Abstract Number: OC 73.1
Meeting: ISTH 2022 Congress
Theme: Platelet Disorders, von Willebrand Disease and Thrombotic Microangiopathies » Acquired Thrombocytopenias
Background: Rilzabrutinib led to rapid and durable platelet responses and was well tolerated in a global phase I/II trial in adult patients with ITP (NCT03395210). We present additional findings observed during the main study period in patients who initiated 400 mg BID as well as patients who are continuing in the LTE.
Aims: Assess efficacy and safety of rilzabrutinib 400 mg BID.
Methods: Patients with 2 baseline platelet counts < 30x10^9/L were required to have responded to ≥1 prior ITP therapy, but at baseline were unable to maintain an adequate response to prior/concomitant therapies. Primary endpoints were safety and efficacy: ≥2 consecutive platelet counts ≥50x10^9/L and increased ≥20x10^9/L from baseline without requiring rescue medication. All patients provided informed consent.
Results: As of 04May2021, 60 patients received rilzabrutinib, 45 initiated a 400 mg BID dose, 16 proceeded to the LTE. At enrollment, patients were heavily pretreated with a median of 4 unique prior therapies. Median ITP duration was 6.1 years and median platelet count was 15×10^9/L. With a median treatment duration of 168 days during the main period, 18 patients (40%) achieved the primary endpoint (Table). In primary responders, platelet counts ≥50×10^9/L were maintained for a median of 72% of the weeks and the median time to first platelet count ≥50×10^9/L was 12.5 days. Figure shows subgroup analysis. Overall, LTE patients received rilzabrutinib for a median of 478 days and 13/14 patients (93%) maintained platelet counts ≥50×10^9/L for ≥50% of their monthly visits in the LTE (Table). Five patients (11%) received rescue medication during the main period + LTE. All treatment-related adverse events were grade 1/2 and transient without related thrombotic events or deaths.
Conclusion(s): Over prolonged treatment, rilzabrutinib 400 mg BID demonstrated a rapid and durable clinical activity and continued to be well-tolerated in patients with ITP.
To cite this abstract in AMA style:
Kuter D, Efraim M, Kaplan Z, Mayer J, Choi P, Jansen A, McDonald V, Baker R, Bird R, Garg M, Gumulec J, Kostal M, Gernsheimer T, Ghanima W, Yao M, Cooper N, Daak A. Updated Main Study Period and Long-Term Extension (LTE) Results With Oral Bruton Tyrosine Kinase Inhibitor Rilzabrutinib in Immune Thrombocytopenia (ITP) [abstract]. https://abstracts.isth.org/abstract/updated-main-study-period-and-long-term-extension-lte-results-with-oral-bruton-tyrosine-kinase-inhibitor-rilzabrutinib-in-immune-thrombocytopenia-itp/. Accessed September 24, 2023.« Back to ISTH 2022 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/updated-main-study-period-and-long-term-extension-lte-results-with-oral-bruton-tyrosine-kinase-inhibitor-rilzabrutinib-in-immune-thrombocytopenia-itp/