What is severe malignant osteopetrosis (SMO)?

Osteopetrosis is a disease of the bones. It is NOT the same as osteoporosis, when the joints wear down over time. That is a different condition. There are different forms of osteopetrosis, but all forms of osteopetrosis have to do with an abnormal increase in the density (thickness) of the bones.

Severe malignant osteopetrosis (SMO) is a form of osteopetrosis that is sometimes called marble bone disease or malignant infantile osteopetrosis (MIOP). This is because SMO affects very young children. Severe malignant osteopetrosis is a very severe form of osteopetrosis. While exact numbers are not known, it is thought that about 1 in 250,000 children are born with SMO.

What happens in the body with SMO?

In normal bone development, bone material is replaced by new bone over and over again. Cells called osteoblasts help create new bone material. Other cells called osteoclasts remove the old bone material.

In people with osteopetrosis, the osteoclasts do not function the right way. As a result, abnormal bone development happens. This can cause many problems in the body, such as:

  • Blood disorders
  • Difficulty fighting infections
  • Bone fractures
  • Problems with vision and hearing
  • Abnormal look of the face and head

Common characteristics of SMO

In SMO, the buildup of bone materials can narrow the space inside the bone. This means there is less space to make bone marrow. Bone marrow is where new blood cells are formed. Less space to make bone marrow can cause:

  • Anemia due to low red blood cells. Symptoms of anemia include pale skin and lack of energy
  • Bleeding problems because of low platelets. Platelets are blood cells the body needs to help stop bleeding
  • Repeated infections because of low white blood cells. White blood cells are needed to fight infections

With SMO, there can also be a narrowing of the tunnels within the bones of the skull. The nerves for vision and hearing pass through these tunnels. These nerves can be squeezed by bones that overdevelop because of SMO. This causes patients to have problems with their vision and hearing.

Patients often suffer serious effects from SMO. These may include:

  • Failure to thrive and slow growth in childhood
  • Difficulty seeing or blindness
  • Hearing loss
  • Abnormal head shape
  • Bone marrow failure, causing anemia
  • Infections that happen often and over and over
  • Repeated bone fractures

SMO can also cause a lower life expectancy. Most children with SMO who are untreated pass away within the first 10 years of life.

Paul and Barbara’s SMO story

Hear from the parents of a child who lost the battle with severe malignant osteopetrosis.

Important Safety Information

What is ACTIMMUNE® (Interferon gamma-1b) used for?

ACTIMMUNE® is part of a drug regimen used to treat Chronic Granulomatous Disease, or CGD. CGD is a genetic disorder, usually diagnosed in childhood, that affects some cells of the immune system and the body's ability to fight infections effectively. CGD is often treated (though not cured) with antibiotics, antifungals, and ACTIMMUNE.

Important Safety Information

What is ACTIMMUNE® (Interferon gamma-1b) used for?

ACTIMMUNE® is part of a drug regimen used to treat Chronic Granulomatous Disease, or CGD. CGD is a genetic disorder, usually diagnosed in childhood, that affects some cells of the immune system and the body's ability to fight infections effectively. CGD is often treated (though not cured) with antibiotics, antifungals, and ACTIMMUNE.

ACTIMMUNE is also used to slow the worsening of severe, malignant osteopetrosis (SMO). SMO is a genetic disorder that affects normal bone formation and is usually diagnosed in the first few months after birth.

When should I not take ACTIMMUNE?

Don't use ACTIMMUNE if you are allergic to interferon-gamma, E coliderived products, or any ingredients contained in the product.

What warnings should I know about ACTIMMUNE?

At high doses, ACTIMMUNE can cause (flu-like) symptoms, which may worsen some pre-existing heart conditions.

ACTIMMUNE may cause decreased mental status, walking disturbances, and dizziness, particularly at very high doses. These symptoms are usually reversible within a few days upon dose reduction or discontinuation of therapy.

Bone marrow function may be suppressed with ACTIMMUNE, and decreased production of cells important to the body may occur. This effect, which can be severe, is usually reversible when the drug is discontinued or the dose is reduced.

Taking ACTIMMUNE may cause reversible changes to your liver function, particularly in patients less than 1 year old. Your doctor should monitor your liver function every 3 months, and monthly in children under 1 year.

In rare cases, ACTIMMUNE can cause severe allergic reactions and/or rash. If you experience a serious reaction to ACTIMMUNE, discontinue it immediately and contact your doctor or seek medical help.

What should I tell my healthcare provider?

Be sure to tell your doctor about all the medications you are taking.

Tell your doctor if you:

  • are pregnant or plan to become pregnant or plan to nurse
  • have a cardiac condition such as irregular heartbeat, heart failure, or decreased blood flow to your heart
  • have a history of seizures or other neurologic disorders
  • have, or have had, reduced bone marrow function. Your doctor will monitor these cells with blood tests at the beginning of therapy and at 3-month intervals on ACTIMMUNE therapy

What are the side effects of ACTIMMUNE?

The most common side effects with ACTIMMUNE are "flu-like" symptoms such as fever, headache, chills, muscle pain, or fatigue, which may decrease in severity as treatment continues. Bedtime administration of ACTIMMUNE may help reduce some of these symptoms. Acetaminophen may be helpful in preventing fever and headache.

What other medications might interact with ACTIMMUNE?

Some drugs may interact with ACTIMMUNE to potentially increase the risk of damage to your heart or nervous system, such as certain chemotherapy drugs. Tell your doctor about all other medications you are taking.

Avoid taking ACTIMMUNE at the same time as a vaccination.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch, or call 1-800-FDA-1088. You may also contact the Horizon Pharma Medical Information Department toll-free at 1-866-479-6742 or medicalinformation@horizonpharma.com.

The risk information provided here is not comprehensive. To learn more, talk about ACTIMMUNE with your healthcare provider or pharmacist. The FDA-approved product labeling can be found at http://www.ACTIMMUNE.com or 1-866-479-6742.