RARE Daily

FDA Grants Rare Pediatric Disease Designation to Three Companies’ Experimental Medicines

July 28, 2020

The U.S. Food and Drug Administration granted Rare Pediatric Disease designation to three companies for their experimental therapies.

The designations cover Protara Therapeutics’ TARA-002 for the treatment of lymphatic malformations; Momenta Pharmaceuticals’ nipocalimab for the prevention of hemolytic disease of the fetus and newborn; and HemoShear Therapeutics’ HST5040 for the treatment of methylmalonic acidemia and propionic acidemia.

Protara’s lead candidate TARA-002 is an experimental cell-based therapy based on the broad immune-potentiator OK-432. OK-432 is approved in Japan and Taiwan for lymphatic malformations (LMs), which are rare, congenital malformations of lymphatic vessels resulting in the failure of these structures to connect or drain into the venous system. In a randomized, phase 2 clinical trial of OK-432 in LMs, 86 percent of mostly pediatric patients treated with OK-432 experienced a complete or substantial response. Long-term control of LMs was favorable, with more than 90 percent of treated patients having no regrowth three years following treatment.

Momenta’s nipocalimab addresses hemolytic disease of the fetus and newborn (HDFN), a rare alloimmune disorder affecting pregnant women that is caused by the placental transfer of alloantibodies from the mother’s circulatory system to the fetus. Maternal antibodies attack the red blood cells of the fetus and can result in pre-term birth, neonatal morbidity, fetal anemia requiring intervention, or fetal or neonatal loss. HDFN typically becomes more severe with subsequent pregnancies, with severe HDFN impacting between 3,000 to 8,000 pregnancies per year. Currently, pregnant women with severe cases are treated with intrauterine blood transfusions, an invasive surgical procedure that can cause significant complications.

Nipocalimab is a high affinity, fully human, aglycosylated, effectorless IgG1 anti-FcRn monoclonal antibody that prevents the transfer if IgG antibodies from the mother to the fetus as well as lowers maternal high levels of pathogenic antibody available to cross the placenta. It is currently being studied in a global multi-center phase 2 clinical trial in HDFN, which is actively enrolling in Europe and five sites in the United States.

Nipocalimab has also been granted Fast Track and Orphan Drug designation by the FDA in this indication.

HemoShear’s HST5040 is a once-daily oral small molecule drug in development to treat methylmalonic acidemia (MMA) and propionic acidemia (PA). MMA and PA are rare genetic disorders caused by the deficiency of certain enzymes required to metabolize amino acids. The diseases result in the rapid buildup of life-threatening metabolites that can lead to severe organ damage, seizures, developmental deficits, and premature death. In June, HemoShear received FDA clearance to conduct a phase 2 clinical study expected to enroll at least 12 patients with MMA and PA at select children’s hospitals in the United States. HST5040 was also granted FDA’s Fast Track designation.

The FDA grants Rare Pediatric Disease designation for serious diseases that primarily affect children ages 18 years or younger and fewer than 200,000 persons in the United States. Under the FDA’s Rare Pediatric Disease Priority Review Voucher program.

The vouchers can be used to reduce the time of an FDA new drug approval review to six months from ten months. The vouchers are potentially lucrative because they are transferable. Most recently, Sarepta sold its priority review voucher to Vifor Pharma $111 million in February 2020.

Editor’s note: This story was updated to correct the most recent sales of a priority review voucher.

Author: Rare Daily Staff

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