FDA Has to Build CRISPR Edit Review Protocol

FDA has to create a protocol to review Intellia Therapeutics’ nex-z, a permanent, single-dose genomic edit in 60,000 base pairs of a living patient’s hepatocytes that targets transthyretin amyloidosis (ATTR). An online Clinical Trial Vanguard post says the therapy uses liquid nanoparticles to deliver CRISPR-Cas9 machinery directly into hepatocytes, editing the TTR gene in vivo and permanently reducing circulating TTR protein. The progressive and frequently fatal disease is caused by misfolded TTR protein deposits in peripheral nerves and the heart, it says.

FDA granted nex-z Regenerative Medicine Advanced Therapy designation on 11/25/2024 and cleared Intellia’s IND on 11/7/2024. The post says a designation and IND clearance are not the same as approval, but rather an “invitation to a conversation the agency has never fully had before.”

While the conventional wisdom in gene therapy circles is that FDA review experience with AAV vectors and ex vivo cell therapies gives it a sufficient template for evaluating in vivo CRISPR, the post says that assumption deserves to be challenged.

The article reviews the ways in which a one-off CRISPR edit differs from other gene therapies, such as the potential difficulty in long-term monitoring of a patient who has a single contact with the sponsor.

“Intellia cannot wait for the agency to build an AI-powered hepatocellular surveillance registry before receiving a decision on a therapy for patients who are dying of ATTR amyloidosis today,” it says.

The post notes that existing ATTR therapies require chronic dosing that can cost either $450,000 or $250,000 per year. Thus, a one-time gene edit that achieves durable TTR knockdown could, in theory, be cost-superior over a 10-year horizon, even at a price point above $1 million. “The economic argument for approval is clear,” it says. “The regulatory science argument for a framework that can actually monitor what happens after approval is the harder problem, and it belongs to FDA to solve, not just to Intellia to propose.”

The article says FDA has an opportunity that it rarely gets — to build review standards for in vivo CRISPR therapies before the field scales, not after five approvals and three post-marketing safety signals force a reactive reckoning. “The Intellia BLA is not just a single product review,” it says. “It is the first draft of a regulatory architecture that will govern every permanent genomic editor that follows it, and the agency’s response will set the evidentiary floor for an entire modality. Whether FDA treats this as a standard CGT (cellular and gene therapy) review or as the category-defining moment it actually is will determine whether sponsors building the next generation of in vivo editors have a coherent path forward, or spend the next decade in a cycle of Type B meetings that never quite resolve the same unanswered questions about durability, off-target risk, and long-term follow-up obligations. The edit, once made, cannot be undone. The regulatory standard set here will be equally permanent.”