BOSTON – The gut microbiome and its prospects for drug development have been matters of debate for a while, sharpened by the high-profile phase II failure of Seres Therapeutics Inc.'s candidate, SER-109, in the summer of 2016. A panel at Biopharm America surveyed the space in light of developments since the stumble with that candidate, composed of about 50 species of firmicutes spores derived from stool specimens from healthy donors, against recurrent Clostridium difficile infection.