Caplacizumab Receives FDA Approval for Thrombotic Thrombocytopenic Purpura (TTP)

Caplacizumab-yhdp (Cablivi), for the rare, life-threatening blood clotting disorder acquired thrombotic thrombocytopenic purpura (acquired Thrombotic Thrombocytopenic Purpura, aTTP), received on 6 February 2019 United States Food and Drug Administration (FDA) approval, becoming the first drug approved for this disease. Caplacizumab had received approval in European Union countries on 31 August 2018.

Patients with acquired thrombotic thrombocytopenic purpura (aTTP) need frequent blood transfusions. Despite immune-suppressing medication, many experience recurrence. Caplacizumab-yhdp is the first targeted treatment preventing blood clot formation in this disease, offering a new option that may reduce recurrence. It is a monoclonal antibody drug developed against the clotting factor vWF (von Willebrand factor). It works by preventing platelet aggregation (joining) to form clots, thereby preventing clots and subsequent ischemia in vessels supplying organs.

Patients with aTTP develop serious clots in small blood vessels. These can cut off oxygen and blood supply to major organs, causing strokes and heart attacks that may result in brain damage or death. Underlying causes may include cancer, HIV, pregnancy, lupus, infections, surgery, bone marrow transplantation, or chemotherapy.

The Clinical Trial Leading to Caplacizumab Approval for aTTP

Caplacizumab-yhdp’s effectiveness was examined in 145 patients randomized to caplacizumab or placebo in the HERCULES clinical trial. Both groups received current treatment—plasma exchange and immunosuppressive drugs. Platelet counts rose more quickly with caplacizumab than placebo.

Caplacizumab-yhdp treatment resulted in fewer patients overall with aTTP-related death, aTTP recurrence, or at least one major thrombotic event during treatment. Throughout the study (drug treatment plus 28 days of follow-up after discontinuation), recurrence was lower in the caplacizumab-yddp group (% 13) than placebo (% 38), a statistically significant difference.

Common caplacizumab-yhdp adverse effects reported in clinical trials were nose or gum bleeding and headache. Prescribing information includes a warning to inform healthcare professionals and patients about serious bleeding risk.

Close monitoring for bleeding is recommended when caplacizumab-yddp is administered to patients already receiving anticoagulants (blood thinners, clot-preventing drugs).