Shares of Viela Bio Inc. /zigman2/quotes/214411364/composite VIE -1.16% were up 4.9% in premarket trading on Friday, the day after the company received approval from the Food and Drug Administration (FDA) to market Uplizna to treat neuromyelitis optica spectrum disorder. It is the second treatment for the rare neuroinflammatory disorder to receive FDA approval. The drug helps reduce the risk of attacks that can lead to paralysis and blindness. Viela said it plans to launch Uplizna this month; a company spokesperson declined to provided pricing information at this time but said the drug will be priced "favorably" and "significantly lower" than Alexion Pharmaceuticals Inc.'s /zigman2/quotes/206262068/composite ALXN -0.36% Soliris. Stifel analysts predict roughly $500 million in sales of Uplizna in the U.S. per year. "From our review of the label, it looks largely in-line with base case expectations," they wrote in a June 12 note to investors. Viela's stock is up 89.5% year-to-date. The S&P 500 /zigman2/quotes/210599714/realtime SPX +0.30% is down 7.1% since the start of the year.