Updated from 11:28 am EDT with Celgene response:
SUMMIT, NJ (TheStreet) -- Mongersen is one of Celgene's (CELG) most important pipeline drugs and a potential blockbuster treatment for Crohn's disease, an autoimmune disorder affecting the bowel. Investors, however, will wait longer than expected for data necessary to resolve a lingering concern about mongersen's potential.
On Sunday, Celgene said results from a recently started phase II study in which doctors are using an endoscope to examine the colons of Crohn's patients to confirm the benefit of mongersen would be available in the first half of 2017.
Investors were expecting to see the mongersen "endoscopy data" in 2016, and if positive, possibly allow Celgene to seek early, accelerated approval for the drug in the U.S.
The ability of mongersen to demonstrate high rates of clinical remission in Crohn's disease patients was called "unprecedented" by a physician in a recent editorial published in the New England Journal of Medicine. However, the same physician reviewing Celgene's previous phase II study also raised a concern that enrolled patients may have had more moderate Crohn's disease, making it easier for mongersen to show an outsized treatment effect.
In that study, Celgene defined remission as a Crohn's Disease Activity Index (CDAI) score of less than 150, maintained for at least two weeks. The study did not call for doctors to use an endoscope to measure patients' Crohn's disease at baseline or after treatment was concluded.
The ongoing endoscopy study -- which Celgene refers to as CD-001 -- is important because it will provide a more rigorous assessment of mongersen's ability to treat Crohn's patients.