Conditions: Takayasu's Arteritis Giant Cell Arteritis
Keywords: Vasculitis Arteritis Takayasu's Temporal Arteritis Abatacept
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 97
Healthy volunteers: no

Brief summary:
Giant cell arteritis (GCA) and Takayasu's arteritis (TAK) are diseases that cause swelling of the arteries in the head, neck, upper body, and arms. TAK specifically affects the aorta, the largest blood vessel in the body, and its branches. Therapies are available to improve the symptoms of GCA and TAK, but relapse often occurs, and better treatments are needed. Abatacept is a drug that interacts with certain cells in the body that are involved with GCA and TAK. This study will evaluate the effectiveness of abatacept in treating GCA and TAK and preventing disease relapse.

Detailed description:
GCA and TAK both cause inflammation in the lining of the arteries, which can interfere with the body's ability to carry oxygen to areas that need it. Symptoms of GCA include headaches, jaw pain, and blurred or double vision. Serious symptoms that occur less commonly are blindness and stroke. TAK symptoms include fever, fatigue, weight loss, arthritis, and non-specific aches and pains. There may also be tenderness near affected arteries. Researchers believe that GCA and TAK are diseases that are controlled by the body's immune system. Activated T-cells, specifically, are critical to the origin and development of these diseases. Abatacept is a medication that modulates the signal required for T-cell activation. This study will evaluate the safety and effectiveness of abatacept in treating GCA and TAK and preventing disease relapse.

Participation in this study may last up to 4 years. Participants will receive abatacept intravenously on specified days during Months 1, 2, and 3. They will also receive daily prednisone, which will be started at a dose of 40 to 60mg, then tapered to 20mg by Month 3, and finally further tapered until discontinuation is reached. At Month 3, participants who have achieved remission will be randomly assigned under double-blind conditions to either continue abatacept or be switched to placebo infusions. Both treatments will be given once a month at study visits. Blood samples will also be collected at the monthly study visits to conduct laboratory-based studies. Participants who remain in remission will continue to receive abatacept or placebo monthly until the common closing date, defined as 12 months after enrollment of the 33rd participant for each disease.

Arms:
arm 1: This is a randomized withdrawal design protocol. All participants will receive abatacept and prednisone (a glucocorticoid) for the first 3 months. Abatacept will be given intravenously on selected days. Prednisone will be started at a dose of 40 to 60mg, then tapered to 20mg by Month 3, and finally further tapered until discontinuation is reached. At Month 3, participants who have achieved remission will be randomly assigned under double-blind conditions to receive monthly infusions of either abatacept or placebo. Participants who are assigned to abatacept at this point will be in Group A for giant cell arteritis and Group C for Takayasu arteritis. arm 2: This is a randomized withdrawal design protocol. All participants will receive abatacept and prednisone (a glucocorticoid) for the first 3 months. Abatacept will be given intravenously on selected days. Prednisone will be started at a dose of 40 to 60mg, then tapered to 20mg by Month 3, and finally further tapered until discontinuation is reached. At Month 3, participants who have achieved remission will be randomly assigned under double-blind conditions to receive monthly infusions of either abatacept or placebo. Participants who are assigned to placebo at this point will be in Group B for giant cell arteritis and Group D for Takayasu arteritis.

Interventions: intervention 1: Abatacept intervention 2: Placebo
Intervention descriptions: intervention 1: Participants will receive a fixed dose of abatacept, approximating 10mg per kilogram of body weight. The following dosing rules will be followed:

* Participants weighing less than 60kg will receive 500mg of abatacept.
* Participants weighing 60 to 100kg will receive 750mg of abatacept.
* Participants weighing more than 100kg will receive 1000mg of abatacept.

Abatacept will be administered in a 30-minute intravenous infusion on Days 1, 15, 29 (Month 1) and at Month 2. In the absence of toxicity or relapse, participants will remain on abatacept at the same dosage until randomization at Month 3. After randomization, only Group A (giant cell arteritis) and Group C (Takayasu arteritis) participants will continue on abatacept. intervention 2: Placebo abatacept infusions will be given monthly after random assignment at Month 3.

Protocol document: