FDA Approves Pasatru for Adults With Rare Bone Disease

The FDA has approved Pasatru (garetosmab) for adults with fibrodysplasia ossificans progressiva (FOP). FOP is an ultra-rare genetic disease. It causes muscles, tendons, and ligaments to gradually turn into bone outside the normal skeleton. Over time, this extra bone growth can make it hard to move, speak, eat, or breathe.Pasatru is a type of medication called a monoclonal antibody. It works by blocking a specific protein in the body called activin A. In people with FOP, activin A triggers the growth of extra bone where it does not belong. By blocking activin A, this medicine helps slow down new bone formation and reduce sudden disease flare-ups.

Why Was It Approved?

The FDA approved this medicine based on a 56-week clinical study involving 63 adults with FOP. People in the study received either Pasatru or a placebo, which is a treatment with no active drug. Researchers used full-body CT scans to look for any new bone growth and tracked the number of flare-ups patients had.

The study showed that Pasatru significantly reduced new bone growth when compared to the placebo. Patients receiving Pasatru had 90% to 94% fewer new bone lesions overall compared to patients receiving the placebo. The medicine also reduced the number of disease flare-ups assessed by a healthcare provider.The main safety concerns identified with Pasatru included skin infections and severe nosebleeds. Serious side effects occurred at similar rates in all people in the study.

What Do I Need to Know About Taking Pasatru?

Pasatru is given by a healthcare provider as an infusion into a vein over 60 minutes once every four weeks. Depending on your needs and mobility, your healthcare provider may give you this treatment in a clinic or at home.

The most common side effects include nosebleeds, skin abscesses, acne, increased hair growth, loss of eyebrow or eyelash hair, mouth sores, nail infections, and skin rashes. Tell your healthcare provider right away if you notice signs of a skin infection, such as a fever, warmth, redness, or pain. You should also seek medical help if you have a nosebleed that is severe or lasts longer than 20 minutes.

You should not use Pasatru if you are pregnant because it can cause serious birth defects or harm a fetus. Females who can become pregnant must take a pregnancy test before starting treatment and use effective birth control during treatment and for six months after the last dose. Breastfeeding is not recommended during treatment and for six months after your last dose. Pasatru may also affect male fertility, so speak with your healthcare provider if you have concerns about fathering a child.