Eltrombopag: TPO-Receptor Agonist in ITP and Severe Aplastic Anemia

　　1.Drug Positioning

　　Eltrombopag is an oral thrombopoietin receptor agonist.It activates TPO-receptor signaling to promote megakaryocyte maturation and raise platelet counts.

　　Main settings:

　　Immune thrombocytopenia(ITP)—persistent/chronic,inadequate prior response;

　　Severe aplastic anemia(SAA)—with immunosuppressive therapy when label-eligible;

　　Selected HCV-associated thrombocytopenia—only under local label.

　　It is not for all thrombocytopenias;infection,hypersplenism,marrow infiltration,or drug-induced causes must be ruled out first.

　　2.Mechanism

　　ITP combines low production and antibody-mediated destruction.Eltrombopag bypasses immune clearance and rebuilds production capacity:

　　binds TPO receptor;

　　drives megakaryocyte proliferation/differentiation;

　　reduces bleeding risk;

　　complements,but does not replace,steroids/IVIG/surgery.

　　3.Earlier-Line Evidence

　　Pediatric new-diagnosis ITP:PINES

　　Randomized open-label trial,ages 1–<18:

　　eltrombopag response~67%at 12 weeks;

　　standard care~35%;

　　many tapered off within~6 months;

　　but 1-year remission rates were similar.

　　Read:faster acute-phase control,not proven disease modification.

　　Adult new-diagnosis ITP

　　Eltrombopag+short-course high-dose dexamethasone:

　　faster rise,possibly fewer relapses;

　　limited sample/follow-up;

　　not yet a universal first-line standard.

　　4.Aplastic Anemia

　　In SAA,eltrombopag+ciclosporin(±ATG):

　　higher overall and complete response;

　　pediatric ESCALATE phaseⅡ:~54.9%response at 26 weeks;

　　transfusion independence in a meaningful subset.

　　Long-term use carries clonal evolution risk​(cytogenetic abnormalities,MDS transition).Requires hematology follow-up with marrow and karyotype monitoring—no self-extension of therapy.

　　5.Dosing Details

　　Once daily.

　　Adults/≥6y ITP:often 50 mg/day;1–5y:25 mg/day.

　　East Asian and hepatic-impairment patients:lower starting dose.

　　Polyvalent cations matter:separate from calcium,iron,magnesium,aluminum,zinc,dairy,antacids by the labeled interval;prefer empty stomach or low-calcium meal.

　　6.Monitoring

　　CBC/platelet trends at start,titration,and after stop.

　　Liver function tests.

　　Thrombosis risk rises with rapid platelet recovery.

　　Long-term:marrow reticulin,peripheral smear,cataract screening.

　　Do not double-dose after a miss,and never stop abruptly—rebound thrombocytopenia can occur.

　　7.Common Questions

　　Q1:How fast does it work?​

　　Some ITP patients respond in 1–2 weeks;variability is high.

　　Q2:Long-term use?​

　　Possible in chronic ITP;in SAA,weigh clonal risk and response durability.

　　Q3:Originator vs overseas generic?​

　　Judge by regulatory approval,manufacturer,quality system,and traceability—not the label alone.