Seres distances itself from quality problems at other microbiome groups

The FDA issued an alert to healthcare providers in June after learning of cases of bacterial infection with muti-drug resistant organisms in patients treated with investigational FMT. One of the infected individuals died.

FMT has emerged as a treatment option for patients with recurrent Clostridium difficile ​infection but the alert showed the potential risks. The infections stemmed from transplantation of donor stools that were not tested for extended-spectrum beta-lactamase-producing gram-negative organisms.

Seres is also trying to treat C. difficile​ by altering the microbiome but the means it uses are different. Kevin Horgan, chief medical officer at Seres, sought to make sure those differences are clear on the company’s second-quarter result conference call with investors.

Horgan said, “This FDA alert does not apply to Seres as our drug candidates are fundamentally different than the unapproved FMT used in medical practice. Seres therapeutic candidates are manufactured under GMP conditions and quality controlled using stringent standards to ensure product quality and consistency​.”

Rather than directly transplant donor stools, Seres produces oral dosages that contain cocktails of bacteria designed to have certain effects under good manufacturing practice conditions.

Those differences have been clear throughout Seres’ high-profile emergence as the early poster child for microbiome therapeutics. Yet, Seres felt compelled to ensure the differences are understood in the wake of the FDA alert.

Horgan said, “We have been in contact with our clinical sites to ensure that they fully understand the differences between FMT and other fecal bacterial preparations and Seres drug candidates​.”

Seres’ contact with clinical sites took place against a backdrop of enrollment challenges in a study of SER-109. The trial is targeting the same population of recurrent C. difficile ​infection patients as FMT.

Faced with the widespread use of FMT, Seres has failed to recruit patients as quickly as expected, leading it to reduce the enrollment target by more than 40% and delay the readout from the study.

Quality control is an area in which Seres could differentiate its offering. Seres CEO Eric Shaff thinks the FDA FMT alert “will be significant for the space​” but cautioned that too little time has passed for its impact to be felt. Seres is yet to see a discernible effect on enrollment in its SER-109 clinical trial.