Shares of Cytokinetics Inc. (CYTK) were down 34.7% to $7.25 ahead of the market open on Tuesday, Nov. 21, after the South San Francisco, Calif.-based firm said its Phase 3 study of tirasemtiv in patients with amyotrophic lateral sclerosis did not achieve primary or secondary endpoints.
No new safety or tolerability findings in connection with tirasemtiv were identified in the study, the company said.
Meanwhile, shares of Ardelyx Inc. (ARDX) rose 7.1% to $6 after the Fremont, Calif.-based company gave an update on the development of its cardiorenal pipeline. The firm said its second registration study for tenapanor for the treatment of hyperphosphatemia will start enrolling shortly.
Ardelyx also reported clinically meaningful potassium-lowering activity from its onset-of-action study for RDX7675 in hyperkalemia. The company, however, said it also had observed an unexpected side effect of decreased serum bicarbonate.
"The company believes this will limit the commercial potential of RDX7675 and, as a result, has decided to discontinue development of RDX7675," Ardelyx said.
The termination will yield cash savings of about $40 million, the company said.
In a note on Tuesday, Leerink Partners LLC analyst Seamus Fernandez wrote that given the limitations the safety issue puts on the chronic opportunity, "we believe the decision to terminate the program is well-conceived."
"Since RDX7675 contributed almost nothing to our valuation (just $0.47/shr or our $13/shr target), we believe the decision should have little or no effect on shares of ARDX after today," Fernandez added.
Among the other biotech stock movers was Prothena Corporation plc (PRTA) , up 5.4% to $47.