Shares of Ionis Pharmaceuticals Inc. /zigman2/quotes/201272020/composite IONS -2.12% were down 19.6% in premarket trading on Tuesday, the day after the company said Roche Holding AG /zigman2/quotes/206324342/delayed CH:ROG +1.22% decided to discontinue a late-stage clinical trial for a Huntington's disease treatment candidate. Roche licensed the investigational therapy, tominersen, from Ionis in December 2017. However, an independent data monitoring committee first made the recommendation to discontinue the study. "The program isn't necessarily dead, but it's unlikely to drive much value for the stock near term," Bernstein's Vincent Chen wrote in a note to investors on Tuesday. "This discontinuation doesn't mean that the program is dead. It depends on why it failed." Ionis' stock is up 33.7% over the past 12 months, while the broader S&P 500 /zigman2/quotes/210599714/realtime SPX +0.74% has gained 70.9%.