Conditions: MYOPATHY
Allocation: NA | Intervention model: SINGLE_GROUP
Enrollment: 7
Healthy volunteers: no

Brief summary:
Myositis is a disease, believed to be due to immune cells, cells which normally protect the body, but are now attacking the muscles and other organ systems within body. As a result, the affected muscles and organs fail to work properly causing weakness, difficulty swallowing, skin rash, respiratory problems, heart problems, joint stiffness, soft tissue calcification and vasculitis (blood circulation problems). The likelihood of progression of this disease is high. This study is designed to examine whether treating patients with high dose cyclophosphamide (a drug which reduces the function of the immune system) and ATG (a protein that kills the immune cells that are thought to be causing this disease), followed by return of previously collected blood stem cells will stop the progression of myositis.

Detailed description:
Conditioning Regimen (In order to assure sterility testing, a minimum of 14 days will be required between stem cell collection and starting the conditioning regimen).

The conditioning regimen is outlined in below:

Cyclophosphamide 50 mg/kg/day will be given IV over 1 hour in 250 cc of normal saline on day -5, -4, -3, and -2. If actual weight is \< ideal weight, cyclophosphamide will be given based on actual weight. If actual weight is \> ideal weight, cyclophosphamide will be given as adjusted ideal weight. Adjusted ideal weight = ideal weight + 40% (actual weight minus ideal weight).

Mesna 50mg/kg/day will be given IV over 24 hours in 250 cc of normal saline or D5W starting at 10AM each dose. Weight base is calculated same as cyclophosphamide as above.

1ATG (rabbit) 0.5 mg/kg on day -6 and 1mg/kg on day -5, -4, -3, -2 and -1 (total 5.5mg/kg, no dose adjustment) will be given IV over 10 hours in 250 cc of normal saline beginning at least 1 hour after infusion of cyclophosphamide. Premedicate with acetaminophen 650 mg po and diphenhydramine 25 mg po/IV 30 minutes before the infusion.

Methylprednisolone- A suggested dose of 250mg IV should be administered 30 minutes before each ATG infusion.

Hydration- A suggested rate of 125 cc/hr NS should be given starting 6 hours before the first cyclophosphamide dose and continued until 24 hours after the last cyclophosphamide dose. The rate of hydration will be aggressively adjusted. BID weights will be obtained. Amount of fluid can be modified based on patient's fluid status. Minimum target urine output is 2 liters/m2/day

G-CSF 5 mcg/kg/day will be given subcutaneously and continued until the absolute neutrophil counts reaches at least 500/µl.

Rituxan 500 mg will be given IV on the day before the first dose of ATG and the day after stem cell infusion.

Arms:
arm 1: Intervention as hematopoietic stem cells transplantation after conditioning regimen: Autologous hematopoietic stem cells will be injected after conditioning regimen

Interventions: intervention 1: Hematopoietic stem cell transplantation intervention 2: Cyclophosphamide intervention 3: Mesna intervention 4: ATG(rabbit) intervention 5: Methylprednisolone intervention 6: G-CSF intervention 7: Rituxan
Intervention descriptions: intervention 1: Autologous hematopoietic stem cell transplantation intervention 2: None intervention 3: None intervention 4: None intervention 5: None intervention 6: None intervention 7: None

Protocol document: