The Safety, Tolerability, Pharmacokinetics, and Preliminary Efficacy of HMPL-523 in Adult Subjects With Immune Thrombocytopenia (ITP)

Inclusion Criteria:

Subjects may be enrolled in this study only if they satisfy all the following criteria:

1. Adult male or female subjects ≥18 years of age

2. Diagnosis of ITP, with a duration of disease of at least 3 months prior torandomization or enrollment

3. Intolerance or insufficient response or recurrence after at least 1 prior ITPtreatment (excluding splenectomy)

4. Response (defined as achieved a platelet count ≥50 × 109/L) to at least 1 prior ITPtherapy (including splenectomy)

5. Adequate hematologic, hepatic and renal function

Exclusion Criteria:

Subjects are not eligible for enrollment into this study if any one of the following criteria are met:

1. Evidence of the presence of secondary causes of ITP

2. Clinically serious hemorrhage requiring immediate adjustment of platelets

3. Known history of vital organ transplantation or hematopoietic stem-celltransplantation or chimeric antigen receptor T-cells (CAR-T) therapy

4. Splenectomy within 12 weeks prior to enrollment

5. Presence of active malignancy unless deemed cured by adequate treatment.

6. History of serious cardiovascular disease corrected QT interval (QTcF) ≥450 ms

7. Uncontrolled hypertension

8. Being unsuitable to participate in this study as considered by investigators