Roger Pomerantz
Analyst · Goldman Sachs
Thanks, Carlo, and thank you all for joining us. Seres is focused on developing new therapeutics for serious human diseases, where dysbiosis of the gastrointestinal microbiome is thought to play a central role. We are using live bacterial consortia, an entirely new treatment modality as the therapeutic development candidates. We believe that microbiome therapeutics have the potential to address multiple disease states and our R&D efforts target therapeutic areas where compelling preclinical and clinical data indicate that the microbiome is important, such as, infectious diseases, metabolic diseases and inflammatory and immune diseases, including immuno-oncology. Seres has made continued strong progress on a number of our clinical and preclinical stage programs. 1; we continue to enroll patients with objectively defined multiply recurrent C. diff infection into our Phase III trial across North America. 2; we have made progress in advancing our SER-287 program for ulcerative colitis into further late-stage clinical development. 3; we obtained important learnings from our SER-262 Phase 1b study results, the first ever rationally designed, synthetically fermented microbiome therapeutic to reach clinical development. The mechanistic insights obtained from this program will inform how we advance SER-262 as well as future synthetic microbiome therapeutic candidates. And number 4; we also continue to make significant progress in our preclinical stage programs, including our SER-401 program designed to increase the efficacy of immune oncology checkpoint inhibitors. So let's begin with SER-109. To remind you, SER-109 has received both Breakthrough and Orphan Drug designations from the FDA for the treatment of multiply recurrent C. diff infection. Last year, we began ECOSPOR III, our SER-109 Phase III study based on the extensive learnings we obtained from our prior SER-109 trials. ECOSPOR III is randomized placebo-controlled study in 320 patients with multiply recurrent C. diff infection. The design of ECOSPOR III incorporates our key learnings from our prior development efforts. We've increased the dose of SER-109 approximately 10-fold as compared to the Phase II. In addition, we have incorporated the more accurate C. diff toxin test as opposed to a PCR-based assay for both patient selection and in-study endpoint determination to reduce false positives. We now have over 100 ECOSPOR III clinical sites open across the U.S. and Canada. We continue to make progress in enrolling ECOSPOR III a top priority for the company. Based on FDA feedback that we've received, we believe that with compelling results, ECOSPOR III may serve as a single pivotal study supporting SER-109 approval as the first ever microbiome therapeutic. Now moving to SER-287. SER-287 is an orally administered, biologically sourced drug candidate comprised of commensal bacterial species that reside in the healthy human gastrointestinal track. Multiple randomized placebo-controlled clinical studies with fecal transplants support our conviction that the microbiome will be an important therapeutic modality in ulcerative colitis. These studies provided compelling proof-of-concept data supporting our microbiome approach in this indication, demonstrating that modulation of the microbiome of ulcerative colitis patients via repetitive fecal microbiota transplants, results in improved clinical outcomes, including endoscopic improvement. Our objective with SER-287 is to replace proinflammatory bacterial species that are often elevated in patients with ulcerative colitis with commensal bacterial species found in healthy individuals. We thus seek to alter the immunological tone in the gut, decreasing inflammation and inflammatory signals from the microbiota. We have previously reported encouraging results from our SER-287 Phase 1b study in patients with ulcerative colitis. Our SER-287 Phase 1b study was a randomized double-blinded placebo-controlled multiple regimen trial in 58 patients with active mild to moderate ulcerative colitis who were failing their currently prescribed therapies. Study subjects were assigned to 1 of 3 SER-287 treatment arms or a placebo arm. The SER-287 arms in this induction study included a daily dosing arm with vancomycin pretreatment, a weekly dosing arm with vancomycin pretreatment and a weekly dosing arm without vancomycin pretreatment. The short course of 6 days of oral vancomycin was included in the study to open an ecological niche in patients existing microbiomes to enable more robust engraftment of SER-287 bacterial species. To remind you of the efficacy that we reported, in a prespecified missing data counted as failure analysis, 40% or 6 out of 15 patients reached clinical remission as compared to 0%, 0 of 11 patients in the placebo group. This result was statistically significant with a p-value of 0.024. Study results demonstrated a dose dependent response in remission, endoscopic improvement, histopathological measures and microbiome engraftment. We observed the most meaningful impact in patients administered vancomycin pretreatment followed by daily