The U.S. Food and Drug Administration (FDA) has approved pozelimab (Veopoz) to treat persons one year and older with complement hyperactivation, angiopathic thrombosis, and protein-losing enteropathy, also known as CHAPLE disease.

CHAPLE disease is a genetic autoimmune disorder due to mutations in the complement regulator CD55 gene. It is an ultra-rare disease, with fewer than 100 patients diagnosed worldwide.

Symptoms can include abdominal pain, nausea, vomiting, diarrhea, loss of appetite, weight loss, impaired growth, and edema (swelling). Severe thrombotic vascular occlusions can also occur and can be life-threating.

The approval is largely based on data from a single-arm clinical trial (NCT04209634), in which patients’ (N=10) outcomes were compared to pre-treatment data in patients with active CD55-deficient protein-losing enteropathy (PLE) who had hypoalbuminemia.

All 10 patients achieved a serum albumin concentration of at least 3.5 g/dL by week 12, which was maintained through at least 72 weeks. Further, all 10 patients demonstrated a reduction in the number of hospitalizations and number of albumin transfusions over the first 48 weeks of treatment as compared to the 48 weeks prior to treatment.

The most common adverse reactions were upper respiratory tract infections, fractures, hives, and alopecia. The orphan drug comes with a Boxed Warning for serious meningococcal infections. Life-threatening and fatal meningococcal infections have occurred in patients treated with complement inhibitors and may become rapidly life-threatening or fatal if not recognized and treated early.

Pozelimab is a complement inhibitor monoclonal IgG4 antibody that binds with high affinity to wild-type and variant human C5. It is designed to block the activity of complement factor C5 and prevent diseases mediated by the complement pathway. The drug is also being investigated as a possible treatment for other complement-mediated disorders such as paroxysmal nocturnal hemoglobinuria (PNH) and myasthenia gravis.

The approval of pozelimab gives the manufacturers, Regeneron, a Rare Pediatric Disease Priority Review voucher. The voucher can be used for subsequent drug applications that would not qualify for a priority review. A Priority Review designation means the FDA must review the drug application within 6 months instead of the standard 10 months. The voucher can also be sold to another company. Recently, Sarepta Therapeutics sold their voucher for $102 million.

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