Baricitinib for Post-HSCT Persistent Thrombocytopenia (BAPT)

Safety and Efficacy of Baricitinib in Thrombopoietin-Receptor-Agonist-Refractory Persistent Thrombocytopenia After Allogeneic Hematopoietic Stem Cell Transplantation: A Phase Ib/II Study

This is a prospective, open-label phase 1b/2 clinical trial to explore the safety and efficacy profiles of baricitinib in patients with thrombopoietin-receptor-agonist-refractory persistent thrombocytopenia after allogeneic hematopoietic stem cell transplantation.

Study Overview

• Status: Not yet recruiting
• Conditions: Allogeneic Hematopoietic Stem Cell Transplantation; Persistent Thrombocytopenia
• Intervention / Treatment: Drug: Baricitinib

Detailed Description

Phase 1 part:

The phase 1b part will use a standard 3+3 design to explore the safety profiles and to establish the recommended phase 2 dose (RP2D) of baricitinib. The initial dose is 2 mg once daily, and the maximum dose is 4 mg once daily. Additional patients may be enrolled to further explore a selected dose defined by dose escalation cohorts (up to 9 patients in each dose level).

Phase 2 part:

The phase 2 part is a single-arm, open-label study to assess the efficacy and safety of baricitinib at RP2D in patients with thrombopoietin-receptor-agonist-refractory persistent thrombocytopenia after allogeneic hematopoietic stem cell transplantation. Patients in phase 1b who were treated with baricitinib at the RP2D will be included in the phase 2 efficacy endpoint analyses.

• Study Type: Interventional
• Enrollment (Estimated): 28
• Phase: Phase 2; Phase 1

Contacts and Locations

• Study Contact: Name: Peng Zhao; Phone Number: +86-18810323668; Email: zpeng702@163.com

Study Locations

• China
  • Beijing Municipality
    • Beijing, Beijing Municipality, China, 100044
      • Peking University People's Hospital
      • Contact: Yue Jin; Phone Number: +86-18161502996; Email: jinyue@pku.edu.cn

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Aged 18-70 years;
• Underwent allo-HSCT;
• Meet the diagnostic criteria for delayed platelet engraftment (DPE) or secondary failure of platelet recovery (SFPR);
• Have platelet counts consistently <20 ×10^9/L or transfusion-dependent within 14 days prior to enrollment;
• Have received adequate corticosteroid and TPO-RA therapy for persistent thrombocytopenia for no less than 4 weeks, with treatment failure or intolerance;
• Complete donor chimerism.

Exclusion Criteria:

• Relapse of hematologic malignancy or MRD positivity;
• Active infection;
• Active graft-versus-host disease;
• Thrombotic microangiopathy;
• Primary graft failure or poor graft function;
• Presence of other factors that may lead to secondary thrombocytopenia at the time of PT diagnosis;
• History of systemic herpes zoster infection within 12 weeks prior to enrollment screening;
• Acute or chronic infection with HBV, HCV, or HIV;
• Evidence of active tuberculosis, or history of active tuberculosis without documented standard anti-tuberculosis treatment, or close contact with active tuberculosis without documented standard tuberculosis prophylaxis;
• Receipt of a live vaccine within 12 weeks prior to enrollment screening, or planned receipt of a live vaccine during the study period;
• Clinically significant thromboembolic event within 24 weeks prior to enrollment screening, or current use of anticoagulant medications deemed by the investigator to carry an uncontrollable risk;
• Estimated glomerular filtration rate <50 mL/min/1.73 m^2;
• Severe pre-existing or current conditions involving the cardiovascular, respiratory, hepatic, gastrointestinal, endocrine, nervous, or neuropsychiatric systems, or other severe or unstable illnesses or laboratory abnormalities that will make the study drug unacceptable for the patient or can interfere study data;
• Participation in another clinical trial within 30 days prior to enrollment.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Baricitinib; Group A: Open label baricitinib at 2 mg daily (Phase 1) Group B: Open label baricitinib at 4 mg daily (Phase 1) Group C: Open label baricitinib at the RP2D (Phase 2)	Drug: Baricitinib; Baricitinib, an orally administered, selective, reversible JAK1/2 inhibitor.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Adverse events in the Ib part	The incidence and severity of adverse events are assessed using the criteria of CTCAE 5.0.	24 weeks
Overall response rate (ORR) for the IIa part	The proportion of patients achieving an overall response (OR), defined as a platelet count ≥20×10^9/L maintained for more than 7 days without transfusion support. Platelet counts obtained within 4 weeks after rescue therapy were not included in the efficacy assessment.	12 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Overall response rate (ORR) for the Ib part	The proportion of patients achieving an overall response (OR), defined as a platelet count ≥20×10^9/L maintained for more than 7 days without transfusion support. Platelet counts obtained within 4 weeks after rescue therapy were not included in the efficacy assessment.	12 weeks
Complete response (CR)	The proportion of patients achieving a complete response (CR), defined as a platelet count ≥50×10^9/L maintained for more than 7 days without transfusion support. Platelet counts obtained within 4 weeks after rescue therapy were not included in the efficacy assessment.	12 weeks
Durable response	The proportion of patients achieving a durable response (DR), defined as a platelet count ≥20×10^9/L maintained for more than 8 weeks without transfusion. Platelet counts obtained within 4 weeks after rescue therapy were not included in the efficacy assessment.	24 weeks
Time to response	The time from the date of the first dose of baricitinib to the date of OR or CR.	12 weeks
Bleeding events	Clinically significant bleeding as assessed using the world health organization (WHO) bleeding scale: 0, no bleeding; 1, petechiae; 2, mild blood loss; 3, gross blood loss; and 4, debilitating blood loss.	24 weeks
Rescue medication	Time and type of rescue medications, defined as any additional treatment intended to prevent bleeding or raise the platelet counts, including a dose increase of more than 10% above baseline of the concomitant medication and any additional PT-modifying agents (e.g., corticosteroids, intravenous immunoglobulin, and platelet transfusions).	24 weeks
Adverse events in the IIa part	Adverse events (AEs) are reported and graded in accordance with the Common Terminology Criteria for Adverse Events (CTCAE), version 5.0.	24 weeks
Overall Survival (OS)	The overall survival of patients who received at least one dose of baricitinib in the study.	104 weeks
Transplantation-related mortality (TRM)	All deaths without relapse or disease progression occurring after transplantation as a direct or indirect consequence of the transplant procedure or associated complications in patients who received at least one dose of baricitinib in the study.	104 weeks
Relapse or progression of underlying disease	Relapse or progression of underlying disease of patients who received at least one dose of baricitinib in the study.	104 weeks
Graft-versus-host disease	The incidence and severity of acute graft-versus-host disease and chronic graft-versus-host disease in patients who received at least one dose of baricitinib in the study.	104 weeks

Collaborators and Investigators

• Sponsor: Peking University People's Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): April 15, 2026
• Primary Completion (Estimated): December 31, 2027
• Study Completion (Estimated): September 15, 2029

Study Registration Dates

• First Submitted: April 6, 2026
• First Submitted That Met QC Criteria: April 14, 2026
• First Posted (Actual): April 17, 2026

Study Record Updates

• Last Update Posted (Actual): April 17, 2026
• Last Update Submitted That Met QC Criteria: April 14, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Allogeneic Hematopoietic Stem Cell Transplantation; Baricitinib; Persistent thrombocytopenia
• Additional Relevant MeSH Terms: baricitinib
• Other Study ID Numbers: 2026PHD005-BAPT

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No