Roger Pomerantz
Analyst · Oppenheimer
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 microbiota has a central role. We use live bacterial consortia, an entirely novel treatment modality, as therapeutic development candidates. We believe that microbiome therapeutics have the potential to address multiple disease states and our R&D efforts target the 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 continued to make strong progress on a number of our late and early clinical and preclinical stage programs. We continue to enroll patients with fully objectively-defined multiply recurrent C. difficile infections in our North American Phase III trial. We have met with the FDA and determined our plan to advance SER-287 into a Phase IIb ulcerative colitis study in the coming months. We obtained the clinical portion of the results from our SER-262 Phase Ib study. The mechanistic insights from this study inform potential development plans for SER-262 and future rationally-designed fermented microbiome therapeutic candidates. We advanced our SER-401 program designed to increase the efficacy of immuno-oncology checkpoint inhibitors and with our collaborators expect to initiate the clinical trial by the end of this year. In addition, we hosted Seres first ever R&D Investor Event in May and presented detailed preclinical and clinical data for a number of our pipeline programs, highlighting immunology and immuno-oncology. So let's begin with a review of SER-109 Phase III program. 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 SR-109 Phase III study. ECOSPOR III is a randomized, placebo-controlled study in approximately 320 patients with multiply recurrent C. diff infection. The design of ECOSPOR III incorporates our key learnings from prior development efforts. We increased the dose of SER-109 approximately 10-fold compared to the Phase II study and have incorporated the more accurate C. diff toxin tests as opposed to a PCR-based assay for both patient selection and in-study endpoint determination to reduce false positives. Based on FDA feedback, we believe that with compelling results ECOSPOR III may serve as a single pivotal study supporting SER-109 approval, which may make SER-109 the first ever FDA approved microbiome therapeutic. ECOSPOR III study enrollment, the top priority for the company, continues to progress forward. We have well over 100 ECOSPOR III clinical sites open across the U.S. and Canada. Several factors have impacted the study enrollment of this orphan disease. In ECOSPOR III, we require that C. diff infection be confirmed by the laboratory detection of the C. difficile toxin. Toxin testing has screened out some individuals, who might have otherwise been included had we used PCR-based testing. However, what is most important is that we include appropriate patients with truly an objectively-active C. diff infection. In addition, the widespread availability of unapproved and unregulated fecal microbiota transplantation approaches has been a challenge for all C. difficile clinical studies. While the use of FMT has, of course, impacted study enrollment, we are confident that the availability of an approved, effective and safe oral microbiome drug would displace the use of these unregulated procedures. We continue to add and implement various operational measures to expedite study enrollment. At this time, we believe it would be premature to provide a time estimate for study completion. Now moving to SER-287, an orally-administered biologically-sourced drug candidate comprised of commensal bacterial species that reside in the healthy human gastrointestinal tract. Our objective with SER-287 is to replace pro-inflammatory bacterial species that are often elevated in patients with ulcerative colitis with commensal bacterial species that modulate inflammation and enhance integrity of the gut barrier. We have made substantial progress preparing for further late-stage development. We reviewed the highly-encouraging Phase Ib clinical and microbiome results with the FDA and gained alignment on the path forward. Based on this feedback, we plan to initiate a Phase - excuse me, SER-287 Phase IIb induction study in patients with mild-to-moderate ulcerative colitis in the coming months. We expect that this study could serve as 1 of the 2 required pivotal induction studies to support product registration. We have obtained orphan designation for SER-287 in pediatric ulcerative colitis and are considering further development in this indication. Our planned SER-287 Phase IIb study will be a randomized, placebo-controlled four-arm induction trial in approximately 268 patients with mild to moderate ulcerative colitis, who are failing their current therapies. In arm A, patients will receive a six-day pre-treatment with oral vancomycin and then receive 10 weeks of the same high-dose regimen used in the most efficacious arm of the Phase Ib trial. In arms B and C, patients will receive two weeks of high-dose [indiscernible] SER-287 followed by eight weeks of a lower dose of the drug. These arms of the study will evaluate pre-treatment with either vancomycin orally or placebo. We believe the microbiome data showing the