Seres Therapeutics: A Novel Approach for Treating Clostridium Difficile Infection

but first: Here is some good news from 


Yesterday we wrote about BioMarin (BMRN) being granted FDA “Rare Pediatric Disease Designation for its Duchenne potential muscular dystrophy (DMD) drug drisapersen.Today, Sarepta Therapeutics (SRPT) also a developer of RNA-targeted therapeutics has been granted the same for its drug eteplirsen, also a potential treatment for DMD patients who are amenable to skipping exon 51. The Rare Pediatric Disease Designation supplements the Orphan Drug Designation and Fast Track Status previously granted by the FDA for eteplirsen.

Sarepta is excited about the news, hoping that the FDA creation of “Rare pediatric disease designation” would lead to expedited treatments for children who desperately need them.

The FDA defines a “rare pediatric disease” as a disease that affects fewer than 200,000 individuals in the U.S. primarily aged from birth to 18 years. Under the FDA’s Rare Pediatric Disease Priority Review Voucher program, a sponsor who receives an approval of a new drug application (NDA) or biologics license application (BLA) for a rare pediatric disease may be eligible for a voucher, which can be redeemed to obtain priority review for a subsequent marketing application for a different product. The Priority Review Voucher may be sold or transferred an unlimited number of times.

Prohost Comments

We see this FDA grant as good news for both BioMarin and Sarepta, offering the firms many advantages, the most important of which is the validation of their sophisticated technologies, which represent an evolution in treating genetic diseases – tomorrow’s vision that’s realized today. Moreover, the grants and validates the work of the rest of the group specialized in RNA-targeted therapeutics — the antisense developers, including the leaders Alnylam (ALNY) and Isis (ISIS) drugs, which some bloggers call difficult to get on with drugs, which is totally misleading.

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Important News

The FDA Granted Orphan Drug Designation to a Novel Therapeutic Approach for Clostridium Difficile Infection (CDI).


The U.S. Food and Drug Administration (FDA) has granted orphan drug designation to SER-109, an oral therapeutic developed by Seres Therapeutics (MCRB). The drug is currently in a Phase 2 clinical trial for the prevention of recurrent Clostridium difficileinfection (CDI) in adults.

SER-109 is a new therapeutic modality aimed at treating recurrent CDI by correcting a dysbiosis of the human microbiome, which is an underlying cause of the condition.

Centers for Disease Control considers CDI one of the top three most urgent antibiotic-resistant bacterial threats. CDI is the leading cause of hospital-acquired infection in the U.S., and is responsible for the deaths of approximately 29,000 Americans each year. Recurrent CDI affects between 85,000 and 110,000 people in the U.S. annually

The orphan designation signifies a landmark event, as it marks the first microbiome drug to achieve this regulatory milestone, and is also rarely given for infectious disease indications,” said Roger Pomerantz, M.D., Chairman, President and CEO of Seres.

According to Dr. Pomerantz, “SER-109 is intended to re-introduce essential bacteria that restore the body’s natural resistance to CDI by re-establishing the ecology of the colonic microbiome. He added, “Because we’re focused on treating the underlying cause of the disease, we believe we have the potential to break the cycle of recurrent CDI and have a significant impact for patients. …”

The press release cites the fact that exposure to antibiotics, which are the only FDA-approved treatment for recurrent CDI, is the greatest risk factor for acquiring CDI.  The press release further explains that antibiotics use to treat CDI may induce or prolong an imbalance of the microbiome, which is comprised of trillions of bacteria and other organisms that inhabit or live on our bodies. When in balance, these organisms play critical, beneficial roles in a wide range of biological processes, including resistance to infection by pathogens such as the Clostridium difficile bacterium, education and regulation of the immune system, and regulation of energy metabolism. In a dysbiotic state, the microbiome cannot carry out some of these roles, which leads to the onset and progression of various diseases and conditions.

SER-109: In a single dose of four capsules, SER-109 re-introduces ecology of purified bacterial spores which restore the microbome to a healthy state, able to once again carry out key biological functions, including resistance to Clostridium difficile.

Results from a Phase 1b/2 study: In this study of SER-109 in recurrent CDI patients, the data demonstrate that 87 percent of patients achieved efficacy endpoint per protocol, and 97 percent of patients achieved a clinical cure, which was defined as the absence of CDI requiring antibiotic treatment during the eight-week period after SER-109 dosing.

Current Trials: Seres is currently conducting a multi-center, randomized, placebo-controlled Phase 2 clinical study to assess the efficacy and safety of SER-109 in preventing recurrent CDI. The primary outcome measure is the absence of CDI through eight weeks following administration of SER-109 compared to placebo. We expect the results from this study to be available in the middle of 2016.

Orphan Drug Designation program: This program provides a special status to drugs and biologics intended to treat, diagnose or prevent rare diseases and conditions that affect fewer than 200,000 people in the U.S., or that affect more than 200,000 people but are not expected to recover the costs of developing and marketing the product in the U.S. The designation provides Seres with certain benefits, including a seven-year marketing exclusivity period for this indication upon approval of SER-109, tax credits for clinical research expenses incurred in the U.S., and an exemption from FDA application user fees.

A Breakthrough Therapy: In June 2015, the FDA granted SER-109 Breakthrough Therapy Designation, which is intended to expedite the development and review of therapeutics for serious conditions that may demonstrate a substantial improvement over existing therapies, based on preliminary clinical evidence.

SER-109: As described by Seres Therapeutics, SER-109 is the lead Ecobiotic® microbiome therapeutic in clinical testing for the treatment of recurrent Clostridium difficileinfection (CDI). The drug was developed utilizing the Seres Microbiome Therapeutics™ platform that provides deep insight into the ecologies of disease and then identifies microbial compositions that can catalyze a shift to a healthier state.

CDI is a rapidly growing problem associated with antibiotic use. Approximately 85,000 to 110,000 CDI patients in the U.S. have more than one recurrence each year.

Seres Therapeutics is a leading microbiome therapeutics platform company developing a novel class of biological drugs that are designed to treat disease by restoring the function of a dysbiotic microbiome.

Prohost Comments

Seres Therapeutics’ approach to the treatment of infection, in this case, CDI is indeed a breakthrough. We hope the current trials will confirm the previous trials. In this case, we believe they will.

MCRB trades at $38.91 Down $0.38 in a down day market. The firm’s market Cap is $1.52 billion.

The firm is on our radar for further analysis.

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