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SER-287 (SERES-101 study)

SERES-101 is a current Phase 1b clinical study evaluating the safety and efficacy of SER-287 versus placebo, in adults with mild-to-moderate ulcerative colitis (UC), which is currently enrolling at sites in the United States. This study is called a Phase 1b study because it is primarily intended to assess the safety and tolerability of SER-287 when taken by adults, but it will also attempt to identify preliminary signs of efficacy in patients with UC. The full name of the clinical study is: “A Phase 1b Multiple Dose Study to Evaluate the Safety, Tolerability, and Microbiome Dynamics of SER-287 in Subjects with Mild-to-Moderate Ulcerative Colitis.”

About Ulcerative Colitis

Ulcerative colitis is a chronic inflammatory condition of the colon, leading to episodes of bloody diarrhea and urgency. The disease mostly affects young and middle-aged individuals. The cause of ulcerative colitis is largely unknown. While genetic factors contribute to disease risk, an abnormal relationship between the immune system and intestinal bacteria may also play a role in triggering the disease.

In several previously reported studies, some UC patients with mild-to-moderate disease administered bacteria through fecal microbiota transplant from a healthy donor experienced improvements in their UC symptoms, suggesting that changes in the bacteria may contribute to this clinical response.

About the SERES-101 Study

This study involves research about SER-287 (an investigational medicine). SER-287 is a preparation of bacterial spores highly purified from stool donations obtained from healthy, screened donors and put into capsules. These bacterial spores are inactive forms of the normal bacteria that live in a healthy intestine. SER-287 is a new investigational drug treatment being studied to determine if providing normal healthy bacteria (via SER-287) to UC patients with active symptoms can help restore the balance of bacteria in their intestines and control disease activity.

This study is being done to look at the effects of SER-287 compared to a placebo (a capsule containing no active drug), in treating active UC. This study will also see if giving the antibiotic vancomycin before starting treatment with SER-287 can improve the effect of SER-287. Samples will be collected throughout the study to see the impact of SER-287 compared to placebo on the intestinal bacteria of patients in the study.

Who is eligible for the SERES-101 Study?

Some of the characteristics that may allow you to be eligible for SERES-101 include:

  • Be 18 years of age or older
  • Have a confirmed diagnosis of UC
  • Have active mild-moderate UC upon study entry

What should I know about the study medicine?

SER-287 is an investigational medication. An investigational medicine is a product that is still being tested and has not been approved by regulatory authorities, including the Food and Drug Administration (FDA), for commercial sale. This means SER-287 can only be used in research studies. Your doctor cannot prescribe it to you.

SER-287 pills contain bacterial spores taken from healthy donors. One (1) dose of SER-287 is given in 4 capsules, each capsule is about the size of a vitamin. These spores may help bring back healthy bacteria into the gut and may improve your UC symptoms.

What will happen during the study?

You will be asked certain questions to find out if you can join the study. If eligible, you will be provided with additional information and asked to give us written permission to join the study.

If you are eligible, you will be randomized, like drawing a name out of a hat, to receive vancomycin (an antibiotic already approved by the FDA) or placebo for 6 days, and then SER-287 or placebo for 8 weeks. A placebo is a capsule that looks like the drug but contains no active drug. You will have a 6 out of 11 chance, or a 55% chance, of receiving vancomycin. You will have a 9 out of 11 chance, or a 82% chance, of receiving SER-287. SER-287, vancomycin and placebo are all capsules given by mouth and will be referred to as "study drug".

If you take part in this study, you will be put into one of the following study groups:

  • Group A subjects take placebo every day for the first 6 days, then for the next 8 weeks they take SER-287 once a week and placebo the other 6 days of the week.
  • Group B subjects take placebo every day for the first 6 days, then for the next 8 weeks they take placebo every day.
  • Group C subjects take vancomycin every day for the first 6 days, then for the next 8 weeks they take SER-287 every day.
  • Group D subjects take vancomycin every day for the first 6 days, then for the next 8 weeks they take SER-287 once a week and placebo the other 6 days of the week.

This is a double- blinded study. That means that neither you nor the study doctors and study staff will know which patient got SER-287 and which patient got the placebo. The results will help researchers tell if SER-287 is working. It will also help the study doctors tell if there are any side effects of SER-287 to be concerned about.

Participation in the study will last approximately 37 weeks and will include 13 study visits. Two of these study visits (at the beginning of study and after completing the study drug treatment, about 9 weeks after beginning the study) will include a medical procedure called a lower endoscopy (flexible sigmoidoscopy or colonoscopy). This procedure allows the study doctor to look closely at the lower part of your colon. The other clinic visits during the study may involve physical exams, measurements of vital signs, and the collection of blood, stool and urine samples, among other assessments.

What is involved in enrolling and participating in this study?

You do not have to be in the study. You should discuss your choices for treating your UC with your doctor.

If you do choose to be in the study, you may leave the study at any time and for any reason. Your decision will be respected, there will not be any penalties, and it will not affect your routine medical care and/or treatment. However, if you leave the study, you will not be allowed to rejoin the study.

How do I enroll in the study?

The SERES-101 study is now open for enrollment. It is posted on

You can find out if there is a study site near you by reviewing the clinical study site locations on the website.

Deciding to be in a clinical trial is an important decision. If a doctor in the study thinks you should be in the study, you will be told everything you should know before you join, including the risks and potential benefits of participating. More information regarding the study is currently available on the website.

What should I know about research studies?

Drug (pharmaceutical) companies conduct research studies like SERES-101 to learn more about investigational medications to determine whether they may be safe and effective before they may be made available to the public.

The results of the SERES-101 study will provide more information about the potential safety and effectiveness of SER-287.

By taking part in this study, participants will be making an important contribution to ongoing ulcerative colitis research.

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