Celltrion specializes in “bio­similars”—cheaper generic versions of the pricey “biologic” drugs that are among Big Pharma’s bestsellers. Wall Street analysts project that the firm could achieve up to 25% future annual growth, with sales in multiple markets. U.S. regulators approved this country’s first ­biosimilar in 2015. Since then, Celltrion and its partners have won FDA approval for copies of Johnson & Johnson’s anti-­inflammatory treatment ­Remicade. And in early October, the team got an important preliminary thumbs-up from an FDA advisory panel for a biosimilar version of Roche’s blockbuster cancer drug Rituxan.