Ionis Slumps, Rival Alnylam Soars as GSK Decides Against Trial

  • Ionis drops as much as 36%, biggest decline since March 2003
  • Alnylam, developing similar therapy, rallies for second day

Ionis Pharmaceuticals Inc. plunged the most since 2003 after GlaxoSmithKline Plc decided not to test a drug the companies were developing together. Alnylam Pharmaceuticals Inc., which is developing a rival therapy, soared on the news.

Glaxo, which can choose to license the treatment, won’t start a final-stage study on the therapy for a rare heart condition after some patients on the drug experienced a severe decline in platelets, Ionis said Thursday. Ionis shares were down 35 percent to $22.86 at 11:44 a.m. in New York.

Alnylam rose 12 percent to $70.95, extending its two-day rally to 23 percent, the most in more than two years. The stock has been soaring as Sanofi, which owns a stake in the company, accelerated its pursuit of another drugmaker and other potential bidders circled, suggesting demand for biotechnology acquisitions may be picking up.

Ionis said last month that the U.S. Food and Drug Administration postponed a study of the drug, known as Ionis-TTRRx, while U.K. drug giant Glaxo answered questions about its setup. The trial was planned to examine the drug’s effects in familial amyloid cardiomyopathy, a lethal genetic disease that occurs when abnormal protein fragments accumulate in heart muscle.

The FDA did allow another late-stage study for a related disorder, in which protein deposits cause nerve damage, to proceed, Ionis Chief Executive Officer Stanley Crooke said in a call with analysts.

That study showed that “less than a handful” of patients “experienced serious declines in platelets,” he said. “We were very surprised by these events because we’ve never seen previously any types of serious platelet declines in the study or in our commercial or clinical experience.”

Glaxo will consider whether to move forward with the drug for the rare heart condition after more clinical data are available, Carlsbad, California-based Ionis said in a statement.

The Ionis update will give Alnylam’s programs “breathing room,” according to Edward Tenthoff, an analyst at Piper Jaffray & Co.

“These safety issues translate to a competitive advantages” to Alnylam’s drugs, he wrote in a note. The analyst rates Alnylam’s stock overweight.

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