Chicago. The subjects in this study will be undergoing treatment for hematologic malignancies such as leukemia. Based on historical data, we expect that over 50% of the subjects will experience infection or graft versus host disease. If SER-155 is able to reduce the incidence of these conditions, we believe we would meaningfully improve health outcomes for these patients. The study is set up with 2 cohorts; the first cohort, including 10 subjects, is designed to assess safety and engraftment of SER-155. The second cohort includes 60 patients in a randomized double-blinded design to further evaluate safety and engraftment, as well as efficacy. This will be measured by assessing the rates of bloodstream infections and acute graft versus host disease. Ideally, we would see significantly reduced incidents of bloodstream infections and/or acute graft versus host disease associated with SER-155 administration. The study will help guide future clinical efforts and which outcomes we should target with future studies. Furthermore, positive results in preventing graft versus host disease would support not only pursuing this outcome in future trials, but exploring next steps forward in immune modulation. I’ll now pass the call to Matt to further discuss our broader plans in infection protection, as well as our efforts in ulcerative colitis. Matt?

Thank you, Lisa. As we highlighted in detail during our January 31st investor event, we believe that both our clinical and preclinical data provide strong evidence supporting the potential for microbiome therapeutics in infection protection. We see the potential to reduce the abundance of targeted pathogens to decrease the potential for pathogen transmission, strengthen epithelial barriers to further reduce the frequency of bloodstream infections, and to modulate immune responses to tackle medical complications such as graft versus host disease. Seres has developed an integrated platform that has enabled the discovery of novel therapeutic candidates designed to protect patients from infections. We are building on the success of SER-109 with SER-155; we’ve also initiated additional preclinical programs targeting infection protection. These include evaluating opportunities in patients receiving autologous hematopoietic stem cell transplant and designing consortia to deploy in settings such as cancer neutropenia and solid organ transplant, as well as combating the slow pandemic of antimicrobial-resistant infections more broadly. We are driving towards initiating additional clinical development programs in 2023 and progressing additional programs into the clinic over the next few years. Now, moving to our ulcerative colitis efforts. Ulcerative colitis is an area of strategic interest for Seres and we believe it is a disease that may be particularly well-suited for microbiome intervention. I’ll begin with a recap of our efforts targeting ulcerative colitis and some prior datasets. Last summer, we announced top-line results from our Phase 2 ECO-RESET study evaluating SER-287, a donor-derived investigational microbiome therapeutic candidate, in patients with mild-to-moderate ulcerative colitis. Our both dosing regimens of SER-287 were generally well tolerated. The study did not meet its primary endpoint of improving clinical remission rates compared to placebo. Late last year, we announced additional microbiome drug pharmacology data from the Phase 2 study that indicated that the engraftment of SER-287 bacteria was on average across patients statistically significant compared to placebo. However, we did not observe metabolomic changes that we had anticipated and that we believe are important for therapeutic impact. In addition to SER-287, we also continue to evaluate data from our Phase 1b study for SER-301, a next-generation rationally designed cultivated microbiome therapeutic candidate for the treatment of ulcerative colitis. The Phase 1b study is designed to include approximately 65 patients distributed across 2 cohorts. Preliminary SER-301 data has been analyzed from the first cohort, which included 15 subjects. Evaluation of the first cohort data by an independent Data Safety Monitoring Board indicated that it would be safe to proceed to the placebo-controlled second cohort. While clinical efficacy was not a defined endpoint in the first cohort, evaluation and outcome data indicated that no subjects achieved clinical remission using the FDA Three-Component definition, though there were improvements in one or more individual components of the disease score, including endoscopic, stool frequency, and rectal bleeding sub-scores. Furthermore, SER-301 bacteria were observed to engraft in subjects across the trial period, and notably, we observed changes in the metabolic landscape in the gastrointestinal tract. Interestingly, the degree of metabolic changes observed following SER-301 administration appeared to be dependent on the baseline metabolic profile of the study subjects. This is an area of particular interest that we continue to explore. Ulcerative colitis is known to be a remarkably clinically and biologically heterogeneous disease, and this has hindered the development of various drug efforts for decades. Based on our available SER-301 and SER-287 data, we believe that certain ulcerative colitis patients may be more receptive to microbiome therapeutics based on definable baseline characteristics. Our research in this area remains ongoing, and we continue to conduct analyses to inform next steps for further development in ulcerative colitis. With that, I’ll now turn the call to David to provide an overview of our financials.

