FDA Awards Second Platform Designation to Krystal Biotech, Validating HSV-1 Vector Technology

The U.S. Food and Drug Administration (FDA) has granted its second platform technology designation to Krystal Biotech for the company's non-replicating HSV-1 viral vector, used in delivering gene therapies. This development comes after the FDA revoked Sarepta Therapeutics' platform designation in July, following a series of deaths linked to their adeno-associated virus vector platform.

Krystal's HSV-1 Platform and Its Implications

Krystal Biotech's HSV-1 technology utilizes a replication-deficient version of the herpes simplex virus type 1. This vector capitalizes on HSV-1's natural characteristics, including a high payload capacity and ability to evade the immune system, aiming to minimize toxicities in gene therapy applications.

The platform technology designation is intended to streamline drug development and regulatory review processes for products using the designated technology. It allows drug sponsors to leverage manufacturing and nonclinical safety data from previous products in future FDA submissions, provided they employ the same technology.

Analysts at William Blair view this designation as a validation of Krystal's HSV-1 vector platform and its cross-program utility. They noted that Krystal is "poised to be the first major beneficiary" of the FDA's platform designation program.

Expanding Applications of Krystal's Technology

Krystal Biotech plans to leverage this FDA designation for its redosable eye drop gene therapy KB801, currently in Phase I/II development for neurotropic keratitis, a rare corneal disease leading to eye injuries.

The company's only approved product, Vyjuvek, a gene therapy approved in 2023 for treating wounds in patients with dystrophic epidermolysis bullosa, also utilizes this HSV-1 platform. Notably, while Vyjuvek is administered as a topical gel, KB801 is formulated as an eye drop.

William Blair analysts suggest that the FDA's decision to grant the platform designation despite these different administration methods indicates the agency views Krystal's HSV-1 vector as likely having reproducible efficacy across various administration methodologies.

FDA's Platform Technology Designation Program

The FDA awards its platform technology designation to companies using a "well-understood and reproducible technology" as an "essential" part of their drugs, according to a May 2024 draft guidance document. The platform technology must be applicable to and used by more than one of the company's assets while standardizing the production or manufacturing of these products.

This program aims to provide efficiencies in drug development and regulatory review processes for products utilizing designated technologies. The recent developments with Krystal Biotech underscore the potential impact of this designation on accelerating gene therapy advancements in the pharmaceutical industry.