Alexion Pharmaceuticals, Inc. ALXN announced that the FDA approved its long-acting C5 complement inhibitor, Ultomiris, for the treatment of children (aged one month and above) as well as adolescents with paroxysmal nocturnal hemoglobinuria (PNH), a serious ultra-rare blood disorder.Following the FDA nod, Ultomiris became the first and only medicine to be approved for treating children and adolescents with PNH in the United States. Alexion plans to immediately launch Ultomiris for pediatric patients in the United States.A regulatory filing, seeking approval for Ultomiris in pediatric patients with PNH, is currently under review in the European Union.The latest FDA nod was based on interim data from the phase-III study, which evaluated Ultomiris in the given patient population. Data from the same showed that Ultomiris was effective in achieving complete C5 complement inhibition in children and adolescents up to 18 years of age through 26 weeks.Shares of Alexion have rallied 12.8% so far this year against the industry’s decline of 4%. Image Source: Zacks Investment ResearchWe remind investors that Ultomiris is already approved for the treatment of adult patients with PNH. It is also approved for adults and pediatric patients of one month of age and older with the atypical hemolytic uremic syndrome (aHUS), which is also an ultra-rare disease that can cause progressive injury to vital organs.Last October, the FDA approved a new advanced formulation of Ultomiris 100 mg/mL for the treatment of PNH in adults and aHUS to inhibit complement-mediated thrombotic microangiopathy for adult and pediatric patients (one month of age and older). The European Commission has also approved a 100 mg/mL intravenous formulation of Ultomiris for the given patient population.We note that Ultomiris’ uptake has been strong since its launch. In the first quarter of 2021, the drug generated sales worth $346.9 million, representing a 56% year-over-year increase.Label expansions of the drug to include a broader patient population should further boost sales in 2021 and beyond. Also, several label expansion studies on Ultomiris for addressing additional indication are currently underway.Zacks Rank & Stocks to ConsiderAlexion currently carries a Zacks Rank #3 (Hold). Some better-ranked stocks in the biotech sector are Repligen Corporation RGEN, Kamada Ltd. KMDA and Bio-Techne Corporation TECH, all carrying a Zacks Rank #2 (Buy) at present. You can see the complete list of today’s Zacks #1 Rank (Strong Buy) stocks here.Repligen’s earnings estimates have been revised 15.7% upward for 2021 and 14.7% upward for 2022 over the past 60 days.Kamada’s earnings estimates have been revised 21.4% upward for 2021 and 18.1% upward for 2022 over the past 60 days.Bio-Techne’s earnings estimates have been revised 8.8% upward for 2021 and 9.1% upward for 2022 over the past 60 days. The stock has gained 32.1% year to date.More Stock News: This Is Bigger than the iPhone!It could become the mother of all technological revolutions. Apple sold a mere 1 billion iPhones in 10 years but a new breakthrough is expected to generate more than 77 billion devices by 2025, creating a $1.3 trillion market.Zacks has just released a Special Report that spotlights this fast-emerging phenomenon and 4 tickers for taking advantage of it. If you don't buy now, you may kick yourself in 2022.Click here for the 4 trades >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Alexion Pharmaceuticals, Inc. (ALXN): Free Stock Analysis Report Repligen Corporation (RGEN): Free Stock Analysis Report BioTechne Corp (TECH): Free Stock Analysis Report Kamada Ltd. (KMDA): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research