Efficacy and Safety of Rapamycin Therapy for Patients With Activated Phosphoinositide 3-Kinase δ Syndrome
Efficacy and Safety of Rapamycin Therapy for Patients With Activated Phosphoinositide 3-Kinase δ Syndrome
The purpose of this proposed research is to evaluate the efficacy and safety of the rapamycin therapy in patients with activated phosphoinositide 3-kinase δ syndrome (APDS).
Activated phosphoinositide 3-kinase δ syndrome (APDS) is a recently described autosomal dominant primary immunodeficiency (PID), caused by the mutations in PIK3CD gene. The manifestations of APDS mainly include recurrent respiratory tract infections, persistent Epstein-Barr virus (EBV)/ cytomegalovirus (CMV)infections, lymphadenopathy, splenomegaly, CD4+T cells lymphopenia, and hyper-IgM syndrome. PIK3CD encodes p110δ, the catalytic subunit of phosphatidylinositol 3-kinase (PI3K) which mainly expresses in leukocytes, being critical for their proliferation, activation and survival. Gain-of-function (GOF) PIK3CD mutations lead to PI3Kδ hyperactivity, with the downstream mediators Akt and mammilian target of rapamycin (mTOR) hyperphosphorylated. Patient-derived lymphocytes had increased levels of phosphatidylinositol 3,4,5-trisphosphate and phosphorylated AKT protein. Hyperactivation of mTOR increases phosphorylation of kinases and increased glycolysis that results in enhanced proliferation and senescence of terminally differentiated CD8+ Tcell populations.
The optimal treatment for these APDS patients is not yet determined; however, there are many kinds of therapeutic approaches (anti-infection prophylaxis, immunoglobulin replacement, conventional immunosuppressants, PI3K/mTOR inhibitors and hematopoietic stem cell transplantation). The APDS patients frequently receive treatment with immunoglobulin replacement and antibiotics. Hematopoietic stem cell transplantation (HSCT) has been currently curative in APDS patients; however, longer-term follow-up to determine the degree of donor chimerism and efficacy is required. There are several subjects without a prompt suitable matched donor or for whom the critical disease conditions force to postpone HSCT.The mammalian/mechanistic target of inhibitor rapamycin was reported to improve circulating T-cell profiles. Individual patients in previous studies experienced a decrease in nonneoplastic lymphoproliferation while taking rapamycin.
The investigators in this study hope to evaluate the efficacy and safety of rapamycin in the treatment for carefully selected patients with APDS.
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