treatment with SER-287, supporting the concept that vancomycin pretreatment conditions the gastrointestinal tract for optimal SER-287 microbiome engraftment. The data also revealed a signature of engrafting bacterial species that were correlated with clinical remission. Notably, we also previously reported preliminary data from our SER-262 Phase 1b study where we demonstrated that pretreatment with vancomycin followed by SER-262 resulted in statistically, significantly more robust and kinetically more rapid engraftment of SER-262 bacterial species as compared to patients treated only with metronidazole. Thus, data from both the SER-287 and SER-262 studies have provided Seres with vital proprietary human clinical data that inform us of the optimal conditions for microbiome engraftment in differing human disease states. Now the SER-287 safety and tolerability profile observed in the Phase 1b study was very favorable. Phase 1b results demonstrated no imbalance in adverse events in SER-287 treated subjects and there were no drug related serious adverse events. The favorable SER-287 safety profile observed was consistent with our expectations based on the use of naturally occurring commensal bacteria comprising our therapeutic candidates. We believe that the favorable safety profile of our drug candidates is an important benefit of our approach and we believe this safety advantage should enable accelerated future development. We have also previously described the robust and durable SER-287 engraftment observed in treated patients. We recently obtained additional microbiome and metabolomic data that we believe provide further mechanistic support for SER-287 efficacy. Some of these data are quite detailed and we look forward to discussing the data in depth at our upcoming R&D event that we will be holding on May 24th in New York City. Overall, we believe that the consistency of the SER-287 clinical efficacy and engraftment data that support a pharmacodynamic data and the favorable safety profile, strongly support continued clinical development. We have continued to make progress towards advancing SER-287 toward the initiation of the next clinical study. Positive dialogue has been ongoing with the FDA where we have reviewed the Phase 1b study results and initial plans for further SER-287 development. Our dialogue with the FDA has been constructive and we recently obtained feedback regarding specific elements of our next planned clinical study. While the specifics of this study are now being finalized, we are still planning to conduct a larger SER-287 induction study in patients with mild to moderate active ulcerative colitis. We intend to initiate this next clinical study in the middle of this year. We will discuss this upcoming trial in more detail at our upcoming R&D Day. Now, moving to our preclinical stage microbiome therapeutic efforts, we are highly focused on advancing our SER-401 immuno-oncology program into clinical development. Our immuno-oncology microbiome program is designed to modify the cancer-immune set point and hopefully meaningfully improve patients' response to checkpoint inhibitor therapy. The scientific basis for this program is supported by multiple high profile recent studies that demonstrate that the composition of bacteria in the gastrointestinal microbiome have important impact on the immunological response to checkpoint inhibitor therapy. The colon is the body's largest immune reservoir, and our own recent important animal data showed that T-cells traffic through the colon and are educated by the microbiome to enhance the response to checkpoint inhibitors. Our preclinical research is focused on understanding how certain bacterial species impact to response to checkpoint inhibitor therapy. Last month, we presented some of our foundational preclinical results in the American Association for Cancer Research Conference in Chicago. These data demonstrate the critical role of the microbiome in the anti-tumor response of anti-PD-1 therapy. Remarkably, the activity of anti-PD-1 inhibitors in these models require a functional microbiome and our research shows that specific lymphocyte classes including CD8 T regulatory cells traffic through the gut and are linked to activity in the tumor. Seres is also leveraging synergistically are human data in ulcerative colitis patients which give us direct insight into the bacterial species and metabolites that modulate immune cell subsets. I will also mention that while our initial focus has been on the impact of the microbiome on checkpoint inhibitor therapy, a recent paper published in February in JCI Insight has shown that the microbiome can also alter the activity of CAR T therapies in animal tumor models. We now look forward to moving this promising research forward towards clinical development in collaboration with both the Parker Institute for immunotherapy and the MD Anderson Cancer Center. We expect to initiate a clinical study later this year to evaluate the potential for SER-401 to augment anti-PD-1 responses in patients with metastatic melanoma. I'll now pass the call to Eric to review our recent financial performance.