Krystal Biotech’s Neurotrophic Keratitis Gene Therapy Viral Vector Secures FDA Platform Technology Designation

Krystal Biotech has received a platform technology designation from the FDA for the genetically modified, nonreplicating herpes simplex virus type 1 (HSV-1) viral vector used in KB801, an investigational gene therapy intended to treat neurotrophic keratitis (NK).¹

KB801, which takes the form of a resodable eye drop, is currently being evaluated in the randomized, placebo-controlled phase 1/2 EMERALD-1 clinical trial (NCT06999733). KB801 is intended to allow epithelial cells located in the front of the eye to consistently produce nerve growth factor (NGF). Current treatment options for NK include NGF eye drops, but according to Krystal these have a high burden of treatment because of the need for “intensive administration” 6 times per day to achieve ideal results.¹

“Receiving a platform technology designation from the FDA is a tremendous milestone for our development team and Krystal, both as recognition of the reproducibility and scalability of our HSV-1 gene delivery platform and for the potential product development benefits it may provide,” Suma Krishnan, MSc, MBA, the president of research and development at Krystal Biotech, said in a statement.¹ “We are excited to work with the FDA under this program to identify potential efficiencies, including opportunities to leverage our prior experience with FDA-approved Vyjuvek (beremagene geperpavec-svdt, also known as B-VEC), to accelerate the development of our genetic medicines pipeline, starting with KB801 for the treatment of NK.”

Vyjuvek, a topical and redosable gene therapy gel formulation, was approved by the FDA for the treatment of dystrophic epidermolysis bullosa (DEB) in patients 6 months or older in May 2023.² Notably, an eye drop formulation of Vyjuvek has been evaluated in a case study of a patient with ocular complications in dystrophic epidermolysis bullosa (DEB).³

“DEB is a devastating disease and patients with ocular complications have no corrective treatment options leaving them at risk of severe vision loss,” investigator Alfonso L. Sabater, MD, PhD, an associate professor of clinical ophthalmology at the Bascom Palmer Eye Institute of University of Miami Miller School of Medicine, said in a statement.⁴ “We are encouraged by the improvements observed in the patient following B-VEC administration as an eyedrop directly to the affected eye and believe this data is supportive of further investigation in DEB patients with ocular complications. If approved, this approach could drastically benefit these patients.”

Krystal is the second company to have received platform technology designation, a relatively new designation established by the FDA with the intent of allowing companies developing a product that uses a well-understood technology that has been previously used in other programs to utilize data regarding that technology from the other programs in support of investigational new drug applications and biologic license applications.^5,6 The first company to have received the designation was Sarepta Therapeutics, for the rAAVrh74 viral vector used in bidridistrogene xeboparvovec (also known as SRP-9003), an investigational adeno-associated virus (AAV) vector-based gene therapy product in development for limb-girdle muscular dystrophy Type 2E (LGMD2E/R4, also known as beta sarcoglycanopathy). Notably, rAAVrh74 is also used in Sarepta’s delandistrogene moxeparvovec-rokl (marketed as Elevidys), an FDA-approved gene therapy intended to treat Duchenne muscular dystrophy (DMD).⁷

Shortly after the FDA granted the platform technology designation to Sarepta in June 2025, however, it revoked the same designation just about a month later in July 2025.⁸ The FDA’s decision followed the death of a 51-year-old patient who was treated with Sarepta’s investigational gene therapy SRP-9004 for nonambulant LGMD type 2D/R3, which uses the AAVrh74 serotype, in a phase 1 clinical trial (DISCOVERY; NCT01976091).^9,10 In its announcement of the revocation, the FDA also made reference to 2 previous deaths that occurred among patients who received Elevidys, which also uses the AAVrh74 vector.⁸

REFERENCES
1. Krystal Biotech receives FDA platform technology designation for HSV-1 viral vector used in KB801 for the treatment of neurotrophic keratitis. News release. Krystal Biotech, Inc. October 14, 2025. Accessed October 15, 2025. https://ir.krystalbio.com/news-releases/news-release-details/krystal-biotech-receives-fda-platform-technology-designation-hsv
2. Krystal Biotech Receives FDA Approval for the First-Ever Redosable Gene Therapy, VYJUVEK™ (beremagenegeperpavec-svdt) for the Treatment of Dystrophic Epidermolysis Bullosa. News release. Krystal Biotech. May 19, 2023. Accessed October 15, 2025. https://ir.krystalbio.com/news-releases/news-release-details/krystal-biotech-receives-fda-approval-first-ever-redosable-gene https://ir.krystalbio.com/news-releases/news-release-details/krystal-biotech-receives-fda-approval-first-ever-redosable-gene
3. Vetencourt AT, Sayed-Ahmed I, Gomez J, et al. Ocular Gene Therapy in a Patient with Dystrophic Epidermolysis Bullosa. New Eng J Med. 2024 (390)6: 530-535. doi: 10.1056/NEJMoa2301244
4. Krystal Biotech Announces Publication in the New England Journal of Medicine on the Application of B-VEC to Treat Ocular Complications in Patient with Dystrophic Epidermolysis Bullosa. News release. Krystal Biotech. February 8, 2024. https://finance.yahoo.com/news/krystal-biotech-announces-publication-england-120000461.html
5. U.S. FDA grants platform technology designation to the viral vector used in SRP-9003, Sarepta’s investigational gene therapy for the treatment of limb girdle muscular dystrophy type 2E/R4. News release. Sarepta Therapeutics, Inc. June 4, 2025. Accessed October 15, 2025. https://investorrelations.sarepta.com/news-releases/news-release-details/us-fda-grants-platform-technology-designation-viral-vector-used
6. FDA Grants Second-Ever Platform Designation to Krystal Biotech After Revoking Sarepta Therapeutics’ Status. News article. Mark Chiang. Gene Online. October 15, 2025. Accessed October 15, 2025. https://www.geneonline.com/fda-grants-second-ever-platform-designation-to-krystal-biotech-after-revoking-sarepta-therapeutics-status/
7. FDA to use new review tool on Sarepta’s gene therapy work. News article. Ben Fidler, Biopharma Dive. June 4, 2025. Accessed October 15, 2025. https://www.biopharmadive.com/news/sarepta-platform-technology-designation-gene-therapy-rare-disease/749845/
8. FDA requests Sarepta Therapeutics suspend distribution of Elevidys and places clinical trials on hold for multiple gene therapy products following 3 deaths. News release. FDA. July 18, 2025. Accessed October 15, 2025. https://www.fda.gov/news-events/press-announcements/fda-requests-sarepta-therapeutics-suspend-distribution-elevidys-and-places-clinical-trials-hold
9. Sarepta Therapeutics provides statement on Elevidys. News release. Sarepta Therapeutics Inc. July 18, 2025. Accessed October 15, 2025. https://investorrelations.sarepta.com/news-releases/news-release-details/sarepta-therapeutics-provides-statement-elevidys
10. Philippidis A. StockWatch: Sarepta shares nosedive after LGMD gene therapy patient dies. Genetic Engineering & Biotechnology News. July 20, 2025. Accessed October 15, 2025. https://www.genengnews.com/topics/genome-editing/stockwatch-sarepta-shares-nosedive-after-lgmd-gene-therapy-patient-dies/