PTC Therapeutics' Rare Genetic Disorder Drug Not Approved by US FDA

The US FDA has declined to approve PTC Therapeutics' drug for a rare genetic disorder. The company's diversified therapeutic portfolio includes products for Duchenne muscular dystrophy, Aromatic L-Amino Decarboxylase deficiency, and spinal muscular atrophy.

The U.S. Food and Drug Administration (FDA) has granted Breakthrough Therapy designation to delpacibart zotadirsen (del-zota), an investigational treatment for Duchenne muscular dystrophy (DMD) developed by Avidity Biosciences. This designation signals a significant advancement in the field of RNA therapeutics for rare genetic diseases.

DMD is a severe, life-limiting genetic disorder that affects approximately 1 in 5,000 newborn boys. It is caused by mutations in the dystrophin gene, leading to progressive muscle degeneration and heart complications. Current treatments have shown modest success, with levels of functional dystrophin remaining below one percent of those found in healthy muscles [1].

Del-zota, an Antibody Oligonucleotide Conjugate (AOC™), represents a novel approach to treating DMD. It combines the gene regulatory potential of antisense oligonucleotides with the targeting capabilities of antibodies, enhancing delivery to muscle tissue. The drug targets exon 44 skipping, a subset of DMD patients that has not yet been served by approved therapies. In a Phase 1/2 clinical trial, del-zota demonstrated unprecedented delivery of PMOs to skeletal muscle, robust increases in dystrophin production, and significant decreases in creatine kinase levels, indicating reduced muscle damage [1].

The Breakthrough Therapy designation is designed to expedite the development and review of drugs targeting serious conditions, offering more frequent FDA interactions and potential eligibility for accelerated approval. Avidity Biosciences, which has previously received Orphan Drug, Rare Pediatric Disease, and Fast Track designations for del-zota, aims to fill a long-standing treatment gap for DMD patients with exon 44 mutations.

Steve Hughes, Chief Medical Officer at Avidity Biosciences, stated, "Breakthrough Therapy designation underscores the FDA's appreciation for the significant potential of del-zota to address the underlying cause of DMD44 and the urgent need to bring innovative treatment options to the DMD community."

References:
[1] https://www.drugdiscoverynews.com/fda-grants-breakthrough-therapy-designation-to-first-in-class-aoc-therapeutic-for-duchenne-muscular-dystrophy-16530