Thanks, Matt. The details of our full year and quarterly financials are included in this morning’s press release, so I won’t reiterate all the figures here. Seres ended the fourth quarter of 2021 with approximately $291 million in cash, cash equivalents, and marketable securities. We are pleased to announce today that we have amended our debt financing agreement with Hercules Capital, providing the company with a debt facility of up to $100 million. This debt financing is a term loan, of which we drew down $50 million upon closing last week. This amendment replaces our prior $50 million debt facility with Hercules, and approximately $22 million of the proceeds we received last week under the amended agreement will pay off the remaining amount owed. With respect to our operating expenses and efforts over the near term, we continue to be focused on a number of critical SER-109 related activities, which include preparing and filing the BLA submission, continuing to ramp up manufacturing operations for commercial supply, including increasing longer-term SER-109 product supply to our Bacthera collaboration and in conjunction with Nestlé, continuing and accelerating launch readiness activities. In addition, we continue to invest to advance and expand our pipeline with a focus on infection protection opportunities, and further build upon and enhance our platforms and capabilities. As a result of these high priority and value-generating activities, we expect our expenses to increase in the coming quarters, but at a moderating rate of growth, as we have already expanded our capabilities across much of the organization. In summary, we believe the company is well-resourced to prepare for SER-109 commercialization, drive our ongoing development and preclinical programs, while also deploying resources to continue to advance our research platforms, where we believe we have differentiated, proprietary, and sustainable advantages. I’ll now pass the call back to Eric.

Thanks, David. I will conclude our remarks by recapping key 2021 progress milestones as well as upcoming anticipated value drivers for the year ahead. These include achieving target enrollment in our SER-109 open-label study and our preparation for our BLA filing in the middle of 2022; continued progress executing on SER-109 pre-commercial readiness, working closely with Nestlé Health Science, Aimmune, including expanded market education efforts; the initiation and ongoing execution of our SER-109 expanded access program; the expansion of our longer-term commercial supply capabilities, including our collaboration with Bacthera; continued data analysis to inform future development in ulcerative colitis; SER-155 study initiation and ongoing execution and expansion of our efforts targeting infection protection, an area of incredible opportunity to serve patients, which directly builds upon the success of SER-109. We also continue to strengthen our microbiome research platform and preclinical efforts. In 2022, we expect to advance new microbiome therapeutic candidates towards clinical developments, particularly in infection protection, where we believe we have clear clinical and mechanistic data supporting our approach. Seres is well positioned to lead the microbiome therapeutic field, and we intend to continue to execute on our mission, working hard to improve the lives of patients. With that now, operator, we’ll open the call up to questions.

[Operator Instructions] Our first question comes from the line of Mark Breidenbach with Oppenheimer.

Hi, good morning. This is Jacquelyn on for Mark, and thanks for taking our questions. My first question is how is the baseline metabolic profile being defined in the SER-301 study acceptor? How many individual biomarkers are used in this characterization? Thank you.

Good morning, and thanks for the question. Matt, do you want to take that one?

Sure. We’ve been looking at a whole suite of disease-relevant metabolic biomarkers in our ulcerative colitis patients that we had predefined to be important. And in addition to that, we have been looking at and discovering novel biomarkers that we believe are important in relevance for disease based on the datasets that we’ve generated. We haven’t disclosed the specifics of the number of biomarkers yet, but what I can tell you is that we have identified a few biomarkers that are consistent, and that we believe could be used potentially for patient stratification.

Okay, that’s good to know. Thanks. And also, do you plan to modify or compensate SER-301 based on observations from the first 15 patients?

Yeah, so all of our data to date supports that the pharmacological properties of SER-301 are consistent with their design, and that the drug is exhibiting pharmacological properties as it was designed to do. So at this time, we do not anticipate any changes to the consortium.

Okay. So my next question is regarding SER-287. So based on the biomarker profiling, what fraction of mild-to-moderate UC patients, do you think could be good candidates for SER-287 and SER-301? And also, is there any difference in the biomarker-defined populations you’re considering for continued development of both molecules?

Matt, do you want to start with that one? And I’ll close with some comments on that.

