A Phase 1b/2a Study of Budoprutug in Subjects With Immune Thrombocytopenia (ITP)

Not Applicable

Recruiting

• Conditions: Immune Thrombocytopenia (ITP); ITP; Biologics; Monoclonal; Anti-CD19
• Interventions: Drug: Budoprutug

• Registration Number: NCT07043946
• Lead Sponsor: Climb Bio, Inc.

Brief Summary

The main objective is to assess the safety and tolerability of budoprutug in adults with ITP. Pharmacokinetics, pharmacodynamics, and preliminary clinical efficacy will also be assessed.

Detailed Description

Budoprutug is a humanized, immunoglobulin (Ig) G1 monoclonal antibody that selectively binds to CD19 and is projected to deplete targeted cells through antibody-dependent cellular cytotoxicity. This Phase 1b/2a, open-label, sequential-cohort, dose escalation and expansion study will evaluate the safety, tolerability, PK, PD, and preliminary clinical effectiveness of budoprutug in subjects with ITP. Budoprutug will be administered as two (2) IV infusions 14 days apart in ascending dose cohorts of patients aged 18 years and above with a platelet count \< 30,000/µL despite an adequate trial of at least one prior therapeutic attempt.

Study Timeline

• Study First Submitted: 2025-06-20
• Study First Submitted QC: 2025-06-20
• Study First Posted: 2025-06-29
• Study Start: 2025-06-30
• Status Verified: 2025-11
• Last Update Submitted: 2025-11-03
• Last Update Posted: 2025-11-05
• Primary Completion: 2027-08
• Study Completion: 2028-08-01

Recruitment & Eligibility

• Status: RECRUITING
• Sex: All
• Target Recruitment: 24

Inclusion Criteria

1. Aged 18 years at the time of consent.
2. Platelet count < 30,000/µL despite an adequate trial of at least one prior therapeutic attempt. Platelet counts of < 30,000/µL must be confirmed on 2 occasions at least 5 days apart, but no more than 14 days apart.
3. Partial thromboplastin time < 1.5 x upper limit of normal (ULN), prothrombin time < 1.5 x ULN, total bilirubin < 1.5 x ULN unless due to Gilbert's syndrome, or an international normalized ratio < 1.5 at screening.

Exclusion Criteria

1. CD19+ B cell count < 80 cells/µL at Screening, or < 40 cells/µL if B-cell depleting therapy was received within 24 weeks to 2 years prior.
2. Diagnosis of paroxysmal nocturnal hemoglobinuria, Evan's Syndrome, or other bleeding disorders affecting safety or data integrity.
3. Prior B-cell depleting therapy (e.g., rituximab) within 24 weeks before first dose or planned during the study.
4. Chronic use of anticoagulants or antiplatelet agents (e.g., aspirin, NSAIDs, thienopyridines) within 14 days before dosing through follow-up. Intermittent NSAID use is allowed.
5. Immunosuppressants (excluding corticosteroids) within 30 days or 5× half-life before Screening; alkylating agents within 180 days.
6. IVIg treatment within 90 days prior to Screening.
7. Active ITP treatment (other than steroids or TPO agonists) within 30 days or 5× half-life before first dose, unless approved by Medical Monitor.
8. Active, chronic, or latent infections including hepatitis B/C or HIV.
9. Active TB or high TB risk.

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: SEQUENTIAL

Arm && Interventions

Group	Intervention	Description
Cohort 1: Dose Level A	Budoprutug	Single IV dose of study product on Day 1 and on Day 15
Cohort 2: Dose Level B	Budoprutug	Single IV dose of study product on Day 1 and on Day 15
Cohort 3: Dose Level C	Budoprutug	Single IV dose of study product on Day 1 and on Day 15
Dose Expansion Cohort	Budoprutug	Single IV dose of study product on Day 1 and Day 15

Primary Outcome Measures

Name	Time	Method
Incidence of Treatment-Emergent Adverse Events (TEAEs)	Up to week 48	Number of participants experiencing TEAEs, graded per NCI CTCAE v5.0.

Secondary Outcome Measures

Name	Time	Method
Apparent Clearance (CL/F)	Up to week 48	Measurement of the apparent clearance in L/hour.
Area Under the Curve (AUC)	Up to week 48	Measurement of the area under the drug concentration-time curve.
Maximum Observed Plasma Concentration (Cmax)	Up to week 48	Measurement of the maximum observed plasma concentration.
Time to Maximum Observed Concentration (Tmax)	Up to week 48	Measurement of the time to maximum observed concentration.
Terminal Half-Life (T1/2)	Up to week 48	Measurement of the terminal half-life in days.
Change from Baseline in CD20+ B-cell Count	Up to week 48	Change in absolute peripheral CD20+ B-cell count
Change in Platelet Count	Up to week 48	Change in platelet count over time
Proportion of Participants with stable, partial or complete platelet response	Up to week 48	Percentage of participants with stable, partial or complete platelet response.
Incidence of Anti-Drug Antibodies (ADAs)	Up to week 48	Number of participants with detectable ADAs.
Steroid Discontinuation Rate	Up to week 48	% of baseline steroid users who discontinue steroids.

Trial Locations

Locations (19)

Climb Bio Investigative Site #359202; 🇧🇬 Plovdiv, Bulgaria

Climb Bio Investigative Site #359203; 🇧🇬 Plovdiv, Bulgaria

Climb Bio Investigative Site #359201; 🇧🇬 Sofia, Bulgaria

Climb Bio Investigative Site #300204; 🇬🇷 Athens, Attica, Greece

Climb Bio Investigative Site #300203; 🇬🇷 Chaïdári, Attica, Greece

Climb Bio Investigative Site #300202; 🇬🇷 Ioannina, Greece

Climb Bio Investigative Site #300201; 🇬🇷 Thessaloniki, Greece

Climb Bio Investigative Site #340206; 🇪🇸 Burgos, Attiki, Spain

Climb Bio Investigative Site #340202; 🇪🇸 Cáceres, Attiki, Spain

Climb Bio Investigative Site #340204; 🇪🇸 Madrid, Attiki, Spain

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