Seres rekindles once-failed microbiome study

Dive Brief:

  • Signaling a rapid turnaround after faltering last July from a failed Phase 2 trial of SER-109 to treat recurrent Clostridium difficile infection, microbiome-therapy pioneer Seres Therapeutics said March 16 it will initiate a redesigned SER-109 clinical study with a nod from the Food and Drug Administration.
  • With FDA’s guidance, Seres said its new ECOSPOR III study is designed to be a randomized, placebo-controlled trial of about 320 patients at dozens of clinics in the U.S. and Canada who are expected to get better diagnoses and dosing – seen as contributing to the downfall of the initial study.
  • In its pipeline, Seres anticipates results from two Phase 1b clinical trials in the second half of 2017: its study of SER-287 for treating ulcerative colitis, and its study of SER-262, the first synthetically derived microbiome candidate to reach clinical development, for primary C. diff. infection.

Dive Insight:

When Seres, the first publicly held microbiome-focused company, had a major clinical trial failure last summer for its fecal transplant aiming to treat recurrent C. diff. infection, the company’s stock fell dramatically Conversely, its shares skyrocketed March 16 after the company reported fourth-quarter revenue that topped estimates, filed for a mixed-shelf offering of up to $150 million, and revealed plans to initiate the new mid-stage study for SER-109.

While there’s significant promise for microbiome-based therapeutics, there’s also market volatility because nobody knows how these companies will perform, said Michael Darcy, a senior business insights analyst at Decision Resources Group, a life sciences market research firm.

"A 50% decline after [Seres’] initial negative Phase 2 news, followed by the 30-plus-percent rebound after the new Phase 2 news is further ‘proof in the pudding’ for investor excitement/sensitivity," Darcy told BioPharma Dive.

On Jan. 31, the Cambridge, Mass.-based company, which raised $134 million in a 2015 initial public offering, had said that findings from its analysis of SER-109’s phase 2 study failure suggested that misdiagnosis of some patients, and possible suboptimal dosing in others, contributed to the poor outcome. At that time, Seres also said it was involved in ongoing discussions with the FDA about launching a new, redesigned clinical trial for SER-109.

The new ECOSPOR III study aims to ensure accurate measurement by confirming the diagnosis of recurrent C. diff infection when patients enter the study and for endpoint analysis by using a C. diff cytotoxin assay. Patients in the SER-109 arm will get a total SER-109 dose, administered by oral capsule over three days, roughly 10-fold higher than the dose used in the prior study. Patients will be evaluated for 24 weeks, and the primary endpoint will compare the C. diff. recurrence rate in subjects who get SER-109 versus placebo at up to eight weeks after dosing.

According to Seres, the FDA has agreed that the new trial may qualify as a pivotal study if it achieves "a persuasive clinical effect" and addresses FDA requirements, including clinical and statistical factors and an adequately sized safety database.

Roger J. Pomerantz,  Seres’ president, CEO and chairman, said his company plans to initiate the new clinical study as soon as possible based on the FDA’s "highly positive and constructive guidance." Previous SER-109 studies provided new data to advance Seres’ efforts, he said, and the company anticipates that the new clinical trial may provide the basis for SER-109’s approval.

"There is an urgent need for improved treatments for C. difficile infection, and we believe SER-109 has great potential to address the underlying cause of the disease and become the first approved microbiome therapeutic in this new field of medicine," Pomerantz said.

Filed Under: Clinical Trials Regulatory / Compliance Corporate News
Top image credit: Ingredients Network