Sure, yeah. So we do think that the patient subpopulations that we’ve identified still represent a significant portion of patients with ulcerative colitis. So those that we have identified to be most receptive are somewhere on the order of about 30% to 40% of the patients in the population. We haven’t provided any details further than that at this time.

Yeah, I might just add a larger comment. We are learning, iterating, and I think it’s worth noting that we have a significant amount of data here with the SER-287 study results, both clinical and microbiome. Now the first 15 subjects of the SER-301 study, we will continue to learn and adjust from the study results, and we’ll follow the data. It’s worth noting, if you think back to the SER-109 experience after the Phase 2 study results, we had a lot of confidence in the underlying thesis and a lot of data to support it. But we didn’t just say, look, let’s run another study and hope that it ends up clinically where we’d like it to. We made a number of adjustments based on data; those adjustments led us to a very positive outcome. That certainly is the process that we have intended to take with our efforts in IBD and UC, and that’s what we’re doing now.

Great, thanks. That’s really helpful. That’s it for me. Thanks again for taking our questions.

Thanks for the questions.

Thank you. And our next question comes from the line of Ted Tenthoff with Piper Sandler.

Great. Thank you, guys. So really exciting point for the company. I’m just trying to get a better sense as you prep for the BLA, obviously, a very strong dataset here. And will you be reporting or presenting the safety data? Or will that be something that simply goes into the BLA? And then also, if I may, with respect to the relationship with Nestlé, how are you guys working to kind of prep for launch together? Thanks so much.

Yeah, Ted, good morning, and thanks for the questions. Maybe I’ll ask Lisa to start with the second. And I’ll ask Terri to hit the – I’m sorry, Lisa, to start with the first one, and Terri to start with the second one. On the first, maybe I’ll just start by commenting that we are still in the process of following these patients out. But maybe, Lisa, you can comment further on the open-label study and how we’ll track it.

Yeah, so we haven’t said yet how we’ll make those data public and how to communicate. But I will say that we are eyeing our possibilities in terms of conferences and other ways to disclose as soon as we have that dataset finalized.

And then, Terri, can you just comment on our work with Nestlé Health Science and some of the pre-commercial work that we have conducted together?

Sure thing. Well, I guess, I’d start by highlighting that we ramped these efforts upon receipt of the data, right, at the Phase 3 data, remarkable data that we had, and then yet again with Nestlé after signing the co-commercialization agreement last year. So we’ve now integrated the team at Nestlé into our efforts. And we’ve worked together to scale both our market education, but also our data dissemination efforts. These are primarily being led in the medical affairs to Lisa’s team, and I’ll ask her to – I’ll hand it back to her in a minute to comment on that, but also in our market access team. For example, we’re developing a robust payer value proposition that is supported by the really strong category-leading profile with SER-109, but also the high cost of treating recurrences that Eric highlighted in his remarks today. This is treating recurrence after recurrence in these patients, and the options today are quite limited. Nestlé has an existing payer field team to engage this important audience. We’ll be doing that pre-launch in accordance with existing FDA guidance on pre-approval information exchange. So that’s a pretty big book of work on the payer front and value proposition front. We also continue to work with them to deepen our understanding of the market opportunity and we’re progressing items like brand positioning efforts, HCP, payer and patient segmentation, and branded campaign development. And finally, last year, we launched a broad disease education campaign at ID, and we’ll be amplifying that campaign as we move throughout 2022. Finally, we’re continuing to hire industry-leading commercial talent into both of our organizations. Now, I’d like to ask Lisa specifically to comment on the medical affairs activities in front particularly in light of the recent publication of the pivotal data in the New England Journal of Medicine.

Yes, thanks, Terri. Yeah, so the med affairs efforts really are spanning a number of areas that you’d expect, including publications. The New England Journal was incredibly impactful with regard to the reception in the physician community, and we’ve already heard of infectious disease physicians bringing this up on rounds, and in their discussions with their colleagues. But the Nestlé group and the Aimmune group are fully integrated as we move through planning further publications, mobilizing the MSLs, they’re out there on the ground, talking to physicians. There are lots of education activities that are going to be culminating and seeing new programs, and we’re also working with the patient advocacy groups. And we’re very pleased with how the Nestlé Aimmune team is blending in and being part of that effort.

Very, very helpful, very thorough and I appreciate it, everybody.

Thanks for the questions, Ted.

Thank you. And our next question comes from the line of Peyton Bohnsack with Cowen.