rapid engraftment following dosing observed in our Phase Ib study provide scientific support for the step-down dosing approach. Recall that by approximately day 10, Phase Ib patients achieved maximum engraftment of SER-287 species and remained stable up to the final four-week time point when samples were obtained. Study arm D will consist a placebo pre-treatment followed by placebo dosing. Consistent with the latest FDA guidance from August 2016, the primary endpoint, the only primary endpoint for this SER-287 Phase IIb study will be clinical remission. However, we also plan to evaluate various secondary endpoints including endoscopic improvement and histological mucosal healing, where we observed encouraging signals in our Phase Ib study. The Phase IIb study is designed to primarily evaluate shorter-term induction dosing. However, we will also evaluate the efficacy and tolerability of longer-term maintenance dosing. SER-287 is a living drug and we have reason to expect that we may observe long-lasting biological and clinical effects. Of note, in the Phase Ib study, we detected no flares in patients treated with SER-287 who obtained clinical remission for a full six months following completion of all SER-287 dosing. The maintenance phase will provide the basis for a final pivotal study that will include both induction and maintenance phases to support product registration. In prior calls, we have reviewed the positive SER-287 Phase Ib study results in some detail, so I won't go over those data again. I would, however, like to discuss some of the more recent supportive microbiome, metabolomic and transcriptomic data that provide key evidence for the biological mechanisms of action for SER-287. Our Phase Ib study was designed with comprehensive sampling of patients' stool, mucosal biopsies and blood to enable an assessment of specific correlates of remission. The engraftment analysis has defined a set of bacterial species that are highly correlated with clinical remission, yielding an affect-based signature. The metabolomic analysis showed significant changes in multiple microbial metabolic pathways that differentiate remitters from non-remitters. This includes aspects of bile acid metabolism, tryptophan metabolism and short-chain fatty acid production. In these and other cases, we have shown that the metabolic - the metabolic products are immunomodulatory in laboratory studies at relevant physiological concentrations. Furthermore, these metabolic products are associated with engrafting species found in SER-287 product, thus directly linking the microbiome changes to affect our molecules made by these bacteria. Most recently, we have analyzed changes in the patients' mucosal transcriptional profiles. These data revealed that multiple pathways including specific cytokine production, epithelial barrier function, innate immune responder sensors and metabolic pathways are differentially modulated in remitting patients as compared to non-remitters. The totality of these data define that some of the specific mechanisms by which SER-287 functions and gives us deep molecular biological insights, as we develop SER-301, our rationally-designed consortium product, that will follow SER-287. Overall, we believe that the consistency of the SER-287 clinical efficacy and engraftment data supporting pharmacodynamic data and favorable safety profile strongly support continued late-stage clinical development. We look forward to initiating the potentially pivotal SER-287 Phase IIb study in the coming months. Now moving to our preclinical stage microbiome therapeutic efforts. We are highly focused on advancing our SER-401 immuno-oncology program into full clinical development. SER-401 is a biologically-sourced microbiome therapy that is designed to replicate the bacterial profile and signature found in patients with a robust response to anti-PD-1 therapy. Our immuno-oncology microbiome program is designed to modify the cancer immune set point and meaningfully improve patient's response to checkpoint inhibitor therapy. The scientific basis for this program is supported by multiple high-caliber publications, which have demonstrated that the composition of bacteria in the gastrointestinal microbiome has an important impact on immunological response to checkpoint inhibitor therapy. Our pre-clinical research is focused on understanding how certain bacterial species impact the response to checkpoint inhibitor therapy. Our internal experiments and data demonstrate the strong role of specific members of the microbiome and anti-tumor response of anti-PD-1 therapy and the impact of the microbiome on specific T cell classes including CD8 and T regulatory cells. In collaboration with the Parker Institute of Immunotherapy and MD Anderson Cancer Center, we are planning to conduct a randomized study in 60 patients with metastatic melanoma where all patients will receive an anti-PD-1 therapy. Anti-PD-1 therapy will be followed by placebo, SER-401 or a microbiota transfer derived from a complete responder to anti-PD-1 in this three-arm trial. Together with our collaborators, we expect to initiate this 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.