Abstract Number: PB0823
Meeting: ISTH 2021 Congress
Theme: Platelet Disorders, von Willebrand Disease and Thrombotic Microangiopathies » Acquired Thrombocytopenias
Background: Avatrombopag is an oral thrombopoietin receptor agonist (TPO-RA) approved for treatment of immune thrombocytopenia (ITP). Data describing effectiveness of avatrombopag following treatment with other TPO-RAs is limited.
Aims: Evaluate ITP treatment outcomes in patients switching from eltrombopag/romiplostim to avatrombopag.
Methods: We retrospectively evaluated all adults with ITP switched from eltrombopag or romiplostim to avatrombopag at four U.S. tertiary ITP referral centers from July 2019 through December 2020 who were treated with avatrombopag for ≥2 months.
Results: 45 patients were included, with a median (range) age of 60 (21-87) years; 53% were female. Mean avatrombopag treatment duration was 9 months. At avatrombopag initiation, patients had ITP for a mean of 8.3 years with a mean (range) of 4.8 (2-10) prior ITP treatments. The reason for switching to avatrombopag was convenience in 51%, ineffectiveness of romiplostim/eltrombopag in 31%, and adverse event on romiplostim/eltrombopag in 18%.
Platelet Outcomes: In all patients, the median platelet count (Plt) on eltrombopag or romiplostim was 45×109/L vs. 114×109/L on avatrombopag (P<0.0001); in patients switched for ineffectiveness of romiplostim/eltrombopag, it was 28×109/L on romiplostim/eltrombopag vs. 88×109/L on avatrombopag (P=0.025), FIGURE. Regardless of the indication for switching, most patients achieved a complete response (Plt≥100×109/L) on avatrombopag (TABLE).
Concomitant Medications/Rescue Therapy: Of the 19 patients who required concomitant corticosteroids while on romiplostim/eltrombopag, 12 (63%) discontinued steroids, 6 (32%) reduced steroid dose, and none increased steroid dose after switching to avatrombopag. 15 patients (33%) required rescue in the year prior to switching versus 9 (20%) following the switch.
Avatrombopag Discontinuation: 2 patients (4%) discontinued for adverse events (headache, portal vein thrombosis) and 1 (2%) discontinued for lack of response.
| Platelet Count Threshold | Reason for Switch from Eltrombopag or Romiplostim to Avatrombopag | |||
| All Patients (N=45) | Ineffectiveness (N=14) | Convenience (N=23) | Adverse Event (N=8) | |
| ≥30×109/L | 42/45 (93%) | 12/14 (86%) | 23/23 (100%) | 7/8 (88%) |
| ≥50×109/L | 42/45 (93%) | 12/14 (86%) | 23/23 (100%) | 7/8 (88%) |
| ≥100×109/L | 39/45 (87%) | 10/14 (71%) | 22/23 (96%) | 7/8 (88%) |
Rates of platelet response following switch to avatrombopag in the absence of rescue therapy (counts were disqualified if <8 weeks from receipt of rescue corticosteroids or <4 weeks from IVIG).
Median platelet counts for each patient prior to switch (during treatment with romiplostim or eltrombopag) vs. following the switch to avatrombopag. For each patient, the median platelet count is the median of the most recent 3 platelet counts measured while receiving that agent. (A) All patients (N=45). (B) Patients switched due to ineffectiveness of romiplostim or eltrombopag (N=14). One patient with median Plt 585×109/L on avatrombopag omitted from both graphs to preserve graph resolution.
Conclusions: In a heavily-pretreated chronic ITP population, avatrombopag was effective following therapy with romiplostim or eltrombopag, with high response rates even in patients with inadequate response to a prior TPO-RA.
To cite this abstract in AMA style:
Al-Samkari H, Jiang D, Gernsheimer T, Liebman H, Lee S, Wojdyla M, Vredenburg M, Cuker A. Switching from Eltrombopag or Romiplostim to Avatrombopag in Immune Thrombocytopenia: A Multicenter Study of U.S. ITP Referral Centers [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/switching-from-eltrombopag-or-romiplostim-to-avatrombopag-in-immune-thrombocytopenia-a-multicenter-study-of-u-s-itp-referral-centers/. Accessed December 11, 2023.« Back to ISTH 2021 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/switching-from-eltrombopag-or-romiplostim-to-avatrombopag-in-immune-thrombocytopenia-a-multicenter-study-of-u-s-itp-referral-centers/