Hey, good morning, guys. And thanks for taking our questions. I’m on for Joe. So just a real quick question about the expanded access program in the U.S. I was wondering how many patients have been treated through this program? How has the demand been? And whether you can share any details about whether this has been mostly first recurrence or multiple recurrence patients? Thank you.

Yeah, Peyton, I would say we’re just getting started with the expanded access. We just at the end of the year included the open-label 300 patients, but we had been targeting. But, Lisa, can you cover that?

Yeah, we haven’t really given specifics, but I can tell you that it’s up and running. We have patients enrolled. We have numerous sites across the country; we’ve tried to strategically place them so that patients can access the site, regardless of where they are. We look forward to giving you more information in the future. But we haven’t really been specific on numbers yet.

Thank you. That’s really helpful. And then maybe a real quick question the SER-155 program. I know that when this was talked about previously, it said that the cohorts could begin enrolling before cohort 1 finishes. Is there a certain level of efficacy that would be required to begin enrolling cohort 2, and then also – are there any plans to expand the number of sites with this trial to be conducted? Or is it just going to be at the Chicago and MSK sites? Thanks.

Lisa, maybe you can comment on both. I think one is the protocol structure and progression. And the other is maybe the last in terms of sites.

Yes. We’re at 2 sites right now, and we were intending to increase those. So I think what you’re referring to with the first part of your question is that there is a pretty long safety follow-up over the course of a year. We don’t need to wait for that entire year to start the second cohort. The first has to finish the first set of patients through an initial safety assessment. And at that point, we’re free to go into the second cohort without waiting that entire year of safety follow-up. I think that’s what you’re probably referring to.

That’s exactly. All right. Thank you so much.

Sure.

Thanks for the questions.

Thank you. And our next question comes from the line of Chris Shibutani with Goldman Sachs.

Hi, this is Steven on for Chris. Thank you for taking our question. I had one on the 301 program. Do you expect that your label would include language on how many recurrences a patient must have prior to going on 301? And then just if you could comment on the difference you’re seeing with these patients with first recurrence versus kind of the Phase 3 trial population? Thank you.

Steven, I want to make sure that we’ve got the numbers or programs right; with the question was 301 around recurrences. Do you mean 109?

Oh, yeah. Sorry about that.

Okay, no problem. Yeah. So look, I think what we said before is that the label, of course, will be part of the negotiation that will happen with the FDA as part of the BLA process. We don’t want to get ahead of that. At the same time, we absolutely think that medically, and Lisa can certainly speak to our view of why we think that recurrent C. difficile patients is an appropriate population for that; and maybe, Lisa, let me hand it to you on that.

Yeah, I think both from a pathophysiology basis as well as how our interactions with physicians are indicating they think about recurrent disease, it pretty much falls into primary disease, primary recurrent, and everything else. From a pathophysiology standpoint, that first recurrence is the marker and happens because the microbiome is unable to suppress the germination of those spores. That’s the point at which it makes sense to start restructuring. And physicians in practice also tend to see a C. diff infection as either my first bout or everything else. So for those reasons, we really see this as an appropriate therapy for all recurrent patients. But as Eric said, the label will reflect the negotiations with the agency.

And maybe just the follow, I think you had asked about the percentage of first recurrence that we’ve seen in the open-label, and we haven’t disclosed that data. But as Lisa mentioned, we kind of have our eyes on opportunities to disclose those data once we’re past the follow-up period.

Got it. Thank you for taking our questions.

Sure. Thanks for the question.

Thank you. And our next question comes from the line of John Newman with Canaccord.

Hi, there, team. Good morning, and thanks for taking my question. So the question about the SER-301 data. I noticed in your press release, as well as in your prepared remarks, you mentioned that SER-301 did modulate short-chain and medium-chain fatty acids, which interestingly is many patients actually will take those types of products sort of off label. But just curious if those types of changes were relatively consistent across the patients in that first cohort. You did mention that based on metabolic state affected the changes in the characteristics of 301. But just curious, specifically on the short to medium chain fatty acids, if that was somewhat consistent across the patients that you looked at? Thanks.

Yeah. John, good morning, and thank you for the question. I’m going to hand it to Matt. But I’ll do so just with the first qualification that you have to remember we’re talking about 15 subjects, right? So it’s a pretty limited data set. And that said, it’s interesting, and we think we’re going to learn quite a bit from it. We are in the process of analyzing some of the datasets that come from it. But maybe I’m going to hand it to Matt.

