Core Viewpoint - Pharming Group N.V. announced that the FDA has accepted its supplemental New Drug Application for leniolisib, aimed at treating children aged 4 to 11 years with activated phosphoinositide 3-kinase delta syndrome (APDS), with a target action date of January 31, 2026 [1][7]. Group 1: FDA Approval Process - The supplemental New Drug Application is based on positive results from a Phase III study showing improvements in lymphadenopathy and naïve B cells over 12 weeks [2]. - The FDA has granted Priority Review status to the application, indicating that the treatment could offer significant improvements in effectiveness or safety for serious conditions [3]. Group 2: Disease Background - APDS is a rare primary immunodeficiency characterized by immune dysregulation and recurrent infections, often leading to severe complications such as lung damage and lymphoma [5]. - The condition affects approximately 1 to 2 individuals per million globally, and patients often experience a median diagnostic delay of 7 years [5]. Group 3: Treatment Details - Leniolisib is an oral PI3Kδ inhibitor, previously approved for patients aged 12 and older, and is the first targeted treatment for APDS [6][4]. - The drug has shown statistically significant improvements in clinical trials, and its safety and tolerability have been supported by long-term data [6]. Group 4: Future Developments - Leniolisib is currently under regulatory review in multiple regions, including the European Economic Area, Japan, and Canada, for its use in APDS [6]. - The company is also evaluating leniolisib in additional clinical trials for other primary immunodeficiencies with immune dysregulation [8].