Roche Holdings AG (OTC:RHHBY) has halted dosing for its Phase 3 study of tominersen, an antisense drug targeting the huntingtin protein and a mutant variant.

• Roche is calling off the study after an independent data committee “made its recommendation based on the investigational therapy’s potential benefit/risk profile for study participants.”
• The drug is an antisense oligonucleotide that was initially developed by Ionis Pharmaceuticals Inc (NASDAQ: IONS) and licensed for $45 million in 2017.
• Tominersen had raised hopes in an earlier trial when it showed dose-dependent reductions of the mutant protein that drives the disease.
• Roche also stopped dosing in an open-label extension study dubbed GEN-EXTEND dosing patients on the same high- and low-dose protocol.
• The company said it would provide further updates on its plan for the drug after data are further evaluated and planned to monitor patients’ safety signals through the study’s trial window.
• Roche is still pursuing Huntington’s disease via its Spark Therapeutics Inc gene therapy unit that it bought in late 2019.
• The Phase 1 PK/PD study (GEN-PEAK) of tominersen and the observational Genentech and Roche Huntington’s disease Natural History Study will continue.
• Price Action: IONS shares tanked 21.2% at $43.81 in premarket trading on the last check Tuesday, while RHHBY shares closed up 3.1% at $42.5 Monday.