FDA Grants Orphan Drug Designation to KB407, Potential Gene Therapy for CF

The U.S. Food and Drug Administration (FDA) has granted the designation of orphan drug to KB407, Krystal Biotech’s potential inhaled gene therapy for the treatment of cystic fibrosis (CF).

“We are pleased to receive Orphan Drug Designation for KB407 to treat cystic fibrosis as this is an important step forward in our efforts to address the continued unmet need in this devastating disease,” Suma M. Krishnan, founder and chief operating officer of Krystal Biotech, said in a press release.

KB407 is a repeat-dose gene therapy that uses a modified version of the herpes simplex virus 1 (HSV-1) to deliver a functional copy of the CFTR gene, which is faulty in CF, to the patients’ cells.

The therapy, which is based on the company’s proprietary STAR-D platform, is being tested in preclinical studies and is expected to enter clinical testing next year, once the company submits an investigational new drug (IND) application to the FDA.

In previous preclinical studies, with data presented at the 2020 annual meeting of the American Society of Gene & Cell Therapy (ASGCT), KB407 was shown to successfully trigger the production of normal CFTR protein in patient-derived cells, as well as in organoids — cells grown in three dimensional structures that mimic organs in a lab dish.

Additional findings from other preclinical studies in mouse models also showed the therapy could be delivered successfully to the animals’ lungs by non-invasive inhalation with the help of a nebulizer.

“We are excited by the results of the in vitro data thus far, as presented at ASGCT earlier this year, and we look forward to sharing in vivo animal data later this year,” Krishnan said.

Orphan drug is a designation given by the FDA’s Office of Orphan Drug Products to support the development of therapies addressing the unmet needs of underserved patients with rare diseases (those affecting less than 200,000 people in the U.S.).

Medications receiving this designation may enable their company manufacturers to retain a seven-year period of U.S. market exclusivity upon their approval, along with other benefits, such as lower tax and clinical research costs and a reduction in the filing fees for a Prescription Drug User Fee Act (PDUFA).