Why Ionis Pharma Is Sinking Despite Solid Late-Stage Results

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Ionis Pharmaceuticals Inc. (NASDAQ: IONS) saw its shares pullback on Monday morning after results were released from its late-stage trial for the treatment of familial amyloid polyneuropathy. Although the results from this Phase 3 trial of inotersen met its primary endpoints, there was still some data that held the stock back.

Unfortunately, adverse effects considered to be related to treatment were seen more commonly with inotersen than in the placebo. Two key safety findings were observed during the study that required changes to the monitoring schedule. Three serious adverse events of thrombocytopenia were observed in inotersen-treated patients. Two patients recovered and one patient died due to intracranial hemorrhage.

One additional inotersen-treated patient discontinued treatment due to non-serious thrombocytopenia. Four inotersen-treated patients discontinued treatment due to a renal observation. Two patients met a predefined renal stopping rule, and two experienced serious renal adverse events, one of whom experienced chronic renal insufficiency.

All five serious adverse events — including one placebo related event — occurred before enhanced monitoring was fully implemented.

Morie Gertz, M.D., MACP, Division of Hematology, and Roland Seidler Jr., Professor Department of Medicine, College of Medicine, Mayo Distinguished Clinician, commented:

Familial amyloid polyneuropathy is a devastating genetic disease that is painful and rapidly progressive leading to early death. The positive results from the NEURO-TTR study today are very encouraging for this underserved patient population. I have been treating patients with this disabling disease for many years, and I am excited about the promise that inotersen holds to restore their lives. I believe inotersen has the potential to transform the current standard of care for patients with TTR amyloidosis.

Shares of Ionis traded down 9% at $42.84 early Monday, with a consensus analyst price target of $45.36 and a 52-week trading range of $19.59 to $57.00.