Prometheus upsizes IPO, fueling chase of Pfizer in bowel disease

Prometheus Biosciences has upsized its IPO, positioning it to reel in $190 million to bankroll clinical development of an anti-TL1A monoclonal antibody in inflammatory bowel disease (IBD).

San Diego-based Prometheus, which is partnered with Takeda, is built on a platform featuring a database and biobank licensed from Cedars-Sinai. Armed with the resource, Prometheus has built a pipeline led by an antibody that entered phase 1a late last year. The antibody hits the same target as Pfizer’s PF-06480605.

Pfizer has already put PF-06480605 through a clutch of early-phase trials and began a 240-participant phase 2b in ulcerative colitis patients late in 2019. Prometheus is well behind its larger rival but has reason to believe it can compete. Prometheus’ PRA023 binds to a different epitope and the biotech plans to use a companion diagnostic to identify patients with TL1A-driven disease.

If the phase 1a generates favorable safety data, Prometheus intends to start further trials in the third quarter. A phase 2 randomized placebo-controlled trial in moderate-to-severe ulcerative colitis and an open-label phase 1b clinical trial in moderate-to-severe Crohn’s disease are in the works. Results from both studies are penciled in for the second half of 2022.

Prometheus has earmarked $60 million for the development of PRA023. The upsizing of the IPO, which was previously expected to gross around $150 million, will give Prometheus greater financial firepower as it moves PRA023 and earlier-stage assets toward the market. 

The preclinical pipeline is led by another IBD drug that targets a member of the TNF superfamily. Prometheus expects to file to study that drug in humans in the second half of next year. Several other programs are also moving through preclinical.