Phase I Safety and Tolerability Study of Staphylococcal Protein A in Adult Patients With Chronic ITP

An Open Label, Sequential, Dose Escalation, Repeat-dose Study of the Safety, Pharmacokinetics, Pharmacodynamics, and Immunogenicity of PRTX-100 in Adult Patients With Chronic Idiopathic Thrombocytopenic Purpura (ITP)

Status

Terminated

Phases

Phase 1

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT00571467

Enrollment

Registered

2007-12-12

Start date

2007-12-31

Completion date

2009-03-31

Last updated

2018-07-20

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Idiopathic Thrombocytopenic Purpura (ITP)

Keywords

Autoimmune Diseases, Bleeding Disorders, Blood and Blood Disorders

Brief summary

The primary purpose of this study is to evaluate the safety of multiple doses of Staphylococcal protein A (PRTX-100) in adult patients with Idiopathic Thrombocytopenia Purpura (ITP). The pharmacokinetics, immunogenicity and pharmacodynamics will also be studied. Patients will be enrolled into 1 of 3 dose groups and receive 4 weekly IV doses of PRTX-100. A Safety Monitoring Committee will review safety data through Day 28 for the first 5 patients in a dose group before escalation to the next higher dose level. Patients will be followed for 8 weeks after dosing for safety, PK, immunogenicity and effect on platelet count(pharmacodynamics).

Interventions

DRUGPRTX-100 (Staphylococcal protein A)

4 weekly IV (in the vein) doses of 1 of the 3 following PRTX-100 dose levels: * Cohort 1: 0.075 mcg/kg * Cohort 2: 0.15 mcg/kg * Cohort 3: 0.30 mcg/kg

Study design

Allocation

Intervention model

SINGLE_GROUP

Primary purpose

TREATMENT

Masking

NONE

Eligibility

Sex/Gender

ALL

Age

18 Years to No maximum

Healthy volunteers

Inclusion criteria

* Diagnosis of chronic ITP \> 4 months * Mean platelet count \<50 x 10\^9/L for patients not receiving corticosteroids; or mean platelet count \>=50 x 10\^9/L for patients receiving stable dose of corticosteroids

Exclusion criteria

* Splenectomy within 45 days of screening * Rituximab within 6 months prior to screening * Cyclophosphamide, vincristine, or any other non-monoclonal antibody treatment for ITP within 3 months prior to screening * IVIG, WinRho or other anti-RhD within 30 days prior to screening

Design outcomes

Primary

Measure	Time frame
Evaluate the overall safety of PRTX-100 during the 3 month study duration	3 months

Secondary

Measure	Time frame
Characterize the pharmacokinetics of multiple doses of PRTX-100	over the first 35 days
Explore immunogenicity of multiple doses of PRTX-10	3 months
Evaluate treatment effect on platelet count	3 months

Countries

Australia, New Zealand

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026