ATGAM (antithymocyte globulin (horse))

The backbone of aplastic anemia treatment for patients who cannot have a bone marrow transplant. Given by IV over several days, it suppresses the immune cells that are destroying the bone marrow.

Antithymocyte globulin is made by injecting human white blood cells into a horse, which then makes antibodies against these cells. These antibodies are collected and purified. The medicine attacks and destroys the T-cells that are mistakenly attacking your bone marrow, allowing healthy blood cell production to resume.

Infusion reactions are common, including fever, chills, and muscle aches, usually occurring during or shortly after the infusion. Serious infections are possible because the drug suppresses immunity. Serum sickness can develop, causing joint pain, rash, and swollen lymph nodes. ATGAM has a boxed warning for anaphylaxis, a life-threatening allergic reaction, so patients are watched during the infusion and for at least 24 hours after. Low platelet and white blood cell counts are also common. Cytokine release syndrome, a reaction that can be fatal and can cause fever, chills, chest pain, low blood pressure, and trouble breathing, has also been reported. The label also warns that because it is made from horse and human blood components it may carry a risk of passing on infections, that live vaccines should not be given before, during, or after treatment, and that it can cause abnormal liver and kidney test results. Report fever or allergic reactions immediately.

Antithymocyte globulin is given intravenously, with each infusion running at least 4 hours. The label dose for aplastic anemia is 10 to 20 mg/kg a day for 8 to 14 days, with extra every-other-day doses possible up to 21 doses in total; your care team will set the exact schedule. Treatment happens at a hospital or specialized center. Patients must be hospitalized or closely monitored due to the serious reactions possible.

Yes, Antithymocyte globulin (horse) (ATGAM) is FDA approved (1981) for the treatment of Aplastic Anemia.

ATG contains antibodies that target and destroy T-lymphocytes, the immune cells attacking bone marrow stem cells in aplastic anemia. By eliminating this autoimmune attack, bone marrow can recover and resume blood cell production.

ATG is given as an intravenous infusion over at least 4 hours. The label schedule for aplastic anemia is daily doses for 8 to 14 days, sometimes followed by every-other-day doses; your care team will set the exact schedule. Patients are hospitalized during administration due to the risk of infusion reactions and serum sickness.

ATG is typically used in combination with cyclosporine (and increasingly with eltrombopag) as the standard immunosuppressive regimen for severe aplastic anemia when bone marrow transplant is not possible.

Infusion reactions including fever, chills, and rash are common. Serum sickness (delayed allergic reaction with fever, joint pain, and rash) typically occurs 7-14 days after treatment. Profound immunosuppression increases infection risk.

Antithymocyte globulin has been used for aplastic anemia since the 1980s. The horse-derived formulation (Atgam) was approved in 1981 and remains the standard for this indication.