Seres Therapeutics Inc (NASDAQ:MCRB) received FDA Fast Track Designation for SER-155, an investigational oral, cultivated microbiome therapeutic designed to prevent GI-associated bacterial infections and to reduce the incidence of severe acute graft-versus-host disease in immunocompromised patients undergoing allogeneic hematopoietic stem cell transplantation.

• SER-155 Phase 1b Cohort 1 clinical data showed favorable tolerability, successful drug bacteria engraftment, and a substantial reduction in pathogen domination in the gastrointestinal microbiome, supporting progression to the placebo-controlled Cohort 2.
• SER-155 Phase 1b placebo-controlled Cohort 2 data readout is anticipated in the third quarter of 2024.
• Seres anticipates that a 2023 year-end cash balance of $128 million, in conjunction with the anticipated savings from the restructuring announced in November 2023 and the expected receipt of the $45 million Tranche B under its existing senior secured debt facility with Oaktree Capital Management, will support its operations into Q4 of 2024.

VOWST, the first FDA-approved orally administered microbiome therapeutic, received FDA approval in April of 2023 and is indicated to prevent the recurrence of Clostridioides difficile infection (CDI) in adults following antibacterial treatment for recurrent CDI (rCDI). 

• Preliminary Q4 net sales were approximately $10.4 million and reflected a gross-to-net reduction of 11%. Total 2023 net sales since launch in June were approximately $19.6 million and reflected a gross-to-net reduction of 13%.
• Q4 completed prescription enrollment forms received for VOWST were 1,322; 1,082 resulted in new patient starts by year-end 2023.
• The total 2023 completed prescription enrollment forms received for VOWST since launch were 2,833; of those, 2,015 resulted in new patient starts by year-end 2023.
• In 2023, prescription enrollment forms were submitted by approximately 1,330 unique healthcare providers since launch; approximately 340 HCPs have prescribed VOWST to more than one patient.