So a couple of – good morning, John. A couple of points. So first, as I started with ulcerative colitis was 15 subjects in 301. So we need to be cautious in terms of the extrapolation of those results. But I think it’s clear that SER-301 certainly demonstrates the pharmacological properties that it was designed to exhibit. And certainly, short-chain fatty acids and medium-chain fatty acids are one particular metabolite that SER-301 is designed and optimized to produce; there are multiple others as well. And these UC patients are certainly a heterogeneous patient population, and we can see variations in the short-chain and medium-chain fatty acids amongst patients at baseline. I will tell you that that is not the biomarker that we are focused on with respect to our patients, and in the population that we’ve identified. But that is certainly an important functional parameter that we continue to assess and evaluate, and know that modulating that can be one important mechanism in the context of reducing inflammation in the gastrointestinal tract. There are multiple others as well that we are focused on. The second part of your question is – and just a comment on – another part of your question, which is a comment that you made that folks taking these compounds off label; what’s important is that, I think what’s important about our drugs is that it’s the bacteria that are producing these and while you have not seen success with patients previously taking things like bile acids or short-chain fatty acids or other metabolites, to vitamins, etc., because of course, these things need to get to the site of activity and where they need to be. I think that’s one of the clear benefits of our technology is that we’re using the bacteria as drugs, and the bacteria naturally have evolved to be at the site where it’s most relevant to have those effects.

Okay, great. Thank you.

Thanks for the question, John.

And our next question comes from the line of Gobind Singh with JMP Securities.

Hey, thanks for taking my questions and congrats on the progress. I could dig a little bit more into the SER-301. Is it possible and would it be accurate to say that the positive metabolic changes, I think, the 301 were meaningful compared to the changes that we’re seeing with 287 or the lack thereof? And since we’re talking about the metabolic profile, just wanted to confirm that the engraftment profile with 301 was presumably robust, and I don’t know if there’s any way to talk about the quantitative difference if there was any compared to 287, and how that could maybe tend towards dependent metabolic changes that you guys are now seeing? This would be a positive indicator. And if there’s any feedback or comments that you could share around our metabolic profile and for the baseline or otherwise, and optimizing that could contend towards clinical remission, maybe on a general level or just from data out there, I know there’s only 15 patients here. That would be great. Thank you.

Yeah, Gobind, good morning, and thank you for the questions. There’s a lot there in your questions regarding some of the depths of our microbiome analysis. And I’m going to pass it to Matt, but I’ll do so with just the caution that we are – we continue to be in the process of analyzing this data. We are striving to put ourselves in the best position to help patients and, of course, return for shareholders based on our efforts in ulcerative colitis. We are iterating and we’re learning and there’s a number of datasets that we think put ourselves in the position to have more visibility perhaps than others as it relates to maximizing our chance of success in ulcerative colitis. But there’s a lot for us to do and maybe Matt can take it from there.

Yeah, Gobind, I think I heard 2 questions in your comments. So one was a question about the engraftment of SER-301 bacteria in patients post-treatment, and the second was the magnitude of metabolic changes in the SER-301 cohort 1 population versus the SER-287 population. So with respect to engraftment, yes, we did see both rapid and durable engraftment of SER-301 bacteria into patients post-treatment. You may recall that one reason we had this first cohort was that we were testing a novel formulation of the drug where we had bacteria in the drug formulated both in the form of spores, as well as in the form of vegetative bacteria. We wanted to evaluate that formulation in the cohort 1 study, and I can tell you that we saw both the engraftment of spore-formulated bacteria as well as vegetatively formulated bacteria, which I think is important because it speaks to the strength and breadth of our manufacturing capabilities. Engraftment, as we have consistently observed across our studies, can have variability from patient to patient; but we certainly consistently get bacteria on board. And importantly, what we have – shifting to the second question you had about the magnitude of metabolic changes, we certainly were able to observe trends and significant differences in multiple predefined metabolites that we think are important and relevant for the treatment of ulcerative colitis, and for which SER-301 is designed to do. In terms of the magnitude of that, as we noted in the Phase 2 study of SER-287, we did not observe these predefined metabolic changes that we had anticipated to, and that was a surprise; whereas in the context of SER-301, we did, and a good number of those were also significantly changed at multiple different time points in the course of the study. So we saw more meaningful changes in the context of SER-301.

