Biotech stocks reversed course and advanced solidly in the week ending Dec. 17, as an increase in risk aversion pushed investors to buy into defensive stocks. The sector also drew strength from some positive stock-specific news. Among the regulatory decisions for the week, the Food and Drug Administration gave the green light to argenx SE’s efgartigimod for the treatment of generalized myasthenia gravis. AstraZeneca plc. and Amgen, Inc. announced an FDA nod for their Tezspire as a treatment option for severe asthma for those aged 12 years and older. Bristol-Myers Squibb Company’s Orencia was approved for the prophylactic treatment of acute graft-versus-host disease. Calliditas Therapeutics AB. (publ) scored an FDA win for Tarpeyo, the first-approved treatment to reduce proteinuria in adults with primary immunoglobulin A nephropathy at risk of rapid disease progression. Galera Therapeutics Inc. was among the biggest gainers in the space following a positive late-stage readout. Novavax Inc. gained about 30 …