Dive Brief:
- Food and Drug Administration officials are giving Prime Medicine new hope for a gene-editing treatment the company was forced to shelve last year.
- The therapy, PM359, is designed to treat chronic granulomatous disease, or CGD, a potentially deadly condition that leaves patients highly susceptible to bacterial and fungal infections. A study of two patients released last year suggested PM359 could correct the genetic anomaly that causes the disease, offering the possibility of a cure.
- But the condition is so rare that Prime opted not to continue development of the therapy amid a cash crunch. Even as it announced the promising early results, Prime said it would deprioritize PM359 and focus on other programs after cutting a quarter of its staff. On Tuesday, Prime said it now sees the possibility of approval based on the two-patient study alone.
Dive Insight:
Prime’s bid will test the limits of the FDA’s promise to help more innovative treatments reach the market. The agency has unveiled a series of initiatives, including a speedy review voucher program, new clinical trial design guidance and a change to make just one pivotal trial the default for development. In November, the FDA also unveiled a “plausible mechanism” pathway to boost bespoke therapies.
Discussion of the plausible mechanism pathway helped spur Prime executives to take another look at PM359 and meet with FDA officials, CEO Allan Reine told STAT. “Based on recent interactions, Prime Medicine believes clinical data generated to date may be sufficient to support an accelerated approval of PM359,” the company said Tuesday. It’s now working on “final alignment” with the FDA before filing.
Prime had originally intended to spend between $20 million and $30 million to study the therapy in as many as 12 patients before deciding it needed to focus resources elsewhere, The New York Times reported. The company estimates that only about 50 patients in the U.S. would be eligible for the treatment, making the costs of development hard to balance with the potential market.
That’s a dilemma facing many makers of treatments for rare diseases. And while the FDA under the second Trump administration has vowed to help, the agency has also issued a series of gene therapy rejections, shifted guidance for drugmakers and elevated a biologics chief who has often appeared skeptical of accelerated approval programs.
The unpredictability has spooked some investors, such as shareholders of UniQure, which has repeatedly faced setbacks at the agency. With pressure building from outside critics, Makary and other officials have taken the unusual step of defending individual review decisions publicly.
Prime, which launched in 2021 with the promise of next-generation, precision gene editing, has faced many of the same challenges as its peers. The company has lost almost three-quarters of its value as it’s struggled to find the best way to efficiently advance therapies built off its technology. The layoffs in 2025 that left PM359 on a shelf followed a downsizing of experimental programs less than a year earlier.
Even with only about 50 eligible patients, company officials see a meaningful market opportunity for PM359 if it can win FDA approval based on the already-completed study, Jefferies analyst Maury Raycroft wrote in a note to clients. Prime might also win a priority review voucher, which could be sold to another company, he said. The vouchers in recent years have fetched $150 million or more.