Yeah, so Gobind, maybe I’ll just close by saying, we will continue to think about as you often do with a Phase 1 study, optimizing dose, continuing to analyze the biomarker data that we think is intriguing, and especially given the heterogeneous disease like ulcerative colitis, thinking about patient segmentation where we can have an impact on the right patient group. So those are the pieces that we are currently continuing to iterate on.

I appreciate you guys making advancements.

Thanks for the question.

Thank you. And our next question comes from the line of Vernon Bernardino with H.C. Wainwright.

Hi, everyone. Thanks for taking my questions and congrats on the progress looking forward to the BLA mid-year. So with SER-109, the results show the highest clinical response rate about 88% yet in a survey you conducted, there’s still a significant percentage of prescribers who might not prescribe SER-109. What is the driver of their hesitancy? And what kind of efforts do you think during commercialization? Do you think you could implement to perhaps target that significant patient population that may not receive SER-109?

Very good morning, and thanks for the question. I’m going to ask Terri to comment. But I would say the conclusion based on the question is that we have a very different point of view from what we found based on the analysis that we did; in fact, we felt extremely favorable in terms of what we heard back from our primary research. But Terri, maybe you can take that one forward.

Yeah, thanks, Eric. I mean, it’s a great question. And I would refer you to a slide that is in our current corporate deck that illustrates feedback that we’ve obtained recently from both HCP and payers. What you’ll see is if you’d look at the HCP response, it’s actually quite remarkable in the positive direction. We have what I would call a sea of green, and this is likelihood to prescribe data, right? So the vast majority of physicians are saying that they are probably or definitely will use SER-109 within their patient population, and for something that’s transformative and such a new approach to care like SER-109, that’s actually quite unusual. I imagine your question is more in the smaller gray percentage that are sort of labeled…

Exactly.

Yeah, as a might or might not. This is actually very typical again in a new category. You get what I call the fence-sitter. They want to, for example, hear from their specialist down the street, they want to wait for FDA approval, they want to understand the data in a little bit more depth. So these fence-sitters don’t tend to sit for very long. But that’s typically the dynamic that you’re dealing with. So how do you deal with it? Then it’s through the approaches we’re taking today around market education from the medical affairs standpoint. And, of course, with that approval, we can deploy our broader field force as well, publications, conferences, and of course, the BLA approval.

I’m sorry, I implied – I do realize there’s a C agreement. I’m sorry, I implied then there’s greater hesitancy. Seems like that would be a low bar. I’m sorry, Eric, go ahead.

No, no, I was going to say, I appreciate the clarification. And I would just say, we feel we’re starting commercially from a very good spot based on the data. It really comes down to the data more than anything else. And we couldn’t be more pleased with the dataset that we have. We think it resonated, as we’ve talked about in the past, in the momentum that we saw as the open-label study was conducted, even amidst the pandemic. We saw with the acceptance of the manuscript into the New England Journal of Medicine. Lisa has commented earlier and can maybe comment again just in terms of the med affairs side, which we think is really important work that we have to do with our partners and ensuring that people know about this technology and they know about this profile. And maybe Lisa, you can comment.

Yeah. No, I think I can’t overstate really the impact from the New England Journal paper in really solidifying the position of the data for so many of the physicians. I think not only within folks who have been watching and wanted to see the whole dataset, but I think I can also say that we’ve heard from people who were still somewhat skeptical and still hanging on to FMT or other potential alternatives, who’ve now contacted us and said now that I’ve seen that dataset in a peer-reviewed journal and I’ve seen the data for myself, I really am just blown away, and I can’t wait to be able to use it. So I think we’re well positioned to be able to do the education that we need to do.

I guess, you are in. And thanks for taking my question, and it looks like the publication of the New England Journal of Medicine is going to help with the fence-sitters. Thank you and congrats on the progress.

Thanks for the question, Vernon.

Thank you. I’m showing no further questions. So with that, I’ll turn the call back over to management for any further remarks.

So thank you and I want to thank everyone for joining our call today for your continued interest in Seres. We look forward to keeping you updated on our progress and with that, will conclude, I hope everyone has a great day. Thanks very much.

Ladies and gentlemen, this concludes today’s conference call. Thank you for participating and you may now disconnect.