VPB0366 - Serial Thrombopoietin Levels in Immune Thrombocytopenia Patients on Treatment.

Sunday, July 10, 2022

6:30 PM – 7:30 PM

Location: Exhibition

Presentation Format: Virtual

Presenting Author(s)

Philippa J. Woolley, MBChB, MRCP, FRCPath

Haematology specialist registrar
University College London Hospitals NHS Foundation Trust, London, United Kingdom
London, England, United Kingdom

Co-Author(s)

JW

John-Paul Westwood

Consultant Haematologist
University College Hospitals London NHS Foundation Trust
London, England, United Kingdom
Marie Scully, MD

Professor of Haemostasis and Thrombosis
Department of Haematology, University College London Hospitals, London, UK
London, England, United Kingdom

Background: Measurement of serum thrombopoietin (TPO) levels may predict treatment response to TPO receptor agonist (TPO-RA) therapy.

Aims: To evaluate the clinical relevance of TPO levels in ITP patients receiving TPO-RAs.

Methods: Serum TPO concentration was measured by ELISA and using linear regression calculation, normal TPO range was 8.8pg/ml -114pg/ml from 50 normal controls. Written consent was obtained

Results: 171 serial TPO samples from 105 patients were included in the analysis and patients divided into 3 groups; ITP patients not on treatment (n=52), patients on Eltrombopag (n=42) and patients on Romiplostim (n=11). There was no correlation between TPO level and platelet count for patients not on treatment (p=0.29). Patients on Eltrombopag had a median platelet count of 75x109/L(range 3x109/L-333x109/L) a median TPO level of 181.45pg/ml. Patients on Romiplostim had median platelet count of 61x109/L (range 2x109/L-425x109/L) with a median TPO level of 61pg/ml. TPO level was inversely proportional to platelet count for patients on Eltrombopag (p=0.04) and Romiplostim (p=0.02), however this relationship was lost for non-responders (platelet count < 30x109/L) on Eltrombopag (median TPO level 184.65pg/ml(range 29.70pg/ml-1299.81pg/ml)(p=0.7)(Figure 1).

Figure 2 demonstrates the difference between Eltrombopag and Romiplostim effect on TPO level. Adjustment for different drug dose removes this as a confounder. As drug dose increased so did platelet count (p= < 0.0001) and for both drugs an inverse relationship between TPO level and platelet count is noted (p= < 0.0001); median TPO level for Eltrombopag 187.81pg/ml and Romiplostim 158.80pg/ml. TPO-RA responders (platelet count >30x109/L) had lower TPO levels than non-responders.

Conclusion(s): TPO level and platelet count have an inverse relationship for patients on TPO-RA therapy. Eltrombopag and Romiplostim affect TPO levels differently at any given platelet count for responsive patients with both drugs showing an inverse relationship to platelet count. This confirms TPO levels are a potentially clinically useful management tool in patients with ITP.