A Study of Rilzabrutinib in Adult Patients With Immune Thrombocytopenia (ITP)

An Adaptive, Open-Label, Dose-Finding, Phase 1/2 Study Investigating the Safety, Pharmacokinetics, and Clinical Activity of PRN1008, an Oral BTK Inhibitor, in Patients With Relapsed Immune Thrombocytopenia

This is a 2 part (Part A and B) adaptive, open-label, dose-finding study of PRN1008 in patients with ITP who are refractory or relapsed with no available and approved therapeutic options, with a platelet count <30,000/μL on two counts no sooner than 7 days apart in the 15 days before treatment begins. The dose-finding portion of the study has been completed. Part B treatment dose is 400 mg twice daily.

This is a 2 part (Part A and B) adaptive, open-label, dose-finding study of PRN1008 in approximately 60 patients in Part A and approximately 25 patients in Part B. Part A enrolls patients with ITP who are refractory or relapsed with no available and approved therapeutic options. Eligible patients have a platelet count <30,000/μL on two counts no sooner than 7 days apart in the 15 days before treatment begins. The active treatment period is 24 weeks and the post-treatment follow-up period is 4 weeks. In the dose-finding part of the study, each patient enrolled in the study is allowed to up-titrate their dose after 28 days of PRN1008 therapy, if they do not experience a platelet response or a dose-limiting toxicity (DLT) at the last dose level. Patients who respond to PRN1008 per protocol may enter a long term-extension. Part B of the study will include approximately 25 patients with ITP who have relapsed or have an insufficient response to prior therapies. Eligible patients will have a platelet count <30,000/µL on two occasions no less than 7 days apart, within 15 days before treatment begins and a platelet count of ≤35,000/µL on Study Day 1 (SD1). The study consists of a 28-day screening period, 24-week active treatment period, and a long-term extension. After the last dose of PRN1008 there will be a 4-week safety follow-up period.

Part A approximately 60 patients: Up to 24 weeks open-label treatment with PRN1008 400mg BID; safety and dose evaluation. Patients who respond to PRN1008 per protocol may enter a long-term extension. Part B approximately 25 patients: Up to 24 weeks open-label treatment with PRN1008 400mg BID; safety and dose evaluation. Patients who respond to PRN1008 per protocol may enter a long-term extension

The incidence, severity and relationship of TEAEs during the treatment period and at the 4-week follow-up from last dose received.

Proportion of subjects able to achieve two or more consecutive platelet counts of ≥ 50,000/μL AND an increase of platelet count of ≥20,000/μL from baseline, without the use of rescue medication

Proportion of patients able to achieve platelet counts ≥50,000/μL on at least 8 out of the last 12 weeks of the 24-week treatment period without the use of rescue medication

Inclusion Criteria: Male or female patients, aged 18 to 80 years old Immune-related ITP (both primary and secondary) Exclusion Criteria: Pregnant or lactating women Current drug or alcohol abuse History of solid organ transplant Positive screening for HIV, hepatitis B, or hepatitis C

Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org

Kuter DJ, Efraim M, Mayer J, Trneny M, McDonald V, Bird R, Regenbogen T, Garg M, Kaplan Z, Tzvetkov N, Choi PY, Jansen AJG, Kostal M, Baker R, Gumulec J, Lee EJ, Cunningham I, Goncalves I, Warner M, Boccia R, Gernsheimer T, Ghanima W, Bandman O, Burns R, Neale A, Thomas D, Arora P, Zheng B, Cooper N. Rilzabrutinib, an Oral BTK Inhibitor, in Immune Thrombocytopenia. N Engl J Med. 2022 Apr 14;386(15):1421-1431. doi: 10.1056/NEJMoa2110297.

Del Pozo Martin Y. 2021 ASH annual meeting. Lancet Haematol. 2022 Feb;9(2):e92-e93. doi: 10.1016/S2352-3026(21)00384-7. Epub 2021 Dec 16. No abstract available.