BUZZ-Septerna slumps after scrapping trial of hormonal disorder drug

Drug developer Septerna's shares SEPN.O fall 66.6% to $4.49 premarket

Co discontinues an early-stage trial of its experimental drug for patients with a hormonal disorder called hypoparathyroidism

In hypoparathyroidism patients, the body does not produce enough levels of a hormone that regulates calcium and phosphorus levels in the blood

SEPN says it stopped the trial after two participants showed unexpectedly high levels of a substance called unconjugated bilirubin, which forms when red blood cells break down

Says it will advance other drugs with distinct and unrelated chemical structures relative to the discontinued treatment

Stock has fallen nearly 40% since its Nasdaq debut in October