ZURICH (Reuters) – Roche’s spinal muscular atrophy (SMA) drug risdiplam hit another clinical trial target, the Swiss drugmaker said on Thursday, which analysts said bolsters its prospects of reaching $2 billion in annual sales.

Zuercher Kantonalbank said the outcome, in infants and toddlers between one month and seven months with the severest form of the genetic muscle-wasting disease, virtually guarantees risdiplam’s approval this year.

U.S. regulators are due to decide by May 24.

Roche’s study of 41 patients measured whether infants could sit independently for at least 5 seconds after 12 months of treatment. Roche, whose risdiplam aims to join Biogen’s Spinraza and Novartis’s gene therapy Zolgensma as approved SMA treatments, said no safety problems emerged that led patients to halt treatment.

“This large, global trial confirms the efficacy of risdiplam in an advanced and difficult-to-treat population, including many infants whose disease had already progressed significantly before starting treatment,” said Levi Garraway, Roche’s chief medical officer.

SMA is rare, but medicines to treat it are among the industry’s costliest, creating a potentially lucrative opportunity. Zolgensma runs $2.1 million per patient, to date the costliest one-time treatment, while Spinraza, injected in the spine, costs $750,000 for the first year and $375,000 annually thereafter at its U.S. list price.

“We’re almost certain of its approval,” Michael Nawrath, a Zuercher Kantonalbank analyst, said in a note to investors, predicting that risdiplam could become the standard treatment for patients with less-acute forms of SMA that emerge months after birth. “The sales peak is around 2 billion Swiss francs ($2.07 billion).”

(Reporting by John Miller; Editing by Michael Shields)