FDA Grants Priority Review to What Could Be the World's First In Vivo CRISPR Therapy
Updated: 1 day ago
On September 8, 2026, Intellia Therapeutics announced that the FDA had accepted its Biologics License Application (BLA) for lonvo-z (lonvoguran ziclumeran) in hereditary angioedema (HAE), with priority review. The agency set a target decision date of March 10, 2027.
If approved, Intellia says lonvo-z would be "the world's first in vivo CRISPR-based therapy," the first medicine to edit genes directly inside a patient's body using CRISPR.
What priority review means
When the FDA accepts an application, it sets a target date under the Prescription Drug User Fee Act, called the PDUFA date. A standard review takes about ten months from acceptance. Priority review shortens that to about six months. It's granted to therapies that could offer a significant improvement in treating a serious condition.
Lonvo-z also carries Regenerative Medicine Advanced Therapy (RMAT) and Orphan Drug designations in the U.S., and PRIME designation in Europe. Together, these signal that regulators on both sides of the Atlantic see it as a potentially major advance.
Ex vivo vs. in vivo: why "inside the body" is the headline
There are two ways to edit genes as medicine.
Ex vivo editing happens outside the body. Doctors collect a patient's blood stem cells, edit them in a lab, and return them after chemotherapy clears the bone marrow. That's how Casgevy, the first approved CRISPR therapy, works for sickle cell disease and beta-thalassemia. It's effective but grueling. It involves months of preparation, high-dose chemotherapy, and a long hospital stay.
In vivo editing happens inside the body. The editing tools are packaged in a delivery vehicle and infused like a regular medicine. For lonvo-z, that vehicle is a lipid nanoparticle, which carries the CRISPR components to hepatocytes. There's no cell collection, no chemotherapy, and no lab processing of cells. It's a single IV infusion.
In vivo editing therefore removes the need for stem cell collection, myeloablative conditioning, and cell manufacturing.
The case for approval
The application is built on the Phase 3 HAELO trial, a randomized, double-blind, placebo-controlled study of 80 patients. A single dose of lonvo-z:
Cut monthly HAE attacks by 87% compared with placebo.
Left 62% of treated patients attack-free and off all preventive medicine, versus 11% on placebo.
Caused no serious adverse events during the primary observation period. Most side effects were mild to moderate infusion reactions, headache, and fatigue.
Lonvo-z works by using CRISPR-Cas9 to disable the KLKB1 gene in liver cells. That lowers production of prekallikrein, the starting point of the pathway that causes the swelling attacks in HAE.
Why this matters beyond HAE
It would open the in vivo era. Many researchers see in vivo editing as the future of the field, because it's far simpler to deliver and could reach many more patients than ex vivo approaches. A first approval would set a regulatory precedent for every in vivo editor that follows.
The liver is only the beginning. Many of the most advanced in vivo programs target the liver, because lipid nanoparticles naturally go there. That includes base editors for cholesterol like VERVE-102 and prime editors for alpha-1 antitrypsin deficiency like PM647. A lonvo-z approval would validate the delivery approach many of them rely on.
It would test the one-time-treatment model. HAE already has several effective preventive drugs, but they require ongoing doses. Lonvo-z will show whether patients, doctors, and insurers embrace a single treatment in place of lifelong therapy, and at what price.
Getting ready for launch
Intellia is preparing for a U.S. launch in the first half of 2027. In early September, the company also secured a debt facility with OrbiMed worth up to $400 million, with $75 million funded upfront. That financial cushion should help carry it through the approval decision and commercial launch.
What to watch before March
Priority review doesn't guarantee approval. The FDA will look closely at manufacturing quality, long-term safety plans, and the risk of off-target edits. Because the edit is permanent, expect a requirement for extended follow-up of treated patients. An advisory committee meeting is possible but not guaranteed.
The bottom line
The FDA has set a decision date for what could be the first approval of a CRISPR therapy that edits genes directly inside the human body. If March 10, 2027 goes Intellia's way, gene editing will move from specialized transplant centers to a single outpatient infusion.
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— T.N., Gene Tech Times
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