Rethymic, a regenerative tissue based therapy is now approved by the US FDA for patients with congenital athymia. It took more than 25 years for its research and development at the Duke University School of Medicine. Enzyvant acquired the license in 2017 and suffered FDA rejection in 2019. For many it was a surprise rejection, which was due to manufacturing issues. Enzyvant is now a subsidiary of Sumitovant Biopharma. Congenital athymia is manifested in children born without a thymus. This condition causes profound immunodeficiency and leads to immune dysregulation, resulting in fatal infections. Rethymic is a onetime regenerative therapy that can offer longer survival. Patients who receive only supportive care may survive only up to two to three years. This newly approved treatment can enhance significant outcomes in pediatric patients.
About Congenital Athymia and Clinical Research with Rethymic
Often described as an ultra-rare disease, congenital athymia is characterized by the absence of a functional thymus. Thymus is a lymphoid organ responsible for the formation of T Cells. The primary function of T Cells is to fight infections, comprising of the body’s adaptive immune system. Absence of T Cells would naturally lead to fatal infections, leading to serious spells of hospitalizations and causing death. About twenty babies are born without thymus every year in the US alone. There has been no dependable treatment for this condition before the introduction of Rethymic.
The recent US FDA approval for this drug is based on the safety and efficacy assessment of its clinical trial outcomes that involved 105 patients. The survival data spanning over twenty five years was studied. Data from patients aged one month to sixteen years who received a single dose of Rethymic formed the basis for its approval. This therapy is delivered through implantation of cultured human allogeneic thymus tissue, which will assist in the reconstitution of immunity. The thymus tissue is derived from a healthy donor. The time taken for the reconstitution of immune function is six months or more with this therapy. The whole therapy in terms of dosage is patient specific and customized.
Future prospects for Enzyvant after Rethymic FDA approval
The pricing and commercial access information of this new drug is yet to be announced by the company. However, the approval of Rethymic is coupled with a lucrative priority review voucher. This helps Enzyvant to accelerate the FDA review for its next research product. This could also fetch about $100 million on the open market, per Endpoints News. Biopharma and cell & gene therapy research companies do well by entering into early collaborations with Big Pharma, a phenomenon vindicated time and again.
