Acceleron said its sotatercept medication achieved its primary and secondary endpoints in a placebo-controlled trial of patients with pulmonary arterial hypertension.
Shares rose $35.57, or 67%, to $88.44 in after-hours action. Shares had edged higher in the regular session on a mostly gloomy day for Wall Street bulls that saw markets post their worst declines since early October.
Pulmonary arterial hypertension, or PAH, is a potentially life-threatening condition in which patients have high blood pressure in the arteries that go from the heart to the lungs.
"PAH is a debilitating disease of high unmet medical need, so we’re encouraged by these data that signal that sotatercept could deliver added benefit to patients," Habib Dable, president and chief executive officer of Acceleron said in a statement.
Elsewhere, biotech stocks were mixed on Monday. Among notable large-cap names, three rose while 13 fell. Biogen (BIIB) - Get Report shares rose $3, or 1.08%, to $281.14, while Mylan (MYL) - Get Report shares fell 69 cents, or 3.16%, to $21.16.
Among biotech stocks with market capitalizations between $2.5 billion and $10 billion, 12 rose while 36 fell. Allakos (ALLK) - Get Report shares rose $3.71, or 5.31%, to $73.60. Nektar Therapeutics (NKTR) - Get Report shares fell $1.36, or 6.44%, to $19.77.
Among biotech stocks with market caps between $1 billion and $2.5 billion, 11 rose while 29 fell. Denali Therapeutics (DNLI) - Get Report shares rose $3.33, or 13.51%, to $27.98. Zogenix (ZGNX) - Get Reportshares fell $2.70, or 5.18%, to $49.43.