KB407 Seen in Animal Studies to Safely Deliver Gene That Might Treat CF

New findings from animal studies support the safety and effectiveness of KB407, a potential inhaled gene therapy for cystic fibrosis, its developer, Krystal Biotech, announced.

Preclinical work is ongoing, and the therapy is expected to enter clinical testing in patients by mid-2021.

“I am particularly encouraged by progress with KB407 for the treatment of cystic fibrosis. The in vivo animal data reported today demonstrates our ability to deliver functional CFTR throughout the lung, which is encouraging in … diseases of the lung where delivery of a therapeutic transgene may be beneficial,” Krish Krishnan, chairman and CEO of Krystal Biotech, said in a press release.

KB407 is an inhaled therapy that delivers a working copy of the CFTR gene, which is faulty in CF, to patients’ cells using an engineered version of herpes simplex virus 1 (HSV-1). It is designed to allow repeat and adjusted dosing.

In a recent corporate presentation, Krystal detailed work showing that KB407, with the help of a nebulizer, could be effectively delivered to the lungs of healthy mice and those of a CF model. No toxicity or significant safety findings were observed.

KB407 was also found to be safe and well tolerated when given to a nonhuman primate, a monkey, in two separate doses delivered two weeks apart.

In both mice and this primate, the gene therapy led to a “robust” expression of the human CFTR gene, the presentation reported.

Further study in 40 nonhuman primates is ongoing, it added.

Previous preclinical data, presented at the 2020 annual meeting of the American Society of Gene & Cell Therapy (ASGCT), showed that KB407 was effective at inducing the production of normal CFTR protein in patient-derived cells, as well as in organoids, or cells grown in three dimensional structures that mimic organs in a lab dish.

KB407 was recently given rare pediatric, and previously orphan drug, status by the U.S. Food and Drug Administration this year, supporting its further development.

Rare pediatric disease designation is given to medicines aiming to treat disorders primarily affecting children, ages 18 and younger. It qualifies the developer for a priority review voucher, meant to speed the approval review process.

Krystal Biotech also announced that it was given a Notice of Allowance by the U.S. Patent and Trademark Office, covering a patent application for the use of KB407 in treating CF and other lung diseases. The company expects to finalize this patent — number 10,829,529 — by Nov. 10, 2020.