ZURICH (Reuters) – Roche expects its risdiplam medicine for spinal muscular atrophy (SMA) to get U.S. approval by May, the Swiss drugmaker said on Monday, as it takes on Novartis and Biogen in the lucrative rare disease area.

The U.S. Food and Drug Administration granted priority review for risdiplam, an oral medicine for those with the potentially deadly muscle-wasting disorder. Roche, whose drug is seen as a rival for Biogen’s Spinraza and Novartis’s Zolgensma gene therapy, said the FDA is due to decide by May 24.

Roche is seeking broad approval for people into adulthood with different forms of SMA, including the deadly Type 1 disease that kills many infants in their first months of life as well as Type 3 disease that may set in later but still leaves its victims with profound physical disabilities.

SMA is becoming a hard-fought battleground for drugmakers, as urgent need for treatments has helped lead to some of the highest prices in the pharmaceuticals industry.

Spinraza, administered via a spinal infusion, costs $750,000 for the first year and half that for every year thereafter, while Novartis’s Zolgensma is the industry’s most-expensive one-time treatment at $2.1 million per patient.

Roche trials “were designed to represent the real world spectrum of people living with SMA and include many people previously underrepresented in clinical trials,” Roche Chief Medical Officer Levi Garraway said in a statement.

Spinraza booked $1.7 billion in revenue in 2018, but this year has begun to face competition from Zolgensma after the gene therapy’s approval in May. Zolgensma sales were $175 million through September.

(Reporting by John Miller, editing by John Revill)