Patient death sparks safety worries in Ionis trial

Ionis Pharmaceuticals announced the results from a Phase 3 trial of its drug to treat patients with familial amyloid polyneuropathy and the results were extremely positive, except for the side-effects. Three patients suffered serious adverse events of thrombocytopenia, one of whom died as a result of intracranial haemorrhage.

The safety issues are a massive blow to the drug’s prospects, particularly as the data showed that there was a clear benefit for most patients being administered inotersen. The company revealed that 80% of patients completed the study and, of those, 95% continued on to an open-label extension of the trial.

Brett P. Monia, Senior Vice President of Drug Discovery and Franchise Leader for Oncology and Rare Diseases at Ionis Pharmaceuticals, commented on the trial: "We are excited about the positive topline results from the Phase 3 NEURO-TTR study. We observed a benefit in disease progression in patients treated with inotersen, regardless of disease stage (Stage 1 and Stage 2) or TTR mutation (V30M and non-V30M). We believe these preliminary results suggest a favourable benefit-risk profile for inotersen in patients with FAP."

The data has not yet been revealed, except that the trial found a statistically improvements in modified neuropathy impairment score and the Norfolk quality of life-diabetes neuropathy measure.

However, it will be hard to detract from the three cases of thrombocytopenia, as well as two cases were treatment had to be stopped due to serious renal adverse events. This allows competitor Alnylam and its drug, patisiran, the opportunity to prove a better safety profile in its own Phase 3 testing.

This has led share prices in the companies to head in opposite directions, with Alnylam up 15% and Ionis’s having fallen by 6.75%.

Ben Hargreaves