Shares of Apellis Pharmaceuticals Inc. /zigman2/quotes/202103251/composite APLS -4.60% gained 5.1% in premarket trading on Friday after it shared details from a late-stage clinical trial evaluating its experimental drug pegcetacoplan against Alexion Pharmaceuticals Inc.'s /zigman2/quotes/206262068/composite ALXN -0.36% Soliris as a treatment for paroxysmal nocturnal hemoglobinuria. The study found that pegcetacoplan was better than Soliris in improving hemoglobin levels in adults with the rare blood disease. Soliris brought in $3.9 billion in revenue in 2019. Apellis said it plans to submit a new drug application for pegcetacoplan to the Food and Drug Administration in the second half of the year. Its stock is down 0.5% year-to-date, while the S&P 500 /zigman2/quotes/210599714/realtime SPX +0.30% has declined 7.1%.