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Effect of Hydroxychloroquine on the Annexin A5 Resistance Assay in Antiphospholipid Antibody-Positive Patients With and Without Systemic Lupus Erythematosus

IRB Number: 10130

August 12, 2011

Institutional Review Board, Hospital for Special Surgery

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Before enrolling in a clinical trial or research study, the investigator will explain the purpose of the trial/study, its expected benefits, any possible risks or side effects, and what your role will be. If you want to join the trial/study, you must sign informed consent documents. You can leave a trial/study at any time without penalty.

For further information, see Understanding Clinical Trials/Research Studies.

Principal Investigator

Doruk Erkan, MD


Alana B. Levine, MD
Michael D. Lockshin, MD
Jacob H. Rand, MD
JoAnn Vega



The purpose of this study is to determine the effects of a medication, hydroxychloroquine (HCQ), on a blood test called the annexin A5 (AnxA5) resistance assay in people with antiphospholipid antibodies (aPL).  People with aPL can be at increased risk for forming blood clots.  AnxA5 is a protein in the blood that protects against blood clotting.  AnxA5 does not seem to provide as much protection against blood clots in people with aPL compared to people without aPL. Studies have suggested that HCQ prevents aPL from interfering with AnxA5’s anti-clotting properties.  We will perform the AnxA5 resistance assay blood test on samples from people before and after they take HCQ.  If we can identify a difference in the test before and after people take the medication, this will allow us to design future studies.

The study will enroll fifty patients.  Subjects will be enrolled from the time of IRB approval until June 1, 2012.  Subjects will be required to participate over a period of 12 weeks.

Inclusion/Exclusion Criteria

Inclusion criteria:

  • Age 18 to 65
  • One or more of the following diagnoses:
    • Systemic Lupus Erythematosus (SLE)
    • Antiphospholipid Syndrome (APS)
    • Positive antiphospholipid antibodies (aPL)
  • Plan to initiate treatment with hydroxychloroquine (HCQ)/Plaquenil (200-400mg/daily) (for all but five of the control subjects)

Exclusion criteria:

  • Current HCQ/Plaquenil use
  • Steroid use greater than or equal to the equivalent of prednisone 0.5 mg/kg/day at the time of enrollment
  • Heparin use at time of enrollment
  • Use of certain immunosuppressive medications
  • Acute thrombosis/blood clot within 2 weeks prior to screening
  • Pregnant women, employees, minors, mentally disabled, prisoners

Contact Information

Alana B. Levine, MD