Primary Immunodeficiency with the PI3K Delta Activation: Clinical Features and Prospective Therapy

Abstract

Primary immunodeficiency (PID) constitute a polymorphic group of genetic life-threatening disorders. APDS (activated phosphoinositide 3-kinase δ) represents a rare PID caused by monoallelic gain of function defects in the PIK3CD gene, or monoallelic loss of function defects in the PIK3R1 and PTEN genes. Disease symptoms usually manifest early in life and include recurrent bacterial infections, non-malignant and malignant lymphoproliferation, persistent herpes virus infections and a whole spectrum of autoimmune manifestations. Immunological features include T and B lymphocytes defects. APDS treatment including immunoglobulin substitution and immunosuppression does not always lead to complete remission of the disease. Hematopoietic stem cell transplantation is a curative option leading to disease resolution in 75–80% of the patients. In 2023 FDA approved leniolisib — selective PI3Kδ inhibitor — for APDS treatment. In the clinical trial the preparation demonstrated safety and efficacy for the patients with APDS ages 12 and above. Approval of the drug created specifically to treat this rare variant of PID opens a new era of the targeted treatment for the patients with this orphan disease.