After three decades and a surprise rejection, first treatment for babies born without a thymus secures FDA approval
Sumitovant Biopharma’s subsidiary Enzyvant late Friday won approval for its first treatment, which is also the first promising treatment for babies without a thymus, an organ that plays a crucial role in helping to fight infections.
The treatment, known as Rethymic (allogeneic processed thymus tissue-agdc), is a one-time regenerative therapy for what’s formally known as congenital athymia. Enzyvant, which licensed the drug from Duke University in 2017, said that usually about 20 babies per year in the US are born with the condition, and many often die from infections or autoimmune manifestations by age two or three.
Duke University Hospital began administering the now-approved treatment in 1993. Of the 105 patients who received it, 76 are still alive. Of the 29 patients who died, 23 passed away in the first year after implantation.
Of the six patients who died more than one year post-implantation, the deaths were considered unrelated to study treatment. Two died due to respiratory failure and one died due to each of the following: cardiopulmonary arrest, intracranial hemorrhage, infection, and unknown cause.
The treatment has been a long time coming, with more than 25 years of development, and a surprise FDA rejection of the drug in 2019 due to manufacturing issues.
The agency said Friday that “most children treated with this product survived at least two years. Children treated with Rethymic who survive past the first year generally survive long-term. Rethymic also reduced the frequency and severity of infections over time.”
Pricing of the new drug and when it might be first available have yet to be announced by Enzyvant, which was sold in 2019 as part of a $3 billion deal with Sumitomo Dainippon Pharma.
With the approval, the company also gains access to a lucrative priority review voucher, which could fetch about $100 million on the open market or be used to speed the FDA review of another drug.
“For too long, families have faced a reality that the brutal journey for pediatric congenital athymia patients receiving supportive care only would end tragically. The FDA approval of RETHYMIC will help patients access this desperately needed therapy beyond clinical study,” Rachelle Jacques, CEO of Enzyvant, said in a statement.