A Pilot Study of N-acetylcysteine in Thrombotic Thrombocytopenia Purpura

Purpura, Thrombotic Thrombocytopenic Clinical Trial

— NACinTTP  

Official title:

A Pilot Study of N-acetylcysteine in Suspected Thrombotic Thrombocytopenia Purpura

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT01808521
• Other study ID #: N-Acetylcysteine in TTP
• Status: Completed
• Phase: Early Phase 1
• First received: February 22, 2013
• Last updated: September 18, 2017
• Start date: May 2013
• Est. completion date: July 2017

Study information

• Verified date: September 2017
• Source: Bloodworks (Puget Sound Blood Center)
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

In this study, the investigators want to determine if N-acetylcysteine(NAC), given intravenously, will decrease complications in patients with Thrombotic Thrombocytopenia Purpura (TTP) who are receiving treatment with therapeutic plasma exchange (TPE). The investigators want to determine, through anti-oxidant activity, if NAC will have additional efficacy in TTP by improving cleavage of the patients' VWF by ADAMTS13, and preventing propagation of platelet/VWF strings. This will be manifest by a more rapid improvement in the patient's platelet count, decrease in number of days requiring TPE, and decrease in microvascular thrombotic complications. The investigators will additionally: 1) Assess safety of NAC by evaluating subjects for adverse events and significant adverse events 2) Determine effects on TTP by measuring clinical and research laboratory values 3) Determine drug effects by measuring clinical and research laboratory values.

Description:

Thrombotic thrombocytopenic purpura (TTP) is a rare hemostatic disorder with life threatening consequences secondary to microvascular thrombosis. While the use of therapeutic plasma exchange (TPE) has greatly improved survival, end organ damage, resistance to therapy, and relapses occur in many patients. Ultra-large von Willebrand factor multimers (ULVWF) are pathogenic in TTP. The investigators have found that N-acetylcysteine (NAC) cleaves ULVWF in vitro and in vivo in the ADAMTS13 deficient mice that are at increased risk of TTP. NAC is well tolerated in humans at intravenous doses used for treatment of acetaminophen overdose. This dosage correlates with that producing an effect in the murine studies noted above, and thus is an attractive treatment for patients with TTP. By cleaving VWF and preventing propagation of platelet/VWF strings, the investigators hypothesize that NAC treatment will decrease complications in patients with TTP receiving treatment with TPE. This will be manifest by a more rapid improvement in platelet count, decrease in number of days requiring plasma exchange, and decrease in microvascular thrombotic complications. To prepare for a larger trial the investigators propose a pilot study in 3 patients with suspected TTP at the University of Washington (UW) Medical Center. The study will be approved by the UW IRB prior to study initiation. Patients who consent to the study will receive daily NAC infusions beginning after the first TPE, in doses used for acetaminophen overdose. Blood samples will be collected for laboratory assays to determine optimal timing for sample collection in the larger multicenter trial, and to pilot the data collection forms. The investigators will also evaluate safety and patient tolerability.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 3
• Est. completion date: July 2017
• Est. primary completion date: July 2017
• Accepts healthy volunteers: No
• Gender: All
• Age group: 18 Years and older

Eligibility

Inclusion Criteria:

1. Age >= 18 years of age

2. Diagnosis of suspected TTP (lab evidence of hemolysis, platelet count <120,000, schistocytes on peripheral smear)

3. Plans for or just initiated therapeutic plasma exchange (TPE), and before 3rd TPE

4. Normal baseline prothrombin time (PT) and activated partial thromboplastin time (aPTT)

5. Anticipated TPE for > 5 days

Exclusion Criteria:

1. Asthma

2. Life expectancy < 1 week

3. Liver function tests abnormal- (ALT, direct bilirubin > three times upper normal limit)

4. Known underlying bleeding disorder

5. Pregnancy or nursing

6. Known allergy to NAC

7. Phosphodiesterase Type 5 inhibitors, nitroglycerin, or carbamazepine current use

Related Conditions & MeSH terms

• Purpura
• Purpura, Thrombocytopenic
• Purpura, Thrombotic Thrombocytopenic
• Thrombocytopenia
• TTP

Intervention

Drug:
• N-Acetylcysteine
IV administration of N-Acetylcysteine at 150mg/kg over 60 min first, then if well tolerated, 150mb/kg over 17 hours

Locations

Country	Name	City	State
United States	Puget Sound Blood Center	Seattle	Washington

Sponsors (2)

Lead Sponsor	Collaborator
Bloodworks (Puget Sound Blood Center)	University of Washington

Country where clinical trial is conducted

United States, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Changes in platelet count	The platelet count will be measured before, daily during 4 days of NAC infusion, the subsequent 3 days and on the day of hospital discharge which is estimated to be at 1-2 weeks post infusion. Changes in platelet count over time will be reported.	Daily for 7 days and at hospital discharge, expected to be at 1-2 weeks post infusion.
Secondary	Laboratory measures of VWF activity	VWF levels, oxidation and activity will be measured before, each day of NAC infusion, the subsequent 3 days and at hospital discharge, expected to be at 1-2 weeks post-infusion. Changes in values over time will be reported.	Daily for 7 days and at hospital dischargewhich is estimated to be at 1-2 weeks post-infusion
Secondary	Laboratory measures of ADAMTS13 activity	ADAMTS13 level, oxidation and activity will be measured before, daily during the NAC infusion, for the 3 subsequent days and at hospital discharge, expected to be at 1-2 weeks post-infusion. Changes over time will be reported.	Daily for 7 days and at hospital discharge which is estimated to be at 1-2 weeks post-infusion
Secondary	Laboratory measures of red blood cell (RBC) hemolysis and oxidation	Laboratory markers of RBC hemolysis and oxidation will be measured before, daily during the NAC infusion, for 3 subsequent days and at hospital discharge, expected to be at 1-2 weeks post-infusion. Changes in values over time will be reported.	Daily for 7 days and at hospital discharge which is estimated to be at 1-2 weeks post-infusion
Secondary	Safety of NAC infusion	Adverse events will be collected daily during the hospitalization, at 2 weeks and 8 weeks following infusion.	Over the study period