Treatment of Chronic ITP with Avatrombopag: A Multicentric Real-World Experience

INTRODUCTION

Chronic immune thrombocytopenia (ITP) is a bleeding disorder characterized by a low platelet count that persists for 12 months or more. Initial treatments usually include corticosteroids or intravenous immunoglobulin (IVIG). For patients who are refractory or relapsed, or who may not adhere well to treatment, second-line therapies come into play. These include: i) Thrombopoietin receptor agonists (TPO-RAs) such as Romiplostim, Eltrombopag, or Avatrombopag, and ii) Rituximab or other immunosuppressive agents such as azathioprine, mycophenolate mofetil, or ciclosporin. Splenectomy, although an option, is generally considered a last resort for patients who do not respond to or tolerate other treatments.

AIM OF THE STUDY

To assess the efficacy and safety of Avatrombopag in patients with chronic ITP, stratified by prior exposure to other TPO-RAs.

RESULT

Fifty-seven patients with immune thrombocytopenia (ITP) treated with Avatrombopag were enrolled from five Italian hematology units. The median age at the start of treatment was 60.8 years (range 20.3 - 92.3), with a slight predominance of women (56.1%). Patients had received a mean of three prior therapies (range 0 - 10), and 43 patients (75.4%) had previously been exposed to at least one other thrombopoietin receptor agonist (TPO-RA).

At baseline, the median platelet count (evaluated in 54 patients) was 11000/mm3 (range 2000-50000). An additional 3 patients switched to Avatrombopag due to intolerance to other TPO-RAs, with no washout time, and had baseline platelet counts > 90000/mm3.

The median time to platelet counts greater than 50000/mm3 (assessed from 54 patients who started with low counts) was 27 days (range 3 - 456 ). At a median follow-up of 4.9 months (range 0.3 - 14.6), 40 patients (70.2%) were still on treatment, with a median platelet count of 96000/mm3 (range 13000 - 403000). Thrombotic events were observed in 4 patients (7%), while bleeding events occurred in 5 patients (8.8%), but only 3 of these led to treatment discontinuation. Additionally, 4 deaths were recorded: 1 due to a COVID infection, 1 from acute renal failure, 1 from a subdural hematoma, and 1 unrelated death.

CONCLUSIONS

To our knowledge, this is the first large real-world experience reported in Italy for Avatrombopag treatment in patients with immune thrombocytopenia (ITP). Our data confirmed the high efficacy of this therapy, even in heavily pretreated patients, including those with prior exposure to one or two TPO-RAs. The safety profile was acceptable, with few adverse events (including thrombotic and hemorrhagic events) leading to discontinuation. However, more data and longer follow-up are needed to evaluate the duration of response.

Scalzulli:Seattle-Genetics, Genmab,Viracta: Membership on an entity's Board of Directors or advisory committees. Pane:GSK Incyte Amgen BMS Janssen Jazz Novartis Pfizer: Speakers Bureau; GSK Incyte: Consultancy.