NEW YORK (AP) -- Shares of Coronado Biosciences plunged Monday after the company said its experimental Crohn's disease treatment using eggs from a parasitic worm failed in a midstage clinical trial.
Coronado said the treatment, called TSO, didn't meet its main or secondary goals in the study. The company said patients who were treated with a placebo did better than expected, so patients treated with TSO did not reach target levels of improvement compared with those patients.
The shares fell $3.87, or 67.1 percent, to $1.90 in morning trading. Earlier they sank to an all-time low of $1.73.
TSO stands for Trichuris suis ova. Trichuris suis is a type of parasitic worm found in pigs, and TSO are the eggs of the worm.
Coronado is studying TSO as a treatment for a variety of autoimmune conditions because the worm can affect the human immune system and it may reduce symptoms of those diseases. Autoimmune diseases such as Crohn's happen when the body's immune system attacks its own cells.
Coronado said the worm does not multiply in humans and can briefly colonize humans without causing disease symptoms before it is cleared from the body.
The midstage study compared TSO to placebo in 250 patients with Crohn's disease. The Burlington, Mass., company said patients treated with TSO did not have a significant improvement in symptoms compared to placebo and patients treated with TSO were not more likely to experience remission.
Coronado said patients with high levels of disease activity experienced some improvement, but the difference between TSO and placebo wasn't statistically significant.
Coronado Biosciences Inc. expects to report interim results from a second midstage study before the end of the year. The company does not have any drugs approved for sale.