Potential Gene Therapy, SPIRO-2101, Named Rare Pediatric and Orphan Disease by FDA

Spirovant Sciences‘ lead gene therapy candidate for select cystic fibrosis (CF) patients, SPIRO-2101, was given rare pediatric disease and orphan drug designations by the U.S. Food and Drug Administration (FDA) to support its development, according to a recent press release.

Orphan drug designation applies to medicines targeting disorders that affect fewer than 200,000 people in the U.S. It grants the therapy’s developer certain tax benefits, fee waivers, and seven years’ exclusive marketing rights upon approval.

Rare pediatric disease designation provides similar benefits but applies to medicines designed to treat conditions mainly affecting people 18 years and younger. It also qualifies the developer for a priority review voucher, meant to speed the approval review process.

SPIRO-2101 is an inhaled gene therapy, designed to replace the faulty cystic fibrosis transmembrane conductance regulator (CFTR) gene with a working copy. The therapy uses a harmless virus called adeno-associated virus, or AAV, to carry the genetic sequence of the healthy CFTR into patient lung cells, which can then produce a functional CFTR protein.

According to Spirovant, its potential therapy is distinct in addressing the genetic root cause of this disease.

SPIRO-2101 aims to treat CF patients with class 1 mutations or who cannot tolerate treatment with an existing CFTR modulator. The company estimates this covers about 10% of the total patient population.

Class 1 mutations are those in which either no messenger RNA (mRNA) — the intermediate molecule between DNA and a protein — is made (class 1A), or in which the cell produces damaged mRNA that it cannot turn into a protein (class 1B).

Current CFTR modulator therapies do not treat these mutations.

SPIRO-2101 has been engineered to target the cells of the outer layer of the airways, called epithelial cells, with high efficiency, the company reports, allowing the therapy to be delivered where it is needed most.

“Cystic fibrosis is an incredibly debilitating and devastating disease. Receiving Orphan Drug and Rare Pediatric Disease Designations for SPIRO-2101 underscores the urgency for a treatment option for these patients, particularly those with very rare and more severe types of cystic fibrosis, the nonsense mutation subtype,” said Joan Lau, PhD, CEO of Spirovant.

Spirovant is investigating two other virus-based gene therapy candidates, also potential inhalation treatments. The company’s work in developing SPIRO-2101 has been supported by the Cystic Fibrosis Foundation.