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SERES THERAPEUTICS, INC. filed this Form 10-K on 03/06/2019
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In December 2018, we initiated our Phase 2b trial, ECO-RESET, evaluating SER-287 in patients with active mild-to-moderate ulcerative colitis. Based on feedback obtained from the FDA on the SER-287 Phase 2b study design, we believe that the study could serve as one of two required pivotal trials supporting potential future registration of SER-287. The Phase 2b study is a three-arm placebo-controlled trial of approximately 200 patients with active mild-to-moderate UC. Two groups of patients will receive different doses of SER-287, both following pretreatment with a short course of oral vancomycin. A third study arm will receive placebo. The study’s primary endpoint will evaluate clinical remission measured after 10 weeks of SER-287 administration. Endoscopic improvement will be measured as a secondary efficacy measure. We expect to complete study enrollment by mid-2020.

In June 2017 we initiated a Phase 3 clinical study of SER-109, termed ECOSPOR III, in approximately 320 patients with multiply recurrent CDI. Based on analysis of the available clinical, microbiome, and chemistry, manufacturing and control data from our Phase 1b and Phase 2 clinical studies of SER-109, diagnosis of CDI for both study entry and for endpoint analysis will be confirmed by C. difficile cytotoxin assay, rather than polymerase chain reaction, or PCR, which was used in the prior studies. Patients in the SER-109 arm will receive a total SER-109 dose, administered over three days, approximately 10-fold higher than the dose used in the Phase 2 clinical study. The study will evaluate patients for 24 weeks and the primary endpoint will compare the CDI recurrence rate in subjects who receive SER-109 verses placebo at up to eight weeks after dosing. ECOSPOR III enrolment continues to progress, with over 100 sites open across the United States and Canada. Several factors have impacted study enrollment, including the C. difficile cytotoxin test required for diagnosis, which has screened out some individuals who might otherwise have been included had we used PCR-based testing, and the widespread availability of unapproved and unregulated fecal microbiota transplantation. We continue to add and implement various operational measures to expedite study enrollment.  Additionally, we are considering alternatives, including study design modification, to expedite the availability of clinical results.

We have initiated a Phase 1b clinical study with our collaborators at MD Anderson Cancer Center, or MD Anderson, and the Parker Institute for Cancer Immunotherapy, or the Parker Institute, of SER-401, a donor derived microbiome therapy designed to replicate the bacterial signature found in the approximately one third of patients who have a robust response to anti-PD-1 therapy.   SER-401 is designed to modify the cancer immune set point and meaningfully improve patients’ response to checkpoint inhibitor therapy.  The scientific basis for SER-401 is supported by published findings from our collaborator, Dr. Jennifer Wargo of MD Anderson, indicating that a specific set of bacteria in the gastrointestinal microbiome can have an important role in determining the immunological response to checkpoint inhibitor therapy. Our own preclinical research has extended these findings and continues to ascertain how specific bacterial species impact the response to checkpoint inhibitors.  These data demonstrate the strong role of specific bacterial species in anti-tumor response to anti-PD-1 therapy and on the impact of the microbiome the immune system and on specific T cell classes, including CD8 and T regulatory cells.  

We continue to evaluate microbiome pharmacokinetic and pharmacodynamic data from the SER-262 Phase 1b study and other completed clinical trials, in addition to insights gained from preclinical research efforts with our other rationally designed Ecobiotic microbiome therapeutic candidates, in order to determine future steps in the development of both SER-262 and SER-155.

While we plan to focus our investment on our highest priority clinical programs in the near-term, our expenses may increase substantially in connection with our ongoing and planned activities, particularly as we:


continue the clinical development of SER-109, our lead product candidate, in the Phase 3 clinical study;


continue the clinical development of SER-287 for the treatment of UC;  


continue the clinical development of SER-401, a microbiome therapeutic candidate for use with CPIs in a Phase 1b clinical trial in patients with metastatic melanoma;


conduct research and continue preclinical development of SER-301, our rationally designed IBD product candidate;


make strategic investments in manufacturing capabilities;


maintain and augment our intellectual property portfolio and opportunistically acquire complementary intellectual property;


potentially establish a sales and distribution infrastructure and scale-up manufacturing capabilities to commercialize any products for which we may obtain regulatory approval;


perform our obligations under the license and collaboration agreement with Nestec Ltd., or NHS;


seek to obtain regulatory approvals for our product candidates; and


experience any delays or encounter any issues with any of the above, including but not limited to failed studies, complex results, safety issues or other regulatory challenges.


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